The studies of cell damaging and cell growth factors which induce cardiomyopathy.

We demonstrated that phosphatidylinositide-specific phospholipase C (PLC) activity was greater in cardiomyopathic hamster hearts (BIO 14.6 and BIO 53.58) then in hamster controls (F1b). Inositol trisphosphate (IP3) production was markedly greater in both of the cardiomyopathic hamsters, BIO 14.6 and BIO 53.58. We have also determined the sarcoplasmic reticulum (SR) function of heart. Calcium uptake into SR markedly increased in BIO 14.6. On the other hand, it significantly decreased in BIO 53.58 compared with F1b. It is well known that IP3 stimulates calcium release from SR. In BIO 14.6, calcium release from SR stimulated by IP3 increased, but its effect decreased in BIO 53.58 compared with F1b. These results suggest that PI response may produce high intracellular calcium levels in both BIO 14.6 and BIO 53.58 myocytes. In addition, in the BIO 53.58 hamster the sarcoplasmic reticulum deteriorate in function. It was concluded from these results that a prolonged high intracellular calcium level may lead to the death of BIO 53.58 myocytes. The expression of angiotensinogen mRNA was observed in the hamster heart. There was no differences in its expression level between F1b, BIO 14.6 and BIO 53.58. There was no effect of ages on its expression in these hamster hearts. We have also determined the distribution of angiotensinogen in these hamsters. At 4 weeks of age, the immunohistochemical study revealed that angiotensinogen was widely distributed in subendocardium in these hamsters. There was no difference in its distribution between F1b, BIO 14.6 and BIO 53.58. But at 20 weeks old of age its immunoreactivity decreased in BIO 53.58.(ABSTRACT TRUNCATED AT 250 WORDS)     

Regulation of pineal rhythms in chickens: effects of blinding, constant light, constant dark, and superior cervical ganglionectomy.

Pineal serotonin N-acetyltransferase activity and melatonin content exhibit marked daily changes in chickens; peak values occur during the period of low locomotor activity which coincides with dark in a 24-hour light-dark cycle. The photic and neural regulation of these daily changes were studied by measuring pineal serotonin N-acetyl-transferase activity, hydroxyindole-O-methyltransferase (HIOMT) activity, and melatonin content in experiments in which chickens were subjected to light-dark cycles, constant light, and constant dark and were surgically blinded or superior cervical ganglionectomized. It was found that: 1) The daily changes in N-acetyltransferase activity and melatonin content appear to persist in constant dark, and they disappear in constant light. 2) The eyes are not necessary for photic control of the daily changes, and the effect of constant light on N-acetyltransferase activity and melatonin content may be non-visual, that is, the eyes not being necessary. 3) The occurrence of the daily change in N-acetyltransferase activity and melatonin content does not require the superior cervical ganglia; the persistence of the changes in constant dark, however, may require the ganglia. 4) HIOMT activity was lower in constant light than in light-dark cycles and lower still in constant dark than in constant light. Neither the presence of the eyes nor the superior cervical ganglia affected HIOMT activity, as previously reported.     

Induction of persistent estrus by constant light: effects of neonatal constant light and Harderian gland function

The effect of constant light on the age at onset of persistent estrus was compared in rats exposed to constant light since birth (LL-0) and those exposed beginning at 70 days of age (LL-70). Persistent estrus occurred about 27 days later in the LL-0 rats than in the LL-70 rats. Exposure to LL for just the 1st 15 days of life (LL-0-15) and then subsequent exposure to LL at 71 days also delayed the induction of persistent estrus. Neonatal injection of a Harderian gland (HG) homogenate to LL-0-15 rats reduced the age of vaginal opening and 1st estrus and reduced the delayed onset of persistent estrus caused by the neonatal LL. Harderianectomy of LL-0 or hematoporphyrin injections in LL-0-15 rats had no effect on the onset of LL-induced persistent estrus.     

The nyctohemeral rhythm of plasma prolactin: effects of ganglionectomy, pinealectomy, constant light, constant darkness or 6-OH-dopamine administration.

