The morphogenesis of electrically and heat-induced dermal changes in pig skin

In order to establish pathological evidence in dermis for distinguishing between sequelae of electrical torture and those of other superficial injuries, the skin of eleven fully anaesthetized Danish Landrace pigs have been exposed to heat and electrical energy from either 50 Hz alternating current (a.c.) or direct current (d.c.) via 12 mm large contact knobs or via a pointed 0.5 mm large electrode (only 50 Hz a.c.). The lesions have been examined from 1 to 126 days after the injury. While heat lesions exposed to energy lower than 60 joule only gave minor changes, heat lesions exposed to more than 60 joule showed changes in both collagen fibres (basophilic or eosinophilic fibres without any birefringence or coarse cross-striation in polarized light, respectively) and dermal cells (granular cytoplasm). Areas exposed to 50 Hz a.c. via 0.5 mm. electrode showed basophilic collagen fibres and in a few biopsies on day 7 calcium salts on collagen fibres. Using 12 mm large electrodes the changes were minor, but basophilic and eosinophilic collagen fibres with no birefringence or with fine/coarse cross-striation respectively were seen. Even cells with 'vesicular nuclei' were seen on day 1 and 2 after the injury. The changes in the anode area showed resemblance to that of heat lesions (basophilic collagen fibres). Eosinophilic collagen fibres with fine densely spaced cross-striation in polarized light and 'vesicular nuclei' as well as collagen fibres with calcium salts were seen in the cathode lesions. It is concluded that the dermal changes in the cathode area are specific for electrical injury from day 1 to 14. However, earlier studies have demonstrated dermal changes specific for electrical injury at day 0 and the presence of calcified collagen fibres up to 2 months after injury. The dermal changes in anode lesions were non specific and could not be differentiated from those found in heat lesions. Alternating current lesions (50 Hz) were specific from day 1 to day 7, when the pointed electrode was used, but only in a few days when the energy was transferred via the 12-mm electrodes.     

Electrically-induced collagen calcification in pig skin. A histopathologic and histochemical study

Deposition of calcium salts on collagen fibres in skin of fully anaesthetized pigs was induced by exposure to direct current (d.c.). In biopsies obtained from cathode areas successively from day 1 to day 7 after exposure the histopathologic and histochemical changes before and after the initial deposition of calcium salts have been examined. For comparison skin sites with intradermal injected calcium hydroxyapatite crystals were studied in addition. Small areas of calcified collagen and elastic fibres were noted in viable tissue 2 days after d.c. exposure. In succeeding days the calcified areas enlarged with new deposits always more superficial and closer to the epidermis than the original calcium deposits. Preconditions for calcification appear to be (1) a pH change in basic direction and/or the electrochemical processes specific to the cathode area and (2) a viable tissue. Elastic fibres appear to have a lower calcification threshold than collagen fibres. A positive staining for glycoproteins (PAS) and glycosaminoglycans (alcian blue pH 2.5) was noted in the calcified collagen fibres simultaneously with the calcification. In succeeding days the intensity of the staining reactions increased. Whether changes in the glycoproteins, collagen and its intimately bound glycosaminoglycans precede the calcification or the staining reactions develop secondarily to this deposition is not known. However, seven days after intradermal injections of Ca-apatite crystals in pig skin small and large crystals were observed ultrastructurally without any relation to collagen fibrils, but the calcified tissue presented a positive PAS and alcian blue reaction from day 2. Thus the PAS and alcian blue stainings in this model develop secondary to the deposition of calcium salts.     

Ultrastructural changes in dermal pig skin after exposure to heat and electric energy and acid and basic solutions

In order to describe the ultrastructure of the histopathological changes in dermis after exposure to electrical energy, heat energy and acid and basic solutions the skin of fully anaesthetized Danish Landrace pigs were exposed to direct current, heat (80 degrees C and 450 degrees C) and acid and basic solutions. Biopsies were obtained immediately after the exposure from all types of injury. Biopsies from the cathode areas biopsies were also taken on day 1 and day 2.5 in order to describe the initial calcium deposits. Homogeneous collagen fibres without any birefringence from heat exposed areas were ultrastructurally composed of filamentous materials. Collagen fibres with fine densely spaced cross-striation from cathode areas and areas exposed to basic solutions were shown ultrastructurally to consist of parallelly arranged collagen fibrils with regular waves. It is concluded that the cross-striation of the collagen fibres observed in polarized light are due to a periodic change in the orientation of the fibres seen as waves of the fibres. The ultrastructure of dermal cells were similar to that of epidermal cells following the different types of influence. Characteristically the nuclei were condensed following heat and more electron-lucent following direct current (d.c.) and acid and basic solutions. In cathode areas and areas influenced by basic solutions the electron-lucent nuclei contained fine fibrils. The ultrastructural study supports the suggestion from light microscopic studies that the morphology of anode and cathode lesions shows resemblance to acid induced and basic induced lesions, respectively. Apatite crystals were observed on day 2.5 at the periphery of the collagen fibrils and in the matrix of elastic fibres.     

