Quantitative Near-Infrared Imaging of Platelets in Platelet-Rich Fibrin (PRF) Matrices: Comparative Analysis of Bio-PRF, Leukocyte-Rich PRF, Advanced-PRF and Concentrated Growth Factors

Platelet-rich fibrin (PRF) is a fibrin matrix enriched with platelets. The PRF matrix is thought to form a steep gradient of platelet density around the region corresponding to the buffy coat in anticoagulated blood samples. However, this phenomenon has not yet been proven. To visualize platelet distribution in PRF in a non-invasive manner, we utilized near-infrared (NIR) imaging technology. In this study, four types of PRF matrices, bio-PRF, advanced-PRF (A-PRF), leukocyte-rich PRF (L-PRF), and concentrated growth factors (CGF) were compared. Blood samples collected from healthy, non-smoking volunteers were immediately centrifuged using four different protocols in glass tubes. The fixed PRF matrices were sagittally divided into two equal parts, and subjected to modified immunohistochemical examination. After probing with NIR dye-conjugated secondary antibody, the CD41⁺ platelets were visualized using an NIR imager. In L-PRF and CGF, platelets were distributed mainly on and below the distal surface, while in bio-PRF and A-PRF, platelet distribution was widespread and homogenous. Among three regions of the PRF matrices (upper, middle, and lower), no significant differences were observed. These findings suggest that platelets aggregate on polymerizing fibrin fibers and float up as a PRF matrix into the plasma fraction, amending the current “gradient” theory of platelet distribution.

Concentrated Growth Factor Matrices Prepared Using Silica-Coated Plastic Tubes Are Distinguishable From Those Prepared Using Glass Tubes in Platelet Distribution: Application of a Novel Near-Infrared Imaging-Based, Quantitative Technique

Platelet-rich fibrin (PRF) matrices were originally prepared using plain glass tubes without the aid of coagulation factors because coagulation factor XII is activated by glass surfaces. Recently, the use of silica-coated plastic tubes as a substitute of glass tubes has been recommended for PRF preparation. This recommendation is owing not only to the shortage of glass tubes for medical use in the market, but also the higher coagulation activity of silica-coated plastic tubes and equal quality of PRF. However, these matrices are not the same. To evaluate the differences, we compared glass- and silica-coated plastic tubes in terms of platelet distribution and quantity in concentrated growth factors (CGF). CGF matrices were immediately prepared from freshly collected blood samples, fixed after red thrombus removal, and divided into two equal pieces sagittally. One piece was used for CD41 detection and the other was applied as an isotype control. Platelet distribution in CGF matrices was examined, without embedding or sectioning, by a novel method using invisible near-infrared imaging. The dehydrated membranous CGF matrix was more transparent. Thus, the fluorescence signal was clearly detectable with less scattering. Platelets were distributed mainly in the distal side of the glass-prepared CGF matrix, but homogeneously in the silica-prepared CGF matrix. Platelet count was positively correlated with fluorescence intensity. Although not yet fully developed, this imaging technique enabled us to recognize the differences in platelet distribution and quantity in CGF matrices by excluding bias caused by the technical limitations of scanning electron microscopy and conventional immunohistochemical methods.

Spectrophotometric Determination of the Aggregation Activity of Platelets in Platelet-Rich Plasma for Better Quality Control

Although platelet-rich plasma (PRP) is now widely used in regenerative medicine and dentistry, contradictory clinical outcomes have often been obtained. To minimize such differences and to obtain high quality evidence from clinical studies, the PRP preparation protocol needs to be standardized. In addition, emphasis must be placed on quality control. Following our previous spectrophotometric method of platelet counting, in this study, another simple and convenient spectrophotometric method to determine platelet aggregation activity has been developed. Citrated blood samples were collected from healthy donors and used. After centrifugation twice, platelets were suspended in phosphate buffered saline (PBS) and adenosine diphosphate (ADP)-induced aggregation was determined using a spectrophotometer at 615 nm. For validation, platelets pretreated with aspirin, an antiplatelet agent, or hydrogen peroxide (H₂O₂), an oxidative stress-inducing agent, were also analyzed. Optimal platelet concentration, assay buffer solution, and representative time point for determination of aggregation were found to be 50–100 × 10⁴/μL, PBS, and 3 min after stimulation, respectively. Suppressed or injured platelets showed a significantly lower aggregation response to ADP. Therefore, it suggests that this spectrophotometric method may be useful in quick chair-side evaluation of individual PRP quality.

Spectrophotometric determination of platelet counts in platelet-rich plasma

BACKGROUND

Platelet-rich plasma (PRP) is widely used in regenerative dentistry and other medical fields. However, its effectiveness has often been questioned. For better evaluation, the quality of individual PRP preparations should be assured prior to use. We proposed a spectrophotometric method for determination of platelet counts and validated its applicability using two types of PRP preparations.

