N-acetyl-cysteine decreases the matrix-degrading capacity of macrophage-derived foam cells: new target for antioxidant therapy?

BACKGROUND

Atherosclerotic plaque destabilization triggers clinical cardiovascular disease and thus represents an attractive therapeutic target. Weakening of tissue through the action of matrix-degrading enzymes, called matrix metalloproteinases (MMPs), released by resident macrophages was previously implicated in unstable vascular syndromes.

METHODS AND RESULTS

We used a hypercholesterolemic rabbit model of atherosclerosis to investigate the gelatinolytic activity associated with macrophage-derived foam cells (FCs). Gelatinolytic activity and expression of MMP-9 but not of MMP-2 cosegregated with macrophage FCs in aortic lesions. Macrophage-derived gelatinases were further investigated in vitro. MMP-9 was identified as the main macrophage-derived gelatinase in cells isolated from aortic lesions and from granuloma induced in the same rabbits to increase cell yield. Importantly, detection of activated MMP-9 in the FC culture medium supports the notion that these cells can independently initiate processing of secreted MMP zymogens to active enzymes. We further examined whether FC gelatinolytic activity is dependent on the presence of reactive oxygen species (ROS). We found that treatment (1 to 5 days) with 1 to 10 mmol/L N-acetyl-L-cysteine (NAC), an ROS scavenger, decreased not only gelatinolytic activity but also gelatinase expression by FCs. Similarly, NAC treatment of explanted lesions abolished in situ gelatinolytic activity and MMP-9 expression.

CONCLUSIONS

Macrophage FCs are an abundant source of gelatinolytic activity that can be inhibited in vitro and in situ by NAC. This newly described action of antioxidant therapy might prove useful to inhibit matrix degradation and to improve vascular stability.

Interaction and dissociation by ligands of estrogen receptor and Hsp90: the antiestrogen RU 58668 induces a protein synthesis-dependent clustering of the receptor in the cytoplasm

The in vivo interaction of estrogen receptor (ER) and Hsp90, demonstrated in the absence of hormone by a nuclear cotranslocation assay of the cytoplasmic Hsp90 with the karyophilic receptor, was disrupted by agonist and antagonist ligands, which, after dissociating the Hsp90, allowed the chaperone protein to be relocalized in the cytoplasm. The pure antiestrogen RU 58668 (RU), which was unable to stimulate an estrogen-dependent reporter gene and completely inhibited its estradiol-induced activity, also profoundly modified the subcellular distribution of ER in a specific time- and dose-dependent manner; ER appeared as speckled fluorescent clusters mainly located in the perinuclear region of the cytoplasm. The kinetics of appearance and reversal of the RU-dependent ER mislocalization in the presence or absence of cycloheximide demonstrated 1) that this effect was reversed by RU withdrawal or estradiol (E2) treatment, and 2) that cycloheximide with RU inhibited and reversed the ER cytoplasmic mislocalization induced by RU alone. These results point to a protein synthesis-dependent step in the mechanism of action of this antiestrogen. After RU treatment, a large portion of ER was found in the particulate fraction of the cytoplasm. However, confocal and electron microscopic analysis showed that ER clusters were not associated with specific cytoplasmic organelles or compartments. Using ER mutants, it was found that the ligand binding domain was sufficient for RU to produce receptor mislocalization, while the constitutive nuclear localization signals were dispensable. We propose that the antiestrogenic properties of RU are primarily due to the induction of an aggregation-prone receptor conformation that cannot undertake the constitutive and the ligand-induced nuclear localization function of the receptor because it is sequestered in the cytoplasm by fast turning over protein(s). We predict that antiestrogens able to block ER nuclear localization will behave as pure antihormones and will inhibit all the nuclear action of ER elicited by agonistic ligands or by ligand-independent mechanisms such as growth factor stimulation.

Genes don't count

It is the regulation of gene expression that determines phenotype and cellular response. Several families of proteins control gene expression in cells and influence the pathogenesis of multiple organ failure, the acute phase response, atherosclerosis, and graft-vs-host disease. Understanding the basics of the regulation of gene transcription will allow the knowledgeable surgeon to target gene expression as a therapeutic modality in multiple diseases. We examine nuclear factor kappa B as an example of a transcription factor that is involved in multiple surgical diseases and has pharmacological inhibitors available to knowledgeable surgeons.

