Influence of short-term fixation with mixed formalin or ethanol solution on the mechanical properties of human cortical bone

Bone specimens obtained for biomechanical experiments are fresh-frozen for storage to slow down tissue degradation and autolysis in long-term storage. Alternatively, due to infectious risks related to the fresh tissues, fixative agents are commonly used. However, fixatives will likely change the mechanical properties of bone. Existing studies on this issue gave controversial results that are hardly comparable due to a variety of measurement approaches. For this reason, the influence of ethanol and a formalin-based fixative agent was evaluated on the mechanical properties of human cortical bone specimens by means of four-point-bending tests. 127 prismatic specimens with rectangular cross sections (2.5 x 2.5 x 20 mm3) were obtained from different regions of two fresh human femora (medial, lateral, dorsal, ventral). Specimens were either fixed in ethanol or in a mixed formalin solution or frozen following a given scheme. After two weeks of storage the samples were re-hydrated in isotonic saline and subsequently tested mechanically. The elastic bending modulus and ultimate bending strength were computed considering the actual dimensions of each specific specimen. For statistical analysis a one-way-ANOVA and an LSD post-hoc-test were performed. For ultimate bending strength no significant differences due to formalin or ethanol fixation, as compared to unfixed-fresh bone specimens could be found. And only for few cases significant differences in elastic bending modulus were observed when the two bones were evaluated separately. Since more differences of significant level due to the anatomical region of the samples were determined, the original location seems to have more influence on the evaluated mechanical properties than the method of (chemical) fixation. Consequently, ethanol and the mixed formalin solution can be recommended as a fixation agent for samples in biomechanical testing, if these samples are rinsed in isotonic saline prior to static mechanical testing.

Experiments to vaccinate marmoset monkeys against malignant lymphoma

Humoral antibodies can be induced in cotton topped (CT) marmosets with killed Herpesvirus saimiri (HVS) vaccines. The serum antibodies delayed, but did not prevent, malignant lymphoma in actively and passively immunized monkeys after inoculation with 10(3.8)TCID50 of cell-free HVS. Experiments are in progress to determine whether the vaccines are able to protect against smaller challenge dosages of HVS. The immunized monkeys were not resistant against transplantation of tumor cells. Infection with Epstein-Barr virus (EBV) and Marek's disease virus (MDV) did not protect against the tumors caused by superinfection with HVS. Attenuation of HVS was not achieved by passaging the HVS genome through different monkey species.

Description of the iliolumbar ligament for computer-assisted reconstruction

STUDY DESIGN

The iliolumbar ligament (IL) was examined using morphometric and virtual methods.

OBJECTIVES

A macroscopic study was performed to measure the anterior (AIL) and the posterior part of the IL (PIL).

SUMMARY OF BACKGROUND DATA

Though being a widely accepted cause of low back pain and lumbosacral instability, the IL is neglected in computer-based biomechanical studies due to the lack of morphometric information.

METHODS

Frozen sections prepared from 29 human subjects were measured and 7-tesla MR images made to distinguish the AIL and PIL. Cuboids were designated as geometric figures to both parts of the ligament, allowing computer-based calculations of length, surface, volume and angle of positional relationships.

RESULTS

Based on 7-tesla MR imaging, virtual reconstruction was conducted for one male pelvis, including the IL. While left- and right-side parameters varied at a statistically significant level, no gender-dependencies could be determined. Lengths of 30 and 25 mm were measured for the AIL and PIL, as well as heights of 17-19 mm, respectively, and a thickness of 4mm.

CONCLUSIONS

Correlations between the side-dependent parameters and the AIL and the PIL of the same side indicate close functional relationships. Additional dependencies suggest that the IL is capable of compensating age-related as well as bone-attributed alterations in lumbosacral morphology. The IL data and the visualised ligament structures contribute to determination of the influence of the IL in spinal and sacroiliac stability by means of computer-assisted biomechanics.

A direct comparison of MR images and thin-layer plastination of the shoulder in the apprehension-test position

Until now, patients with a shoulder instability being examined using magnetic resonance imaging have been placed in a position with the arm adducted or in the ABER position, as a result of the way conventional MR systems are built. Magnetic resonance systems with an open configuration have made it possible, for the first time, to examine patients in the apprehension-test position, which is a representative diagnostic position for anterior shoulder instability. This new examination position requires an exact understanding of layered imaging anatomy in order to clearly identify MR structures. The purpose of this study is to make possible a direct comparison of the respective abilities of MR cross-section imaging and thin-layer plastination to clearly identify all MR structures of the shoulder positioned in the apprehension-test position. The two shoulders of a body donor were separated and stored in special position supports in the apprehension-test position. The magnetic resonance examination was carried out using a vertically open 0.5-T MR system (Signa SP/i, General Electric Medical Systems, Milwaukee, WI). The following sequences were used: 2D GRE, TR 42.5 ms, TE 20 ms, layer width 3 mm, matrix 512x512, FOV 24 cm. The coronary und transversal MR cross-section segments were subsequently planned in conjunction with thin-layer plastination for both shoulders. Using a direct comparison of MR images with the corresponding thin-layer plastination, it was possible to clearly identify all MR structures.

Plastinated body slices for verification of magnetic resonance tomography images

Plastinated body slices provide a higher resolution than photos taken from frozen objects as obtained for the "Visible Human Project". The impregnation with curable polymer gives those slices transparency. Since the thickness of a plastinated slice determines its optical resolution, very thin plastinated slices are necessary for comparison with MRT-images (MRIs) of high quality. The present technical note describes how very thin plastinated slices can be prepared by modification of the classical plastination technique and for comparison with MRI. Having labelled the object's planes recorded as MRIs, we, for the first time, plastinated 800 microm thick body slices superior in resolution to the corresponding MRIs, confirming and extending their structures. Thus, very thin plastinated body slices can be regarded as a helpful tool for radiological studies.