In male rats maintained on a 12 h light-dark schedule (6 AM-6 PM), there is a nyctohemeral cycle of plasma prolactin which consists of a nadir at 11:30 AM and an apogee at approximately 11:30 PM. In rats exposed to constant darkness, this rhythm persists for 7 days. Seven days of constant light, however, reverses this diurnal variation such that plasma prolactin levels peak at 11:30 AM and reach a nadir at approximately 11:30 PM. In animals maintained on a 12 h light-dark cycle, ganglionectomy and lateral ventricular injections of 6-OH-dopamine (250 mug) also appear to reverse the diurnal variation of plasma prolactin, whereas a single injection of 6-OH-dopamine (250 mug) into the third ventricle decreases plasma prolactin values at all times intervals but does not alter the diurnal rhythm. Both sites of 6-OH-dopamine administration markedly deplete hypothalamic dopamine and norepinephrine, but injection of 6-OH-dopamine into the lateral ventricle destroys the catecholaminergic terminals in the pineal, whereas injection of 6-OH-dopamine into the third ventricle does not. Pinealectomy slightly increases the early morning values of plasma prolactin, but otherwise has no effect on the diurnal variation of prolactin. Five conclusions appear to be justified: 1) there is a nyctohemeral rhythm of plasma prolactin, which is reversed by constant light; 2) the pineal gland probably plays no role in the diurnal regulation of plasma prolactin secretion; 3) the diurnal rhythm of plasma prolactin is controlled by sympathetic input into the brain via the superior cervical ganglion; 4) a rhythm of plasma prolactin develops in constant light which is the exact opposite of the normal diurnal variation; 5) there appears to be a noradrenergic pathway in the hypothalamus or brainstem which stimulates release of prolactin.     

Responses to light of solitary rod photoreceptors isolated from tiger salamander retina.

Single, isolated rod photoreceptors were obtained by enzymatic dissociation of the tiger salamander (Ambystoma tigrinum) retina. These solitary cells retained the morphological features of rods of the intact retina and could be maintained in culture for several days. When impaled with micropipettes for electrophysiological recording, dark-adapted solitary rods had during darkness a resting potential of approximately -45 mV and a steady-state slope resistance of 500 Momega at rest. The current-voltage relationship showed both inward- and outward-going rectification. The responses to light of solitary rods were similar to those recorded from rods in the intact retina stimulated with large-diameter spots of light. The reversal potential of the light response of solitary rods was near 0 mV when measured in either the inner or outer segment.     

Bridging endometrial receptivity and implantation: network of hormones, cytokines, and growth factors

The prerequisite of successful implantation depends on achieving the appropriate embryo development to the blastocyst stage and at the same time the development of an endometrium that is receptive to the embryo. Implantation is a very intricate process, which is controlled by a number of complex molecules like hormones, cytokines, and growth factors and their cross talk. A network of these molecules plays a crucial role in preparing receptive endometrium and blastocyst. Furthermore, timely regulation of the expression of embryonic and maternal endometrial growth factors and cytokines plays a major role in determining the fate of embryo. Most of the existing data comes from animal studies due to ethical issues. In this study, we comprehend the data from both animal models and humans for better understanding of implantation and positive outcomes of pregnancy. The purpose of this review is to describe the potential roles of embryonic and uterine factors in implantation process such as prostaglandins, cyclooxygenases, leukemia inhibitory factor, interleukin (IL) 6, IL11, transforming growth factor-β, IGF, activins, NODAL, epidermal growth factor (EGF), and heparin binding-EGF. Understanding the function of these players will help us to address the reasons of implantation failure and infertility.     

Plasma melatonin in the scincid lizard, Trachydosaurus rugosus: diel rhythm, seasonality, and the effect of constant light and constant darkness.

Melatonin was assayed in the plasma of the scincid lizard, Trachydosaurus rugosus, using a specific radioimmunoassay. The levels of this indole exhibited a daily fluctuation similar to that observed in many other vertebrates. Plasma melatonin titers were low during the light phase and elevated during the dark phase when exposed to a lighting regimen of 13 hr light and 11 hr dark. In lizards captured in spring and transferred to this regimen, the amplitude of the plasma melatonin oscillation appeared damped in comparison to those sampled in the autumn. This damping was attributed to higher light phase and lower dark phase concentrations in spring. In one experiment, a correlation between size and plasma melatonin concentration was evident, higher levels being present in smaller animals. In contrast to birds and mammals, where a rhythm in blood melatonin content persists in constant dark, the plasma melatonin rhythm of T. rugosus was abolished by both constant light and constant darkness under constant temperature conditions.     