[Comparative study of portal-systemic shunt rate measured by formula and radioactive method]

OBJECTIVE

To establish a new simple and useful formula for the observation of portosystemic shunt.

METHOD

In the same animals and the same patients, portosystemic shunt rate was measured individually by the two different methods, i.e. formula and radio active method. Using the results of the radio active method as a gold standard, the reliability of the formula method was assessed tested.

RESULT

In 11 normal dogs, the portal-systemic shunt rate measured by the formula and radio active methods was 7.03% and 7.55% respectively (P > 0.05). In 9 portosystemic shunting model dogs, the portosystemic shunt rate calculated from the two methods was 48.64% and 51.11% respectively (P > 0.05). In 22 patients with portal hypertension, the preoperative results from the formula and radioactive methods were 52.38% and 55.86% respectively (P > 0.05). In these patients, the postoperative portal-systemic shunt rate was 26.22% and 31.00% respectively (P > 0.05).

CONCLUSION

These results fully testified the reliability of the formula method we had established.

A conserved p38 mitogen-activated protein kinase pathway regulates Drosophila immunity gene expression

Accumulating evidence suggests that the insect and mammalian innate immune response is mediated by homologous regulatory components. Proinflammatory cytokines and bacterial lipopolysaccharide stimulate mammalian immunity by activating transcription factors such as NF-kappaB and AP-1. One of the responses evoked by these stimuli is the initiation of a kinase cascade that leads to the phosphorylation of p38 mitogen-activated protein (MAP) kinase on Thr and Tyr within the motif Thr-Gly-Tyr, which is located within subdomain VIII. We have investigated the possible involvement of the p38 MAP kinase pathway in the Drosophila immune response. Two genes that are highly homologous to the mammalian p38 MAP kinase were molecularly cloned and characterized. Furthermore, genes that encode two novel Drosophila MAP kinase kinases, D-MKK3 and D-MKK4, were identified. D-MKK3 is an efficient activator of both Drosophila p38 MAP kinases, while D-MKK4 is an activator of D-JNK but not D-p38. These data establish that Drosophila indeed possesses a conserved p38 MAP kinase signaling pathway. We have examined the role of the D-p38 MAP kinases in the regulation of insect immunity. The results revealed that one of the functions of D-p38 is to attenuate antimicrobial peptide gene expression following exposure to lipopolysaccharide.

Adenosine reduces cardiac TNF-alpha production and human myocardial injury following ischemia-reperfusion

Myocardial tumor necrosis factor-alpha (TNF-alpha) is an autocrine contributor to myocardial dysfunction and cardiomyocyte death in ischemia-reperfusion injury (I/R), sepsis, chronic heart failure, and cardiac allograft rejection. Cardiac resident macrophages and cardiomyocytes themselves produce TNF-alpha. In this regard, adenosine (ADO) has been reported to reduce macrophage TNF-alpha production. Our purposes were to determine whether (1) I/R induces rat myocardial TNF-alpha production; (2) ADO decreases ischemia-induced rat myocardial TNF-alpha production; (3) ADO functionally protects human myocardium against I/R; and (4) TNF-alpha-binding protein (TNFBP; p55) confers similar protection when substituted for ADO pretreatment. To study this, human atrial trabeculae were obtained during cardiac surgery and suspended in organ baths, paced at 1 Hz, and force development was recorded during I/R (45/120 min) with or without ADO pretreatment (125 microM x 10 min), or TNFBP (1 microgram/ml) during I/R. Isolated rat hearts were perfused using the Langendorff method undergoing I/R (20/40 min) with or without ADO pretreatment (125 microM x 2 min) and rat myocardial expression of TNF-alpha was assessed by ELISA. Results demonstrated that I/R increased rat myocardial TNF-alpha levels from 324 +/- 36 to 902 +/- 77 pg/g (P < 0.05; ANOVA and Bonferroni/Dunn) and decreased human myocardial developed force (DF) to 18 +/- 2% of baseline (%BDF; P < 0.05). ADO pretreatment decreased ischemia-induced rat myocardial TNF-alpha production (356 +/- 107 pg/g; P < 0.05) and increased postischemic DF of human myocardium to 39 +/- 3% BDF (P < 0.05. Further substantiating the link between ischemia-induced TNF-alpha production and injury, TNFBP administration similarly improved post-I/R function of human myocardium (55 +/- 5% BDF; P < 0.05 vs. I/R alone). We conclude that (1) I/R induces rat myocardial TNF-alpha production; (2) ADO pretreatment decreases I/R-induced rat myocardial TNF-alpha production; (3) ADO improves human myocardial function; (4) TNFBP confers similar protection; and (5) inhibition/neutralization of TNF-alpha represents a novel strategy for protecting human myocardium against ischemia and reperfusion injury.

