Local Tissue Response Research Articles

Strategic considerations on the configuration of free flaps and their vascular pedicles combined with Ilizarov distraction in the lower extremity.

For the injury of the lower leg associated with both bone and soft-tissue defect, the combined free flap and the Ilizarov distraction method were described as a useful treatment modality. During the procedure of distraction, however, revisions were frequently needed to change the pin position or to change the flap configuration. In case of flap ischemia, distraction should be delayed or abandoned. Then, a vascularized bone transfer might be necessary. To avoid these complications and achieve safe distraction, the configuration of the flap with its vascular pedicle should be carefully planned in terms of the future bony lengthening procedures and the concomitant soft-tissue changes of the lower leg. According to the response of local tissue to the distraction process, the lower limb can be divided into four compartments (active mobile, passive mobile, receptive, and restrictive). The configuration of the transferred free flap with its vascular pedicle can be classified into five types. To minimize the undue forces to the vascular pedicle and reduce the possibility of vascular compromise, the transferred free flap should have the configuration that its vascular pedicle lies in the territory of the mobile compartment. In performing free-tissue transfer combined with the Ilizarov method in the lower extremity, the configuration of the flap with its vascular pedicle should be carefully planned, and the characteristics of lower leg tissue should be kept in mind during the distraction.

Sterilization, storage stability and in vivo biocompatibility of poly(trimethylene carbonate)/poly(adipic anhydride) blends

Biodegradable blends of poly(trimethylene carbonate) (PTMC) and poly(adipic anhydride) (PAA) have been proven to be strong candidates for controlled drug delivery polymers in vitro. We now report on the stability, sterilizability and in vivo local tissue response of these matrices. Blend matrices were sterilized by β-radiation or ethylene oxide gas treatment, stored at different times and temperatures, and analyzed for changes in physicochemical properties. Moisture uptake at different relative humidities and storage times was determined. Sterilization procedures induced hydrolysis of the matrices. Ethylene oxide gas sterilization had a significantly more marked effect upon the matrix properties than radiation treatment. The onset of degradation was reflected in a decrease of crystallinity and molecular weight along with a change of blend composition. A similar onset of matrix degradation was observed upon storage in air. The physicochemical properties of the blends were well preserved upon storage under argon atmosphere. Biocompatibility of PTMC/PAA implants was assessed in the anterior chamber of rabbits eyes for 1 month. At selected post-operative time points, aqueous humor was analyzed for white blood cells and the corneal thickness was measured. The results suggest good biocompatability of PTMC-rich matrices, whereas fast eroding PAA-rich matrices caused inflammatory responses, due to a burst release of degradation products.

B7h and B7-H1: new members of the B7 family: Swallow, M.M. et al. (1999) B7h, a novel costimulatory homolog of B7.1 and B7.2, is induced by TNF-α. Immunity 11, 423–432; Dong, H. et al. (1999) B7-H1, a third member of the B7 family, co-stimulates T-cell proliferation and interleukin-10 secretion. Nat. Med. 5, 1365–1369

Two novel members of the B7 family, murine B7h and human B7-H1, have recently been identified. B7h was identified using a subtractive screen designed to isolate tumour necrosis factor α (TNF-α)-induced genes that are specifically regulated by NF-κB/Rel transcription factors, whereas B7-H1 was identified by searching an EST database for homologues of B7-1 and B7-2.The classic costimulatory molecules, B7-1 and B7-2, are constitutively expressed on dendritic cells and upregulated after activation on monocytes, macrophages, and B and T cells. B7h is expressed on antigen-presenting cells (APCs) but can also be expressed on other cell types in response to TNF stimulation. The inducible expression of B7h on non-APCs and the higher threshold of T-cell receptor activation required for costimulation via B7h, suggest a distinct functional role for B7h compared with B7-1 and B7-2. The authors speculate that instead of costimulating naive T cells, B7h may influence local tissue responses by costimulating T cells following their primary activation in lymph nodes.Both B7h and B7-H1 stimulate T-cell proliferation independent of CD28 and CTLA-4. However, B7h may interact with ICOS, a recently described homologue of CD28 and CTLA-4. B7-H1 also stimulates T-cell proliferation and increases cytokine secretion, especially interleukin 10 (IL-10); IL-2, although produced in small amounts, is necessary for B7-H1 costimulation. The data from these two papers suggest that, in contrast to B7-1 and B7-2, the newer members of the family might act as negative regulators of cellular immune responses.

