DNA Damaging Effects, Oxidative Stress Responses and Cholinesterase Activity in Blood and Brain of Wistar Rats Exposed to Δ9-Tetrahydrocannabinol.

Currently we are faced with an ever-growing use of Δ9-tetrahydrocannabinol (THC) preparations, often used as supportive therapies for various malignancies and neurological disorders. As some of illegally distributed forms of such preparations, like cannabis oils and butane hash oil, might contain over 80% of THC, their consumers can become intoxicated or experience various detrimental effects. This fact motivated us for the assessments of THC toxicity in vivo on a Wistar rat model, at a daily oral dose of 7 mg/kg which is comparable to those found in illicit preparations. The main objective of the present study was to establish the magnitude and dynamics of DNA breakage associated with THC exposure in white blood and brain cells of treated rats using the alkaline comet assay. The extent of oxidative stress after acute 24 h exposure to THC was also determined as well as changes in activities of plasma and brain cholinesterases (ChE) in THC-treated and control rats. The DNA of brain cells was more prone to breakage after THC treatment compared to DNA in white blood cells. Even though DNA damage quantified by the alkaline comet assay is subject to repair, its elevated level detected in the brain cells of THC-treated rats was reason for concern. Since neurons do not proliferate, increased levels of DNA damage present threats to these cells in terms of both viability and genome stability, while inefficient DNA repair might lead to their progressive loss. The present study contributes to existing knowledge with evidence that acute exposure to a high THC dose led to low-level DNA damage in white blood cells and brain cells of rats and induced oxidative stress in brain, but did not disturb ChE activities.

Irinotecan and Δ8-Tetrahydrocannabinol Interactions in Rat Liver: A Preliminary Evaluation Using Biochemical and Genotoxicity Markers.

There is growing interest regarding the use of herbal preparations based on Cannabis sativa for medicinal purposes, despite the poorly understood interactions of their main constituent Δ8-tetrahydrocannabinol (THC) with conventional drugs, especially cytostatics. The objective of this pilot study was to prove whether the concomitant intake of THC impaired liver function in male Wistar rats treated with the anticancer drug irinotecan (IRI), and evaluate the toxic effects associated with this exposure. IRI was administered once intraperitoneally (at 100 mg/kg of the body weight (b.w.)), while THC was administered per os repeatedly for 1, 3, and 7 days (at 7 mg/kg b.w.). Functional liver impairments were studied using biochemical markers of liver function (aspartate aminotransferase-AST, alanine aminotransferase-ALP, alkaline phosphatase-AP, and bilirubin) in rats given a combined treatment, single IRI, single THC, and control groups. Using common oxidative stress biomarkers, along with measurement of primary DNA damage in hepatocytes, the degree of impairments caused at the cellular level was also evaluated. THC caused a time-dependent enhancement of acute toxicity in IRI-treated rats, which was confirmed by body and liver weight reduction. Although single THC affected ALP and AP levels more than single IRI, the levels of liver function markers measured after the administration of a combined treatment mostly did not significantly differ from control. Combined exposure led to increased oxidative stress responses in 3- and 7-day treatments, compared to single IRI. Single IRI caused the highest DNA damage at all timepoints. Continuous 7-day oral exposure to single THC caused an increased mean value of comet tail length compared to its shorter treatments. Concomitant intake of THC slightly affected the levels of IRI genotoxicity at all timepoints, but not in a consistent manner. Further studies are needed to prove our preliminary observations, clarify the underlying mechanisms behind IRI and THC interactions, and unambiguously confirm or reject the assumptions made herein.

Abdominal Wall Defect Reconstructed by Breast Flaps Using a Mercedes Closure Pattern.