Therapeutic antidysrhythmic and functional protection in human atria

Approximately 30% of patients suffer supraventricular dysrhythmias after cardiac bypass. While the heart can be constructively preconditioned to maintain function against subsequent ischemic insult using a variety of stimuli across many species, preconditioning in experimental animals is associated with decreased postischemic reperfusion cardiac dysrhythmias. This mode of therapeutic preconditioning has not been previously examined in human atrial myocardium. We therefore hypothesized that preconditioning provides both antidysrhythmic and functional protection to human atria. To study this, human atrial trabeculae were suspended in organ baths, paced at 1 Hz, while force development and ectopy were recorded before and after simulated ischemia. The study consisted of five groups: (1) control trabeculae (n = 12), (2) trabeculae exposed to dysrhythmogenic stimuli (phenylephrine 50 microM and isoproterenol 25 microM (n = 8)), (3) trabeculae exposed to ischemia-reperfusion (I/R) injury and then drug stimulated (n = 10), (4) trabeculae preconditioned with adenosine (ADO 125 microM) then drug stimulated (n = 10), and (5) trabeculae preconditioned with ischemic preconditioning (IPC) then drug stimulated (n = 6) each at end reoxygenation. Differences between groups were assessed using X2 analysis and ANOVA (Bonferroni/Dunn). Results demonstrated that human atrial trabeculae did not exhibit dysrhythmia at baseline or when stimulated with alpha and beta agonists. After I/R, control trabeculae exhibited stimulated reperfusion dysrhythmia, while trabeculae preconditioned with either ADO or transient ischemia exhibited decreased stimulated dysrhythmia (each P < 0.05 vs. I/R). Functionally, I/R decreased developed force (DF) to 16 +/- 2% of baseline (%BDF) while ADO pretreatment increased postischemic DF to 41 +/- 3% BDF (P < 0.05 vs. I/R) while IPC increased DF to 49 +/- 3% BDF (P < 0.05 vs. I/R). We conclude that (1) human atrial trabeculae can ve functionally preconditioned with either ADO or IPC, and (2) protective preconditioning/ cardioprotection does extend to dysrhythmia control and is therapeutically accessible in human atrial myocardium.

[An antimicrobial experimental study on the traditional drug Anuqitabiao used by the Yi minority nationality]

The result of experimental study on the antimicrobial effect in vitro of the decoction, water-soluble ingredients and liposoluble ingredients of Anuqitabiao shows that decoction and water-soluble ingredients have certain inhibitory effect on all the tested bacteria, while the liposoluble ingredients do not, indicating the antimicrobial ingredients to be water-soluble. The result of antimicrobial experiment in vivo shows that neither different concentrations nor different separated parts of the decoction have any obvious protective effect on the pneumonococci-infected or staphylococciaureus-infected mice.

Calcium preconditioning in human myocardium

BACKGROUND

Ischemic stress and other protein kinase C (PKC)-linked receptor stimuli can induce rapid cardiac protection against ischemia-reperfusion injury. We and others have demonstrated that exogenous calcium (Ca2+) pretreatment confers PKC-mediated cardiac functional and infarct protection in animal models, but it remains unknown whether Ca2+ preconditioning confers similar postischemic functional protection in human myocardium, and, if so, whether the mechanism is mediated by PKC. We postulated that Ca2+ preconditioning confers ischemic tolerance to human myocardium by a PKC-dependent mechanism.

