Substance use, harm reduction attitudes and behaviors among attendees of nature rave parties in Israel

BACKGROUND

Few studies have analyzed harm reduction behaviors and attitudes among rave party attendees. Since the late 1980s, there has been a large Israeli rave scene, also known as 'Nature Parties'. However, only a few studies have been conducted among nature party attendees and almost all of them are from a qualitative perspective. This study's aim was to fill the gap and conduct quantitative research to investigate the patterns of substance use, harm reduction attitudes and behaviors among Israeli nature rave party attendees.

METHODS

A cross-sectional online survey recruited 1,206 people who reported having attended nature rave parties. All of the participants were aged 18-60 years (M = 29.9; SD = 7.4), and 770 (64%) were male.

RESULTS

The most common illicit substances used at Israeli nature rave parties in the past year were cannabis (62.2%), followed by LSD (41.4%), MDMA (31.7%), mushrooms/psilocybin (23.9%), ketamine (19.6%) and cocaine (17.2%). A significant but weak association was found between harm reduction behaviors and attitudes toward harm reduction interventions (r = .26, p < .001) and attitudes toward drug testing kits (r = .33, p < .001). It seems that although we found higher positive harm reduction attitudes, it is harder to implement harm reduction behaviors. Logistic regressions demonstrated stronger associations with high harm reduction behaviors and higher levels of positive attitudes toward drug testing kits (OR = 4.53; CI 2.97-6.90; p < .001), higher levels of positive attitudes toward harm reduction interventions (OR = 4.06; CI 2.62-6.29; p < .001), marital status of widower/divorced (OR = 2.22; CI 1.49-3.32; p < .001), using MDMA (OR = 1.63; CI 1.19-2.23; p <  = .01) and using LSD (OR = 1.41; CI 1.03-1.94; p <  = .05).

CONCLUSIONS

Formal harm reduction policies and interventions are needed for Israeli nature rave parties in addition to prevention and information programs, which are also very rare. Future studies should examine the subjects of harm reduction attitudes and behaviors among the public, policy makers and professionals.

Cannabis use is associated with lower retention in methadone maintenance treatment, but not among schizophrenic- and other chronically psychotic patients

The findings of studies on cannabis use and retention in methadone maintenance treatment (MMT) are inconsistent.

To study cannabis use and its relationship to patients' outcomes in MMT with/without lifetime DSM-IV-TR schizophrenia/chronic-psychosis diagnosis.

Since June 1993, 877 patients with available lifetime DSM-IV-TR psychiatric diagnosis were followed-up until December 2017. Urine drug screens on admission and after one year were analyzed.

Lifetime schizophrenia/psychosis was diagnosed in 50 (5.7%) patients. They did not differ from the other 827 by admission cannabis use (18.0% vs. 12.3%) and had similar 1-year retention rates (76.0% vs.77.0%, respectively). Cumulative retention of the cohort excluding schizophrenia/chronic-psychosis was longer for the 667 patients who did not use cannabis after 1-year (9.1 years, 95%CI 8.4-9.9) compared with the 118 cannabis-users after 1-year (6.0 years, 95% CI 4.8-7.2, p<.001). Among the schizophrenia/chronic-psychosis group, cannabis was not related to retention (38 non-users, 7.9 years 95%CI 5.2-10.5 vs. 9 cannabis-users, 9.9 years, 95% CI 3.8-16.0, p=.5). Survival was shorter for the 41 schizophrenia/chronic-psychosis non-users (15.2 years, 95% CI 12.8-17.7) than for the 719 non-schizophrenia/chronic-psychosis non-users (18.5, 95%CI 17.9-19.2, p = 0.009). However, survival was comparable among the 9 cannabis-users with schizophrenia/chronic-psychosis (20.1, 95% CI 16.2-24.1) and 101 other cohort users (18.6, 95% CI 16.9-20.4).

Cannabis use is associated with decreased retention among MMT patients, however the effects of cannabis on schizophrenia/psychosis patients on retention and survival cannot be verified due to the small sample size and the limited data regarding chronicity of cannabis use. Future larger, prospective studies are needed.

Of/Lb collagen promotes chemoinvasion of breast-cancer cells and directs epithelial-cell migration into granulation-tissue of experimental dermal wounds

OF/LB collagen is a recently described once-fetal form of collagen, with laminin-binding properties, composed of three alpha(1)(I)-sized chains, one of which displaying an unusually acidic pI. This collagen appears able to direct the migration of breast cancer cells through Matrigel, and of injury-activated epithelial cells into the underlying granulation stromal tissue. The effect exerted by OF/LB collagen in vitro appears preferentially linked to its acidic chain. The data reported strongly support the hypothesis that the presence and accumulation of OF/LB collagen in cancer may play a fundamental role in the invasive growth.