The role of cytokines and growth factors in fibroproliferative lung disease

A new hypothesis of the pathogenesis of fibroproliferative lung disease suggests that fibrosis is caused by abnormal and excessive wound healing and pathologic tissue remodelling. Inflammation is possibly an epiphenomenon. Cytokines are critical players in the pathologic process and attractive targets for pharmacological intervention. TGF beta is a key profibrotic growth factor, a variety of approaches are known to modify and inhibit its activity. This article reviews the basic pathological concepts of pulmonary fibrogenesis and outlines its potential clinical benefit.     

Oval cell-mediated liver regeneration: Role of cytokines and growth factors

In experimental models, which induce liver damage and simultaneously block hepatocyte proliferation, the recruitment of a hepatic progenitor cell population comprised of oval cells is invariably observed. There is a substantial body of evidence to suggest that oval cells are involved in liver regeneration, as they differentiate into hepatocytes and biliary cells. Recently, bone marrow cells were shown to be a source of a stem cells with the capacity to repopulate the liver. Presently, the relationship between bone marrow cells and oval cells is unclear. Investigations will be greatly assisted by the availability of in vitro models based on a knowledge of cytokines that affect oval cells. While the cytokines, which regulate the different hematopoietic lineages, are well characterized, there is relatively little information regarding those that influence oval cells. This review outlines recent developments in the field of oval cell research and focuses on cytokines and growth factors that have been implicated in regulating oval cell proliferation and differentiation.     

Identification, purification, and functional reconstitution of the cyclic GMP-dependent channel from rod photoreceptors.

The cyclic GMP-dependent cation channel from bovine rod outer segments has been purified to greater than 90% homogeneity by a rapid two-step chromatographic procedure. The purified channel has an apparent molecular mass of 63 kDa as determined by NaDodSO4/gel electrophoresis. When incorporated into the membrane of liposomes, the purified protein mediates the cyclic GMP-dependent efflux of entrapped Ca2+. The reconstituted channel protein exhibits properties similar to the cyclic GMP-dependent channel observed in excised patches of the plasma membrane and in disk membranes. Cyclic GMP activated the channel cooperatively (Hill coefficient n = 3.1) with an apparent Michaelis constant of approximately 11 microM. After reconstitution of the purified protein into a planar lipid bilayer, we recorded cyclic GMP-stimulated single-channel activity. The single-channel conductance at physiological salt concentrations and in the absence of divalent cations was 26 pS. The drug l-cis-diltiazem, shown to block the cyclic GMP-dependent channel in excised patches of the plasma membrane and in isolated disks of rod outer segments, was ineffective against the purified channel.     

Multiple effects of growth hormone on insulin release from isolated pancreatic islets

The direct effects of growth hormone (GH) on the endocrine pancreas were studied in isolated islets of rats. To study GH-induced insulin release, islets were incubated in RPMI 1640 medium containing 1 or 10 micrograms/ml of bovine GH for 120 minutes. Islets incubated in the absence of GH served as controls. During the incubation, GH significantly increased the insulin concentration in the medium. To study the effect of GH on subsequent glucose-induced insulin release, islets were preincubated with GH; then the islets were transferred to perifusion chambers and after a 30-minute stabilization period with 2.8 mM glucose, the islets were stimulated by addition of 16.7 mM glucose for 60 minutes. These perifusions were performed in the absence of GH. Glucose-induced insulin release from control and GH-pretreated islets peaked at five minutes during the first phase (0-8 minutes) and plateaued at 25 minutes during the second phase (9-60 minutes). Preincubation with GH (1 microgram/ml) did not change baseline or first phase release, but significantly suppressed the second phase of insulin release. When islets were preincubated with 10 micrograms/ml of GH, both phases of glucose-induced insulin release were suppressed; the total amount of insulin released by GH-pretreated islets was suppressed by 36.6% during the subsequent glucose stimulation period. These data indicate that GH stimulates insulin release by itself (GH-induced insulin release) but inhibits subsequent glucose-induced insulin release in a dose-dependent manner.     