METHODS

Human atrial trabeculae were suspended in organ baths and paced at 1 Hz, and force development was recorded. After 90 minutes of equilibration, all trabeculae were subjected to ischemia (45 minutes) and reperfusion (120 minutes). Exogenous CaCl2 (3.0 mmol/L for 5 minutes) or vehicle (saline solution) was administered before simulated ischemia, with or without concurrent PKC inhibition (bisindolylmaleimide I, 150 nmol/L).

RESULTS

Ischemia-reperfusion resulted in decreased postischemic developed force, Ca2+ preconditioning protected human myocardium against ischemia-reperfusion injury (p < 0.05 versus control ischemia-reperfusion), and concurrent PKC inhibition abolished the salutary effect of Ca2+ preconditioning in human myocardium (p < 0.05 versus Ca2+ preconditioning).

CONCLUSIONS

Preconditioning with Ca2+ represents a potent means of accessing PKC-mediated protection of the human myocardium against ischemia-reperfusion injury.

Tissue-specific protein kinase C isoforms differentially mediate macrophage TNFalpha and IL-1beta production

Macrophage subpopulations are differentially activated during sepsis, shock, or trauma; however, it is unknown whether inherent mechanistic and phenotypic differences exist between macrophage subpopulations that may account for region-specific inflammation. We hypothesized that macrophage expression/function of protein kinase C (PKC) isoforms is tissue specific (alveolar versus peritoneal). Rat alveolar and peritoneal macrophages were each probed for the expression of PKC isoforms alpha, beta1, beta2, gamma, delta, epsilon, zeta, and theta by immunoblot. PKC isoforms alpha, beta1, beta2, and zeta were detected in both populations; however, isoforms epsilon, gamma, and eta were found in alveolar macrophages only. To investigate the functional role of the Ca2+-dependent PKC (cPKC) versus Ca2+-independent PKC (nPKC) isoforms, pan-PKC isoform inhibition (cPKC and nPKC), or cPKC isoform selective inhibition (alpha, beta1, beta2, gamma) was performed before endotoxin (lipopolysaccharide, Salmonella minnesota, 100 ng/mL) stimulation in vitro. Pan-PKC isoform inhibition attenuated TNFalpha and IL-1beta production by each population; however, selective cPKC (alpha, beta1, beta2, gamma) inhibition decreased peritoneal, but not alveolar, macrophage TNFalpha production. IL-1beta production was not affected by cPKC inhibition in either population.

CONCLUSIONS

1) alveolar and peritoneal macrophages constitutively express different PKC isoforms; 2) alveolar macrophages uniquely express isoforms epsilon, gamma, eta; 3) TNFalpha production is regulated by cPKCs in peritoneal macrophages, but by nPKCs in alveolar macrophages; 4) nPKCs regulate IL-1beta production in both populations. These results suggest that tissue-specific PKC isoforms differentially mediate macrophage function, which may have important regulatory implications in the compartmentalization of immune function. Further understanding may allow region-specific manipulation of inflammation.

Keratinocyte gene therapy for systemic diseases. Circulating interleukin 10 released from gene-transferred keratinocytes inhibits contact hypersensitivity at distant areas of the skin

This study has examined the systemic effects of a circulating gene product, human interleukin 10 (IL-10), released from transduced keratinocytes. IL-10 is an anti-inflammatory cytokine which has an inhibitory effect on contact hypersensitivity (CHS). An expression vector (phIL-10) was constructed for human IL-10 and was injected into the dorsal skin of hairless rats. Local expression of IL-10 mRNA and protein was detected by reverse-transcriptase polymerase chain reaction and immunohistochemical staining, respectively. Enzyme-linked immunosorbent assay showed that the amount of IL-10 in the local keratinocytes and in the circulation increased with the dose of phIL-10 transferred. To determine whether circulating IL-10 could inhibit the effector phase of CHS at a distant area of the skin, various doses of phIL-10 were injected into the dorsal skin of sensitized rats before challenge on the ears. Our results showed that the degree of swelling of the ears of phIL-10- treated rats was significantly lower than that in the negative control animals. These results suggest that IL-10 released from transduced keratinocytes can enter the bloodstream and cause biological effects at distant areas of the skin. This study demonstrates that it may be possible to treat systemic disease using keratinocyte gene therapy.

