Biomedical subjects

R Zellweger

Publications and source records attributed to R Zellweger.

32 records · Page 2Linked to original sources

PubMed1996

Increased melatonin levels after hemorrhagic shock in male and female C3H/HeN mice.

Although hemorrhagic shock leads to significant alterations of several hormones, e.g. ACTH, corticosterone and beta-endorphin, it is not known whether plasma melatonin levels are affected under this condition and if so, whether the effects are comparable in males and females. Using a radioimmunoassay, it was found that plasma melatonin levels were significantly increased in male and proestrus female C3H/HeN mice immediately after hemorrhagic shock. However, in male mice, by two hours after hemorrhage and resuscitation, plasma melatonin returned to levels comparable to those seen in control and sham-operated animals. Proestrus female mice, on the other hand, showed significantly increased plasma melatonin levels at two hours after surgery when compared to unoperated control animals. Although the significance and biological role of the transient increased plasma melatonin levels after hemorrhagic shock remain to be determined, it appears that the pineal gland and/or an extrapineal source of melatonin, of both male and proestrus female mice responds to severe hypotension by increased release of melatonin.

Animals↗

PubMed1996

Immune function is more compromised after closed bone fracture and hemorrhagic shock than hemorrhage alone.

OBJECTIVE: To determine whether closed bone fracture in conjunction with hemorrhagic shock compromises immune functions more severely than hemorrhagic shock alone. DESIGN: In a randomized, controlled trial, closed bone fracture of the right lower leg and/or hemorrhagic shock (mean +/- SEM arterial blood pressure, 35 +/- 5 mm Hg for 90 minutes) were induced in male C3H/HeN mice (weight, 25 g). Animals subjected to hemorrhage were resuscitated with the shed blood and lactated Ringer solution. At 72 hours after the experiment, all animals were killed to obtain whole blood, splenocytes, and splenic and peritoneal macrophages. Macrophage interleukin-1 and splenocyte interleukin-2 and interleukin-3 release were determined by bioassay, and splenocyte proliferation was measured by tritiated thymidine incorporation. RESULTS: Closed bone fracture alone did not affect immune functions 72 hours after the trauma. Hemorrhagic shock, however, induced a significant depression of splenocyte and macrophage functions. Bone fracture followed by hemorrhagic shock further depressed splenocyte proliferation and splenocyte interleukin-2 and interleukin-3 release as well as interleukin-1 release. CONCLUSION: Since bone injury coupled with hemorrhagic shock produces more severe depression of immune functions than hemorrhage alone, bone injury appears to play a contributory role in further depressing immune functions in trauma patients who experience major blood loss.

Animals↗

PubMed1996

Mechanism of immunosuppression in males following trauma-hemorrhage. Critical role of testosterone.

OBJECTIVE: To determine whether male sex steroids contribute to the depression in cell-mediated immunity following trauma-hemorrhage and resuscitation. DESIGN: Two weeks before the induction of soft-tissue trauma (2.5-cm midline laparotomy) and hemorrhagic shock (mean [+/-SEM] blood pressure, 35 +/- 5 mm Hg), male C3H/HeN mice were castrated or sham castrated. Following trauma-hemorrhage, the mice were resuscitated and killed 24 hours thereafter to obtain whole blood and the spleen. RESULTS: Splenocyte proliferation and splenocyte interleukin-2 and interleukin-3 release were significantly depressed in sham-castrated animals after trauma-hemorrhage. In contrast, these variables in castrated mice after trauma-hemorrhage were similar to those in sham-operated animals. Corticosterone plasma levels were significantly elevated in both trauma-hemorrhage groups compared with those in sham-operated mice. Plasma testosterone levels were undetectable in castrated animals and detectable in sham-castrated mice. CONCLUSIONS: Castration before soft-tissue trauma and hemorrhagic shock maintains normal immune function in male mice, but sham-castrated male mice show significant immunodepression. The maintenance of immune function by androgen deficiency does not seem to be related to changes in the release of corticosterone. We conclude that male sex steroids are involved in the immunodepression observed after trauma-hemorrhage. Thus, the use of testosterone-blocking agents following trauma-hemorrhage should prevent the depression of immune functions and decrease the susceptibility to sepsis under those conditions.

Androgens↗

PubMed1996

Prolactin inhibits the increased cytokine gene expression in Kupffer cells following haemorrhage.

