Interleukin-1 and the response to injury

Relationship between Inflammatory Response and Estimated Complication Rate after Total Hip Arthroplasty

BACKGROUND

After total hip arthroplasty (THA), there is a noteworthy inflammatory response. The inflammatory response is associated with postoperative recovery and complications. However, there had been few reports on the relationship between inflammatory response and postoperative complication rate. The aim of the present study was to investigate early inflammatory response in the first 3 days after THA, and to identify the relationship between inflammatory response and estimated complication rate after surgery.

METHODS

It was a prospective, nonrandomized cohort study. There were 148 patients who underwent unilateral THA in our hospital enrolled. Blood samples were collected preoperatively in the morning of the surgery and at 24, 48, and 72 h after surgery. C-reactive protein (CRP) and interleukin-6 (IL-6) in peripheral blood were measured. The modified physiological and operative severity score for the enumeration of the morbidity (POSSUM) was recorded pre- and intra-operatively. Based on the score, estimated complication rate was calculated. Harris score was used to assess hip function before and after surgery.

RESULTS

IL-6 levels reached the peak at 24 h after surgery and CRP at 48 h. After that, both of the levels decreased. The mean Harris scores significantly increased from 41.62 ± 23.47 before surgery to 72.75 ± 9.13 at 3 days after surgery. The Harris scores after surgery did not have a significant relation with either IL-6 or CRP peak levels (P = 0.165, P = 0.341, respectively). Both CRP and IL-6 peak levels significantly and positively correlated with estimated complication rate after surgery. The estimated complication rate calculated using the POSSUM system was 43 cases of 148 patients. Actually, there were only 28 cases that were observed to get postoperative complications during hospitalization. However, there was no significant difference between estimated and observed complication rates (P = 0.078). In the group with complications, the CRP and IL-6 peak levels were significantly higher than those in the group without complications (both P< 0.001).

CONCLUSIONS

There were significantly positive relationships between both peak levels of CRP and IL-6 and estimated complication rate after THA. Inflammatory response could predict the incidence of complications after THA.

Survivors versus nonsurvivors postburn: differences in inflammatory and hypermetabolic trajectories

OBJECTIVE

To evaluate whether a panel of common biomedical markers can be utilized as trajectories to determine survival in pediatric burn patients.

BACKGROUND

Despite major advances in clinical care, of the more than 1 million people burned in the United States each year, more than 4500 die as a result of their burn injuries. The ability to predict patient outcome or anticipate clinical trajectories using plasma protein expression would allow personalization of clinical care to optimize the potential for patient survival.

METHODS

A total of 230 severely burned children with burns exceeding 30% of the total body surface, requiring at least 1 surgical procedure were enrolled in this prospective cohort study. Demographics, clinical outcomes, and inflammatory and acute-phase responses (serum cytokines, hormones, and proteins) were determined at admission and at 11 time points for up to 180 days postburn. Statistical analysis was performed using a 1-way analysis of variance, the Student t test, χ test, and Mann-Whitney test where appropriate.

RESULTS

Survivors and nonsurvivors exhibited profound differences in critical markers of inflammation and metabolism at each time point. Nonsurvivors had significantly higher serum levels of interleukin (IL)-6, IL-8, granulocyte colony-stimulating factor, monocyte chemoattractant protein-1, C-reactive protein, glucose, insulin, blood urea nitrogen, creatinine, and bilirubin (P < 0.05). Furthermore, nonsurvivors exhibited a vastly increased hypermetabolic response that was associated with increases in organ dysfunction and sepsis when compared with survivors (P < 0.05).

CONCLUSIONS

Nonsurvivors have different trajectories in inflammatory, metabolic, and acute phase responses allowing differentiation of nonsurvivors from survivors and now possibly allowing novel predictive models to improve and personalize burn outcomes.

Inflammatory response to orthopedic biomaterials after total hip replacement

BACKGROUND

The aim of the present study was to investigate early inflammatory response in the first 3 days after the implantation of hip prostheses, and to compare the early inflammation responses associated with the use of different combinations of bearing materials.

METHODS

34 patients were enrolled, all of whom underwent unilateral total hip replacement and had identical hip prostheses, except for the bearing materials. These consisted of polyethylene on alumina (n = 8), polyethylene on CoCr (n = 11), or alumina on alumina (n = 15). Blood samples were collected preoperatively in the morning of the day of surgery, and at 6 h, 1 day, 2 days, and 3 days postoperatively. CK, CRP, and IL-6 in peripheral blood were measured. Pain score was obtained at 2 days after surgery.