The effect of mechanical force on mRNA levels of collagenase, collagen type I, and tissue inhibitors of metalloproteinases in gingivae of dogs

Orthodontic force causes an injury to and subsequent degradation of the attachment apparatus, thus leading to the transposition of the tooth. The gingiva, however, is compressed and sometimes becomes hypertrophic with tooth movement and often shrinks after treatment. To study the effect of force on the gingiva, we applied orthodontic force in dogs and analyzed gingival tissues 1, 2, 3, 7, 14, and 28 days later as well as after removing the force. The effect of force on mRNA levels of collagen type I (col-I), matrix metalloproteinase-1 (MMP- 1), and tissue inhibitors 1 and 2 (TIMPs) genes was analyzed by RT-PCR, and MMP-1 activity was determined by zymography. The results showed that force significantly increased both the mRNA levels of MMP-1 and its interstitial activity. After the removal of force, MMP-1 gene expression was significantly decreased. The results could partly explain the clinically observed shrinkage and adaptation of the gingiva during tooth movement.

Retinoic acid enhances the effect of collagen on bone union, following induced non-union defect in guinea pig ulna

OBJECTIVE AND DESIGN

The aim of the present study is to evaluate the involvement of retinoic acid and collagen in wound healing, by combining them in a therapeutic modality for treating a non-union bone defect in a guinea-pig ulnar-bone model.

METHODS

a 4-mm disc was excised from the guinea-pig's ulnar-bone, and the space formed between the two ulnar fragments was filled with either collagen solution, retinoic acid solution or a combination of both. The guinea-pigs were sacrificed 2 or 6 weeks later, and the defected ulnar bones were studied by X-ray, by histology and by computerized histomorphometry.

RESULTS

After 6 weeks, the long bone area fraction within the histological sections of the bone, was increased after treatment with this mixture by 180%, as compared to the untreated controls. The cartilage area in those sections was decreased by 44% after the combined treatment, as compared to increases of 133% and 182% following treatments with collagen alone.

CONCLUSION

These findings demonstrate that addition of 500 IU of retinoic acid to collagen at a site of a bone defect, is superior to either agent in enhancing regeneration of new bone, achieving union across the defect and leading to its complete repair.

Gingival response to orthodontic force

Orthodontic tooth movement is brought about by prolonged application of force on the attachment apparatus. This results in cellular and extracellular changes within the periodontium. As shown in numerous studies, tooth movement is achieved after the remodeling of alveolar bone and the response of the periodontal ligament to the mechanical force. Although gingival changes have also been found to be an important factor in the overall response, the effect of orthodontic tooth movement on the gingiva has been investigated to a lesser extent. Unlike bone and periodontal ligament, which regain their original structure after removal of force, the gingival tissue does not regain its pretreatment structure, a fact on which a hypothesis has been made that tooth relapse after removal of retention may be associated with changes in the gingiva. The present review summarizes available data on the effect of orthodontic force on collagen, elastin, and collagenase in the gingiva and its relevance to understanding the mechanism of tooth relapse.

Exogenous non-crosslinked collagen enhances granulation tissue formation in dermal excision wounds in guinea pigs

Based on previous observations indicating a role for collagen peptides in eliciting a positive feedback for collagen biosynthesis, this study was initiated to elucidate the effect of non-crosslinked collagen on granulation tissue formation in dermal excision wounds. The wounds were treated with either non-crosslinked or crosslinked native collagen, or left untreated as controls. Granulation tissue was analyzed for collagen type I mRNA, for levels of interstitial collagen and for the number of blood vessels. The results indicated significant increases in procollagen type I mRNA, in interstitial collagen, in the number of blood vessels and in epithelial advance in the non-crosslinked collagen-treated wounds relative to the untreated controls. It is assumed that the presence of non-crosslinked collagen in a healing wound enhances both procollagen type I biosynthesis and the repair process of dermal wounds, due to the more readily released collagen peptides derived from this exogenous collagen dressing.

Reduction in basic fibroblast growth factor mediated angiogenesis in vivo by linomide

Linomide (N-phenylmethyl-1,2-dihydro-4-hydroxyl-1-methyl-2-oxoquinoline-3-carboxa mide) is a novel immunomodulator with a potent anti-tumoral activity. This study was undertaken to test the effect of Linomide on basic fibroblast growth factor (bFGF) induced angiogenesis in vivo, which manifests itself in an increased number of blood vessels per unit of cell infiltrated area. Subcutaneously implanted polyvinyl alcohol sponges (PVS) in guinea pigs were used as a model system to quantitate angiogenesis in vivo. Oral treatment with Linomide was able to reduce significantly the bFGF induced blood vessel growth and proliferation within the implanted PVS, relative to untreated controls. In addition, Linomide significantly reduced the bFGF mediated augmentation of protein and collagen content in the implanted PVS, indicating an inhibition in the deposition of extracellular matrix (ECM). We conclude that the potent inhibition of bFGF induced angiogenesis by Linomide in vivo in addition to immunomodulatory effects may have potentially important clinical applications.

