Calcitonin producing tumour. Effects on fracture repair and normal bone in rats

Analysis and prevalence of inflammatory cells in subtypes of lumbar disc herniations under cyclooxygenase-2 inhibitor therapy

OBJECTIVE

The aim of the present study was to analyse inflammatory cells in lumbar disc tissue under cyclooxygenase-2 (COX-2) inhibitor therapy, to detect their prevalence in different subtypes of lumbar disc herniations and to assess the influence of inflammatory reactions in herniated disc tissue on postoperative outcome.

METHODS

In this prospective study, intervertebral disc specimens were obtained from 50 patients. All the patients were given COX-2 inhibitor therapy (Rofecoxib) 25 mg/day for 10 days before surgery. The herniated disc specimens were routinely fixed in a 10% buffered formaline solution and paraffin-embedded; 5 microm thin sections were stained with monoclonal antibodies CD-68 for macrophages, CD-45 RO for T cells and CD-20 for B cells. The specimens were microscopically examined and classified by two independent examiners in a blinded manner.

RESULTS

CD-68 macrophages were evident in herniated lumbar disc tissue in 40% of the cases, but abundant inflammation was observed in only 18% of the cases. Macrophages were significantly common in sequesters with a prevalence of 80%, and no macrophages were observed in the protrusions. We obtained the best outcome scores in the patients with a sequestrated lumbar disc herniation.

CONCLUSION

Although most of the specimens from all the patients showed no significant inflammatory reaction, maybe due to COX-2 inhibitor therapy, they all needed surgery with no relief of the symptoms despite conservative therapy. Nerve root compression still seems to be the leading pathomechanism.

Effects of calcitonin on the biomechanics, histopathology, and radiography of callus formation in rats

BACKGROUND

This study was designed to examine the effect of salmon calcitonin on fracture repair.

METHODS

A transverse middiaphyseal fracture of the right tibia was surgically induced, and stabilized by an intramedullary Kirschner wire. Eighty male Wistar rats were arbitrarily assigned to four groups of 20 animals each. Groups I and II were the controls and did not receive any medication but did receive placebo injections. The other two groups received 5 IU/kg/day salmon calcitonin intramuscularly for 6 weeks (Group III) or for 10 weeks (Group IV) postoperatively. The formation and healing of the bones were determined by radiographic and histopathological analyses and by biomechanical tests.

RESULTS

In radiographic examinations, there were no statistically significant differences between groups I and III at week 6 or between groups II and IV at week 10. However, the histopathological evaluation scores were higher in the calcitonin group at the early stage (6 weeks) of fracture healing, which indicates a more mature callus formation (P < 0.05). The values for maximum torsional moment during fracture were higher in the calcitonin group in both stages of fracture healing (P < 0.01).

CONCLUSIONS

This study could have two important clinical implications. (1) Higher scores for the histopathological evaluation and a greater resistance to moment force applied at an early stage (week 6) of fracture healing imply that calcitonin intake might enable us to allow earlier mobilization and weight-bearing in clinical cases with rigid fixation. (2) At a late stage of fracture healing (week 10), the significantly better (P < 0.0001) results obtained in the biomechanical parameters used might imply that calcitonin intake could enable us to perform early implant removal, and strongly suggest that the strength and quality of the callus formation could be improved by administering calcitonin following a fracture.

Fundamentals of biomechanics in tissue engineering of bone

The objective of this review is to provide basic information pertaining to biomechanical aspects of bone as they relate to tissue engineering. The review is written for the general tissue engineering reader, who may not have a biomechanical engineering background. To this end, biomechanical characteristics and properties of normal and repair cortical and cancellous bone are presented. Also, this chapter intends to describe basic structure-function relationships of these two types of bone. Special emphasis is placed on salient classical and modern testing methods, with both material and structural properties described.

Phospholipase A2 activity in herniated lumbar discs. Clinical correlations and inhibition by piroxicam

STUDY DESIGN

Prospective study of phospholipase A2 activity in the serum and intervertebral discs of patients undergoing surgery for sciatica due to disc herniation.

OBJECTIVES

To determine correlations between herniated disc phospholipase A2 and clinical, radiographic, and anatomic signs of common sciatica; to evaluate serum phospholipase A2 activity as a marker of disc phospholipase A2; and to investigate the in vivo effect of piroxicam on disc phospholipase A2.