The effect of sodium hydroxide and hydrochloric acid on pig dermis. A light microscopic study

In order to compare the dermal changes after exposure to direct current (d.c.) with changes after influence of acid and base influence, the skin of fully anaesthetized Danish Landrace pigs were exposed to acid and basic solutions. Biopsies were obtained immediately after and up to day 7 after the injury. Collagen fibres with increased affinity for eosin and irregular cross-striation in polarized light together with shrunken cells with dark stained nuclei were found just beneath the epidermis immediately after application of 1 N HCl. Immediately after exposure to 1 N NaOH dispersed collagen fibres showed increased eosinophilia and a fine densely spaced cross-striation in polarized light and vesicular nuclei were present within dermal cells. During the following days a narrow demarcation zone of neutrophilic granulocytes separated the zone containing abnormal collagen fibres from normal tissue below. Calcified collagen fibres were not observed and no other abnormal histochemical reactions were present. It is concluded that the morphology of acid induced lesions and base induced lesions shows resemblance to the morphology of anode and cathode lesions, respectively, but not to heat lesions. The reason for not finding depositions of calcium salts on collagen fibres in skin exposed to basic solutions could be a non-optimal pH in the tissue or that other electrochemical processes than shift in pH are necessary for the calcification process.     

Diagnosis of electrical skin injuries. A review and a description of a case.

This paper presents a brief review of the results of research in the area of electrical skin injuries. It also includes a case report of a 5-year-old girl noted on her admission to the hospital to have injuries to the skin of her chest and left arm. Histological examinations demonstrated that the skin lesions were segmental and showed necrosis and inflammation. Deposits of calcium salts distinctly located to collagen fibers were observed below the regenerated epidermis at the periphery of two skin lesions of the chest wall, in the lower part of dermis at the periphery of a skin lesion of the left arm, and within connective tissue adjacent to elastic arteries and peripheral nerves from the thoracic cavity. The pattern of calcification localized to collagen fibers and situated both superficially and deeply in the skin in a zone of viable tissue close to necrotic tissue is characteristic of electrically induced lesions. Although there have been reports of deposition of calcium salts on collagen fibers after application of calcium salts in high concentration at the skin surface, the collagen calcification in the pattern observed in this patient is probably diagnostic of electrical injury.     

The significance of collagen in determining the age of a wound

The aim of the present study was to find out whether the quantitative and/or qualitative analysis of collagen can be useful in the determination of the age of healing skin wounds in various body regions of patients of different ages and sex. The quantitative measurement of total wound collagen revealed no clear time-dependent changes. Immunohistochemical staining for collagen types I and III demonstrated the presence of type III as early as 2 days after injury. Procollagen type I was found in wounds beginning from 4 days on, while type I collagen was not present before 6 days after the injury. Immunohistochemical analysis of specific basement membrane proteins, collagen type IV and laminin, showed a reconstruction of the epithelial basement membrane beginning from on day 5, while a completely rebuilt basement membrane was found in most cases after more than 14 days, depending on the dimension of the wound and its treatment.     

Connexin 43, angiotensin II, endothelin 1, and type III collagen alterations in heart of rats having undergone fatal electrocution