Parathyroid adenomas with pronounced lymphocytic infiltration: no evidence of autoimmune pathogenesis.

Pronounced lymphocytic infiltration in parathyroid adenoma is rare, with only six previously reported cases in the literature. The aims of this study are to review the features and investigate the pathogenesis of this rare entity. Two solitary parathyroid adenomas having this feature were reported, and the clinicopathologic features of all the documented cases were reviewed. The nature of the lymphoid infiltrate and the presence of Epstein-Barr virus (EBV) were analyzed to unveil the pathogenesis of this infiltrate. One adenoma was found in a 70-yr-old woman with primary hyperparathyroidism and valvular heart disease. The other was an autopsy finding in a 48-yr-old man who had presented with hypercalcemic crisis. The lymphoid cell population within the tumors was composed of B cells and different subsets of T cells. EBV was not detected in the infiltrates. The lymphocytic infiltrate in parathyroid adenoma is an unusual histologic entity. Its presence is unlikely to imply an autoimmune disorder. We hypothesize that the lesion may be a result of local tissue response to parathyroid adenoma.

BLADDER HISTOLOGICAL CHANGES ASSOCIATED WITH CHRONIC INDWELLING URINARY CATHETER

Purpose Chronic urinary catheters induce histological changes in the bladder with time. The exact etiology of these changes is postulated to arise from inflammation and local tissue response. We elucidate the incidence of nonmalignant histological change in bladder biopsies of patients with chronic indwelling urinary catheters. Materials and Methods During 7 years 208 spinal cord injured patients underwent bladder biopsies as part of a surveillance program for vesical malignancy. All patients had chronic (more than 8.5 years) indwelling urethral or suprapubic catheters as definitive management for neurogenic voiding dysfunction. Biopsies were obtained from 4 to 6 sites within the bladder, including areas that were visually abnormal. All samples were routinely fixed with hematoxylin and eosin staining, and interpreted by an experienced pathologist. Results A total of 17 patients were identified with malignancy, including 10 with squamous cell carcinoma, 5 with transitional cell carcinoma and 2 with adenocarcinoma. Nonmalignant changes occurred in 48 patients (23%) with keratinizing squamous metaplasia or cystitis glandularis, each of which is considered a premalignant lesion. Conclusions To our knowledge our study represents the largest group of signal cord injured patients to undergo biopsy evaluation after chronic catheter use. A spectrum of inflammatory and proliferative pathological conditions were identified, which were predominantly inflammatory and squamous. The need to survey ongoing transitional mucosal changes in this population is underscored by the spectrum of histological abnormalities and the significant occurrence of malignant pathologies in our patients.

In vitro and in vivo comparison of bulk and surface hydrolysis in absorbable polymer scaffolds for tissue engineering

This article describes preliminary in vitro and in vivo studies comparing bulk and surface hydrolysis in absorbable polymer scaffolds proposed for tissue engineering of bone. The two polymers systems used were a bulk hydrolyzing 50:50 poly(DL-lactide-co-glycolide) (PLGA) and a surface hydrolyzing self-catalytic poly(ortho ester) (POE). Polymer scaffolds were exposed to physiological saline at body temperature and changes in polymer mass loss and inherent viscosity were monitored over time. New bone formation and local tissue response were evaluated by implanting scaffold disks of both polymer systems into non-critical-size calvarial defects in rabbits. New bone formation was determined by bone mineral density measurements, and local tissue response was determined by qualitative histology. Preliminary results confirmed that one of the main design characteristics for absorbable polymers in tissue engineering of bone, coordination of controlled polymer mass loss with new tissue formation, appeared to be achieved better using a surface hydrolyzing POE, rather than with a bulk hydrolyzing 50:50 PLGA. Bone mineral density at 6 and 12 weeks was an average 25% higher in the surface hydrolyzing scaffold. Unfortunately, the amount of bone formed was so inconsequential that this observation is of little relevance. Use of a water-soluble signaling factor such as basic fibroblast growth factor (bFGF) failed to increase bone formation. The histological response of these two polymer systems was similar and unaffected by the presence or absence of bFGF. The persistence of structural integrity for self-catalytic POE scaffolds after 6 and 12 weeks implantation, while 50:50 PLGA scaffolds had partially collapsed after 6 weeks, suggests surface hydrolyzing scaffolds may have some advantage over bulk hydrolyzing scaffolds in resisting normal in vivo stresses when used in a calvarial defect. © 1999 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater;rpar; 48: 602–612, 1999