A modified Spalteholz technique with preservation of the histology

The Spalteholz technique for producing clear macroscopic specimens was introduced 100 years ago, and is still in use today because it immediately provides transparent three-dimensional specimens. The classical clearing procedure with peroxide severely damages formalin-fixed tissue and inhibits further investigation on a histological level. We, therefore, wanted to make a transparent specimen by a modified Spalteholz method and chose the human larynx as an example of a large specimen. Its blood vessels were injected with gelatin, the specimen treated with acetone and peracetic acid and subjected to freeze substitution. After complete dehydration, benzyl benzoate and dimethylphthalate were used for impregnation. The cleared specimen satisfactorily revealed the laryngeal blood vessels and such structures as muscles, cartilage and the thyroid gland. The histology of the laryngeal glands, thyroid tissue, and infrahyoid muscle fibres was preserved. Tissue shrinkage became apparent with subsequent steps of the clearing procedure. We conclude that our modifications maintain the transparency of the specimen and allow histological investigation. The herein described technique thus constitutes an improvement of the classical Spalteholz technique.

["The honor of being right": Experiment and theory in the dispute over the doctrine of irritability]

In the middle of the 18th century the leading physiological concepts shift from mechanism to vitalism. The turning point of this change is Albrecht von Haller's Dissertation on the irritable parts (1752/53). The decisive discussion about irritability takes place between strictly empirical Hallerians and their opponents who try to build new medical systems on this property. Hence, the debate is also about experiment and theory. The 'sociology of scientific knowledge' furnishes models and theories that help us to conceive the argumentations and strategies of the leading figures. Thus, we understand why even Haller--the 'founder of modern experimental physiology'--has to allow general conclusions and to support vitalistic interpretations if he wants to succeed with some of his views. Only in its modified form the 'Irritabilitas Halleriana' meets the interest needed for dissemination.

Oncornaviruslike particles in human malignancies

Mesenchymal and epithelial human malignancies were examined in the simultaneous detection test for the presence of particles with 70 S RNA and reverse transcriptase. Out of the 23 tumors tested 14 were found to be positive (61%). The finding that 2 uterine cancers contained 70 S RNA and reverse transcriptase indicates that uterine cancers may belong to the list of malignancies where the involvement of oncornaviruses is suspected. Out of the 10 human sarcomas examined in this study 4 were shown to contain particles with properties of oncornaviruses.

Vaccination of nonhuman primates with killed oncogenic herpesviruses

Killed herpesvirus cancer vaccines were prepared by inactivation of oncogenic herpesviruses (Herpesvirus saimiri and Herpesvirus ateles) with heat and formaldehyde. The killed vaccines, which are not free of viral nucleic acid, were safe in 121 vaccinated monkeys of 4 different species. Some of these monkeys have now been under observation for 2 years. The vaccines induced high titers of specific humoral antibodies in all vaccinated monkeys. The killed vaccines proved to be efficient against the i.m. challenge with cell-free oncogenic herpesviruses. The challenged animals remained clinically well without signs of an infection and have now been under observation for 1 year, while the nonvaccinated control monkeys died of malignant lymphoma 34 to 52 days after inoculation. The protection against H. saimiri could be passively transmitted with the serum of the vaccinated monkeys. The vaccination did not prevent but delayed tumor development after tumor cell transplantation. The resistance against the oropharyngeal route of infection remains to be determined.

A killed vaccine derived from the oncogenic Herpesvirus ateles

A killed herpesvirus vaccine was prepared by inactivation of the oncogenic Herpesvirus ateles (HVA) with heat and formaldehyde. The vaccine proved safe in 9 marmosets (Saguinus oedipus) during a period of 461 days. The vaccinated marmosets developed high titers of serum antibodies against HVA and were resistant to 316 lethal dose 50 (LD50) cell-free HVA; the nonvaccinated control monkeys died of malignant lymphoma. The 5 challenged monkeys are clinically well and have now been under observation for 362 days.

The effect of an immunosuppressive drug (azathioprine) on the latent infection of marmoset monkeys (Callithrix jacchus) with the oncogenic Herpesvirus saimiri

Callithrix jacchus (CJ) marmoset monkeys can be latently infected with Herpesvirus saimiri (HVS). In order to determine whether this resistance to the oncogenic potential of HVS could be due to the immune surveillance, azathioprine, a known immunosuppressive drug, was given to 7 latently infected CJ marmosets. The animals died within 147 days probably from side effect caused by azathioprine, but no animal developed a tumor.

No evidence for particles encapsulating RNA-instructed DNA polymerase and high molecular weight virus-related RNA in herpesvirus induced tumours of non-human primates

The simultaneous detection test gave no evidence for the presence of RNA tumour viruses in herpesvirus induced malignant lymphomas of non-human primates. The 12 tumours tested were obtained from three different monkey species inoculated with Herpesvirus saimiri or herpesvirus ateles. Particles encapsulating RNA-instructed DNA polymerase and high mol. wt. virus-related RNA were easily demonstrated in tumours of the mouse induced by type-C or type-B oncornaviruses and in human lymphoid cells infected with simian sarcoma virus type I which were examined in parallel. Attempts to demonstrate partial expression of an oncornavirus genome in the herpesvirus induced tumours and attempts to detect an interspecies antigen related to monkey oncornaviruses were negative and strengthened the observations made with the simultaneous detection test.