Death due to accidental electrocution occurs frequently. The aim of this study was to investigate alterations in cardiac connexin 43 (Cx43), angiotensin II (Ang II), endothelin 1 (ET-1), and type III collagen associated with fatal electrocution.Twenty-four Sprague-Dawley rats were divided into control, fatal electrocution (220 V, 50 Hz, 60 seconds), and electrical injury (220 V, 50 Hz, 60 seconds) groups. Animals were deeply anesthetized with sodium pentobarbital before each treatment, with the anode connected to the left foreleg and the cathode to the right hindleg, followed by cervical dislocation. Control animals received cervical dislocation alone. Immunohistochemical analysis was performed to evaluate the cardiac protein expression of Cx43, Ang II, ET-1, and type III collagen. Sections were analyzed by digital image analysis.The expression of Cx43 was significantly reduced after fatal electrocution, with the integrated optical density also lower when compared with control (P < 0.05). Expression of both Ang II and ET-1 was significantly increased after fatal electrocution, supported by integrated optical density when compared with control (P < 0.05). But no significant difference was found in type III collagen expression between the fatal electrocution group and the control group.In summary, cardiac protein expression of Cx43, Ang II, and ET-1 was found to be significantly altered with fatal electrocution, suggesting that these 3 proteins may be important underlying mechanisms of death during fatal electrocution. The current findings indicate that such alterations would be reflected in abnormal cardiac function and a possible cause of sudden death.     

The persistence of fibres on skin in an outdoor deposition crime scene scenario

Textile fibres were transferred to a pig skin carcass and their persistence determined at daily intervals for up to a 12 day period during which time the carcass was left outdoors exposed to the prevailing weather conditions and animal activity. In the absence of strong winds and precipitation, the loss of fibres was found to be exponential. Stronger winds and heavier precipitation caused an increase in the rate of loss of fibres. The results of this study showed that the majority of fibres transferred to a body deposited outdoors, can be expected to be lost after the first 2 days, however, none of the experiments performed resulted in a complete loss of fibres, even after 12 days exposure. These persistence characteristics differed from those observed in a similar study using small sections of skin, rather than carcasses.The implications of the results of the present study in relation to the examination of fibre evidence in cases of homicide are discussed.     

Investigating the effect photodegradation has on natural fibres at a microscopic level

It is a known fact that when fabric is left exposed to sunlight photodegradation occurs. However, no study has ever looked at the photodegradation that occurs to individual fibre filaments as commonly recovered from a scene of crime. To look at photodegradation of individual fibres, wool and cotton fabric were dyed using CI Acid Red 27 and CI Direct Red 80 respectively at two depths of shade, 0.25% and 2.0% owf. Pieces of fabric and individual fibre samples were then placed in a Light Fastness Q-Sun 1000 Xenon test chamber which simulated exposure to sunlight over two time periods, 64 h (equivalent to one weeks sun exposure) and 128 hrs (equivalent to two weeks sun exposure). The resulting pieces of fabric and fibres where then examined using high power comparison microscopy, as well as graded for colour fading using SDC Grey Scale for Assessing Change in Colour (including half steps). Results show that in both fibre types, photodegradation occurs in all samples, however, the degree of fading is shown to vary within a given fibre population showing it is unpredictable in nature.     

Degradation of biomolecules in artificially and naturally aged teeth: implications for age estimation based on aspartic acid racemization and DNA analysis

Postmortem teeth are the most stable structures, and can be used to gain different information (age estimation, genetic data). Over long postmortem intervals (PMI), degradation processes may alter the molecular integrity and thus affect the reliability of applied molecular methods. Whereas some knowledge on the degradation of biomolecules in bone during the PMI exists, data for teeth are lacking. In particular, the impact of degradation processes in dentine on age estimation based on aspartic acid racemization (AAR) cannot be estimated yet. Hence, the molecular stability of both collagen and DNA was analyzed systematically, and their impact on the reliability of age estimation based on AAR and genetic analyses was checked. Two hundred and ten human and 59 porcine teeth were heated (90 degrees C in water) to simulate collagen and DNA diagenesis; 14 naturally aged teeth (PMI: 3 days to 1700 years) were analyzed comparatively. Peptide patterns of cyanogen bromide (CNBr)-cleaved collagen were employed as a new approach to check the collagen integrity. In the same samples, collagen yields, amino acid compositions, AAR in different protein fractions, and DNA integrity were analyzed. In heated human and porcine teeth the collagen content declined during the heating experiment. The amino acid composition in human samples was collagen-like until 12 days of heating. In naturally aged teeth, the collagen yielded from 9.5 to 15%, and no discrepancy of amino acid composition to that of modern collagen was observed. Electrophoresis of CNBr-peptides showed an altered pattern in experimentally degraded samples from day 10 on; naturally aged collagen displayed the typical collagen pattern. AAR increased in all protein fractions with increasing duration of the heating experiment; naturally aged samples displayed a slow accumulation of AAR. DNA degraded progressively, and after 32 h of heat exposure no more DNA was detectable, whereas the amplification of nuclear and mitochondrial DNA was successful up to 48 h. STR typing was reliable up to 16 h, and sex determination up to 40 h of heat exposure. In naturally aged samples of DNA quality, yield and typing success did not correlate with PMI. The data highlight a remarkable stability of collagen dental proteins. Within relevant forensic periods a postmortem rise of AAR under normal conditions is negligible, and analyses of dental DNA has a high chance to be successful. However, after large PMI and/or extreme postmortem conditions age estimation based on AAR and genetic analyses lose their reliability.     