Regulation of expression of cytokines and growth factors in osteoarthritic cartilage explants

Osteoarthritis (OA) is a degenerative joint disease characterised by the breakdown of the extracellular matrix of chondrocytes in the affected joints. Cytokines and growth factors which are known to play a role in the synthesis and degradation of cartilage matrix have been shown to be upregulated in osteoarthritic cartilage. This upregulation resulted in two different phenotypes, overexpressing either TNF-α and IL-6 or IL-1β, TGFβ₁, IL-4 and IL-10. To investigate the hierarchy among growth factors and cytokines involved in cartilage metabolism, we analysed osteoarthritic cartilage explants for their responses to human recombinant (rh) cytokines and growth factors. The cytokine expression patterns of the explants before and after in vitro culture were compared by immunohistological staining of cartilage sections. We found a coordinate expression of TNF-α and IL-6 on the one hand, and of IL-1β, TGFβ₁, IL-4 and IL-10 on the other. Although TNF-α and IL-6 stimulated each other’s expression, they downregulated TGF β₁, IL-4 and IL-10 or IL-1β, TGF β₁ and IFNg, respectively. IL-1β upregulated the expression of TGF β₁, IL-4 and IL-10, and jointly these four cytokines and growth factors downregulated IL-6. Both of the expression patterns described for OA cartilage can be explained by these regulatory mechanisms. Interestingly, no cytokine efficiently downregulated TNF-α, and even though IL-1β is upregulated in one of the OA phenotypes, none of the growth factors and cytokines tested – except for IL-1β itself – seemed capable of mediating this upregulation. This unresponsiveness to cytokine stimulation might hint at a genetic cause for the elevated expression in the respective phenotypes. Received: 15 September 2000 / Accepted: 17 April 2001     

Perception of the damaging effects of smoking, and brief cessation counselling by doctors

An open prospective study was conducted among the patients visiting an urban medical policlinic for the first time without an appointment to assess whether the immigrants (who represent more than half of our patients) are aware of the health effects of smoking, whether the level of acculturation influences knowledge, and whether doctors give similar advice to Swiss and foreign smokers. 226 smokers, 105 Swiss (46.5%), and 121 foreign-born (53.5%), participated in the study. 32.2% (95% CI [24.4%; 41.1%]) of migrants and 9.6% [5.3%; 16.8%] of Swiss patients were not aware of negative effects of smoking. After adjustment for age, the multivariate model showed that the estimated odds of "ignorance of health effects of smoking" was higher for people lacking mastery of the local language compared with those mastering it (odds ratio (OR) = 7.5 [3.6; 15.8], p < 0.001), and higher for men (OR = 4.3 [1.9; 10.0], p < 0.001). Advice to stop smoking was given with similar frequency to immigrants (31.9% [24.2%; 40.8%] and Swiss patients (29.0% [21.0%; 38.5%]). Nonintegrated patients did not appear to receive less counselling than integrated patients (OR = 1.1 [0.6; 2.1], p = 0.812). We conclude that the level of knowledge among male immigrants not integrated or unable to speak the local language is lower than among integrated foreign-born and Swiss patients. Smoking cessation counselling by a doctor was only given to a minority of patients, but such counselling seemed irrespective of nationality.     