Kupffer cells are an important source of proinflammatory cytokines and contribute to the systemic inflammatory response observed following haemorrhagic shock. The systemic release of cytokines, such as TNF-alpha, IL-1 beta, IL-6, etc., has been associated with the decreased host immune and organ dysfunction following hypotension. Studies indicate that anterior pituitary hormone prolactin (PRL) plays an important role in the regulation of lymphocyte proliferation and macrophage function in vivo, as well as in vitro. However, it is not known what effects PRL administration has on Kupffer cells proinflammatory mediator release following haemorrhage. Therefore, it was the aim of this study to determine the effect of in vivo PRL administration on cytokine gene expression in Kupffer cells after haemorrhage. To study this, C3H/HeN male mice were bled to and maintained at a mean arterial pressure of 35 mmHg for 60 minutes, then resuscitated with shed blood, and segregated into two groups: one group was treated with PRL (100 micrograms/25 g body weight subcutaneously) while the other group received saline-vehicles. This was followed with lactated Ringer's solution (2 x the volume of shed blood). Two hours thereafter, the animals were sacrificed, Kupffer cells were isolated and stimulated with or without 10 micrograms/ml LPS for 1 hour. Total RNA was extracted and cytokine mRNA was detected by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). The results demonstrated that haemorrhage markedly increased the level of mRNA for IL-1 beta, IL-6, TGF-beta and TNF-beta in Kupffer cells. However, in vivo PRL treatment significantly decreased the cytokine gene expression in Kupffer cells following haemorrhage. This indicates that PRL may be useful in blunting the systemic inflammatory response associated with cell and organ depression following shock.

Animals↗

PubMed1996

Enhanced immune responses in females, as opposed to decreased responses in males following haemorrhagic shock and resuscitation.

Although haemorrhagic shock produces immunodepression in both humans and experimental animals, no information is available concerning gender differences in the immune and endocrine response to shock. To study this, male and female (proestrus and diestrus) C3H/HeN mice (25 g body weight) were bled and maintained at a mean arterial blood pressure of 35 +/- 5 mmHg for 1 h and then adequately resuscitated. The animals were killed at 2 h after resuscitation to obtain splenocytes, macrophages (M phi, peritoneal and splenic), as well as whole blood. IL-1 release by M phi, splenocyte proliferative capacity and splenocyte IL-3 release in female mice was significantly increased. Male mice, however, showed decreased release of all interleukins (IL-1, 2, 3, 6) as well as splenocyte proliferative capacity after shock. Plasma corticosterone levels decreased in proestrus female mice, as opposed to increased levels in males following shock. Corticosterone may therefore, be in part responsible for the observed gender differences. To the authors' knowledge, this is the first study which shows that immune responsiveness in female mice is enhanced after haemorrhagic shock, as opposed to decreased responsiveness in males. Thus, unlike males which exhibit increased susceptibility to sepsis/infections, females should be able to better tolerate the deleterious effects of shock.

Animals↗

PubMed1996

Prolactin: a novel and safe immunomodulating hormone for the treatment of immunodepression following severe hemorrhage.

Recent studies have shown that the anterior pituitary hormone prolactin, together with various cytokines, plays an important role in maintaining normal immune responses. Although there is evidence that prolactin may be a significant immunotropic hormone that can counteract the immunosuppressive effects of drugs such as cyclosporine, morphine, or glucocorticoids, it remains unknown whether prolactin administration has any salutary effects on the depressed immune responses following severe hemorrhage. To study this, mice were bled to and maintained at a mean arterial pressure of 35 mm Hg for 60 min, then adequately resuscitated and segregated into two groups. One group received saline-vehicle (hem-SS); animals in the other group were treated with prolactin (hem-PRL) (100 micrograms per 25 g BW, subcutaneously) immediately before resuscitation. Two hours following saline or prolactin injection, splenocytes (SPL) were harvested and assessed for proliferative capacity (PC) and their ability to release IL-2 and IL-3. Supernatant lymphokine levels were determined by bioassay. The proliferative capacity of the splenocytes, as well as their ability to release IL-2 and IL-3, was significantly depressed in the vehicle-treated hemorrhaged animals, compared to shams. Treatment with prolactin restored the depressed splenocyte functions seen after severe hemorrhage. These results support the notion that the immunosuppression following hemorrhage and trauma may be mediated by hormones from the hypothalamic-pituitary-adrenal axis. Furthermore, our results suggest that the use of prolactin, which did not produce any adverse hemodynamic effects, represents a novel and safe immunomodulating hormone for the treatment of immunodepression following severe blood loss.