Characterization of protective immune responses in local lymphoid tissues after drug-attenuated infections with Ostertagia ostertagi in calves

In the present study, cell-surface markers and cytokine gene expression of lymphocytes from the local lymph nodes were studied 9 days after primary infection with Ostertagia ostertagi in previously naive calves or in calves previously immunized with multiple, chemically attenuated infections. Changes in lymphocyte populations were assessed by flow cytometry utilizing monoclonal antibodies specific for bovine cell-surface markers. Changes observed in the percentages of lymphoid populations after challenge were similar in animals immunized by either three or five drug-attenuated infections. In both immunized groups, the CD4 +/CD8 + ratio was significantly higher than in naive animals after challenge infections. In addition, both immunized groups showed significantly lower levels of Ig-bearing cells upon experimental challenge when compared to animals with a primary experimental infection. No differences were observed in the number of γδ or interleukin 2 receptor (IL-2R) positive cells. The levels of mRNA for IL-4, IL-10, IL-15, IFN-γ and TGF-β1 were examined by competitive RT-PCR. After challenge, the levels of these cytokines were lower in animals immunized by five drug-attenuated infections, and in the case of IL-4 and TGF-β1, these differences were statistically significant. These results indicate that animals exhibiting protection from reinfection with O. ostertagi do not show a shift to higher percentages of Ig + cells characteristic of a primary infection. In addition, protected animals appear to show a decreased IL4 and TGF-β1 response upon challenge when compared to non-immune animals.

Factor XIIIa-positive dermal dendritic cells and HLA-DR expression in radial versus vertical growth-phase melanomas.

Fifty nevomelanocytic lesions, including 10 typical compound nevi and 20 radial and 20 vertical growth-phase melanomas, were evaluated for factor XIIIa and HLA-DR (LN3) expression within dermal dendritic cells (DDCs) or dermal dendrocytes to determine if DDCs proliferate and/or participate as possible antigen-presenting cells in the local tissue response to benign and malignant nevomelanocytic lesions. There was no statistical difference in factor XIIIa staining of DDCs between nevi and radial or vertical growth-phase melanomas, suggesting that DDCs do not significantly proliferate in nevomelanocytic lesions. However, studies to determine proliferation rate, apoptosis, and influences of local mediators on cell growth and/or recruitment were not done. HLA-DR staining by DDCs was significantly increased (p<0.001) in both melanoma groups when compared to compound nevi, but did not significantly differ between radial and vertical growth-phase melanomas. The intensity of HLA-DR expression appeared to correlate with the presence or absence of lymphocytic inflammation; HLA-DR intensity was judged greater in melanomas characterized by a brisk and infiltrative lymphocytic host response. We propose that DDCs may participate in the dermal immune response to invasive melanomas, probably as antigen-presenting cells to skin-associated lymphocytes.

Metal release in patients who have had a primary total hip arthroplasty. A prospective, controlled, longitudinal study.

There is an increasing recognition that, in the long term, total joint replacement may be associated with adverse local and remote tissue responses that are mediated by the degradation products of prosthetic materials. Particular interest has centered on the metal-degradation products of total joint replacements because of the known toxicities of the metal elements that make up the alloys used in the implants. We measured the concentrations of titanium, aluminum, cobalt, and chromium in the serum and the concentration of chromium in the urine of seventy-five patients during a three-year prospective, longitudinal study. Twenty patients had had a so-called hybrid total hip replacement (insertion of a modular cobalt-alloy femoral stem and head with cement and a titanium acetabular cup without cement), fifteen had had insertion of an extensively porous-coated cobalt-alloy stem with a cobalt-alloy head and a titanium-alloy socket without cement, and twenty had had insertion of a proximally porous-coated titanium-alloy stem with a cobalt-alloy head and a titanium socket without cement. The remaining twenty patients did not have an implant and served as controls. The results of our study showed that, thirty-six months postoperatively, patients who have a well functioning prosthesis with components containing titanium have as much as a threefold increase in the concentration of titanium in the serum and those who have a well functioning prosthesis with cobalt-alloy components have as much as a fivefold and an eightfold increase in the concentrations of chromium in the serum and urine, respectively. The predominant source of the disseminated chromium-degradation products is probably the modular head-neck junction and may be a function of the geometry of the coupling. Passive dissolution of extensively porous-coated cobalt-alloy stems was not found to be a dominant mode of metal release. Increased concentrations of circulating metal-degradation products derived from orthopaedic implants may have deleterious biological effects over the long term that warrant investigation. This is a particularly timely concern because of recent clinical trends, including the reintroduction of metal-on-metal bearing surfaces and the increasing popularity of extensively porous-coated devices with large surface areas of exposed metal. Accurate monitoring of the concentrations of metal in the serum and urine after total hip replacement also can provide insights into the mechanisms of metal release. Our findings suggest that fretting corrosion at the head-neck coupling is an important source of metal release that can lead to increased concentrations of chromium in the serum. Determinations of the concentrations of metal in the serum and urine may be useful in the diagnosis of patients who are symptomatic after a total joint replacement as increased levels are indicative of at least one mode of mechanical dysfunction (for example, fretting corrosion) of the device.