RESULTS

There were no significant differences in the pre- and postoperative background variables among the groups. Pain scores of different groups were not significantly different either (P > 0.05). There were also no significant differences in the levels of CK, CRP, and IL-6 when patients with the three combinations of bearing materials were compared.

CONCLUSIONS

We concluded that varying the bearing materials used in the hip prosthesis did not influence the early inflammatory response after prosthesis implantation.

Serum concentrations of interleukin-6 in patients following unilateral versus bilateral total knee arthroplasty

BACKGROUND

Surgical stress is known to affect body temperature, white blood cell (WBC) count, C-reactive protein (CRP), and interleukin-6 (IL-6). The aim of the present study was to investigate which parameter is most suitable for quantitative analysis of surgical stress.

METHODS

Unilateral total knee arthroplasty (U-TKA) and bilateral TKA (B-TKA) were selected for the subjects of this study because the B-TKA creates approximately double the surgical stress of the U-TKA. The temperature, WBC count, CRP, and IL-6 in the blood were measured pre- and postoperatively in both groups. The IL-6 in the drainage fluid was also measured after the operation.

RESULTS

The temperature, WBC count, CRP, and IL-6 in the blood significantly increased on the first day after the operation in both groups. There were significant differences between the two groups in the WBC count (P < 0.05) and the IL-6 level in the blood (P < 0.05) on the first day after the surgery. There were no significant differences between the two groups for the CRP and IL-6 levels in the drainage fluid. The relative proportions--(B-TKA/U-TKA) x 100 (%)--were 170.4% for the operating time, 219.4 % for total blood loss, 200.0% for blood transfusion, 100.3% for temperature, 128.9% for WBC count, 127.4% for CRP, and 246.5% for the IL-6 level in the blood.

CONCLUSIONS

The serum IL-6 level may best reflect surgical stress and could therefore be a quantitative marker of surgical stress.

Characterization of the inflammatory response during acute and post-acute phases after severe burn

Severe burn causes a pronounced hypermetabolic response characterized by catabolism and extensive protein wasting. We recently found that this hypermetabolic state is driven by a severe inflammatory response. We characterized in detail the kinetics of serum levels of a panel of cytokines in a rat model, which may serve as reference for the development of therapeutic interventions applicable to humans. Male Sprague-Dawley rats (n = 8) received a full-thickness burn of 60% total body surface area. Serum was harvested 1, 3, 6, 12, 24, 48, 96, and 168 h after burn. Eight serum cytokines commonly used to assess the inflammatory response in humans, such as IL-1beta, IL-6, IL-10, TNF, vascular endothelial growth factor, and monocyte chemotactic protein 1, and the rat-specific cytokines cytokine-induced neutrophil chemoattractant (CINC) 1, CINC-2, and CINC-3 were measured by enzyme-linked immunosorbent assay technique and were compared with controls (n = 4). Statistical analysis was conducted using the t test, with P < 0.05 considered as significantly different. Thermal injury resulted in significantly increased serum levels of IL-1beta, IL-6, IL-10, monocyte chemotactic protein 1, CINC-1, CINC-2, and CINC-3 when compared with the concentrations detected in nonburned rats (P < 0.05). Serum levels of TNF-alpha and vascular endothelial growth factor in burned rats were not found to be significantly different to controls. Burn causes a profound inflammatory response in rats. Specific cytokines known to increase in humans postburn such as IL-1 beta, IL-6, IL-10, MCP-1, and IL-8 (CINC-1, CINC-2, and CINC-3 in the rat) were also observed in our rat burn model, which now allows us to study new anti-inflammatory treatment options.

A pilot study of cytokine levels and white blood cell counts in the diagnosis of necrotizing fasciitis

STUDY OBJECTIVES

To characterize the early cytokine response of patients presenting to the emergency department with necrotizing fasciitis (NF) and to determine whether serum cytokine levels and white blood cell (WBC) counts may be useful in distinguishing NF from other severe soft-tissue infections.

METHODS

White blood cell counts and cytokine levels (IL-1beta, IL-1Ra, IL-6, IL-8, IL-18, and IFN-gamma) were measured in patients presenting to the emergency department with severe soft-tissue infections and high suspicion of NF. Necrotizing fasciitis was confirmed intraoperatively and by surgical pathology. Cytokines were measured via the liquid-phase electrochemiluminescence method.