METHODS

Blood samples were obtained from healthy male volunteers and pure PRP (P-PRP) and leukocytes-rich PRP (L-PRP) were prepared using the double-spin method. In serial dilutions, platelet counts in P-PRP and L-PRP were determined using an automated hematology analyzer and a compact spectrophotometer. For validation, P-PRP and L-PRP independently prepared by three well-trained operators were used for comparison of the calculated and measured platelet counts.

RESULTS

In the two types of PRP samples evaluated, platelet counts were almost equal and greater amount of both white blood cells (WBCs) and red blood cells (RBCs) were included in L-PRP preparations. The calibration curve obtained from serially diluted P-PRP showed a strong correlation (R2 = 0.995), whereas that of L-PRP was relatively weaker (R2 = 0.975). In validation testing, the scatter plot of the calculated platelet counts versus the measured values showed a strong correlation in P-PRP (R2 = 0.671), whereas that of L-PRP showed a much weaker correlation (R2 = 0.0605).

CONCLUSIONS

This method can precisely determine platelet counts in PRP preparations when the inclusion of WBCs or RBCs is minimized. Therefore, we recommend that clinicians use this method for quality assurance of individual PRP preparations.

An on-site preparable, novel bone-grafting complex consisting of human platelet-rich fibrin and porous particles made of a recombinant collagen-like protein

Platelet‐rich fibrin (PRF) is widely used in regenerative medicine. Nonetheless, major issues include its controversial effects on bone regeneration and a lack of quality‐assured glass tubes required for coagulation. We used porous particles (FBG) comprising a recombinant RGD motif‐enriched collagen I‐like protein to activate the coagulation pathway and examined the effects of the resulting PRF–FBG complex on bone regeneration. Human whole‐blood samples were mixed with FBG in plastic tubes and centrifuged to prepare a PRF–FBG complex. Platelet‐derived growth factor‐BB (PDGF‐BB) levels and cell growth activity were determined by ELISA and a bioassay using osteoblasts. Bone regenerative activity was assessed using a mouse model of calvarial bone defect. FBG facilitated PRF‐like matrix formation during centrifugation. In this PRF–FBG complex, the microstructure of fibrin fibers was similar to that of PRF prepared conventionally in glass tubes. PDGF‐BB levels and mitogenic action were not significantly influenced by FBG. In the bone defect model, although PRF did not exert any significant positive effects on its own, in combination with FBG, it synergistically stimulated new bone formation. This study demonstrated that incorporation of FBG into whole‐blood samples induces PRF formation without the aid of glass tubes. The resulting PRF–FBG complex could be a promising bone grafting material in clinical settings. © 2018 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1420–1430, 2019.

Direct activation of platelets by addition of CaCl2 leads coagulation of platelet-rich plasma

Background

Based on the notion that full activation of platelets is required for a growth factor release, in regenerative dentistry, platelet-rich plasma (PRP) in liquid form is usually clotted by addition of CaCl₂ in glassware before topical implantation. However, there has been no evidence as to which is better, full or partial activation of platelets, for minimizing the loss of growth factors and improving the controlled release of growth factors from coagulated PRP. To address this matter, here, we primarily examined direct effects of CaCl₂ on platelets in PBS and on coagulation in citrated PRP.

Methods

PRP was prepared from healthy volunteers’ blood. Platelets’ actions were monitored by scanning electron microscopy, flow cytometry, digital holographic microscopy, and immunofluorescent staining. Clot formation was examined in plasma.

Results

In plasma-free PBS, 0.1% CaCl₂ immediately upregulated CD62P and CD63, causing a release of microparticles and fibrinogen/fibrin; consequently, platelets aggregated and adhered to polystyrene culture dishes with enlargement of their attachment area. In a clot formation assay in plasma, CaCl₂ initially induced platelet aggregation, which triggered loop-like matrix formation and subsequently induced coagulation on a watch glass. Such changes were not clearly observed either with PRP in a plastic dish or in platelet-poor plasma on a watch glass: coagulation was delayed in both conditions.

Conclusions

These findings indicate that besides the well-known coagulation pathway, which activates platelets via thrombin conversion in a coagulation cascade, CaCl₂ directly activates platelets, which then facilitate clot formation independently and in cooperation with the coagulation pathway.