Extracellular matrix modulates macrophage functions characteristic to atheroma: collagen type I enhances acquisition of resident macrophage traits by human peripheral blood monocytes in vitro

Activated resident macrophages sustain atheroma, and a high macrophage content is associated with plaque vulnerability. Factors leading to differentiation and activation of these blood-derived cells remain largely uncharacterized. We investigated the contribution of interaction with collagen type I, the predominant component of atherosclerotic matrix, to differentiation and modulation of characteristic macrophage functions, including intracellular lipid accumulation and production of the typical matrix-degrading enzyme matrix metalloproteinase (MMP)-9. When used as an adhesion substrate for human peripheral blood monocytes in vitro, collagen type I increased monocyte differentiation, assessed by analysis of CD71 expression and cell spreading. Culturing on collagen type I doubled the number of differentiated monocytes at 24 hours (44.9+/-1.4% versus 18.4+/-1.7% on uncoated dishes, P<.001, n=3 independent experiments) and was a stronger stimulus for differentiation than phorbol myristate acetate, a known inducer of monocyte differentiation. The effect of substrate on intracellular accumulation of modified lipoproteins was assessed by quantitative confocal microscopy of monocytes incubated with fluorescent acetylated LDL. The collagen type I substrate also doubled the number of macrophages containing intracellular lipid and significantly increased the individual intracellular loading. Monocytes cultured on collagen type I also released more MMP-9 than did cells plated directly on plastic. The role of monocyte spreading was further assessed by treatment with colchicine, an inhibitor of cytoskeletal function, or with genistein, a nonspecific inhibitor of tyrosine kinases, shown to participate in cell adhesion. Cell spreading was inhibited in 72.3+/-6.7% of colchicine-treated and in 62.4+/-6.4% of genistein-treated monocytes (n=3, P<.01 in both cases). The same conditions also decreased secretion of MMP-9, and genistein reduced the number of acetylated LDL-containing cells (from 286+/-7 to 184+/-8 cells/mm2 with genistein, n=3, P<.001). Data showed a strong correlation (r>.98) between monocyte spreading on collagen type I and intracellular lipid accumulation. Our results indicate that interaction with vascular matrix may play an important role in differentiation of peripheral blood monocytes into resident lipid-laden macrophages, which act as central stimulators throughout the natural history of atheroma.

[Ultrasound bone measurement of the tibia: comparison with vertebral dual-energy X-ray absorptiometry and appendicular single photon absorptiometry]

OBJECTIVE

Ultrasonic techniques have been used to assess the mechanical properties of bone. Recently, a new ultrasonic bone instrument, which measured the SOS (speed of sound) at the tibial shaft, has been introduced (Sound Scan 2000, Myriad Ultrasound Systems Ltd.). The aim of this work was to investigate the correlation of tibial SOS with bone mineral density (BMD).

METHODS

The tibial SOS was measured in 213 healthy women (aged 22-83 years) and 56 female primary osteoporosis with vertebral fractures (aged 53-82 years). Values of SOS were compared with BMD assessed by dual energy x-ray absorptiometry (DEXA) at spine and hip sites and single photon absorptiometry (SPA) at the distal forearm.

RESULTS

Tibial SOS correlated more closely with the BMD of lumbar, hip and forearm (r = 0.387-0.928, P < 0.001). The tibia SOS values and the BMD values measured by the DEXA and SPA were negatively correlated to age and years since menopause. In particular, they were obviously lower in the group of 50 years old. The tibial SOS of vertebral fracture group was significantly lower than that of well-matched non-fracture-group (n = 104, aged 51-84 years).

CONCLUSIONS

Tibial SOS was significantly correlated with BMD measured by DEXA or SPA respectively and able to discriminate patients with vertebral fracture from the age-matched controls.