BACKGROUND: Surgery of the abdominal cavity may lead to postoperative defects to the ventricular segment of the abdominal wall. The reconstruction of these defects, especially in the area of the median line, represents an issue during the course of healing due to the role of the abdominal cavity in respiratory processes. METHODS: Reconstructive surgical procedure was performed on an infected vast defect to the ventral segment of the abdominal wall in a 77-year-old woman by a modified "Mercedes closure pattern," i.e., by combining three fasciocutaneous flaps: bipedicle flap of the upper segment of the abdominal wall and two sliding breast flaps. RESULTS: Application of a modified complex Mercedes closure pattern was successful and positively affected the redistribution of pressure forces at the places where the edges of the wound were in contact. CONCLUSIONS: The applied and described technique of closing the abdominal cavity decreased the possibility of infection to the prosthetic material, because direct contact between the sutures and the prosthetic no longer existed. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

FRACTURE OF THE HUMERUS IN CHILDREN ­ CAUSES AND MECHANISMS OF INJURY. / PRIJELOMI NADLAKTICNE KOSTI U DJECE ­ OKOLNOSTI I UZROCI NASTANKA.

Due to hyperactivity, children are often exposed to injuries of the upper arm and fractures of the humerus can leave permanent damage even after the surgical treatment. The high incidence of fractures justifi es questioning the possible prevention of this injury. Preventive actions are possible only with the knowledge of the causes and circumstances of the fracture. Aim is to analyze the circumstances of the injury, critical places and activities engaged in at the time of the humeral fracture by age groups. The paper analyzed 102 children that were treated at the University Hospital Centre in Zagreb due to fractures of the humerus in the period from 2010 to 2014. In this study, we analyzed 45 girls (44%) and 57 boys (56%). The average age of children was 8.3 years. Fractures of the distal third of the humerus accounted for 4/5 of all analyzed fractures. The right hand was affected more frequently. Nearly 80% of fractures were unstable, which generally require surgical treatment. The injury occurred most often among the 5-9 year-olds. Most injuries took place at the recreational facilities (47%), followed by injuries at home (31%), on streets or roads (15%) and at school or kindergarten (7%). Mechanism of the injury was mainly a fall onto the arm (94%) and the rest of the injuries were due to a direct blow. Almost half of the children got injured in sports or recreational activities. Due to close physical contact and engagement in games, children in preschool and early school age are by far the most susceptible to injuries. To reduce the incidence of such injuries, preventive actions should be taken during daily activities under the supervision of parents towards the most vulnerable age group (5-9 years), along with increasing the supervision in preschools and schools. Of all the activities, the most dangerous to cause fractures of the humerus occur in sports grounds and recreational facilities of preschool children and children in the lower grades of elementary school.

[EXOTHERMIC REACTIONS OF PLASTER IMMOBILIZATION ­ ANALYSIS OF THREE KINDS OF PLASTER BANDAGES].

Exothermic reaction of plaster is a very important characteristic to understand, especially when it comes to complications which can occur during local temperature change during molding plaster of Paris. And these complications directly influence the speed and quality of treatment. In this paper we measured temperatures of plaster bandage tiles 10×10 cm, from three different manufacturers in Croatian hospitals: Safix plus (Hartmann, Germany), Cellona (Lohmann &Rauscher, Austria) and Gipsan ( Ivo Lola Ribar, Croatia). We made three different plaster tiles 10×10 cm, from 10, 15 and 30 layers of plaster bandages. We immersed plaster tiles in two different water temperatures, one group in water 22 °C, and another in 34 °C. Although all plaster bandages have similar chemical characteristics, we have measured some differences. All three kinds of plaster bandages used in Croatia have low exothermic reaction when plaster molding is done in standard conditions, average local temperature is low and there is no danger of local burns. We immersed a plaster tile with 15 layers in water on 34° C, and highest average temperature was measured at Gipsan (46.2 °C), then Cellona (41.3 °C) and Safix plus (38.9 °C). On the same water immersion temperature, on plaster tile with 30 layers average temperatures were Gipsan (48.4°C), Cellona (45.4 °C), and lowest in Safix plus (41.3 °C). Plaster tiles form all manufacturers, when used 15-30 layers thick, and water immersion temperature is 34°C, develop average temperature over 40°C, in duration from 8-12 minutes. Between three different plaster bandages analyzed, Gipsan (Ivo Lola Ribar, Croatia) developed highest temperature, and some plaster tiles were measured over 50 °C.