The effect of centrifugal force on the transcription levels of collagen type I and collagenase in cultured canine gingival fibroblasts

An orthodontically treated tooth is often destabilized in its newly corrected location and relapses towards its original position. Hitherto, the explanation for this phenomenon was that orthodontic force brings about "stretching" of gingival collagen fiber, which "pull back" the tooth towards its pretreatment position. A previous ultrastructural study showed that after force application the gingival collagen fibres were torn, laterally spaced and of increased diameter. Therefore, they could not "pull back" the tooth and be the cause of the relapse. In the present study, in order to find a more plausible explanation at the molecular level, the effect of pressure on the gene transcription of collagen type I and tissue collagenase was examined by semiquantitative, reverse transcriptase-polymerase chain reaction assay. Attached buccal gingiva was excised from anaesthetized dogs and gingival fibroblasts were grown in culture. Following application of pressure (0.167 kg/l g cell mass), the transcription of collagen type I was increased while that of tissue collagenase was decreased. These results corroborate the ultrastructural in vivo findings that orthodontic force is associated with larger amounts of collagen type I in the gingiva.

Thalidomide reduces vascular density in granulation tissue of subcutaneously implanted polyvinyl alcohol sponges in guinea pigs

The efficacy of thalidomide in the treatment of erythema nodosum leprosum is a well established fact; there is also accumulating evidence of its therapeutic value in a number of other inflammatory and immune-mediated conditions. In addition, thalidomide has been shown to be an inhibitor of angiogenesis induced by basic fibroblast growth factor (bFGF). Nevertheless, its mechanism of action remains speculative. Using guinea pigs, orally administered thalidomide significantly enhanced the response of multinucleated foreign body giant cells (p<0.05) in subcutaneously implanted polyvinyl alcohol sponges. Furthermore, the drug exerted a dual effect in that it reduced vascular density (p<0.05), which was not abolished by recombinant human bFGF, and at the same time amplified the granulomatous response with and without bFGF (p<0.05 and p<0.01, respectively). The results of our experiments represent a further step toward understanding the mechanism of action of thalidomide, with implications for its potential use in wound healing and scar formation as well as in the control of tumorigenesis.

Lack of influence of cyclosporin A on levels of gingival procollagen types I and III mRNAs in rats of different ages

Previous studies showed that gingival overgrowth following cyclosporin A (CsA) administration is not associated with an increase in interstitial collagen. It also was shown that CsA causes a significant decrease in collagen content within the gingival stroma. In order to determine whether this decrease is caused by down-regulation of collagen mRNA, the procollagen mRNA level in gingiva of young and old rats was measured correlated with the ratio of interstitial collagen to DNA in these regions. Hybridization of 32P-labelled cDNA probes for procollagen types I and III with total RNA extracted from the molar gingiva showed that administration of Csa did not change the steady-state levels of mRNAs for both procollagens in the gingiva of either young or old rats. The ratio of gingival interstitial collagen to DNA was significantly reduced in the CsA-treated animals (4.2 +/- 0.85) relative to the controls (7.8 +/- 1.6). It is concluded that the reduction in interstitial collagen following CsA treatment is not age-related, and is most probably caused by increased degradation rather by decreased biosynthesis.

Reduction in pulmonary fibrosis in vivo by halofuginone

Pulmonary fibrosis is a disorder causing a high mortality rate for which therapeutic options are limited. Therefore, the effect of halofuginone, a novel inhibitor of collagen type I synthesis, on bleomycin-induced pulmonary fibrosis was studied in rats. Pulmonary fibrosis was induced by intraperitoneal injections of bleomycin for seven consecutive days, and halofuginone was administered intraperitoneally every second day during the entire experimental period of 42 d. Collagen determination in the lungs and the examination of histologic sections showed that halofuginone significantly reduced fibrosis relative to the untreated control rats. We conclude that halofuginone is a potent in vivo inhibitor of bleomycin-induced pulmonary fibrosis, and that it may potentially be used as a novel therapeutic agent for the treatment of this dysfunction.

