Treatment of Supracondylar Humerus Fractures in Children: Minimal Possible Duration of Immobilization

In the period from January 1980 until December 1990 we treated 147 children and adolescents with supracondylar humerus fracture, and followed the outcome in 127 of them. Three (2.4%) patients had no displacement of fractured bones and were treated only with plaster cast immobilization. Twenty three (18.1%) underwent closed reduction of fragments and application of a plaster cast. The majority (97; 76.4%) required manual reduction and the fixation of segments with Kirschner\u27s wires laterally and medially. Four (3.1%) patients were treated with open reduction and fixation with Kirschner\u27s wires. Both plaster cast immobilization and fragment fixation with Kirschner\u27s wires lasted only 14 days and were immediately followed by rehabilitation. Such a short immobilization of extremities or fixation of fragments did not result in any complication. Of 56 children available for long-term follow-up, we achieved excellent treatment results in 43 (76.6%) of the patients, good and fair in 12 (21.5%), and a poor result in only 1 patient (1.8%). There were no permanent vascular or neurological complications apart from slight weakness of the ulnar nerve in 3 patients. In conclusion 14 days seemed to be the biological minimum of time needed for this type of fracture to heal in children and adolescents. Fixation of the fragments with Kirschner\u27s wires and immobilization of the extremity for only 14 days brings a significant reduction of total treatment expenses, avoids repeated x-ray examination, facilitates early physical therapy and returns the child to its family

Graphene-based waveguide resonators for submillimeter-wave applications

Utilization of graphene covered waveguide inserts to form tunable waveguide resonators is theoretically explained and rigorously investigated by means of full-wave numerical electromagnetic simulations. Instead of using graphene-based switching elements, the concept we propose incorporates graphene sheets as parts of a resonator. Electrostatic tuning of the graphene surface conductivity leads to changes in the electromagnetic field boundary conditions at the resonator edges and surfaces, thus producing an effect similar to varying the electrical length of a resonator. The presented outline of the theoretical background serves to give phenomenological insight into the resonator behavior, but it can also be used to develop customized software tools for design and optimization of graphene-based resonators and filters. Due to the linear dependence of the imaginary part of the graphene surface impedance on frequency, the proposed concept was expected to become effective for frequencies above 100 GHz, which is confirmed by the numerical simulations. A frequency range from 100 GHz up to 1100 GHz, where the rectangular waveguides are used, is considered. Simple, all-graphene-based resonators are analyzed first, to assess the achievable tunability and to check the performance throughout the considered frequency range. Graphene–metal combined waveguide resonators are proposed in order to preserve the excellent quality factors typical for the type of waveguide discontinuities used. Dependence of resonator properties on key design parameters is studied in detail. Dependence of resonator properties throughout the frequency range of interest is studied using eight different waveguide sections appropriate for different frequency intervals. Proposed resonators are aimed at applications in the submillimeter-wave spectral region, serving as the compact tunable components for the design of bandpass filters and other devices

Normal and Cut-Off Values of the Cytokinesis-Block Micronucleus Assay on Peripheral Blood Lymphocytes in the Croatian General Population