Increased myocardial tumor necrosis factor-alpha in a crystalloid-perfused model of cardiac ischemia-reperfusion injury

BACKGROUND

The heart is a tumor necrosis factor-alpha (TNF-alpha)-producing organ. Recent basic experimental and clinical evidence suggests that TNF-alpha is an important mediator of myocardial injury during acute myocardial infarction, chronic heart failure, cardiac allograft rejection, and cardiopulmonary bypass operations. Although it is known that the myocardium itself is capable of producing TNF-alpha in response to endotoxin, it is unknown whether there is an increase in myocardial tissue TNF-alpha levels after ischemia-reperfusion injury. We hypothesized that ischemia-reperfusion induces the production of TNF-alpha by the heart.

METHODS

To avoid blood-borne TNF-alpha as a potentially confounding variable, we examined myocardial TNF-alpha production in a crystalloid-perfused model of cardiac ischemia-reperfusion injury. Isolated rat hearts were perfused with crystalloid solution and subjected to ischemia-reperfusion. Postischemic myocardial TNF-alpha was measured using an enzyme-linked immunosorbent assay and correlated with developed pressure, coronary flow, end-diastolic pressure, and creatine kinase loss (assay of activity in coronary effluent).

RESULTS

Ischemia-reperfusion induced a marked increase in myocardial TNF-alpha that was associated with decreased myocardial contractility and coronary flow and with increased end-diastolic pressure and postischemic creatine kinase loss.

CONCLUSIONS

The heart produces TNF-alpha in response to ischemia-reperfusion. Ischemia-induced TNF-alpha production may contribute to postischemic myocardial stunning, necrosis, or both. Strategies designed to limit ischemia-induced myocardial TNF-alpha production may have therapeutic utility in the settings of planned myocardial ischemic events.

[Inferior pulmonary ligament spindle-shaped covering on the anastomotic orifice in the surgery of cardiac carcinoma: experience in 772 patients with no anastomotic leakage or stricture successively]

OBJECTIVE

To prevent anastomotic leakage and stricture after the resection of cardiac carcinoma.

METHODS

Since complications are the main causes of postoperative death and poor living quality, we modified anastomotic method, and projected anastomotic orifice to be covered with inferior pulmonary ligament(IPL) in spindle shape.

RESULTS

From March 1987 to December 1996, 772 cases of cardiac carcinoma underwent surgical treatment with this method and no anastomotic leakage and stricture developed.

CONCLUSION

The IPL has strong ability to adhere and heal. Anastomotic orifice is covered tightly and safely. No forth row 13 needed in not introsed anastomotic orifice, thus preventing stricture, because of lung expanding, IPL adheres to anastomotic orifice tightly, making stump space disappeared. IPL possesses well tenacity and can be used easily.

The determinative role of intraoperative echo in tricuspid valvuloplasty

A transesophageal echocardiography (TEE) was used in monitoring the operation of tricuspid valvuloplasty. Nine patients with rheumatic heart disease were studied. The results showed that intraoperative TEE was important on the improving method of tricuspid annuloplasty, it help to determine surgical procedure, control annulus-reducing procedure and assess the result immediately after operation. The results suggested that intraoperative TEE can be widely used in valvuloplasty in future.

Adenosine decreases post-ischaemic cardiac TNF-alpha production: anti-inflammatory implications for preconditioning and transplantation

Tumour necrosis factor-alpha (TNF-alpha) is an autocrine contributor to myocardial dysfunction and cardiomyocyte death in ischaemia-reperfusion injury (I/R), sepsis, chronic heart failure and cardiac allograft rejection. Cardiac resident macrophages, infiltrating leucocytes, and cardiomyocytes themselves produce TNF-alpha. Although adenosine reduces macrophage TNF-alpha production and protects myocardium against I/R, it remains unknown whether I/R induces an increase in cardiac TNF-alpha in a crystalloid-perfused model (in the absence of blood), and, whether adenosine decreases cardiac TNF-alpha and protects function after I/R. To study this, isolated rat hearts were crystalloid-perfused using the Langendorff method and subjected to I/R, with or without adenosine pretreatment. Post-ischaemic cardiac TNF-alpha (enzyme-linked immunosorbent assay and bioassay) and function were determined (Langendorff). I/R increased cardiac TNF-alpha and impaired myocardial function. Adenosine decreased cardiac TNF-alpha and improved post-ischaemic functional recovery. This study demonstrates that: first, I/R induces an increase in cardiac tissue TNF-alpha in a crystalloid-perfused model: second, adenosine decreases cardiac TNF-alpha and improves post-ischaemic myocardial function; third, decreased cardiac TNF-alpha may represent a mechanism by which adenosine protects myocardium; and fourth, adenosine-induced suppression of cardiac TNF-alpha may provide an anti-inflammatory link to preconditioning and have implications for cardiac allograft preservation.