Gingival response to a new multipurpose dental adhesive: a histologic study in dogs

The biocompatibility of cementing materials is a prerequisite for any dental procedure. In this study, the tolerance of gingival tissue to an advanced fourth-generation dental adhesive (High-Q-Bond) was tested in dogs. The results from High-Q-Bond adhesive were compared with those obtained from Superbond C&B adhesive. Buccal class V subgingival cavities were restored with either High-Q-Bond or Superbond C&B adhesive Untreated teeth served as normal intact controls. The teeth with the attached buccal gingivae were extracted and processed for histologic examination. The histologic observations showed an inflammatory response in the gingiva of the Superbond C&B adhesive-treated teeth, whereas the High-Q-Bond fillings exhibited no noticeable adverse effect on the gingival tissue.

The response of supraalveolar gingival collagen to orthodontic rotation movement in dogs

An orthodontically rotated tooth relapses toward its pretreatment position. Explanations for this phenomenon have been given after light microscopic studies, according to which it had been assumed that stretched supraalveolar gingival fibers pulled back the tooth and brought about relaxation of the stretched fibers. The rotational relapse, however, can be prevented by supraalveolar fiberotomy of the gingiva around the tooth. This investigation was initiated to reevaluate the validity of the hitherto assumed causes for the relapse, by obtaining ultrastructural data on the response of collagen fibers after orthodontic intervention. Lateral maxillary incisors in the dog were rotated with bonded fixed appliances. The teeth were divided into groups according to different orthodontic procedures. Scanning and transmission electron microscopic analyses were performed on gingival samples after proper processing. Analyses of the untreated control samples showed well-organized, parallel, and densely packed thick bundles of collagen fibers, interconnected with thin fibers. After rotation-followed-by-retention, the gingival fibers were torn, ripped, disorganized, and laterally spaced and of increased diameter. Thus it was concluded that all these patterns are incompatible with stretching. Also, an increased number of elastic fibers were seen in proximity to the torn collagen fibers. After gingival fiberotomy, most fibers resumed the appearance of the organized pattern of large fiber bundles similar to those seen in the controls.

Levels of cytokines and collagen type I and type III as a function of age in human gingivitis

The objective of this study was to examine the age-dependent relationships between levels of inflammatory cytokines and collagen in human gingival inflammation. The gingival biopsies were obtained from 142 patients, divided into the following age groups: 6 to 14 years (prepubertal children); 18 to 35 years (young adults); 36 to 54 years (mature adults); and 55 years or above. The patients were also divided according to the severity of gingivitis. The tissues were analyzed for the contents of the inflammatory cytokines interleukin (IL)-1 beta, IL-6, IL-8, and tumor necrosis factor alpha (TNF-alpha) using specific ELISA kits, and interstitial collagen type I and type III using the ELISA method and specific antibodies. We found that in young adults, levels of IL-1 beta and IL-6 were significantly higher in inflamed than in non-inflamed gingiva. Total collagen in the young adults, however, was lower in inflamed than in non-inflamed gingiva. There was no significant difference in the levels of either IL-8 or TNF-alpha between inflamed and non-inflamed gingiva independent of age. No difference in the level of collagen type I between the inflamed and non-inflamed gingiva was found in any age groups. The level of collagen type III was lower in inflamed than in non-inflamed gingiva in both children and > or = 55 year group. The results indicate a disparity in the effect of age on the levels of cytokines and of collagen type I and type III in both clinically normal and inflamed gingiva.

Topically applied halofuginone, an inhibitor of collagen type I transcription, reduces peritendinous fibrous adhesions following surgery

To test in vivo the effect of previously observed inhibition of collagen type I transcription by the plant alkaloid Halofuginone, deep flexor tendons of 12 chickens were severed and sutured, and Halofuginone was applied topically at the site of surgery. Intact tendons, and severed but untreated tendons served as controls. The effect of the treatment was assessed by histological, biochemical, and biomechanical examinations of the operated and intact tendons three weeks after surgery. The results indicated an almost complete absence of fibrous peritendinous adhesions in the histologic sections of the Halofuginone treated tendons. There was a statistically significant decrease in collagen contents of and in both force and energy required to pull out the Halofuginone treated tendons from their sheath, relative to the untreated controls. Halofuginone had no effect on the cellularity of the healing tissue. We conclude that Halofuginone is a potent inhibitor of fibrous peritendinous adhesions with potentially important clinical applications.

Hereditary leukoencephalopathy and palmoplantar keratoderma: a new disorder with increased skin collagen content

We report a new neurocutaneous syndrome of apparent autosomal recessive inheritance consisting of early-childhood-onset palmoplantar keratoderma followed in adulthood by progressive tetrapyramidal syndrome and cognitive impairment. Of the four affected siblings, two were available for evaluation. Investigation disclosed cerebral white-matter involvement on MRI and arylsulfatase A pseudodeficiency carrier state, which was also identified in clinically unaffected family members. Since skin biopsies showed dermal connective tissue abnormalities, we studied collagens I, III, and VI biosynthesis. Northern blotting of RNA extracted from cultured skin fibroblasts revealed an increased steady-state messenger RNA (mRNA) level of alpha 1(VI) collagen, whereas no differences were detected for pro alpha 1(I), pro alpha 1(III), and tropoelastin mRNAs. The skin content of collagen and total protein was higher in the patients than in controls. We suggest that an extracellular matrix abnormality may be involved in the pathogenesis of this disorder.