Mikronukleus (MN) test na limfocitima periferne krvi jedna je od najvažnijih metoda koje se primjenjuju u citogenetičkom nadzoru. Osnovni preduvjet za primjenu nekog testa u svrhu nadzora profesionalno izloženih populacija jest poznavanje normalnih vrijednosti promatranoga biološkog pokazatelja (biomarkera) u kontrolnoj populaciji. Baze podataka na razini opće populacije moraju se redovito obnavljati novim podacima. Cilj ovog istraživanja bio je utvrditi normalne i granične vrijednosti MN-testa na limfocitima periferne krvi 200 zdravih ispitanika obaju spolova iz opće populacije Republike Hrvatske te ispitati koji čimbenici pridonose spontanom nastanku MN. Na razini istražene populacije utvrđeno je prosječno (6,90±3,32) MN (medijan 7 MN), dok je raspon pojedinačnih vrijednosti iznosio 0 do 18 MN u 1000 binuklearnih stanica. Gornja granična vrijednost dobivena izračunavanjem 95. percentila za cjelokupnu promatranu populaciju iznosi 12,5 MN na 1000 limfocita. Utvrđeno je da na spontani nastanak MN utječu spol, dob i navika pušenja. Žene u prosjeku imaju više vrijednosti svih parametara MN-testa od muškaraca, a u njih je bio i naglašeniji porast vrijednosti citogenetičkog nalaza zbog navike pušenja. Kako su literaturni podaci o utjecaju pušenja cigareta na nastanak MN kontradiktorni, planiran je nastavak istraživanja radi razjašnjavanja utjecaja dnevno utrošenog broja cigareta i ukupnog trajanja pušačkog staža na vrijednosti parametara MN-testa. Usporedba rezultata s literaturnim podacima potvrdila je da su dobivene vrijednosti u skladu s vrijednostima MN-testa zabilježenim na općoj populaciji u drugim svjetskim laboratorijima. Normalne i granične vrijednosti MN-testa utvrđene u ovome istraživanju poslužit će kao osnova za usporedbu i tumačenje nalaza MN-testa u ispitanika izloženih populacija te daljnju nadogradnju laboratorijske baze podataka.The cytokinesis-block micronucleus (CBMN) assay on peripheral blood lymphocytes is one of the most important methods employed in cytogenetic biomonitoring. For the purposes of biological dosimetry, it is important to kno the spontaneous frequency of a biomarker and its normal values in general population. These values are used for population databases, which should be updated regularly. In this study, MN levels were investigated in cytokinesis-blocked lymphocytes of 200 healthy male and female blood donors selected at random from the general population of Croatia. The aim was to assess the variability and determine possible infl uences of external and/or internal factors on the background levels of MN and to establish the cut-off value for the CBMN assay. The background frequency of MN was (6.90±3.32) MN (median 7 MN) and the range was 0 to 18 MN per 1000 binuclear lymphocytes. The cut-off value, which corresponds to 95th percentile of the distribution of 200 individual values, was 12.5 MN. Spontaneous formation of MN was infl uenced by sex, age, and smoking. Women had higher MN levels than men. However, only age and smoking signifi cantly increased the values of all parameters evaluated by the CBMN assay. Since the existing literature data on smoking-related formation of MN are contradictory, we will continue these investigations to resolve how the number of cigarettes smoked per day and the duration of smoking in years infl uence the results of the CBMN assay. Our results are consistent with the background MN frequencies reported by other cytogenetic laboratories worldwide. Normal and cut-off values estimated in this study will be used to update the current general population data and as reference for occupationally or accidental exposure

The frequency of premature segregation of centromeres in persons exposed to ionizing radiation

U ovom radu istraživana je učestalost prevremene centromerne deobe (PCD) u metafazama medicinskog osoblja profesionalno izloženog jonizujućem zračenju koji su imali pozitivan nalaz hromozomskih aberacija, u odnosu na kontrolnu grupu koja nije profesionalno izložena efektima pomenutog zračenja. Evaluacija klastogenog efekta izvedena je pomoću Moorchaedove mikrometode te aplikacijom tehnika fluorescentne in situ hibridizacije (FISH). Analizom rezultata zapaženo je da postoji statistički značajna razlika (p lt 0.05) u frekvenciji metafaza PCD na bilo kom od observiranih hromozoma kao i na ukupnom broju hromozoma sa PCD između dve grupe ispitanika (profesionalno izloženi i kontrole). Fluorescentnom in situ hibridizacijom (FISH) praćenje centromerni region hromozoma 18 na metafazama i interfaznim jedrima, što je pokazala da je pojavljivanje PCD na hromozomu 18 bilo 11,19% na metafazama i 10.88% na interfaznim jedrima, dok je kod kontrolne grupe ispitanika pojavljivanje PCD na hromozomu 18 bilo 7,58%, na metafazama, i 7.78% na interfaznim jedrima. Dakle, ovim istraživanjemj e utvrđeno da kod ispitanika profesionalno izloženih jonizujućem zračenju, postoji fenomen PCD verifikovan u metafazama i interfaznim jedrima, u značajno frekventnijem obimu nego što je to slučaj sa kontrolnom grupom ispitanika. Indukcija PCD raznim genotoksičnim agensima upućuje da se PCD sagleda kao parametar genotoksičnog rizika po čoveka i njegovu životu sredinu.The objective of study was to establish the incidence of PCD in metaphases of medical personnel occupationally exposed to ionizing radiation in relation to the controls. Moorchaed's micromethod and fluorescent in situ hybridization (FISH) were used for evaluation of clastogenic effect. The analysis of results revealed statistically significant difference (p lt 0.05) of PCD manifestation in metaphases any chromosome and the control group. In addition, significantly higher values were found in a total number of chromosomes with PCD than in the controls (p lt 0.05). Fluorescent in situ hybridization (FISH) was used to monitor the centromeric region of chromosome 18 in metaphases and interphasic nuclei. Cytogenic analysis showed that the manifestation of PCD in chromosome 18 was 11.19% in metaphases and 10.88% in interphasic nuclei, while in the controls, the presentation of PCD in chromosome 18 was 7.58% in mataphases and 7.78% in interphasic nuclei. The study confirmed that the subjects occupationally exposed to ionizing radiation had PCD phenomenon, wich was verified in metaphases and interphasic nuclei in a significant frequency rate. The induction of PCD by various genotoxic agents directs us to recognize PCD as parametar of genotoxic risk to mankind and its environment