Intrinsic membrane characteristics distinguish two subsets of nociceptive modulatory neurons in rat RVM

Pain modulating neurons of the rostral ventromedial medulla (RVM) include three physiologically distinct classes of neurons in intact, anesthetized animals: and cells that change their activity before the onset of withdrawal reflexes and cells, which have activity unrelated to withdrawal reflexes. A previous in vitro intracellular study demonstrated that the RVM contains two types of neurons that are distinguished by their action-potential characteristics. The present in vivo intracellular study examined whether these intracellularly recorded action-potential characteristics are correlated with the physiological response properties of RVM neurons recorded. RVM neurons exhibited two distinct types of action potentials in vivo. Fast-spike (FS) neurons (n = 30) had short-duration action potentials (0.27 +/- 0.02 (SE) ms at half amplitude) and biphasic afterhyperpolarizations with a characteristic rapid overshooting spike repolarization. Slow-spike (SS) neurons (n = 25) had longer duration action potentials (0.44 +/- 0.02 ms at half-amplitude) due to a slower-spike repolarization rate and monophasic afterhyperpolarization. and cell classes included both FS and SS neurons. FS and neurons had an early onset response to noxious heat stimulation. SS and cells showed a delayed onset response to noxious heat. cells (n = 13) were all SS cells. Among the SS neurons, only cells had action potentials longer than 0. 45 ms (n = 9). FS and SS neurons were intermingled throughout the RVM. The majority of intracellularly labeled cells (n = 15) had fusiform somata with two to five fine caliber primary dendrites and a predominantly mediolateral orientation of the long axis of their dendritic tree. All labeled FS cells (n = 5) had large, multipolar somata with four to nine large caliber primary dendrites. The present study defines in vivo membrane and morphological characteristics of RVM neurons that correlate with physiological differences and may be used for identification of nociceptive modulatory RVM neurons in slice preparations.

[The hepatic ischemia/reperfusion injury in cirrhotic rats]

We assessed ischemia/reperfusion injury in carbon tetrachloride induced cirrhotic liver as compared to normal liver in the rats. Hepatic vein nitric oxide (NO) level was measured by method of luminol chemiluminensence, and portal vein endotoxin level by limulus lysate with chyomogenic substract. In cirrhotic liver, instead of diminishing the hepatic vein NO level increased significantly after ischemia and remained high till 5 hrs postreperfusion. The portal vein endotoxin level was also increased but to a higher level than that of normal liver. In cirrhotic liver, ischemia/reperfusion injury is aggrevated as evidenced by higher level of endotoxin, increased generation of NO.

Glial-cell-line-derived neurotrophic factor is required for bud initiation from ureteric epithelium