Animals↗

PubMed1996

Melatonin administration attenuates depressed immune functions trauma-hemorrhage.

The pineal hormone melatonin has been used in clinical trials in patients suffering from AIDS and also as an adjuvant for cancer therapy. Although melatonin has been reported to have beneficial effects in some animal models of immune dysfunction, it remains unknown whether this hormone has any salutary effects on immunity following soft-tissue trauma and/or major blood loss. To study this, soft-tissue trauma (2.5-cm midline laparotomy) and hemorrhagic shock (arterial BP 35 +/- 5 mm Hg) were induced in C3H/HeN mice. The mice were resuscitated after 90 min of hypotension with the shed blood and lactated Ringer's solution. Treatment with saline, vehicle, or melatonin (10 mg/kg BW) subcutaneously was administered in the evening of the day of surgery and again on the following evening. All animals were sacrificed at 48 hr following trauma-hemorrhage and resuscitation to obtain plasma, splenocytes, as well as splenic and peritoneal macrophages (Mphi). The results indicate that melatonin administration after trauma-hemorrhage significantly improved the depressed immune functions, as evidenced by the restoration of Mphi IL-1 and IL-6 release, as well as significantly improved splenocyte IL-2 and IL-3 release and splenocyte proliferative capacity. No differences in circulating corticosterone levels between vehicle- and melatonin-treated animals were observed. This is the first study to show that melatonin, which is reported to be free of adverse side effects, can be considered a safe and effective therapeutic agent for restoring the depressed immunological function after soft-tissue trauma and hemorrhagic shock.

Acquired Immunodeficiency Syndrome↗

PubMed1995

Cytokine gene expression in splenic macrophages and Kupffer cells following haemorrhage.

TNF-alpha, IL-1, IL-6 and TGF-beta are important macrophage-derived mediators which play the pleiotropic role in inflammatory, metabolic, hematopoietic and immunologic processes. Studies have shown that haemorrhagic shock without significant tissue trauma induces profound immunosuppression which is associated with elevated plasma levels of TNF-alpha IL-1, IL-6 as well as TGF-beta. Furthermore, Kupffer cells but not the splenic M phi isolated from post-haemorrhaged animals showed an increased capacity to release inflammatory cytokines in response to LPS stimulation in vitro. However, it remains unknown whether the innate (i.e. in the absence of LPS stimulation) cytokine genes expression in Kupffer cells and splenic M phi is affected by haemorrhage. To determine this, C3H/HeN male mice were bled to and maintained at a mean arterial blood pressure of 35 mmHg for 60 min, and then adequately resuscitated. Splenic macrophages and Kupffer cells were isolated at 1 h after haemorrhage. Total RNA was extracted and cytokine mRNA was detected by semi-quantitative reverse transcription and polymerase chain reaction (RT-PCR). The results demonstrate that haemorrhage significantly elevated the mRNA accumulation of TNF-alpha, IL-1 beta, TGF-beta while IL-6 gene expression in Kupffer cells and splenic M phi was only slightly increased. Since Kupffer cells but not the splenic M phi showed increased cytokine release, it could be concluded that the differential regulation of cytokine release by these two macrophage populations following haemorrhage may be due to the divergence of the cytokine at the translational level.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

A novel nonanticoagulant heparin improves splenocyte and peritoneal macrophage immune function after trauma-hemorrhage and resuscitation.

Recent studies have shown that heparinization of animals prior to or even after hemorrhagic shock improves tissue perfusion and organ function. However, the anticoagulant properties of conventional heparin preclude its clinical use in trauma care. The aim of our study, therefore, was to determine whether chemically modified heparin, i.e., a novel nonanticoagulant heparin (GM1892), which does not have significant anticoagulant activity (approximately 2% of the anticoagulant activity of conventional heparin), produces any beneficial effects on splenocyte and macrophage immune function following trauma-hemorrhage and resuscitation. To determine this, following the induction of tissue trauma (i.e., a midline laparotomy), mice were bled to and maintained at a mean arterial pressure of 35 mm Hg for 1 hr. The animals then received GM1892 (7 mg/kg body wt), conventional heparin (7 mg/kg body wt), normal saline prior to resuscitation with three times the volume of shed blood with Ringer's lactate. Two hours after resuscitation the animals were sacrificed, splenocytes were isolated, and splenic, as well as peritoneal macrophage, cultures were established. The ability of the splenocytes to release IL-2 and IL-3 in response to mitogen was markedly improved in hemorrhaged animals which were treated with GM1892 or conventional heparin compared to saline-treated mice. Furthermore, the capacity of splenic and peritoneal macrophages to release IL-6 was restored in the hemorrhaged animals that received GM1892 or conventional heparin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