Electrical and thermal injuries in pig skin — Evaluated and compared by light microscopy

The morphology of pig skin after electrical (el) and thermal exposure was studied in order to find methods applicable for disclosing electrical torture.Biopsies from pig skin exposed 24 hours earlier to either heat or electrical current under general anesthesia were studied by light microscopy. The amount of energy used of either type ranged from about 6 to about 100 joule deposited on two circular areas of the skin measuring 12 mm in diameter.In sections stained with hematoxylin and eosin alterations were found in heat-influenced specimens following the administration of moderate and large doses of energy. Changes were observed in el-influenced specimens also after the administration of low amounts of energy, which did not lead to macroscopical changes in the skin. The two types of energy induced different patterns of alterations inside the epidermis. The most characteristic change following heat exposure was the presence of a granular or fibrillar eosinophilic cytoplasm and subepidermal clefts, while el-expoure often produced white homogeneous cytoplasm and shadowy nuclei (“white necrosis”) in the attached epidermis. The individual changes could be produced by both types of injury, but to a highly different degree. However, the alteration classified as “vesicular nuclei” was only observed in el-damaged skin. The dermis from the more severely injured skin of both groups showed a homogeneous appearance (“necrosis”). While the changes of epidermis and dermis in response to heat were diffusely distributed, the changes created by electrical injury were often present in segments. By electrical damage homogeneous areas with loss of stainability and shadowy nuclei were occasionally observed in sweat glands, hair sheaths and in vessel walls, structures which are suggested to serve as conductors for the electrical current. “Vesicular nuclei” were observed in similar structures.Some of the findings may be associated with differences in intensity of energy during exposure to heat and electricity. Furthermore, the existence of different biological patterns following the two types of exposure should be considered. The studies are being continued to elucidate these basic questions, and to study further the medical diagnostic potential of examining skin biopsies from tortured individuals.     

Skin changes following defibrillation. The effect of high voltage direct current

Previously, electrical injuries have been suggested caused only by the concomitant heat developed during the passage of an electrical current. Recent experimental studies on fully anesthetized pigs and the study of one human case have, however, shown typical electrical alterations. The purpose of the present study was further to evaluate the histology of electrically induced changes in the skin in humans. In addition, supplementary in vivo methods for evaluation of skin changes as high-frequency ultrasound and Raman spectroscopy were used. The skin of 11 patients treated with a defibrillation of the heart was examined for macroscopic changes, the skin of eight of them also for histologic changes and for changes observable via supplementary methods. Immediately and 7 days after the defibrillation, fractions of a narrow red ring were observed along the periphery of the tin-foil electrode. Epidermis showed signs previously observed following electrical influence: segmental alterations often related to the openings of sweat ducts, darkstaining or "empty" nuclei and homogeneous cytoplasm, eosinophilic or pale. Dermis did not show the specific sign of electrical influence: deposits of calcium salts on dermal fibres, neither via histologic examination nor via high-frequency ultrasonography and Raman spectroscopy. Fractions of a narrow red ring along the periphery of the electrode showing histological signs of electric influence in epidermis thus appear to be characteristic of high voltage electrical injury.     