RESULTS

Thirty-five patients were enrolled, 18 were diagnosed with NF, and 17 were diagnosed with cellulitis and/or abscess (CAB). On admission, patients with NF had significantly higher WBC counts and lower levels of interleukin 1beta (IL-1beta) compared with patients with CAB. There were no statistically significant differences in the levels of the other cytokines between the 2 groups.

CONCLUSION

Patients with NF have higher WBC counts and lower IL-1beta levels compared with patients with CAB.

Less systemic cytokine response in patients following microendoscopic versus open lumbar discectomy

The magnitude of the tissue damage from surgery impacts the trauma response. This response is proportional to the severity of surgical stress. Systemic cytokines are recognized as markers of postoperative tissue trauma. Microendoscopic discectomy (MED) recently has become popular for treating lumbar disc herniations, and is associated with favorable clinical outcomes compared with open discectomy (OD). This study postulates that MED is a less traumatic procedure, and therefore has a lower surgical stress response compared to OD. In this study, a quantitative comparison of the overall effects of surgical trauma resulting from MED and OD was performed through analyzing patient systemic cytokines response. From April, 2002 to June, 2003, 22 consecutive patients who had symptomatic lumbar disc herniations were prospectively randomized to undergo either intracanalicular MED (N=10) or OD (N=12). In this study, the Vertebroscope System (Zeppelin, Pullach, Germany) was used to perform the endoscopic discectomy procedure in all MED patients. Serum levels of tumor necrosis factor-alpha (TNF-alpha), Interleukin-1beta (IL-1beta), Interleukin-6 (IL-6), and Interleukin-8 (IL-8) were measured before surgery and at 1, 2, 4, 8 and 24h after surgery using an enzyme-linked immunosorbent assay. Serum C-reactive protein (CRP) was measured at the same time interval. The results showed the MED patients had shorter postoperative hospital stay (mean, 3.57+/-0.98 vs. 5.92+/-2.39 days, p=0.025) and less intraoperative blood loss (mean, 87.5+/-69.4 vs. 190+/-115 ml, p=0.042). The operating length, including the set-up time, was longer in the MED group (mean, 109+/-35.9 vs. 72.1+/-17.8 min, p=0.01). The mean size of skin incision made for the MED patients was 1.86+/-0.13 cm (range 1.7-2.0 cm); and 6.3+/-0.98 cm for the OD patients (range 5.5-8 cm), p=0.001. The patients' pain severity of the involved limbs on 10-point Visual Analog Scale before operation in MED group was 7.5+/-0.3 (range 6-9) and 8+/-0.2 (range 7-9) in OD group, p=0.17; and after surgery, 1.5+/-0.2 (range 1-2) in MED group and 1.4+/-0.1 (range 1-3) in OD group, p=0.91. CRP levels peaked at 24h in both groups, and OD patients displayed a significantly greater postoperative rise in serum CRP (mean, 27.78+/-15.02 vs. 13.84+/-6.25mg/l, p=0.026). Concentrations of TNF-alpha, IL-1beta, and IL-8 were detected only sporadically. Serum IL-6 increased less significantly following MED than after OD. In the MED group, IL-6 level peaked 8h after surgery, with the response statistically less than in the open group (mean, 6.27+/-5.96 vs. 17.18+/-11.60 pg/ml, p=0.025). A statistically significant correlation was identified between IL-6 and CRP values (r=0.79). Using the modified MacNab criteria, the clinical outcomes were 90% satisfactory (9/10) in MED patients and 91.6% satisfactory (11/12) in OD patients at a mean 18.9 months (range 10-25) follow-up. Based on the current data, surgical trauma, as reflected by systemic IL-6 and CRP response, was significantly less following MED than following OD. The difference in the systemic cytokine response may support that the MED procedure is less traumatic. Moreover, our MED patients had achieved satisfactory clinical outcomes as the OD patients at a mean 18.9 months follow-up after surgery.

Effects of interleukin-1alpha administration on intestinal ischemia and reperfusion injury, mucosal permeability, and bacterial translocation in burn and sepsis

OBJECTIVE

To evaluate the effect of interleukin-1alpha (IL-1alpha) on the mesenteric circulation, intestinal mucosal integrity, and bacterial translocation in a burn/endotoxemia chronic porcine model.