PAF-antagonist administration after hemorrhage-resuscitation prevents splenocyte immunodepression.

A number of studies have suggested that the inflammatory and chemotactic autocoid platelet activating factor (PAF), together with various cytokines, plays an important role in the pathophysiology of trauma, sepsis, and shock. However, little is known about PAF's contribution to the immunosuppression associated with hemorrhage. The aim of our study was, therefore, to determine if the use of a PAF-antagonist following hemorrhage has any salutary effects on splenocyte lymphokine production. To study this, mice were bled to and maintained at a mean arterial pressure of 35 mm Hg for 60 min. The mice were then segregated into three groups and were resuscitated with shed blood plus lactated Ringer's solution (2x the volume of shed blood), containing either a potent PAF-antagonist (Ro 24-4736, a thienodiazepine) in dimethyl sulfoxide (DMSO) or DMSO-vehicle. Sham-operated mice received either DMSO-vehicle in saline or saline alone. Twenty-four hours thereafter the animals were sacrificed and splenocyte cultures established and stimulated for 48 hr with Con A (2.5 micrograms/ml). Supernatant lymphokine levels were determined by bioassay. The cellular release of interleukin-2 and -3 (IL-2 and IL-3) by splenocytes was significantly depressed in the nontreated or vehicle-treated hemorrhaged animals compared to shams. Treatment with the PAF-antagonist Ro 24-4736 restored IL-2 and IL-3 release values to levels comparable to those of the sham-operated animals. Thus, (1) PAF appears to play a significant role in hemorrhage-induced immunosuppression and (2) the use of a PAF-antagonist to uncouple the PAF-generated feedback loops prevents the depression in splenocyte function following hemorrhage.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Effect of surgical trauma on splenocyte and peritoneal macrophage immune function.

Although previous studies have shown that simple laparotomy produces a depression in peritoneal macrophage (Mphi) antigen presentation capacity, it remains unknown whether the adverse effects of laparotomy are limited to peritoneal Mphi or whether such an insult also affects splenocyte immune function. To study this, mice were anesthetized and a 1-inch midline abdominal incision was made, followed by abdominal closure. At 2 and 24 hours after the surgical procedure, the animals were killed, splenocyte cultures established and stimulated for 48 hours with concanavalin A (2.5 micrograms/mL), while peritoneal macrophage cultures were stimulated with LPS (10 micrograms/mL). The proliferative capacity of the splenocytes, as well as their ability to release interleukin-2 and interleukin-3, was markedly decreased at 2 as well as 24 hours after laparotomy. Furthermore, the release of interleukin-6 by splenic and peritoneal macrophages from animals that underwent laparotomy were also significantly depressed at both 2 and 24 hours. These results support the concept that surgical stress in the form of midline laparotomy per se is sufficient to produce a significant impairment in cell-mediated immunity, thus setting the stage for increased incidence of postoperative complications.

Animals↗

PubMed1995

Trauma-hemorrhage causes prolonged depression in cellular immunity.

A number of clinical studies have shown that multiple and severe trauma causes immunosuppression and increases the susceptibility to sepsis. However, because there is a close temporal relationship between trauma and hemorrhage in humans, it is difficult to dissociate the effects of tissue trauma versus hemorrhage on immunity in the clinical setting. Studies in mice have shown that simple hemorrhage per se as well as laparotomy alone produces a marked depression in cellular immunity and no difference was seen in the extent of depression at 2 h if these two insults were combined. Nonetheless, it remains unknown whether the combined model of trauma-hemorrhage produces a more protracted depression in immune function. To study this, 5 days after either sham operation, laparotomy (i.e. trauma), hemorrhage alone (35 mmHg for 1 h, followed by resuscitation), or the combination of laparotomy and hemorrhage, mice (C3H/HeN) were sacrificed, after which splenocyte and peritoneal macrophage cultures were established. The proliferative capacity of the splenocytes, as well as their ability to release IL-2 and IL-3, was markedly decreased in the trauma-hemorrhage animals but was normal in the other groups. Furthermore, the release of IL-6 by peritoneal macrophages from animals that underwent trauma-hemorrhage was also significantly depressed. These results support the concept that traumatic injury in the form of a midline laparotomy combined with hemorrhage produces a more protracted impairment in cell-mediated immunity than laparotomy or hemorrhage alone.