[FRONTAL, AXILLARY AND TYMPANIC TEMPERATURE MEASUREMENTS IN CHILDREN]. / TIMPANICNA, FRONTALNA I AKSILARNA TEMPERATURA U DJECE.

The purpose of this study was to compare the results of body temperature measurements obtained by standard axillary thermometers with the results of infrared tympanic and frontal skin thermometry in afebrile children. This study comprises a single-center, prospective comparison trial. A total of 345 afebrile children aged 4 to 16 years hospitalized in the pediatric surgery department for elective surgery were included. One thousand axillary, tympanic and frontal measurements were obtained and compared. We used two different infrared thermometers in this study; one type measured the tympanic temperature, the other the temperature on the forehead. The axillary temperature measured with the glass thermometer was set as the standard. Each patient was exposed to a constant environmental temperature for a minimum of 10 min before simultaneous temperature measurements. The mean-frontal temperature 36.9 ± 0.38 °C was equal to the axillary temperature 36.9 ± 0.16 °C. The mean tympanic temperature was 36.3 ± 0.98 °C. The mean difference between the tympanic and axillary temperatures was -0.4 °C. The tympanic temperature had a threefold greater dispersion than frontal and a fivefold greater dispersion than axillary temperature. The results of this study suggest that the axillary temperature measured with glass thermometer has the least dispersion. Somewhat less reliable is the frontal temperature measured with infrared thermometer. The least reliable is tympanic temperature measurement.

[HAND FRACTURES IN CHILDREN - CAUSES AND MECHANISMS OF INJURY]. / PRIJELOMI KOSTIJU SAKE U DJECE - OKOLNOSTI I UZROCI NASTANKA.

Hand is extremely exposed to various loads and traumas of everyday tasks and activities, resulting in fist fractures being fairly common injuries. The most common mechanism of injury is a direct blow. This retrospective study analyzed the data on 274 children admitted for hand fractures at Clinical Hospital Center Zagreb in the period from 2006 to 2014. The study included 76 girls (28%) and 198 boys (72%). The average patient age was 11.9 years and most were between 10 and 13 years of age. Phalangeal fractures accounted for 80%, metacarpal fractures for 17%, and carpal fractures for 3% of all injuries. Most commonly injuries occurred during recreation (4 1%), at home (37%), at school (18%) and in the street (4%). Direct blow was the major cause of injury (76%), and 24% were caused by fall. Injuries during sport activities are the most common cause of the hand fractures in pediatric population and direct blow is the main mechanism of injury. The peak incidence is at the age of 10-13 years in boys and girls, so prevention should be aimed at this age group. Preventive actions should be focused on injuries that tend to occur in parks, schools and during sport activities.

[Radius fractures in children--causes and mechanisms of injury]. / Prijelom palcane kosti u djece--okolnosti i uzroci nastanka.

Radius fractures are the most common fractures in childhood. The main mechanism of injury is fall onto an outstretched hand. This retrospective study analyzed the data on 201 children admitted for radius fractures at KBC-Zagreb in the period 2011-2013. The study included 85 girls (42.3%) and 116 boys (57.7%) . The average age of the children was 9.6 years. Radius was injured in the distal segment in 79.1% of children. The sites of injuries were: park, campi and beach (24.9% of all children), playground, skate park and swimming pool (23.9%), kindergarten or school (20.9%), at home and around the house (17.9%), in the street (11.4%) and in the store or at a hotel (0.9%). The boys were mostly injured at playgrounds, during skating and at swimming pools (37.1% of all boys), while girls were mostly injured in parks, camps and at beach (42.4% girls). Fall was the major cause of the injury (49.3%), and children usually fell during ice skating and skating (32.3% of all falls). In 20.4% the injury was caused by pushing and hitting. The smallest percentage (9.5%) of children were injured in traffic accidents while riding a bike (only one child was hit by a car). Sport related activities caused injuries in 53.7% of the cases. Sport activities are the most important cause of the radial fractures in the pediatric population and falls during sports are the main mechanism of injury. The peak incidence is at 12 years for boys and at 10 years for girls, so intervention and/or prevention should be aimed at the age groups. Preventive actions should be focused on injuries that tend to occur in parks, schools and during sport activities.