Gross and histologic postmortem changes of the skin

Many methods have been attempted to accurately and systematically determine the estimated time of death in autopsy cases. Gross changes of the skin which occur during the postmortem interval have occasionally been used to estimate the time of death under different conditions; however, the postmortem gross and histologic changes of the skin have not been systematically analyzed. We sequentially studied the gross and microscopic appearance of skin in 3 individuals during the early postmortem interval (<1 week) in an outdoor, shaded, cool to temperate climate. Photos and skin biopsy specimens were taken from 4 sites (acral skin, scalp, dependent truncal skin, and nondependent truncal skin) every 12-24 hours on each individual. The gross appearance of the skin remarkably did not change significantly in any of the sites after 1 week of decomposition. Three main histologic changes were seen in the skin biopsy specimens: focal dermal-epidermal separation, eccrine duct necrosis, and dermal degeneration. Although bullae were not present in the gross examination of the skin, focal separation of the epidermis from the dermis was appreciated in several skin biopsies; however, the timing of development was unpredictable. Eccrine duct necrosis was another histologic finding and was relatively predictable, occurring in dependent and nondependent truncal skin biopsies from all 3 individuals between days 4 and 7. Dermal degeneration was a uniform histologic finding only in biopsies from nondependent truncal skin, occurring in all individuals on day 2. Although this study is limited by the small number of subjects and uncontrolled extrinsic factors, histologic findings, such as eccrine gland necrosis and dermal degeneration, in select cutaneous biopsies may be useful in estimating the time of death in the early postmortem interval.     

Multiplicative-innovation synergies: tests in technological acquisitions

Technological innovations enjoy synergies that vary in their speed and magnitude of impact, depending upon whether they are additive or multiplicative in nature. Additive-innovation synergies build incrementally on familiar technologies (as is reflected in the technologies built upon within their patents’ respective antecedents) and the duration of their effect is shorter-lived. Multiplicative-innovation synergies arise from combining greater proportions of diverse technologies and their effects have longer duration. The most-effective organizational-learning processes accompanying exposure to exotic technology streams via technological acquisition will occur if firms have properly invested in adaptive capacity to synthesize inventions using the unfamiliar knowledge. In the first tests of innovation synergies on firm performance, we find that technological novelty in patent content improves return on assets for firms that consistently invested in R&D. Using patent-content scores to characterize whether inventors have integrated greater proportions of exotic technological antecedents into their inventions (or not), we test the impact of innovation synergies on firms’ performance after technological acquisitions. Diversification posture (which could be an alternative explanation for performance differences) is negatively-correlated with innovation synergies in our results.     

An investigation into the persistence of textile fibres on buried carcasses

A significant amount of research has been carried out on fibres to aid the forensic scientist in determining the significance of these when found on a victim or suspect. This work has focused on open-air environments, and as such no research has been undertaken to examine the persistence of fibres on bodies in the burial environment.Wool and cotton fibres, known to fluoresce under ultraviolet (UV) light, were transferred onto the skin of four porcine (Sus scrofa) carcasses (two carcasses per fibre type). The number of fibres transferred was recorded from images taken under UV light. The remains were subsequently placed in four burial sites and left interred for 14 days. After this period the carcasses were excavated and lightly brushed down to remove the soil layer that had adhered to the skin. Once again photography under UV light was used to record the number of fibres which persisted on the skin.Results showed that after 14 days, wool and cotton fibres remain on the surface of the buried carcasses. In no circumstance was there a total loss of fibres suggesting that in such scenarios, the likelihood of finding fibres is high but the initial number of fibres transferred would be strongly diminished. This has important implications for both the excavation protocol for buried remains and the subsequent analysis for physical evidence.     

CT‐Guided,Minimally Invasive,Postmortem Needle Biopsy Using the B‐Rob II Needle‐Positioning Robot

CT‐guided, minimally invasive needle biopsy techniques can be used to retrieve tissue or body fluid samples for histologic tissue diagnoses in forensic investigations. The purpose of this study was an evaluation of CT‐guided needle‐positioning robot B‐Rob II. To operate under CT guidance, we adopted the B‐Rob II robotic needle placement system and its workflow. The accuracy and speed of the procedure were tested on a gelatin phantom in a series of 21 biopsies. We achieved an average needle placement accuracy of 1.8 mm (±1.1 mm) using robotic assistance. The procedure required an average of 2 min 21 s. The needle placement accuracy for minimally invasive needle biopsies using the B‐Rob II biopsy robot is sufficiently accurate and fast for forensic postmortem examinations of focal organ changes. Further tests will be performed to test the feasibility of the robot for performing biopsies of focal organ changes in human bodies.     