Animals↗

PubMed1995

The role of bacterial translocation on Kupffer cell immune function following hemorrhage.

Studies have shown that Kupffer cell and splenic macrophage, as well as peritoneal macrophage antigen presentation function, was significantly depressed following hemorrhage and remained so for at least 96 hours after resuscitation. Although macrophage antigen presentation was depressed, in all the cell populations studied, it was only the Kupffer cells which were upregulated to produce increased inflammatory cytokines. Furthermore, Kupffer cells from hemorrhaged animals exhibited enhanced, as opposed to reduced toxicity by peritoneal and splenic macrophages. This correlated well with increased cell-associated TNF on Kupffer cells. as well as increased capacity of Kupffer cells to release inflammatory cytokines after hemorrhage. It, therefore, could be postulated that while the enhanced Kupffer cell cytotoxicity may be beneficial in the destruction of pathogens seen in the liver due to bacterial translocation, this same activity may also contribute directly or indirectly to hepatocellular dysfunction and injury which is seen following hemorrhagic shock. Nonetheless, the depression in various immune functions after hemorrhage and resuscitation was comparable in both endotoxin-tolerant and -intolerant mice. Thus, it is debatable whether the alterations in immune function seen after hemorrhage are primarily due to the release of endotoxin into the blood stream during and/or following the hemorrhagic insult. Although translocation and/or endotoxemia occurs following severe hemorrhage, endotoxin may not be the sole or primary agent responsible for the induction of immunodepression after hemorrhage. The depressed Kupffer cell functions and increased inflammatory cytokine release by these cells can be significantly improved by post-treatment of animals with chloroquine, ibuprofen, diltiazem or ATP-MgCl2. Thus, these agents offer new therapeutic modalities in restoring the depressed Kupffer cell immune functions and in the treatment of generalized immunosuppression, as well as for decreasing the susceptibility to sepsis which is observed following severe blood loss.

Animals↗

PubMed1994

Peritoneal macrophages show increased cytokine gene expression following haemorrhagic shock.

Tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), IL-1 and transforming growth factor-beta (TGF-beta) have been recognized as important mediators of pathophysiological and immunological events associated with shock. Previous studies have indicated that although peritoneal macrophage (PM phi) antigen presentation was depressed following haemorrhage, the cytokine release capacity in response to lipopolysaccharide (LPS) was not affected in vitro. To determine the effect of haemorrhagic shock on PM phi cytokine mRNA transcription, C3H/HeN male mice were bled to and maintained at a mean arterial blood pressure of 35 mmHg for 60 min, and then adequately resuscitated. PM phi were isolated at 1 or 24 hr after haemorrhage and were incubated without or with 10 micrograms LPS/ml for 1 hr. Total RNA was then extracted followed by Northern blot analysis, as well as semi-quantitative reverse transcription and polymerase chain reaction (RT-PCR). The results of Northern blot analysis indicated that haemorrhage markedly increased LPS-induced IL-1 beta, IL-6, and TNF-alpha mRNA accumulation in PM phi at both 1 and 24 hr after haemorrhage and resuscitation. Furthermore, competitive RT-PCR demonstrated that mRNA of IL-1 beta, IL-6, TNF-alpha, as well as TGF-beta, was increased in PM phi obtained 1 hr after haemorrhage either with or without LPS stimulation. The data from Northern blot analysis and semi-quantitative RT-PCR also revealed that LPS enhanced the effect of haemorrhage on PM phi cytokine gene expression. Thus, following haemorrhage, PM phi showed elevated cytokine mRNA accumulation which was not followed by an increased ability to release cytokines in response to LPS in vitro. These results, therefore, suggest that different mechanisms regulate gene expression and subsequent cytokine secretion by PM phi following haemorrhage.

Animals↗