[PHYSICAL PROPERTIES OF PLASTER BANDAGES]. / FIZIKALNA SVOJSTVA SADRENIH ZAVOJA.

The physical properties of plaster bandages are a very important factor in achieving the basic functions of immobilization (maintaining bone fragments in the best possible position), which directly affects the speed and quality of fracture healing. This paper compares the differences between the physical properties of plaster bandages (mass, specific weight, drying rate, elasticity and strength) and records the differences in plaster modeling of fast bonding 10 cm wide plaster bandages, from three different manufacturers: Safix plus (Hartmann, Germany), Cellona (Lohman Rauscher, Austria) and Gipsan (Ivo Lola Ribar ltd., Croatia). Plaster tiles from ten layers of plaster, dimension 10 x 10 cm were made. The total number of tiles from each manufacturer was 48. The water temperature of 22 °C was used for the first 24 tiles and 34 'C was used for the remainder. The average specific weight of the original packaging was: Cellona (0.52 g/cm3), Gipsan (0.50 g/cm3), Safix plus (0.38 g/cm3). Three days after plaster tile modeling an average specific weight of the tiles was: Gipsan (1.15 g/cm3), Safix plus (1.00 g/cm3), Cellona (1.10 g/cm3). The average humidity of 50% for Safix plus and Cellona plaster tiles was recorded 18 hours after modeling, while for the Gipsan plaster tiles, this humidity value was seen after 48 hours. On the third day after plaster modeling the average humidity of the plaster tiles was 30% for Gipsan, 24% for Safix and 16% for Cellona. Cellona plaster tiles made with 34 °C water achieved the highest elasticity (11.75±3.18 MPa), and Gipsan plaster tiles made with 22 °C had the lowest (7.21±0.9 MPa). Cellona plaster tiles made with 34 °C water showed maximum material strength (4390±838 MPa), and Gipsan plaster tiles made with 22 °C water showed the lowest material strength (771±367 MPa). The rigidity and strength of Cellona and Gipsan plaster are higher in tiles made in warmer water, and for Safix plus are higher in tiles made in cooler water. All three types of plaster differentiate in physical properties. The differences in mass and specific weight before and after plaster modeling are minimal. There are greater differences in drying rate, elasticity and strength between the three different plaster materials.

[CLAVICLE FRACTURES IN CHILDREN--CIRCUMSTANCES AND CAUSES OF INJURY]. / PRIJELOM KLAVIKULE U DJECE--OKOLNOSTI I UZROCI NASTANKA.

Clavicle fractures in children occur twice as often as in adults. During a child's growth period they account for 10-15% of all fractures sustained. The questions which should be asked are how these fractures are sustained and under which circumstances are the children injured. In the study 256 children with clavicle fractures treated during the period 2008-2013 were analyzed. The underlying cause and place of injuries were classified using the ICD-10 classification system, using environmental causes of injury. The circumstances were in each case accidental injury. Environmental causes were traffic accidents (V01-V99) or mishaps/accidents (W00-X59). Fracture injuries were caused in traffic accidents in 24 (9.4%), and in mishaps/accidents in 232 (90.6%) children. Of the injuries caused by mishaps/accidents, in 204 children these were caused by falls (W00-W19). In 123 of them the injuries were caused by falls from a ground level, and in 81 were from a greater height. Direct blow injuries, caused by another person or a blunt instrument, weere the causes of fractures seen in 28 children. Place of fracture sustainment was dominantly at home. This was followed by injuries sustained outside in recreational areas, while least were suffered at school or kindergarden facilities. Bicycle riding was the cause of clavicle fractures in 48 children, which was 18.7% of all fractures seen. Sports related injuries and fractures were seen in 47 (18.4%) out of 256 children: 30 in football, 10 in defensive sports (wrestling, judo, karate), three in hockey, while basketball and gymnastics accounted for two each. Preschool children were injured more often while in the care of their parents while school aged children were adaquately protected, but in after-school activities they were often injured. The most common injuries after school were those suffered in traffic accidents and recreational sports activities. In the adolescent period, the most common injuries seen were again those in traffic accidents, bicycle riding, recreational sports activities and injuries sustained at home.