Topological differences in the expression of collagen type I and collagen type III mRNAs in the rat gingiva

Collagen mRNA levels in the gingival cells of molars and incisors in rats were measured and correlated with the ratio of interstitial collagen to DNA in these regions. Hybridization of 32P-labeled specific cDNA probes for collagen types I and III with total RNA isolated from gingival tissue of rat molars and incisors showed that the steady-state levels of mRNAs of type I was significantly higher in the molars than in the incisors (molars/incisors = 2.12 +/- 0.12, P < 0.004). However, the ratio of interstitial collagen to DNA in the gingiva of the molars was significantly lower than that found in the incisors (collagen/DNA = 4.13 +/- 0.90 and 12.89 +/- 1.24 respectively, P < 0.001). It is suggested that the difference between the mRNA levels and those of interstitial collagen may reflect an intrinsic characteristic presumably associated with the different modes of mastication between molars and incisors of the rat.

Healing process of laser-welded intestinal anastomosis

Intestinal welding by means of low-power laser has been reported as an efficient method for intestinal anastomosis. We designed an experimental model in rats to investigate collagen and DNA concentrations in CO2 laser-welded anastomoses as compared with those in sutured anastomoses on the 4th, 7th, and 10th postoperative days. The results revealed that DNA, total collagen, and insoluble collagen concentrations were significantly lower in the lased anastomoses than in the sutured anastomoses on the 4th postanastomotic day. On the 7th and 10th postanastomotic days, collagen concentrations increased in the laser-treated group attaining significantly higher levels than in the sutured group at that time. These findings are compatible with other studies demonstrating that laser-welded intestinal anastomoses are more prone to dehiscence during the first 4 postanastomotic days, but become at least as effective as the sutured ones with passage of time.

Type I and type III collagen mRNA levels in kidney regions of old and young rats

Interstitial fibrosis is a common feature of renal aging. The steady-state levels of type I and type III collagen mRNAs as well as DNA, protein and collagen deposition were investigated in the cortex, inner and outer medulla of aged (22 months old) rats in comparison to young (5 months old) controls. Our data show that the cortex and outer medulla of old rats expressed significantly higher percentage of type I collagen mRNA compared to the respective regions in the young rat kidneys. Moreover, within the group of the old rats, the cortex expressed significantly higher percentage of type I collagen mRNA compared to the inner medulla whereas in the group of the young rats the expression was similar in all kidney regions. The ratio of extracellular collagen to DNA was significantly higher in the cortex, inner and outer medulla of old compared to young rats. The ratio of collagen to total protein, although showing a similar age-related difference, attained statistical significance in the cortex only. Thus, the present study indicates a close relationship between the expression of the mRNA for type I collagen, the major structural constituent of fibrotic tissues, and the deposition of collagen in both the cortex and outer medulla of the kidney. Moreover, the clear differences found between old and young rat kidneys can serve as markers for renal aging and might explain at least some of the kidney impairments caused by fibrosis during senescence.

Bone marrow stromal elements in murine leukemia: decreased CSF-producing fibroblasts and normal IL-1 expression by macrophages

A study of bone marrow stromal elements in murine acute myeloid leukemia (AML) was carried out. Our previous studies had indicated marrow stromal deficiency in murine AML. In the current investigation, separate stromal cells were cultured and the results obtained have shown that, while marrow stromal macrophages are normal in leukemia and express adequate amounts of IL-1, the fibroblasts are markedly reduced. However, if sufficient fibroblasts are pooled in vitro, they produce adequate amounts of CSF. Test of TNF alpha in leukemic cells CM, as possible cause of marrow stromal inhibition in leukemia, had not disclosed this cytokine. Further, it was observed that total body lethal irradiation of leukemic mice aggravates the stromal deficiency, confirming results of our previous investigations. It is concluded that bone marrow stromal deficiency in murine AML is due to decreased fibroblasts and, implicitly, reduced CSF production.

Prolonged systemic administration of cyclosporin A affects gingival epithelium

Gingival biopsies were obtained from 12 patients suffering from Behcet's disease who were treated with Cyclosporin A (CsA) for up to 20 months. Preparations were made for examination with both light and scanning electron microscopy (SEM). Along with known changes in the gingival epithelial structure observed following CsA treatment, we also found unusual clusters of needle-like crystallites embedded in the epithelium, mostly at the base of the acanthotic projections. Toluidin blue staining revealed increased numbers of both intact and degranulated mast cells in the attached epithelium. It is concluded that CsA affects the gingival epithelium and that the clinically observed enlargement of gingival tissue following prolonged treatment with CsA is due primarily to CsA-epithelial interaction.