Loss of heterozygosity detected in a short tandem repeat (STR) locus commonly used for human DNA identification

Short tandem repeat (STR) markers are commonly used in basic genetic research and in human identification testing. Clinically, STRs can be used to study genetic alterations in tumors. A genetic deletion common to many types of cancer is referred to as the loss of heterozygosity (LOH). Numerous examples of LOH in cancer have been described and some have been mapped to areas located in close proximity to markers employed in human identity testing. Despite this fact, LOH has rarely been observed for STR loci commonly employed in forensic testing. Recently, for medico-legal purposes, we were asked to determine whether a tissue biopsy originated from a particular individual. For a reference source we assessed two specimens, one from normal tissue and one from cancerous tissue. When both reference specimens were used to generate DNA profiles, we observed LOH at one STR locus, D13S317. As demonstrated in other cancers only the cancerous biopsy demonstrated LOH. The forensic community should be cognizant of these unusual circumstances because, as identification of human DNA continues to be used more extensively, certain instances will arise in which reference material will not be readily available. In these situations, archived specimens may be employed as a reference source. Clinical specimens such as tissue biopsies should be used with caution if they have not been confirmed to contain normal tissue.     

Pathological myophosphorylase reaction in malignant hyperthermia

In malignant hyperthermia, myophosphorylase reaction shows characteristic changes that take place within minutes: (1) a generally strongly weakened reaction; (2) numerous negatively reacting fibres; (3) frequently, fibre sections that show spotty and/or striatal weak or negative reactions and fibre sections with strong striatal reactions with relatively narrow sarcomere spacings (a "sign of hypercontraction"). Obviously, the morphological findings that show characteristic "striated fibres" are typical of the malignant hyperthermia syndrome! It is important to note that the muscular fibres showing such changes are, as a rule, inconspicuous when using other stains and reactions. These pathological myophosphorylase reactions were observed in five deceased patients (one independently of anaesthesia after an extended walk) and in 19 pigs (18 times after halothane testing and once in an experimental animal with clinical evidence of the presence of malignant hyperthermia). These reactions were not noted in pigs with negative halothane reactivity or prior to halothane testing. They were also not seen in a large number of very different healthy and diseased control and reference cases from our biopsy and autopsy material. Myophosphorylase reaction enables convincing demonstration of malignant hyperthermia, past or present. Hence, it is possible to elucidate puzzling deaths or verify apparently clear death occurring during or subsequent to anaesthesia or simply following stress ("human stress syndrome"). Many of these deaths doubtlessly escape the attention of clinicians using the usual morphological examination methods. However, the reaction cannot be used to identify potential victims.     

FAMILY VIOLENCE,TELEVISION VIEWING HABITS,AND OTHER ADOLESCENT EXPERIENCES RELATED TO VIOLENT CRIMINAL BEHAVIOR*

This study employs multivariate analyses with retrospective self-report data to assess the relative importance of certain childhood and adolescent experiences to the commission of violent crimes as an adult. Specifically, the relationship is examined between violent criminal behavior and exposure to family violence, exposure to television violence, school performance, other adolescent activities, and differential reinforcement for previous illegal acts. The exploratory model is based on data collected on 100 male inmates incarcerated for violent crimes and 65 nonincarcerated, nonviolent males matched in terms of age, race, and neighborhood. Findings, from analyses which estimate both additive and interactive effects, indicate that the background experiences associated with violent crime vary depending upon an individual's race. The discussion focuses on the implications of these findings for further research on the causes of violent criminal behavior.     

Examination of a long-term clozapine administration by high resolution segmental hair analysis

The long-term administration of clozapine could be verified by fine segmentation and analysis of single hairs of one person to examine the history of a multiple poisoning case. Segments of 1-2.5mm length were extracted by ultrasonification in 30 microl of the mobile phase (mixture of methanol+water, 50+50). By application of isocratic liquid chromatography and using narrow bore columns (Synergy Polar-RP, Phenomenex), an acceleration and miniaturization of the HPLC-MS-MS assay could be achieved. Total amounts of clozapine down to 30 fg (on column) and its desmethyl metabolite could be analysed in multiple reaction monitoring mode. According to typical sample amounts of approximately 16 microg, relevant hair concentrations higher than 1 pg/mg were detected. Significant and reproducible concentration profiles along the hair fibres revealed characteristic administration cycles. The administration time course - in particular the time of its termination - could be verified with a precision of a few days. The accuracy and reproducibility of the concentration profile was proven based on multiple investigations of single hairs. An individual hair growth rate of 0.55 mm/day was determined with a relative standard deviation of 8% by comparison of concentration profiles in hairs collected after a time span of 165 days.