High Doses of Δ9-Tetrahydrocannabinol Might Impair Irinotecan Chemotherapy: A Review of Potentially Harmful Interactions.

This review proposes the hypothesis that the effectiveness of irinotecan chemotherapy might be impaired by high doses of concomitantly administered Δ9-tetrahydrocannabinol (THC). The most important features shared by irinotecan and THC, which might represent sources of potentially harmful interactions are: first-pass hepatic metabolism mediated by cytochrome P450 (CYP) enzyme CYP3A4; glucuronidation mediated by uridine diphosphate glycosyltransferase (UGT) enzymes, isoforms 1A1 and 1A9; transport of parent compounds and their metabolites via canalicular ATP-binding cassette (ABC) transporters ABCB1 and ABCG2; enterohepatic recirculation of both parent compounds, which leads to an extended duration of their pharmacological effects; possible competition for binding to albumin; butyrylcholinesterase (BChE) inhibition by THC, which might impair the conversion of parent irinotecan into the SN-38 metabolite; mutual effects on mitochondrial dysfunction and induction of oxidative stress; potentiation of hepatotoxicity; potentiation of genotoxicity and cytogenetic effects leading to genome instability; possible neurotoxicity; and effects on bilirubin. The controversies associated with the use of highly concentrated THC preparations with irinotecan chemotherapy are also discussed. Despite all of the limitations, the body of evidence provided here could be considered relevant for human-risk assessments and calls for concern in cases when irinotecan chemotherapy is accompanied by preparations rich in THC.

Optimisation of a gas chromatography-mass spectrometry method for the simultaneous determination of tetrahydrocannabinol and its metabolites in rat urine.

In order to evaluate the effect of irinotecan (IRI) on urinary elimination of delta-9-tetrahydrocannabinol (THC) in a rat experimental model, we developed an analytical method for the determination of the mass concentration of THC and its metabolites [11-hydroxy-delta-9-tetrahydrocannabinol (THC-OH) and 11-nor-9-carboxy-delta-9-tetrahydrocannabinol (THC-COOH)] in the urine of rats treated only with THC and treated simultaneously with THC and irinotecan. For this purpose, hydrolysis and solid phase extraction conditions of the investigated analytes were optimised and a gas chromatography-mass spectrometry (GC-MS) method was developed to determine all three analytes in rat urine. The most effective hydrolysis method for THC, THC-OH, and THC-COOH conjugates was so-called tandem hydrolysis by the ß-glucuronidase enzyme from Escherichia coli at 50 °C for 2 hours and followed by alkaline hydrolysis. The proposed method was then applied for determining concentrations of analytes in 24-hour rat urine. THC was not detected in either sample, THC-OH was detected in 50 % of samples, and THC-COOH in all of the samples. Enhanced urinary THC-COOH excretion was noted in rats administered combined treatment compared to single THC treatment. The method described herein was suitable for determining the mass concentration of THC metabolites in the rat urine due to its sensitivity (detection limits: 0.8-1.0 µg/L), accuracy (>96 %), and precision (RSD <6 %).

Effects of Δ9-tetrahydrocannabinol on irinotecan-induced clinical effects in rats.