HEMA/MMMA microcapsule implants in hemiparkinsonian rat brain: biocompatibility assessment using [ 3H]PK11195 as a marker for gliosis

Microencapsulation of dopamine-secreting cells in biocompatible, semi-permeable polymer membranes has been proposed as an alternative strategy for dopamine replacement for Parkinson’s disease. In order to assess the viability of this proposal, dopaminesecreting PC12 cells were immunoisolated via microencapsulation in a 75 : 25 2-hydroxyethyl methacrylate/methyl methacrylate (HEMA/MMA) copolymer. A submerged nozzle-liquid jet method was used to produce small diameter (400 μm) microcapsules, which were stereotaxically implanted in the denervated striatum of hemi-Parkinsonian rats. A 96% survival rate was associated with the implantation surgery and no deleterious side effects were apparent. Light microscopy revealed good biocompatibility between the HEMA/MMA copolymer and the host brain, as evidenced by the absence of gross tissue damage at the neuronal tissue/capsule interface. Autoradiographic analyses using [ 3H]PK11195 as marker for reactive astrocytes revealed a moderate inflammatory response, confined to the immediate vicinity of the injection tract. Quantitative analyses indicated that the local tissue response did not differ significantly between brains implanted with PC12-containing capsules and those implanted with vehicle-containing capsules. Taken together, these results support the biocompatibility of HEMA/MMA copolymer as well as the feasibility and safety of stereotaxic implantation of microcapsules.

Role of carbon fibre implants in osteochondral defects of the knee.

Articular cartilage defects of the knee are a common condition diagnosed at arthroscopy. The management of these osteochondral lesions is controversial. We present our experience using carbon fibre implants to repair these defects in 18 patients. Eleven patients (61 per cent) had an osteochondral defect of the medial femoral condyle. Two patients had isolated patellar defects. The mean knee assessment and functional scores were 75 and 80 respectively using The Knee Society Clinical Rating System. Serial post-operative M.R.I. scanning revealed that there was no loss of implant position with an extensive local tissue response and good joint congruity. Overall, 11 patients (61 per cent) returned to their normal sporting activity, while 3 patients (18 per cent) had a poor result. One of these underwent a patellectomy. We conclude that carbon fibre implants may have a role to play in the management of osteochondral defects of the femoral condyles.

Corrosion of metal orthopaedic implants.

In situ degradation of metal-alloy implants is undesirable for two reasons: the degradation process may decrease the structural integrity of the implant, and the release of degradation products may elicit an adverse biological reaction in the host. Degradation may result from electrochemical dissolution phenomena, wear, or a synergistic combination of the two. Electrochemical processes may include generalized corrosion, uniformly affecting the entire surface of the implant, and localized corrosion, affecting either regions of the device that are shielded from the tissue fluids (crevice corrosion) or seemingly random sites on the surface (pitting corrosion). Electrochemical and mechanical processes (for example, stress corrosion cracking, corrosion fatigue, and fretting corrosion) may interact, causing premature structural failure and accelerated release of metal particles and ions. The clinical importance of degradation of metal implants is evidenced by particulate corrosion and wear products in tissue surrounding the implant, which may ultimately result in a cascade of events leading to periprosthetic bone loss. Furthermore, many authors have reported increased concentrations of local and systemic trace metal in association with metal implants1,4,5,9-11,14,18,25,26,28,29,47,49-55,58,71,72,75-77,87,90,108-110. There also is a low but finite prevalence of corrosion-related fracture of the implant. This review focuses on electrochemical corrosion phenomena in alloys used for orthopaedic implants. A summary of basic electrochemistry is followed by a discussion of retrieval studies of the response of the implant to the host environment and the response of local tissue to implant corrosion products. The systemic implications of the release of metal particles also are presented. Finally, future directions in biomaterials research and development …

Preliminary in vivo report on the osteocompatibility of poly(anhydride-co-imides) evaluated in a tibial model.