SUMMARY BACKGROUND DATA

Major burn and sepsis are associated with a high mortality, ischemia/reperfusion injury to the intestine, and an increased rate of bacterial translocation. Pathologic alterations of IL-1 synthesis, degradation, and binding to receptors have been reported. Manipulation of IL-1-mediated effects might be of therapeutic utility.

METHODS

Twenty-one female pigs were instrumented with an ultrasonic flow probe on the superior mesenteric artery and a catheter into the superior mesenteric vein. After 5 days, all animals were anesthetized, and 14 received 40% total body surface area third-degree burn. IL-1alpha was administered intravenously at 1,000 ng/kg to seven pigs immediately after burn. Eighteen hours after burn, 100 microg/kg lipopolysaccharide (LPS) was administered intravenously. Systemic and splanchnic hemodynamics were measured and blood samples were drawn for blood gas analysis. Intestinal permeability was assessed every 6 hours by measuring the lactulose/mannitol (L/M) excretion ratio. At the end of the study (42 hours), tissue samples were harvested for bacteriologic cultures.

RESULTS

Mesenteric blood flow was significantly decreased after burn and endotoxin. Administration of IL-1alpha significantly improved mesenteric blood flow postburn and post-LPS. Mesenteric oxygen supply and consumption showed a significant reduction after burn. In contrast, animals treated with IL-1alpha showed an increase in postburn mesenteric oxygen supply and consumption. LPS-induced mesenteric hypoxia was also ameliorated by IL-1alpha treatment. Intestinal permeability, as assessed by the L/M ratio, showed a 7- and 10-fold elevation after thermal injury and LPS, respectively. In contrast, IL-1alpha-treated animals showed an increase of only three- and fourfold in the L/M ratio, respectively. Bacterial translocation was significantly increased in the burn/endotoxin group. IL-1alpha significantly reduced the rates of bacterial translocation.

CONCLUSIONS

IL-1alpha treatment attenuates mesenteric ischemia and reperfusion injury induced by thermal injury and endotoxemia by improving mesenteric blood flow and oxygenation. Subsequently, IL-1alpha reduces intestinal permeability and bacterial translocation after burn and sepsis.

Biomaterial implants induce the inflammation marker CRP at the site of implantation

Following implantation of biomaterial patches into the gastrointestinal tract, we analyzed the host's response towards the foreign material. Asymmetric patches of polydioxanone covered Vicryl or poly-3-hydroxybutyrate were sutured onto the rat stomach. Tissue samples were generated at distinct time intervals after surgery, and RNA profiles were compared by Differential Display. RT-PCR analysis of gene candidates that seemed differentially expressed showed that vitamin D binding protein mRNA was induced in stomach tissue after implantation of the biomaterial patches. In parallel, the amount of C-reactive protein mRNA was found to be increased transiently as well. Implants induce a tissue response that is specific for a given material.

Plasma neopterin/C-reactive protein ratio as an adjunct to the assessment of infection and cancer cachexia

Neopterin (NPT), a pteridine intermediate metabolite in the biopterine synthetic pathway, is synthesized and secreted by monocytes/macrophages upon stimulation, mainly by gamma-interferon produced by activated T cells. C-reactive protein (CRP) is one of the major acute-phase reactants and its release is thought to be mediated by interleukin-6. Plasma concentrations of NPT and CRP were synchronously analyzed in 25 determinations of 5 patients with severe infectious complications and 50 determinations of 10 cancer-burden patients representing cachexia. The mean value of NPT (pmol/ml) was 201.6 in the infection group and 16.5 in the cancer cachexia group. The mean value of CRP (mg/dl) was 12.5 in the infection group and 3.4 in the cancer cachexia group. The number of samples in which NPT alone exceeded the cut-off level were 0/25 (0%) in the infection group and 38/50 (76.0%) in the cancer cachexia group. The number of samples in which both NPT and CRP exceeded the cut-off level was 25/25 (100%) in the infection group and 12/50 (24.0%) in the cancer cachexia group. The mean ratio of NPT to CRP was 11.3 in the infection group and 30.7 in the cancer cachexia group, respectively. These results suggest that gamma-interferon could play the principal role in the pathogenesis of cancer cachexia and that interleukin-6 modified the disease status. Interleukin-6 would be the critical mediator of host responses in infectious complications.