SUMMARY OF BACKGROUND DATA

Several studies suggest disc inflammation as a mechanism of sciatica due to disc herniation, and phospholipase A2 emerges as a key enzyme of cartilage and disc tissues.

METHODS

Phospholipase A2 activity was determined, using the degradation of a specific substrate, in the serum and discs of 31 patients (14 treated with acetaminophen and 17 treated with piroxicam) undergoing surgery for sciatica due to lumbar disc herniation. Visual analog scale for pain, Dallas Pain Questionnaire, Lasègue's sign, radiographic stage of degeneration of the herniated disc, volume of disc herniation shown by computed tomography, and surgical findings were recorded.

RESULTS

Disc phospholipase A2 activity was independent of the patient's age or sex, the radiologic stage of disc degeneration, and the volume of the herniation, and showed no significant correlation with Lasègue's sign or pain measured on a visual analog scale. The correlation between disc phospholipase A2 and the Dallas category of items measuring the impact of pain on daily activities approached the level of significance (P = 0.07). Disc phospholipase A2 activity was significantly higher in cases of sequestrated discs than in other herniations. Disc phospholipase A2 was significantly correlated with serum phospholipase A2, and was significantly lower in patients treated with piroxicam than in those treated with acetaminophen.

CONCLUSIONS

Disc phospholipase A2 is thought to participate in the physiopathology of sciatica and to bemodulated by nonsteroidal anti-inflammatory drug therapy. Serum phospholipase A2 is suggested as a biologic marker of disc inflammation in patients with sciatica.

Toward a biochemical understanding of human intervertebral disc degeneration and herniation. Contributions of nitric oxide, interleukins, prostaglandin E2, and matrix metalloproteinases

STUDY DESIGN

Normal and herniated human intervertebral disc specimens were cultured to study the effects of interleukin-1 beta on the production of nitric oxide, interleukin-6, prostaglandin E2, and matrix metalloproteinases. The effects of endogenously produced nitric oxide on the synthesis of other mediators also were studied.

OBJECTIVES

To test the hypothesis that the cells of the intervertebral disc are metabolically active and are capable of responding to biochemical stimuli such as interleukin-1 beta in a manner that could engender degenerative changes. As part of this study, the authors also investigated some of the possible autocrine regulatory mechanisms that may operate during the biochemical responses of disc cells.

SUMMARY OF BACKGROUND DATA

The authors previously showed, for the first time, that herniated cervical and lumbar disc specimens spontaneously produce increased amounts of nitric oxide, interleukin-6, prostaglandin E2, and certain matrix metalloproteinases. These results suggest that these biochemical agents are in some manner involved with degenerative processes in the intervertebral disc. This novel hypothesis merits further evaluation; the current communication reports the results of experiments designed to do so.

METHODS

Fourteen normal, nondegenerated discs (control group) were obtained from seven patients undergoing anterior spinal surgery for trauma or lumbar scoliosis. Thirty-six herniated discs (18 lumbar and 18 cervical) were obtained from 30 patients undergoing surgery for persistent radiculopathy. The specimens were placed into tissue culture and incubated for 72 hours in the presence or absence of interleukin-1 beta and NG-monomethyl-L-arginine, and inhibitor of nitric oxide synthases, and the media were subsequently collected for biochemical analysis. Biochemical assays for matrix metalloproteinases, nitric oxide, interleukin-6, and prostaglandin E2 were performed.

RESULTS

Normal, control disc specimens significantly increased their production of matrix metalloproteinases, nitric oxide, interleukin-6, and prostaglandin E2 in response to interleukin-1 beta. Herniated lumbar and cervical discs, which were spontaneously releasing increased levels of these biochemical agents, further increased their production of nitric oxide, interleukin-6, and prostaglandin E2 in response to interleukin-1 beta. Blocking the biosynthesis of nitric oxide in interleukin-1 beta-stimulated disc cells provoked a large increase in the production of interleukin-6.

CONCLUSIONS

Cells of the intervertebral discs are biologically responsive and increase their production of matrix metalloproteinases, nitric oxide, interleukin-6, and prostaglandin E2 when stimulated by interleukin-1 beta. The effect is more dramatic in normal, nondegenerated discs where spontaneous synthesis of these mediators is low. Nevertheless, cells of the herniated degenerated discs where spontaneous production was high were still capable of further increasing their synthesis of several of these biochemical agents in response to interleukin-1 beta. Endogenously produced nitric oxide appears to have a strong inhibitory effect on the production of interleukin-6, which suggests that autocrine mechanisms play an important role in the regulation of disc cell metabolism.