A novel class of polymers with mechanical properties similar to cancellous bone are being investigated for their ability to be used in weight-bearing areas for orthopedic applications. The poly(anhydride-co-imide) polymers based on poly[trimellitylimidoglycine-co-1,6-bis(carboxyphenoxy)hexan e] (TMA-Gly:CPH) and poly[pyromellitylimidoalanine-co-1,6-bis(carboxyphenoxy)hexa ne] (PMA-Ala:CPH) in molar ratios of 30:70 were investigated for osteocompatibility, with effects on the healing of unicortical 3-mm defects in rat tibias examined over a 30-day period. Defects were made with surgical drill bits (3-mm diameter) and sites were filled with poly(anhydride-co-imide) matrices and compared to the control poly(lactic acid-glycolic acid) (PLAGA) (50:50), a well-characterized matrix frequently used in bone regeneration studies, and defects without polymeric implants. At predetermined time intervals (3, 6, 9, 12, 20, and 30 days), animals were sacrificed and tissue histology was examined for bone formation, polymer-tissue interaction, and local tissue response by light microscopy. The studies revealed that matrices of TMA-Gly:CPH and PMA-Ala:CPH produced responses similar to the control PLAGA with tissue compatibility characterized by a mild response involving neutrophils, macrophages, and giant cells throughout the experiment for all matrices studied. Matrices of PLAGA were nearly completely degraded by 21 days in contrast to matrices of TMA-Gly:CPH and PMA-Ala:CPH that displayed slow erosion characteristics and maintenance of shape. Defects in control rats without polymer healed by day 12, defects containing PLAGA healed after 20 days, and defects containing poly(anhydride-co-imide) matrices produced endosteal bone growth as early as day 3 and formed bridges of cortical bone around matrices by 30 days. In addition, there was marrow reconstitution at the defect site for all matrices studied along with matured bone-forming cells. This study suggests that novel poly(anhydride-co-imides) are promising polymers that may be suitable for use as implants in bone surgery, especially in weight-bearing areas.

Liver ischemia/reperfusion induces an increase of microvascular leukocyte flux, but not heterogeneity of leukocyte trafficking.

Leukocytic response plays a major role in the manifestation of hepatic ischemia/reperfusion (I/R) injury. To clarify whether post-ischemic hepatic leukocyte accumulation is based on increased leukocyte flux to the hepatic tissue due to systemic inflammation or chemoattractant activities or whether it represents solely a local tissue response without changing overall leukocyte flux and trafficking characteristics through the microvasculature, we studied acinar and sinusoidal leukocyte flux and distribution in rat livers in vivo both under normal (sham, n = 8) and post-ischemic (60' ischemia/75' reperfusion) conditions (I/R, n = 8), using fluorescence epi-illumination microscopy (rhodamine-6G). Hepatic ischemia/reperfusion significantly (p < 0.05) increased acinar leukocyte flux (58.4 +/- 20.9 cells/min vs 36.4 +/- 12.8 cells/min in sham controls); however, it did not exhibit increased heterogeneity of acinar leukocyte distribution, as indicated by the unchanged coefficient of variance (CV) of 0.36 +/- 0.16 (sham controls: 0.31 +/- 0.14). In parallel, analysis of individual sinusoidal leukocyte flux demonstrated significantly (p < 0.05) higher values (8.9 +/- 3.7 cells/min) after ischemia/reperfusion when compared with sham controls (5.7 +/- 1.9 cells/min), which, however, was not associated with increased heterogeneity of sinusoidal leukocyte trafficking (CV: 0.85 +/- 0.15 vs 0.85 +/- 0.16 in sham controls) and manifestation of preferential pathways. Analysis of blood cell count did not demonstrate an overall increase of total blood leukocyte count; however, an increased (p < 0.01) fraction of polymorphonuclear leukocytes (65.2 +/- 11.2%) and stab cells (9.5 +/- 7.9%) during post-ischemic reperfusion when compared with sham controls (8.8 +/- 3.5% and 0.2 +/- 0.4%) was demonstrated. Thus, the increase of hepatic leukocyte flux after ischemia/reperfusion may be the result of both the manifestation of a systemic inflammatory response and the increase of local chemoattractant activities, such as the production and release of the cytokine-induced neutrophil chemoattractant of the IL-8 family.