Interleukin 1 beta inhibits synaptic strength and long-term potentiation in the rat CA1 hippocampus

Cytokines such as interleukin-1 beta (IL-1 beta) are released in the nervous system following inflammation or infection. Recently, IL-1 beta was shown to enhance synaptic inhibitory mechanisms. We therefore investigated the effect of IL-1 beta superfusion on long-term potentiation (LTP), the cellular model of memory and learning, evoked in the CA1 region by tetanic stimulation of the stratum radiatum in the rat hippocampal slice. IL-1 beta (150 pM-1.5 nM) superfused 10 min before tetanic stimulation significantly reduced LTP of the slope of the population excitatory postsynaptic potential (pEPSP) and the population spike (PS) amplitude in CA1 in a concentration-dependent manner. IL-1 beta (1.5 nM) applied for 10 min 1 h before tetanus significantly inhibited LTP of the PS amplitude and pEPSP slope and reduced pEPSP and PS values before tetanus as well, although the PS returned to control values before tetanus. Heat-inactivated IL-1 beta had no effect on pre-tetanus pEPSP or PS values or the induction of LTP. These data demonstrate that IL-1 beta modulates synaptic potentials and reduces LTP. These findings have important implications for the role of IL-1 beta in neuronal disorders following infection, perhaps best exemplified by HIV-1-associated dementia.

Post-operative circulating cytokine patterns--the influence of infection

OBJECTIVE

To study post-operative plasma concentrations of tumor necrosis factor alpha (TNF), interleukin-1 beta (IL-1) and interleukin-6 (IL-6) in infected and non-infected patients.

DESIGN

Prospective controlled clinical study.

SETTING

The intensive care unit (ICU) of a university hospital.

PATIENTS AND PARTICIPANTS

The study comprised 20 patients, 9 infected and 11 non-infected, consecutively admitted to the ICU after moderate or major surgery. Twelve healthy volunteers were used as controls.

MEASUREMENTS AND RESULTS

Leucocyte count, CRP and the plasma TNF, IL-1 and IL-6 concentrations were studied 24-48 h after the start of surgery. Axillary temperature, the duration of surgery, the number of packed red cells transfused, the APACHE II score and outcome were registered. Both infected and non-infected patients had higher plasma concentrations of IL-6 than the controls (p < 0.001 and p < 0.01 respectively). Patients with infection had a higher plasma IL-6 concentration than non-infected patients (p < 0.05). Similar analyses of plasma TNF concentrations revealed no differences between infected and non-infected patients. Plasma IL-1 was detected only occasionally. Non-survivors (n = 4) had higher plasma concentrations of TNF and IL-6 than survivors (p < 0.05 and p = 0.05 respectively). In non-infected patients a correlation between the number of units of packed red cells transfused and the plasma IL-6 concentration was observed (r = 0.73, p < 0.05).

CONCLUSION

No specific plasma cytokine pattern for infected patients subjected to surgery was observed. The effect of surgery and infection on the plasma IL-6 concentration seemed to be additive. Transfusion of packed red cells appeared to elevate the post-operative plasma IL-6 concentration.

Evaluation of PDGF-BB, PDGF-AA, bFGF, IL-1, and EGF dose responses in polyvinyl alcohol sponge implants assessed by a rapid histologic method

Polyvinyl alcohol sponge implants were used in rats, mice, and guinea pigs to determine dose responses of growth factors. Eight differently treated sponges per rat or guinea pig (4/mouse) were injected with test material on alternate days and evaluated at day 8. Much of the observed response occurred in and around the capsule and was manifest as densely cellular granulation tissue. Including this capsular response in a single histologic slide ranking system provided a more sensitive and faster method of assessing growth factor effects than measurement of connective tissue ingrowth alone. Clear dose responsive effects were seen with recombinant human PDGF-BB, PDGF-AA, bFGF, and IL-1 beta, while EGF gave a lesser response. Lipopolysaccharide did not affect the connective tissue response, alone or in combination with PDGF-BB. PDGF-BB was tested in each species, and the dose response characteristics were qualitatively and quantitatively similar across species.