Because of the great interest for research on the potential use of cannabis preparations as co-medication for alleviation of toxic effects in cancer management, we investigated the influence of Δ9-tetrahydrocannabinol (Δ9-THC) to modulate irinotecan (CPT-11)-induced toxicity. Male Wistar rats were treated either with a single irinotecan intraperitoneal dose, 100 mg/kg body-weight (b.w.), or with irinotecan in combination with THC (7 mg/kg b.w., p.o., administered repeatedly for 1, 3 and 7 days). Serial blood samples were obtained up to seven days after dosing and were analyzed for complete blood count and biochemical parameters (liver enzymes, creatinine, inflammatory markers, and lipid status). Serial urine samples were collected in the first 24 h to monitor the time-course of THC metabolite 11-nor-9-carboxy-Δ9-THC (THC-COOH) excretion with concomitant irinotecan treatment or without. Both irinotecan and irinotecan + Δ9-THC administration caused moderate leukopenia but a greater decrease in leukocyte count was observed in the irinotecan + Δ9-THC treated compared to the single irinotecan suggesting higher cytotoxic effects in combined treatment. Irinotecan treatment induced elevation of aspartate aminotransferase (AST) in rats without diarrheal symptoms and without an increase in circulating pro-inflammatory mediators. Interestingly, the elevation of AST was not observed in the irinotecan + Δ9-THC group. The median creatinine-corrected urinary THC-COOH concentration was higher in the irinotecan + THC group compared to the THC-only group in a time-dependent manner, suggesting a possible early interaction between cannabinoids and irinotecan. Further studies are needed to investigate the role of cannabinoids particularly on hematological toxicity, irinotecan metabolism and their role as a possible modifiable factor among irinotecan-treated hosts.

Evaluation of HI-6 oxime: potential use in protection of human acetylcholinesterase inhibited by antineoplastic drug irinotecan and its cyto/genotoxicity in vitro.

The function of acetylcholinesterase (AChE) is the rapid hydrolysis of the neurotransmitter acetylcholine (ACh), which is involved in the numerous cholinergic pathways in both the central and the peripheral nervous system. Therefore, AChE measurement is of high value for therapy management, especially during the course of intoxication with different chemicals or drugs that inhibit the enzyme. Pyridinium or bispyridinium aldoximes (oximes) are able to recover the activity of the inhibited enzyme. Since their adverse effects are not well elucidated, in this study the efficiency of HI-6 oxime in protection and/or reactivation of human erythrocyte AChE inhibited by the antineoplastic drug irinotecan as well as its cyto/genotoxicity in vitro were investigated. HI-6 was effective in protection of AChE and increased its activity up to 30%; the residual activity after irinotecan inhibition was 7%. Also, it reactivated the enzyme previously inhibited by 50% irinotecan (4.6 microg/ml) applied at 1/4 of the IC50 value. The tested concentrations of HI-6 exhibited acceptable genotoxicity towards white blood cells, as estimated by the alkaline comet assay, DNA diffusion assay and cytogenetic endpoints (structural chromosome aberrations and cytokinesis-block micronucleus assay). The results obtained warrant the further investigation of HI-6 in vivo, as well as its development for possible application in chemotherapy.

Comparative evaluation of acetylcholinesterase status and genome damage in blood cells of industrial workers exposed to carbofuran.

Literature data on carbofuran genotoxicity in vitro and in vivo are very scarce. There are few papers indicating that occupational exposure to this AChE inhibiting insecticide might be connected to increased risk of developing non-Hodgkin's lymphoma and lung cancer. Other authors showed its genotoxicity in vitro. We used comet and CBMN micronucleus assay combined with centromere probes to evaluate genome damage in lymphocytes of workers employed in carbofuran production. Also, the level of AChE activity in blood and plasma was measured. Only few workers exhibited AChE activity below 85%. Comet assay parameters were slightly but significantly elevated compared to control subjects, especially the long-tailed nuclei ratio. We found poor correlation between AChE activity and comet assay parameters, but significant effect of smoking and alcohol intake on the latest. In binucleated lymphocytes of workers significantly increased number of micronuclei, nuclear buds, and nucleoplasmic bridges was detected. Proportion of micronuclei with centromere, DAPI signal positive micronuclei was also elevated. Micronucleus assay parameters also appeared to be significantly influenced by duration of exposure to carbofuran. Together with published data on carbofuran's effect on health our results might indicate the need for further evaluations of its genotoxicity using a range of different cytogenetic techniques.