Herniated lumbar intervertebral discs spontaneously produce matrix metalloproteinases, nitric oxide, interleukin-6, and prostaglandin E2

STUDY DESIGN

Herniated lumbar disc specimens were obtained from patients undergoing surgical discectomy for persistent radiculopathy and cultured in vitro to determine whether various biochemical agents were being produced.

OBJECTIVES

Our hypothesis is that biochemical mediators of inflammation and tissue degradation play a role in intervertebral disc degeneration and in the pathophysiology of radiculopathy.

SUMMARY OF BACKGROUND DATA

Low back pain with or without radiculopathy is a significant clinical problem, but the etiology of low back pain and the exact pathophysiology of radiculopathy remain elusive. The biochemical events that occur with intervertebral disc degeneration and, in particular, the role of biochemical mediators of inflammation and tissue degradation have received sparse attention in the literature. There is some preliminary evidence that inflammatory mediators may have an important role in the pathophysiology of radiculopathy.

METHODS

Eighteen herniated lumbar discs were obtained from 15 patients undergoing disc surgery. The specimens were cultured and incubated for 72 hours, and the media were collected subsequently for biochemical analysis. Biochemical assays for matrix metalloproteinases, nitric oxide, prostaglandin E2, and a variety of cytokines were performed. As a control group, eight lumbar disc specimens were obtained from four patients undergoing anterior surgery for scoliosis and traumatic burst fractures, and similar biochemical analyses were performed.

RESULTS

The culture media from the herniated lumbar discs showed increased levels of matrix metalloproteinase activity compared with the control discs. Similarly, the levels of nitric oxide, prostaglandin E2, and interleukin-6 were significantly higher in the herniated discs compared with the control discs. Interleukin 1 alpha, interleukin-1 beta, tumor necrosis factor-alpha, interleukin-1 receptor antagonist protein, and substance P were not detected in the culture media of either the herniated or control discs.

CONCLUSIONS

Herniated lumbar discs were making spontaneously increased amounts of matrix metalloproteinases, nitric oxide, prostaglandin E2, and interleukin-6. These products may be involved intimately in the biochemistry of disc degeneration and the pathophysiology of radiculopathy. Their exact roles certainly need further investigation, but their mere presence implicates biochemical processes in intervertebral disc degeneration.

Calcitonin and fracture healing. An experimental study on rats

The effects of systemically administered calcitonin (CT) on fracture healing were analyzed in an experimental study on rats. The healing of a fracture was followed from 3 days up to 9 weeks postoperatively. Half of the rats in each age group were given daily CT 10 MRC-U/kg body wt s.c. Mechanical properties of the healing tibial fractures (tension strength) as well as various connective tissue components of the callus tissue were analyzed. No difference in the radiological or microscopical appearance of the fractures was detectable between the animals receiving CT and the controls. In the biochemical analysis matrix production as assessed from the concentrations of nitrogen, hexosamines, and hydroxyproline within the callus followed the usual lines of undistributed fracture union without any difference between the groups with and without CT. No differences could be detected in the mineralization of the callus between the specimens from animals receiving CT and those without. The tensile strength values of the fractures increased almost linearly up to 9 weeks. At 1 week the tensile strength values for fractures union in the animals without CT were approximately 50% higher, but later on no differences could be detected between the groups. These results indicate that although in the early phases of long-term CT therapy collagen synthesis may be impaired, there will be no effect on the net content of collagen or calcifying tissue in the callus or on the mechanical strength of healing fractures.

Calcitonin and granulation tissue formation in the rat. An experimental study

The effects of systemically administered calcitonin (CT) on granulation tissue development were compared using viscose cellulose sponges as wound model in the rat. The ingrowth of new granulation tissue was analyzed for the contents of various connective tissue components (total nitrogen, hydroxyproline, DNA, and RNA) and for the differential counts of the cells infiltrating the sponges. The results indicate that up to 4 weeks postoperatively (p.o.) CT did not affect the net amount of collagen, measured as hydroxyproline, total nitrogen, aminosugars nor the dynamics of differentiation and viability of the invading cells. The present observation that CT has negligible effects, if any, on the early stages of connective tissue formation and on the cell population indicates that surgical procedures could be carried out safely during systemic CT therapy without an increased risk of wound complications.