Effects of anaesthesia and surgery on the immune response

Alterations have been found to occur in every component of immune response during anaesthesia and surgery. These alterations represent the body's general physiological responses and are mainly dependent on the extent of surgery, as well as other factors such as the patient's age and health status, medication and blood transfusion. Anaesthetic and operative complications have profound effects on these responses. Basically, the immune response to anaesthesia and surgery is a beneficial reaction, needed in local host defences and wound healing and in preventing the body from making autoantibodies against its own tissues. The responses may, however, contribute to the development of postoperative infections and spread of malignant disease. During uncomplicated conventional surgery, the immune response usually passes clinically unnoticed without any harmful effects. Absent responses and excessively high responses, on the other hand, harm the patient. Our understanding of immunological phenomena and our possibilities of controlling mediator activation are now lagging behind the technical advances made in operative treatment. If we want to decrease operative morbidity and mortality to below their present levels, more attention should be directed to immune responses to major surgery, injuries and operative complications with massive mediator release which place the surgical patient at risk. Experimental evidence suggests that results of treatment in injured and operated patients can in the future be improved by controlling immune responses and their mediator systems. Our current level of knowledge of immune responses is already helping us to avoid many immune-mediated complications. However, routine interference with these responses is not indicated.

Interleukin-1 produced by tumorigenic fibroblasts influences tumor rejection

Oncogene-transformed BALB/c-3T3 fibroblasts which spontaneously or upon immune-activation with cytokines and lipopolysaccharide (LPS) generate IL-1 alpha, were tested for their tumorigenicity as well as their interaction with natural immune defense by NK cells and macrophages. Oncogene-transformed fibroblasts were weakly tumorigenic, since not all mice developed tumors despite application of high doses of tumor cells. This was independent of the immune status of the host. However, in the immunocompetent host those transformed fibroblast lines which spontaneously produced IL-1 alpha grew only transiently and then regressed. After induction of IL-1 alpha production, a decrease in the rate of tumor take was noted and the rate of regression of developing tumors was increased. Regression of IL-1-producing transformed fibroblasts was strongly reduced but not completely abolished in sublethally irradiated mice. This indicated that IL-1 production may predominantly influence T-cell-mediated defense, but some influence on non-adaptive immunity could not be excluded a priori. IL-1 production did not influence susceptibility of transformed fibroblasts towards NK cells and macrophages. However, IL-1-producing transformed fibroblasts were most potent stimulators of NK cells and macrophages, the stimulatory effect being locally restricted. In conclusion, IL-1 producing, oncogene-transformed fibroblasts which generated the cytokine constitutively or upon immune-activation, were rejected from the tumor-bearing host following initial growth. Fibroblast-induced local activation of NK cells and macrophages was shown to play some role in tumor graft rejection. The influence of IL-1 production of transformed fibroblasts on T-cell-mediated defense is addressed in the accompanying report.

Multiple Organ Failure Syndrome—Part I: Epidemiology, Prognosis, and Pathophysiology

The multiple organ failure syndrome (MOFS) is the leading cause of death in intensive care units. Although sepsis is an important cause of MOFS, it is clear that MOFS can occur in the absence of infection. The pathophysiology of MOFS is complex and multifactorial and includes derangements in oxygen delivery and consumption, the release of inflammatory and vasoactive mediators capable of inflicting tissue damage, and alterations in the barrier function of the intestinal mucosa. Although advances have been made in our understanding of MOFS, treatment remains nonspecific and largely supportive. Early and aggressive restoration of tissue perfusion, adequate treatment of infection, timely nutritional support, and support of individual failed organs remain the mainstay of therapy. Therapeutic agents directed against the various mediators associated with the pathophysiology of MOFS may prove useful in the future.