Analysis of Airborne Dust as a Result of Plaster Cast Sawing.

Plaster splints are used daily in surgical and orthopedic fields in order to immobilize injured children and adults. The aim of this study was to measure the aerodynamic diameter and concentration of dust particles in the air caused by sawing plaster splints (calcium sulfate dehy-drate). We performed fractional measurements of airborne dust particles. The measured particles, which can potentially be inhaled, may have a specific negative effect on human health. Measurements were conducted in laboratory research facilities that simulated hospital conditions within a casting room and the associated waiting room. Measurements within the casting room were made using two particle collector devices and one laser photometer. The measurement for the simulated waiting room was performed using the same principles and devices. The collected plaster dust particles differed in aerodynamic diameter and concentration according to the various locations observed. The highest concentration of particles of all sizes was recorded at the site of cast sawing. There was direct correlation between distance from the source and concentration of airborne particles; this concentration was lowest in the waiting room. The concentrations of plaster dust recorded were lower than the recommended minimal limit values for total and respiratory fractions in Croatia. Accordingly, it can be assumed that sawing of plaster splints has no harmful health effects on the exposed patients and health personnel.

Reducing damage to the periosteal capillary network caused by internal fixation plating: An experimental study.

BACKGROUND: The importance of the periosteum in fracture healing is well-known. Preserving periosteal vascularisation is essential during internal plate fixation of fractures. METHODS: This was an experimental randomised, controlled animal study on nine sheep. Standard dynamic compression plate (DCP) and four different newly designed reefed plates, with different plate-bone contact surface areas and different reef directions, were fixated on to the tibia or radius. After two weeks the plates were removed and the underlying periosteum was analysed. Blood vessels were marked by immunohistochemical staining (CD31 and CD34), microphotographs were taken and blood vessels counted to calculate blood vessel density. RESULTS: Median blood vessel density beneath the standard plate was significantly lower than in the intact periosteum (18.0 vs 27.7mm(3)/cm(3)). Blood vessel density in the periosteum beneath plates with reefs was significantly increased compared with the intact periosteum, and was highest beneath the plate with the lowest bone-plate contact area and crosswise reefs (51.5mm(3)/cm(3)), followed by plates with transverse, oblique and longitudinal reefs, respectively. The direction of the reefs did not have much influence on the periosteal capillary network. Lower contact surface area seems to be the main factor that increases blood vessel density beneath the plates. CONCLUSIONS: The results show that plates with lower contact surface area stimulate angiogenesis in the underlying periosteum, which results in much higher blood vessel density compared with standard DCP. A randomised clinical trial is needed to prove the clinical relevance of these findings.

RESULTS OF CLAVICLE FRACTURE TREATMENT IN CHILDREN.

Treatment of clavicle fracture is principally outpatient. Operative treatment is accompanied by the need for more x-rays and possible complications. Fractures with absolute indications for operative treatment occur only sporadically and these indications are relatively clear, but children often undergo surgery because of relative indications (shortening, fragment displacement, multifragmentary fractures), which are open to debate. In a retrospective study on 256 children, of 44 (17%) patients that received operative treatment only one 17-year-old boy had an absolute indication for surgical intervention. Other indications were fragment distraction (22 mm on average), age, associated injuries, and multifragmentary fracture. The placement of K-wire of appropriate thickness is often difficult, since the wire tends to bend and break, and patients have to undergo two additional operations of plate and screw fixation and later removal. In this retrospective study, we considered the advantages of using titanium or an elastic steel pin. All patients had favorable outcome, although some experienced numbness around the operation scar (4.5%), skin infections around the wire (15%), and/or the implanted K-wire damage (7%).