The effect of cyclosporin A (CsA) treatment on gingival tissue of patients with Behçet's disease

Gingival biopsies were obtained at various intervals for a period of two years from 12 patients suffering from Behçet's disease who were under a clinical trial of cyclosporin A (CsA) treatment. The levels of nondialyzable hydroxyproline (Hypro) were determined in the medium of the cultured tissues. Histologic examinations were also performed every three months. Correlations between the CsA blood levels and the levels of nondialyzable Hypro indicated a reciprocal relationship, especially at blood levels of CsA higher than 600 ng/ml. Histologic examination of gingival sections from CsA-treated patients showed swelling of the epithelial cells, formation of perinuclear clear zones, widening of intercellular gaps and formation of several basal cell layers. In addition, foci of PAS-positive material were found in both the epithelium and stroma. It is assumed that the gingival enlargement observed in the CsA-treated patients was not due to an increase in tissue collagen but rather to an increase in epithelium combined with an accumulation of noncollagenous extracellular matrix material.

A novel method to study directed cell migration in culture

Directional migration of gingival fibroblasts was elicited in a cell culture system using reconstituted type I collagen fibers as a source of the putative chemoattractant. The rate of migration was expressed as Migration Index which turned out to be dependent on and directly related to the distance between the cells and the collagen. It is believed that this method enables one to study many different phenomena associated with extracellular matrix and cell interactions.

Decreased adhesion formation in flexor tendons by topical application of enriched collagen solution--a histological study

In order to improve gliding function of damaged flexor tendons in chickens, we topically applied enriched collagen solution (ECS) to the tendon sheaths of severed tendons. Previous studies using the same experimental model showed improvement of gliding function in the damaged tendons biomechanically and increased collagenolytic activity in the area of the damage after application of ECS. In the present study we evaluated the influence of ECS on peritendinous adhesion formation and on the healing process of the tendons histologically. We found that topically applied ECS reduced adhesion formation, mostly during the first week, without adversely affecting tendon healing or scar maturation.

Re-attachment of periodontal ligament by collagen in experimentally-induced alveolar bone dehiscence in dogs

Fifty-four bone dehiscences were made in nine dogs by reflecting mucoperiosteal flaps on the labial aspect of lower and upper incisors and premolars and removing alveolar bone. One half of the dehiscences were treated with native enriched collagen solution (ECS) prepared from acid-soluble dog-skin collagen. Six weeks later, histologic sections were prepared from both the ECS-treated and untreated control sites. Re-attachment was promoted by the ECS preparation; there was arrest of epithelial migration apically and formation of new bone and cementum, as well as proliferation of fibrous connective tissue that became attached to the newly-formed cementum. This effect could be due to an influence of ECS on the chemotaxis of connective-tissue cells and to an anti-migratory (barrier) effect on gingival epithelium.

Capsule around silicone implants in diabetic rats: histological and biochemical study

Polydimethylsiloxane (silicone) implants were subcutaneously placed in the back of diabetic and normal rats. After three months the rats were killed and the fibrous capsule around the implants was histologically and biochemically examined. A significant quantitative difference (p less than 0.001) was found in the thickness of the capsules, which were two to three times thicker in the diabetic animals. The biochemistry showed an increase of neutral salt-soluble collagen in the diabetic group; electrophoresis revealed only type I collagen in the diabetic and type I and III in the normal rats. From this experimental trial it seems that diabetes mellitus is another factor in formation of a thick capsule around silicone implants.

Cessation of epithelial cell movement at native type I collagen-epithelial interface in vitro

Two foci of gingival epithelial cells from the dog were grown in culture in dishes which were coated with gingival epithelial extracellular matrix (GEEM). A streak of native, reconstituted type I collagen fibers had been placed at the midline of the dish between the two foci. The epithelial cells spread and proliferated in all directions, but their motility ceased at the collagen-epithelial interface, where they piled up and formed several layers. It is concluded that type I collagen may serve as a biological barrier to stop undesirable epithelial cell movement in vivo.