Coronary restenosis.

Return of angina within 6 months of a catheter-based treatment of coronary artery disease usually reflects restenosis due to an overly aggressive local healing response to the procedure-related arterial injury. The restenotic lesion should be treated aggressively. Patients with preexisting diabetes mellitus, renal failure requiring hemodialysis, and left anterior descending artery lesions should be considered to be at exceedingly high risk for clinically significant restenosis. Exercise testing is indicated for all patients who experience a return of their angina within 6 months of an interventional procedure. Nurse practitioners in the primary care setting may be the first clinicians to hear of the return of angina. Patients should always be reassured that repeat intervention is almost always possible and is generally effective in providing long-term relief. New devices (in particular the Palmaz-Schatz stent) may help reduce the likelihood of restenosis, to the extent that they provide a large acute post-treatment lumen diameter that is more tolerant of intimal hyperplasia without producing significant narrowing. Until adjunctive drug therapy is found that effectively reduces the local tissue response to interventional therapy, all clinicians involved in caring for patients following such procedures will need to be vigilant and knowledgeable about recognizing and treating restenosis.

Tissue reaction to gutta‐percha particles of various sizes when implanted subcutaneously in guinea pigs

Tissue reaction to gutta-percha was studied using subcutaneously implanted Teflon cages in guinea pigs. Gutta-percha was tested in three forms: (i) as large particles prepared by dividing gutta-percha cones into pieces, (ii) as fine particles prepared by ball-milling of gutta-percha, and (iii) as particles produced by dissolving gutta-percha in rosin-chloroform. Gutta-percha evoked two distinct types of tissue response. The large pieces were well encapsulated and the surrounding tissue was free of inflammation. The fine particles evoked an intense, localized tissue response, characterized by the presence of macrophages and multinucleated giant cells. The rosin-chloroform treated gutta-percha induced a similar tissue reaction to that observed with the fine particles of gutta-percha. In addition, cell remnants were present in association with the material, which indicates an initial toxicity to rosin-chloroform treated gutta-percha. These results show that the size and surface character of gutta-percha can determine the type of tissue reaction to the material. The accumulation of macrophages around gutta-percha may be an important factor in the impairment of healing of periapical lesions when teeth are root filled with excess material.

Comparison of the pharmacokinetics of parenteral parathyroid hormone-(1-34) [PTH-(1-34)] and PTH-related peptide-(1-34) in healthy young humans.

The amino-terminal fragments of human PTH [hPTH-(1-34)] and PTH-related peptide [PTHrP-(1-34)] appear to be equipotent in several rodent models. However, continuous i.v. infusions of these peptides to young human volunteers suggested that a 10-fold higher molar dose of PTHrP was required to produce comparable circulating levels of the peptide and biochemical responses similar to PTH. As PTHrP has a wide variety of target tissues in mammalian species and may, therefore, play a paracrine, rather than an endocrine, hormonal role in vivo, we evaluated whether enhanced metabolic clearance of injected PTHrP might explain its apparently reduced potency as a PTH-like hormone. Ten healthy subjects [age, 25 +/- 9 (+/- SD) yr] received in random order either hPTH-(1-34) or hPTHrP-(1-34) given by bolus i.v. injections in a dose of 10.7 nmol. Measurements of plasma immunoreactive peptide indicated a comparable volume of distribution for each, but the apparent t1/2 (8.3 +/- 1.6 min) and plasma clearance (4.0 +/- 1.4 L/min) for hPTHrP were significantly (P < 0.05) accelerated compared to those of hPTH (t1/2, 10.2 +/- 0.5 min; clearance, 2.0 +/- 0.4 L/min). Peak plasma cAMP levels were 9-fold lower in response to hPTHrP (29.5 +/- 19 vs. 190 +/- 63 pmol/L; P < 0.01), and increases in urinary cAMP excretion were 5-fold lower (2.1 +/- 1.1 vs. 11.2 +/- 3.7 nmol/mmol creatinine; P < 0.01). No major differences were observed in the urinary excretion of phosphate, calcium, or sodium between the two peptides. Although hPTHrP-(1-34) has a 2-fold higher MCR than hPTH-(1-34), this may not explain the more than 5-fold lower plasma or urinary cAMP response to PTHrP in humans. The comparable effects of PTH and PTHrP on urinary phosphate, calcium, and sodium may indicate a non-cAMP-dependent pathway for these responses, although the intracellular pool of cAMP generated to either peptide, and thus the local target tissue response, could not be estimated in the present study.