The shapes of different organs can be explained largely by two fundamental characteristics of their epithelial rudiments - the pattern of branching and the rate of proliferation. Glial-cell-line-derived neurotrophic factor (GDNF) has recently been implicated in the development of metanephric ureteric epithelium (Pichel, J. G., Shen, L., Sheng, H. Z., Granholm, A.-C., Drago, J., Grinberg, A., Lee, E. J., Huang, S. P., Saarma, M., Hoffer, B.J., Sariola, H. and Westphal, H. (1996). Nature 382, 73–76; Sanchez, M.P., Silos-Santiago, I., Frisen, J., He, B., Lira, S.A. and Barbacid, M. (1996). Nature 382, 70–73; Vega, Q.C., Worby, C.A., Lechner, M.S., Dixon, J.E. and Dressler, G.R. (1996). Proc. Nat. Acad. Sci. USA 93, 10657–10661). We have analysed the target cells of GDNF and the manner in which it controls ureteric development, and have compared it with other growth factors that have been associated with the regulation of branching morphogenesis, namely hepatocyte growth factor (HGF) and transforming growth factor-beta1 (TGFbeta1). We show that GDNF binds directly to the tips of ureteric bud branches, and that it has the ability to promote primary ureteric buds from various segments of Wolffian duct and to attract ureteric branches towards the source of GDNF. It increases cell adhesion, but is not obviously mitogenic for ureteric cells. The data indicate that GDNF is required primarily for bud initiation. Comparison of GDNF, HGF and TGFbeta1 suggests that the latter act later than GDNF, and may represent a partially redundant set of mesenchyme-derived growth factors that control ureteric development. Thus, GDNF is the first defined inducer in the embryonic metanephric kidney.

LPS induces late cardiac functional protection against ischemia independent of cardiac and circulating TNF-alpha

Lipopolysaccharide (LPS) and tumor necrosis factor (TNF)-alpha independently induce cardioprotection against ischemia in the rat at 24 h after administration, suggesting that endogenously synthesized TNF-alpha may play a role in LPS-induced protection. The purposes of this study were 1) to delineate the time course of LPS-induced cardiac functional protection against ischemia and its relation with myocardial and circulating TNF-alpha profile, 2) to examine whether prior protein synthesis inhibition abrogates the protection, and 3) to assess the effects of TNF-alpha inhibition and neutralization on the protection. Rats were treated with LPS (0.5 mg/kg i.p.). Cardiac functional resistance to normothermic global ischemia-reperfusion was examined at sequential time points after LPS treatment in isolated hearts by the Langendorff technique. Myocardial and circulating TNF-alpha was determined by enzyme-linked immunosorbent assay at 1-24 h after LPS treatment. Protection was apparent at 24 h, 3 days, and 7 days but not at 2 or 12 h. Maximal protection at 3 days was abolished by cycloheximide pretreatment (0.5 mg/kg i.p. 3 h before LPS treatment). Increases in myocardial and circulating TNF-alpha preceded the acquisition of protection. Dexamethasone pretreatment (4.0 or 8.0 mg/kg i.p. 30 min before LPS treatment) abolished peak increase in myocardial TNF-alpha and substantially suppressed circulating TNF-alpha (54.3 and 85.9% inhibition, respectively) without an influence on the maximal protection. Similarly, maximal protection was not affected by TNF binding protein (40 or 80 microg/kg i.v. immediately after LPS treatment). The results suggest that LPS-induced cardiac functional protection against ischemia is a delayed and long-lasting protective response that may involve de novo protein synthesis. Although LPS-induced increase in myocardial and circulating TNF-alpha precedes the delayed protection, it may not be required for the delayed protection.

Differential regulation of gastrulation and neuroectodermal gene expression by Snail in the Drosophila embryo

The initiation of mesoderm differentiation in the Drosophila embryo requires the gene products of twist and snail. In either mutant, the ventral cell invagination during gastrulation is blocked and no mesoderm-derived tissue is formed. One of the functions of Snail is to repress neuroectodermal genes and restrict their expressions to the lateral regions. The derepression of the neuroectodermal genes into the ventral region in snail mutant is a possible cause of defects in gastrulation and in mesoderm differentiation. To investigate such possibility, we analysed a series of snail mutant alleles. We found that different neuroectodermal genes respond differently in various snail mutant background. Due to the differential response of target genes, one of the mutant alleles, V2, that has reduced Snail function showed an intermediate phenotype. In V2 embryos, neuroectodermal genes, such as single-minded and rhomboid, are derepressed while ventral invagination proceeds normally. However, the differentiation of these invaginated cells into mesodermal lineage is disrupted. The results suggest that the establishment of mesodermal cell fate requires the proper restriction of neuroectodermal genes, while the ventral cell movement is independent of the expression patterns of these genes. Together with the data showing that the expression of some ventral genes disappear in snail mutants, we propose that Snail may repress or activate another set of target genes that are required specifically for gastrulation.