Increased collagenolytic activity in severed and sutured tendons following topical application of exogenous collagen in chickens

To verify the role of collagenase in reduction of peritendinous adhesion by topical application of exogenous collagen, the flexor tendons of 30 chickens were severed and sutured. Exogenous, native enriched collagen solution (ECS) was introduced in the tendon sheath via a polyethylene catheter. The effect of ECS on collagenolytic activity in the healing tendon was assessed 1, 2, and 3 weeks later both by determining the relative amounts of dialyzable protein and hydroxyproline and by using the collagen film collagenase assay. The results obtained indicated a significant increase in both dialyzable hydroxyproline level and collagenolytic activity in the ECS-treated tendons as compared with the untreated controls. It is suggested that the effect of the topically applied exogenous collagen on increasing the collagenolytic activity may be directly related to previously observed increased gliding capacity of the tendons in the same experimental model.

In vitro incorporation of proline into keratoconic human corneas

Corneal buttons were obtained from four young adults with advanced keratoconus following perforating keratoplasty. The corneal buttons were incubated in organ culture media containing 3H-proline. Autoradiographs of corneal sections showed that the incorporation of the radioisotope was significantly higher in all layers of the kerotoconic corneas than that found in the normal controls, indicating an increased protein biosynthesis in the former. It is suggested that in spite of the found increased synthetic activity, slow destruction and thinning of the cornea in keratoconus might occur as the result of inadequate compensation for tissue loss due to increased collagenolytic activity in the disease.

Restoration of periodontal attachment employing enriched collagen solution in the dog

Three wall intrabony defects were produced in 11 dogs using a round bur followed by curettes and hoes. A copper band was fixed to the tooth with stainless steel ligature wire. Six weeks later, the copper band was removed and the defect was treated with an enriched collagen solution (ECS) prepared from acid-extracted dog skin collagen. Thirty-three defects were treated with ECS and 33 defects were controls. Healing was assessed histologically 4 and 6 weeks after treatment for the presence of new cementum, periodontal ligament and alveolar bone, as well as arrested epithelial downgrowth along the dental root. Unlike the controls, treatment with ECS resulted in restoration of periodontal attachment after 4 weeks. This included formation of new cementum, new alveolar bone and dense connective tissue fiber running between bone and cementum. Control sections showed epithelial migration along the root, separating it from the adjacent connective tissue and thus preventing new attachment.

Electroconductivity of bone in vitro and in vivo

In view of conflicting data in the literature regarding the electroconductivity of bone, measurements were performed both in vivo and in vitro by using alternating current of 100.0 mA and 1.0 mA at a frequency of 1000 cycles/second and the four-electrode method. Electrodes were inserted through all of the bone layers into the bone marrow space of the femora of seven rabbits. Bone electric resistance was measured also in situ 30 minutes after the death of the animals. A threefold increase in resistance of bone, from about 600 to about 1700 ohm, occurred in situ 30 minutes after the death of the animals, and an enormous resistance, about 10(10) ohm, was measured in vitro. It was also apparent that femora from the different rabbits had different values of electric resistance both in vivo and in vitro. If electroconductivity of bone is determined by body fluids rather than by the bone tissue per se, measuring the "specific resistance" of bone in vivo is meaningless.

Demonstration of collagenase activity in adult Strongyloides ratti (Nematoda:Strongyloididae) and its absence in the infective larvae

Larvae and adults of Strongyloides ratti were examined for collagenolytic activity on 14C proline-labelled, native, guinea-pig skin collagen substrate. The activity was measured by determining either the amount of hydroxyproline released or the amount of radioactivity in the solubilized fraction of the collagen substrate. Bacterial collagenase was used for enzyme control and trypsin served as substrate control. No collagenolytic activity was found in living larvae, their extracts or metabolites. The collagenolytic activity of the metabolites of adult worms appeared weak, whereas that of the extracts of the adults was pronounced. It is suggested that collagenase is active in the adult females at the time of migration in the intestinal mucosa during oviposition.

Cellular sensitivity to collagen in thromboangiitis obliterans

We studied 39 patients with thromboangiitis obliterans to determine their cellular and humoral immune responses to native human collagen Type I and Type III, which are constituents of blood vessels. Cell-mediated sensitivity to these collagens was measured by an antigen-sensitive thymidine-incorporation assay. The mean stimulation index--the ratio of thymidine incorporation in the presence of antigen to that in its absence--with both Type I and Type III collagens used as antigens was significantly higher in patients with thromboangiitis obliterans than in patients with arteriosclerosis obliterans or in healthy male controls. Lymphocytes from 77 per cent of the patients with thromboangiitis obliterans exhibited cellular sensitivity to human Type I or Type III collagens (or both). Furthermore, in 17 of 39 serum samples from the patients with thromboangiitis obliterans a low but significant level of anticollagen antibody activity was detected, whereas there was no antibody activity in serum samples from controls. These results suggest that there is a distinct etiologic factor in this disease and also raise the possibility of differentiating between thromboangiitis obliterans and arteriosclerosis obliterans by immunologic means.