Molecular cloning, characterization, and tissue distribution of rat lipopolysaccharide binding protein. Evidence for extrahepatic expression.

LPS binding protein (LBP) is a glycoprotein present in normal serum that becomes markedly elevated during acute phase responses. LBP has been reported to greatly potentiate host responses to endotoxin or LPS. Therefore, LBP may play a critical role in the body's response to injury and infection. Little is known about the factors regulating production of LBP. To investigate the regulation of LBP expression, we have cloned the full-length cDNA for rat LBP. The deduced amino acid sequence of rat LBP was highly homologous with that reported for rabbit and human LBP. The sequence of rat LBP further refines the conserved regions found within the family of proteins that bind LPS; this family is comprised of bactericidal permeability-increasing protein and LBP from multiple species. Use of the rat LBP cDNA clone for Northern blot analysis reveals that LBP mRNA levels are markedly up-regulated in liver during acute phase responses. However, in contrast to previous reports, we also find evidence of extrahepatic expression of LBP under these induced conditions. The presence of LBP mRNA in activated tissues other than liver suggests that LBP may play a larger role in local tissue responses to LPS than previously appreciated.

Local immune inflammatory response to infected total hip and knee replacements.

We studied the tissue response for periprosthetic pseudosynovial tissue in seven patients with a purulent endoprosthetic infection and six patients with common prosthesis loosening, using specific monoclonal antibodies in avidin-biotin-peroxidase complex staining. In infected cases, proline 4-hydroxylase positive fibroblasts dominated the stroma of the vascularized periprosthetic connective tissue, whereas diffuse local infiltrations of mononuclear cells characterized the cellular histological overview. Local cellular response consisted of CD11b and MHC locus II antigen-positive immunoreactive monocytes/macrophages and of T lymphocytes, mostly of the CD4 subset. Only a few CD25-positive cells could be detected. The local cellular response in six patients with prosthesis loosening of nonbacterial origin was mild, showing a sparse perivascular infiltration of CD11b- and Ia-positive monocytes/macrophages and CD4/CD8-positive T lymphocytes in a proportion of 2:1. Only occasional CD15- or lactoferrin-positive neutrophils and CD25-positive lymphocytes could be detected. Our results from chronically infected joint replacements suggest that neutrophils, being virtually absent in the tissue compartment, do not contribute to pathological events in the "pseudojoint" cavity, whereas local tissue response consists of a mononuclear inflammatory cell reaction of a macrophage-dependent foreign-body type.

Serum immunoglobulin G antibodies to Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Streptococcus sanguis during experimental gingivitis in young adults.

Twenty-eight young, healthy adults completed an experimental gingivitis study in which blood and clinical recordings were obtained at baseline; after a 4-week period of thorough oral hygiene; after a subsequent 3-week period of plaque accumulation; and after another 2 weeks of thorough oral hygiene. Serum immunoglobulin G antibodies against whole cells of Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Streptococcus sanguis were determined using enzyme-linked immunosorbent assay. Mean serum immunoglobulin G antibody levels to P. intermedia, F. nucleatum and S. sanguis remained essentially constant during the experiment, whereas the immunoglobulin G antibodies to P. gingivalis declined during the initial period of oral hygiene and the subsequent period of plaque accumulation to an average of 84.5% of the baseline value. This reduction could be attributed to the people who developed marked gingival inflammation during the period of plaque accumulation, indicating that the systemic host response may be associated with local tissue responses to variations in oral hygiene. These people were, however, also characterized by higher initial serum immunoglobulin G responses to P. gingivalis than people who developed less pronounced gingival inflammation during the experiment. The variability and individuality noted in the host response to potential pathogens have important implications for attempts to use such measures for establishing a diagnosis or prognosis for the individual patient.