Tooth movement

This article reviews the evolution of concepts regarding the biological foundation of force-induced tooth movement. Nineteenth century hypotheses proposed two mechanisms: application of pressure and tension to the periodontal ligament (PDL), and bending of the alveolar bone. Histologic investigations in the early and middle years of the 20th century revealed that both phenomena actually occur concomitantly, and that cells, as well as extracellular components of the PDL and alveolar bone, participate in the response to applied mechanical forces, which ultimately results in remodeling activities. Experiments with isolated cells in culture demonstrated that shape distortion might lead to cellular activation, either by opening plasma membrane ion channels, or by crystallizing cytoskeletal filaments. Mechanical distortion of collagenous matrices, mineralized or non-mineralized, may, on the other hand, evoke the development of bioelectric phenomena (stress-generated potentials and streaming potentials) that are capable of stimulating cells by altering the electric charge on their membrane or their fluid envelope. In intact animals, mechanical perturbations on the order of about 1 min/d are apparently sufficient to cause profound osteogenic responses, perhaps due to matrix proteoglycan-related "strain memory". Enzymatically isolated human PDL cells respond biochemically to mechanical and chemical signals. The latter include endocrines, autocrines, and paracrines. Histochemical and immunohistochemical studies showed that during the early places of tooth movement, PDL fluids are shifted, and cells and matrix are distorted. Vasoactive neurotransmitters are released from periodontal nerve terminals, causing leukocytes to migrate out of adjacent capillaries. Cytokines and growth factors are secreted by these cells, stimulating PDL cells and alveolar bone lining cells to remodel their related matrices. This remodeling activity facilitates movement of teeth into areas in which bone had been resorbed. This emerging information suggests that in the living mammal, many cell types are involved in the biological response to applied mechanical stress to teeth, and thereby to bone. Essentially, cells of the nervous, immune, and endocrine systems become involved in the activation and response of PDL and alveolar bone cells to applied stresses. This fact implies that research in the area of the biological response to force application to teeth should be sufficiently broad to include explorations of possible associations between physical, cellular, and molecular phenomena. The goals of this investigative field should continue to expound on fundamental principles, particularly on extrapolating new findings to the clinical environment, where millions of patients are subjected annually to applications of mechanical forces to their teeth for long periods of time in an effort to improve their position in the oral cavity.(ABSTRACT TRUNCATED AT 400 WORDS)

Induction of interleukin-1 beta mRNA in adult rat brain

The ability of the central nervous system to produce the cytokine interleukin-1 beta (IL-1 beta) in response to challenge by activators of the mononuclear phagocyte system has been examined in vivo. Unilateral injection of a mixture of gamma-interferon (IFN-gamma) and lipopolysaccharide (LPS) into the forebrain of adult rats induced expression of IL-1 beta mRNA. In situ hybridization of IL-1 beta mRNA showed a gradient of cellular hybridization, which was most intense at the site of IFN-gamma/LPS injection. The reverse transcription--polymerase chain reaction (RT-PCR) was used to demonstrate the presence of IL-1 beta mRNA in normal rat brain, and to confirm increases in IL-1 beta mRNA levels following IFN-gamma/LPS injection. These studies show that IL-1 beta can be induced to high levels within the CNS as a consequence of exposure to potent stimulators of macrophage activation.

Cellular and morphological changes in lymphoid organs after a single injection of interleukin 1 alpha in the mouse

We investigated the effects of a single i.v. injection of recombinant human interleukin 1 alpha (IL-1 alpha) on the morphology and the cellularity of several lymphoid organs in normal mice. The injection of 100 U of IL-1 alpha resulted in maximal neutrophilia and leukocytosis at 1 h. By 72 h, the numbers of mononuclears, but not that of polymorphonuclears, returned to baseline levels. Absolute increase in mononuclears was paralleled by relative lymphopenia. Changes in the peripheral blood coincided with rapid decrease in the spleen cellularity and white pulp volume (especially the marginal zone), and an increase in the red pulp volume. Bone marrow cellularity was increased at 1 h, but returned to control levels by 6 h after IL-1 injection. Thymus cell depletion and cortex atrophy were maximal at 6 h and could be observed throughout the experiment. These findings indicate that leukocytosis induced by a single i.v. injection of IL-1 alpha in normal mice is concomitant with a rapid cell depletion of the spleen and thymus. Morphological and cellular changes in lymphoid organs may represent the mobilization of immunocompetent cells during the development of the inflammatory response.

Serum interleukin 6, C-reactive protein and pancreatic secretory trypsin inhibitor (PSTI) as acute phase reactants after major thoraco-abdominal surgery

We measured serum immunoreactive interleukin 6 (IL-6) levels in patients after major thoraco-abdominal surgery and compared them with changes in serum C-reactive protein (CRP) and pancreatic secretory trypsin inhibitor (PSTI) levels. Serum IL-6 levels were elevated earlier than serum CRP or PSTI. There were significant relationships between the peak levels of serum IL-6 and the operation time (p less than 0.05) or the volume of blood loss during surgery (p less than 0.05), showing that serum IL-6 can be a useful laboratory test for the evaluation of tissue injuries due to surgical intervention. Though there was a significant relationship between the peak levels of IL-6 and CRP (p less than 0.01), there was no relationship between the peak levels of IL-6 and PSTI.