The role of cytokines and growth factors in rheumatoid joint destruction]

Cytokines and growth factors are important mediators of inflammation and play a major role in both the physiological regulation of bone and cartilage metabolism, and in the destruction of joint-related structures. These complex biological regulatory events have to be regarded as net effects which are dependent on the individual actions of the different cytokines and their corresponding inhibitors in the pericellular environment of the cells present in the inflamed tissues. These effects can be antagonized on various levels by natural or artificial inhibitory molecules. The determination and characterization of cytokines and their inhibitors in body fluids and tissues may contribute to a better understanding of the basic mechanisms of the pathogenesis of inflammatory joint diseases, and may help to develop better modalities of therapy. The objective of the present review is to outline important actions of selected cytokines and growth factors on cells and the surrounding matrix of bone and cartilage in rheumatoid arthritis. It will focus on interleukin-1 (IL-1), IL-1 inhibitors, Tumor-Necrosis-Factor-alpha (TNF-alpha), TNF inhibitors, Interleukin-6 (IL-6), colony-stimulating factors (CSF's), Interferon-gamma (IFN-gamma), growth factors, eicosanoids and prostaglandins, all of which are important in the effector phase of tissue destruction.     

CD40L induces proliferation,self-renewal,rescue from apoptosis,and production of cytokines by CD40-expressing AML blasts

OBJECTIVE: Conflicting experimental and clinical results have been reported regarding the role of CD40 in acute myeloid leukemia (AML). In the present study, we analyzed the capability of CD40L/CD154 to modulate several functional aspects of CD40-expressing AML blasts. METHODS: After defining the constitutive expression levels of CD40 in a wide panel (n = 67) of AMLs and evaluating the capability of cytokines to modulate its expression, we investigated the effects of CD40 engagement by soluble (s) CD40L on proliferation, self-renewal capacity, apoptosis, homotypic adhesion, and cytokine production of leukemia cells. RESULTS: CD40 was detected in blast cells from about 37% of AMLs, the highest frequency being documented in monocytic subtypes, and its expression was upregulated or de novo induced by treatment with interleukin (IL)-1alpha, IL-3, IL-4, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon-gamma, and tumor necrosis factor-alpha. Exposure of CD40(+) AML blasts to sCD40L resulted in a dose-dependent proliferative response, enhancement of clonogenic growth and self-renewal capacity, and a striking increase in colony size. CD40 engagement was able to rescue AML blasts from apoptosis induced by serum deprivation, as demonstrated by reduced expression of APO2.7 and annexin-V binding, as well as upregulation of the anti-apoptotic protein bcl-x(L). CD40 triggering upregulated cell surface expression of the adhesion molecules CD54, CD58, and CD15 and resulted in homotypic aggregation of leukemia cells at least in part CD54-dependent. An increased production of IL-6 and GM-CSF by CD40(+) AML blasts was also documented upon sCD40L exposure. CONCLUSIONS: This study indicates a possible involvement of CD40 in the interactions of AML blasts with other growth-sustaining microenvironmental accessory cells and immune effectors, in turn expressing CD40L. Caution in the use of CD40 triggering in immunotherapy of AMLs is also suggested.     

Inhibitory effects of the bone-derived growth factors osteoinductive factor and transforming growth factor-beta on isolated osteoclasts.

Demineralized bone matrix contains a number of growth factors for osteoblast-like cells. Two of these, the novel glycoprotein osteoinductive factor (OIF) and transforming growth factor-beta (TGF beta), act together to cause ectopic bone formation in vivo. Since OIF, like TGF beta, is likely released from bone when the matrix is resorbed, we examined the effects of homogeneous OIF and TGF beta on osteoclast function. Osteoclast function was tested in isolated avian osteoclasts and was measured in terms of tartrate-resistant acid phosphatase (TRAP) activity, oxygen-derived free radical production, and formation of characteristic resorption lacunae on slices of sperm whale dentine. OIF (50-100 ng/ml) inhibited the capacity of these osteoclasts to form lacunae whether assessed by the number of excavations per slice or by the total area resorbed. OIF (10-100 ng/ml) or TGF beta (10-20 ng/ml) caused a decrease in TRAP activity as well as a reduction in oxygen-derived free radical generation detected by nitroblue tetrazolium staining. TGF beta had no effect on the resorption capacity of isolated osteoclasts in concentrations that inhibited TRAP activity and nitroblue tetrazolium staining. These results suggest that growth regulatory factors, such as OIF and TGF beta, released during the resorption of bone may be endogenous inhibitors of continued osteoclastic activity. This cessation of osteoclast activity may be an essential preliminary step to the new bone formation that occurs at resorption sites during bone remodeling.