Collagenolytic activity in keratoconus

Corneal buttons were obtained from eight young adult patients with advanced keratoconus and were incubated in an organ culture system. The medium was assayed for collagenolytic activity using 14C-labeled reconstituted native collagen fibers as substrate. The assay was performed with and without prior collagenase activation with trypsin. The results indicated that the medium obtained from keratoconic corneas showed higher levels of collagenolytic activity compared with normal control corneas. We suggest that the level of collagenase activation may be a pathogenic factor in the development of keratoconus.

One-year follow up for the use of collagen for biological anchoring of acrylic dental roots in the dog

Second premolars in both upper and lower jaws of 6 dogs were extracted and acrylic resin replicas were made of the roots. Horizontal channels were drilled across the root replica perpendicular to the long axis. Before implantation, the prepared root replicas were immersed in a solution of native collagen. One year after implantation, proliferation of connective tissue and newly-formed viable bone were observed within the channel as well as surrounding the treated implants. All control implants without collagen treatment were rejected leaving chronically inflamed implantation sites.

Collagen metabolism and phenotype after prostaglandin E2 treatment of granuloma: direct and macrophage-modulated effects

Local administration of PGE2 (2 micrograms) to polyether sponges, implanted s.c. in rats, inhibited hydroxyproline and total protein accumulation, without altering relative amounts of collagen, when administered early during granuloma development. In contrast, while DNA as well as total protein accumulation was inhibited by local PGE2 treatment of established granuloma, hydroxyproline accumulation and the relative amounts of collagen were enhanced. This PGE2-induced collagen enhancement was associated with an increased type III : type I collagen ratio, possibly due to differential intracellular breakdown of newly synthesized collagen. The solubility of granuloma collagen was unaffected by PGE2. Impregnation of sponges with carrageenan before implantation, thereby giving macrophage-dominated granuloma, did not affect the changes in protein and DNA induced by later treatment with PGE2, but did reverse the PGE2-induced accumulation of hydroxyproline. This latter effect probably reflects macrophage-mediated, PGE2 enhancement of collagenolytic activity.

Inhibition of collagen breakdown by diphenylhydantoin

Gingival tissue obtained from diphenylhydantoin-treated patients was cultured in the presence of [14C]proline for 24 h. The radioactive medium was removed and the tissue cultured for three days more. DNA, protein, hydroxyproline, proline and radioactivity determinations in the tissue indicated increased cellular proliferation, increased collagen contents and decreased breakdown of collagen in the affected tissues. The media were assayed for dialyzable and non-dialyzable hydroxyproline contents. It was found that the media in which diphenylhydantoin tissues were cultured contained more than twice as much non-dialyzable hydroxyproline than the controls. It was concluded that diphenylhydantoin brought about a reduction in collagen breakdown thus explaining the accumulation of hydroxylated collagen in the tissue.

Improvement of gliding function of flexor tendons by topically applied enriched collagen solution

The long flexor tendons of the second, third and fourth toes of 94 chickens were cut and sutured. After operation the birds were divided into three groups. To reduce peritendinous adhesions, an aqueous solution of beta-aminopropionitrile (BAPN) was added to a solution of enriched native collagen (ECS) and applied to the cut tendons of one group; untreated controls and controls treated with collagen solution alone comprised the other groups. Chickens from each group were killed one, two, three, four and five weeks after operation. The results were evaluated both biomechanically and biochemically. It was found that the collagen solution alone had the same effect as the treatment with BAPN. It is suggested that the exogenous collagen present at the site of injury binds the collagenase inhibitor released by tendon cells, thus providing enough active collagenase to control the formation of fibrous adhesions. The inefficiency of BAPN in these experiments might have been due to either inadequate dosage or wrong timing, or both.

Electroconductivity of collagen in vitro and in vivo

Electrical conductivity was measured on thermally reconstituted collagen fibers in vitro and on isolated rat tail tendon collagen fiber bundles in vivo. The results obtained indicated that collagen per se is not an electroconductor under physiological conditions, but rather a biological insulator.

Three-dimensional organization of collagen fibres in tendon

Electron microscopic observations are presented on thin sections of excised chicken breast tendon following the introduction and diffusion of aqueous solutions of heavy metal salts. The dark banded regions of the collagen fibrils are seen to be in near-perfect register throughout the diameter of each fibril and, in many cases, to be continuous across the intervening ground substance. Clusters of uranyl ions form well-defined chains extending across the interfibrillar space between neighbouring fibrils, a distance of several hundred nanometres. It is suggested that the high degree of organization characteristic of collagen fibrils in tissue may perhaps be a property not only of the protein but also of the ground substance in which it is embedded, the fibres merely rendering visible a lattice pattern of their surroundings to which they have conformed.