Quantitative evaluation of morphological changes in activated platelets in vitro using digital holographic microscopy

Platelet activation and aggregation have been conventionally evaluated using an aggregometer. However, this method is suitable for short-term but not long-term quantitative evaluation of platelet aggregation, morphological changes, and/or adhesion to specific materials. The recently developed digital holographic microscopy (DHM) has enabled the quantitative evaluation of cell size and morphology without labeling or destruction. Thus, we aim to validate its applicability in quantitatively evaluating changes in cell morphology, especially in the aggregation and spreading of activated platelets, thus modifying typical image analysis procedures to suit aggregated platelets. Freshly prepared platelet-rich plasma was washed with phosphate-buffered saline and treated with 0.1% CaCl₂. Platelets were then fixed and subjected to DHM, scanning electron microscopy (SEM), atomic force microscopy, optical microscopy, and flow cytometry (FCM). Tightly aggregated platelets were identified as single cells. Data obtained from time-course experiments were plotted two-dimensionally according to the average optical thickness versus attachment area and divided into four regions. The majority of the control platelets, which supposedly contained small and round platelets, were distributed in the lower left region. As activation time increased, however, this population dispersed toward the upper right region. The distribution shift demonstrated by DHM was essentially consistent with data obtained from SEM and FCM. Therefore, DHM was validated as a promising device for testing platelet function given that it allows for the quantitative evaluation of activation-dependent morphological changes in platelets. DHM technology will be applicable to the quality assurance of platelet concentrates, as well as diagnosis and drug discovery related to platelet functions.

Mechanical and degradation properties of advanced platelet-rich fibrin (A-PRF), concentrated growth factors (CGF), and platelet-poor plasma-derived fibrin (PPTF)

BACKGROUND

Fibrin clot membranes prepared from advanced platelet-rich fibrin (A-PRF) or concentrated growth factors (CGF), despite their relatively rapid biodegradability, have been used as bioactive barrier membranes for alveolar bone tissue regeneration. As the membranes degrade, it is thought that the growth factors are gradually released. However, the mechanical and degradable properties of these membranes have not well been characterized. The purpose of this study was to mechanically and chemically characterize these membranes.

METHODS

A-PRF and CGF clots were prepared from blood samples collected from non-smoking, healthy donors and were compressed to form 1-mm-thick membranes. Platelet-poor plasma-derived fibrin (PPTF) clots were prepared by adding bovine thrombin to platelet-poor plasma. A tensile test was performed at the speed of 1 mm/min. Morphology of the fibrin fibers was examined by SEM. A digestion test was performed in PBS containing trypsin and EDTA.

RESULTS

In the tensile test, statistical difference was not observed in Young's modulus, strain at break, or maximum stress between A-PRF and CGF. In strain at break, PPTF was significantly weaker than CGF. Likewise, fibrin fiber thickness and crosslink density of PPTF were less than those of other membranes, and PPTF degraded faster than others.

CONCLUSIONS

Although the centrifugal conditions are different, A-PRF and CGF are prepared by essentially identical mechanisms. Therefore, it is conceivable that both membranes have similar mechanical and chemical properties. Only PPTF, which was prepared by a different mechanism, was characterized as mechanically weaker and enzymatically more degradable.

Platelet-rich fibrin prepared from stored whole-blood samples

Background

In regenerative therapy, self-clotted platelet concentrates, such as platelet-rich fibrin (PRF), are generally prepared on-site and are immediately used for treatment. If blood samples or prepared clots can be preserved for several days, their clinical applicability will expand. Here, we prepared PRF from stored whole-blood samples and examined their characteristics.

Methods

Blood samples were collected from non-smoking, healthy male donors (aged 27–67 years, N = 6), and PRF clots were prepared immediately or after storage for 1–2 days. Fibrin fiber was examined by scanning electron microscopy. Bioactivity was evaluated by means of a bioassay system involving human periosteal cells, whereas PDGF-BB concentrations were determined by an enzyme-linked immunosorbent assay.

Results

Addition of optimal amounts of a 10% CaCl₂ solution restored the coagulative ability of whole-blood samples that contained an anticoagulant (acid citrate dextrose) and were stored for up to 2 days at ambient temperature. In PRF clots prepared from the stored whole-blood samples, the thickness and cross-links of fibrin fibers were almost identical to those of freshly prepared PRF clots. PDGF-BB concentrations in the PRF extract were significantly lower in stored whole-blood samples than in fresh samples; however, both extracts had similar stimulatory effects on periosteal-cell proliferation.

Conclusions

Quality of PRF clots prepared from stored whole-blood samples is not reduced significantly and can be ensured for use in regenerative therapy. Therefore, the proposed method enables a more flexible treatment schedule and choice of a more suitable platelet concentrate immediately before treatment, not after blood collection.

An Evaluation of the Accuracy of the Subtraction Method Used for Determining Platelet Counts in Advanced Platelet-Rich Fibrin and Concentrated Growth Factor Preparations

Platelet concentrates should be quality-assured of purity and identity prior to clinical use. Unlike for the liquid form of platelet-rich plasma, platelet counts cannot be directly determined in solid fibrin clots and are instead calculated by subtracting the counts in other liquid or semi-clotted fractions from those in whole blood samples. Having long suspected the validity of this method, we herein examined the possible loss of platelets in the preparation process. Blood samples collected from healthy male donors were immediately centrifuged for advanced platelet-rich fibrin (A-PRF) and concentrated growth factors (CGF) according to recommended centrifugal protocols. Blood cells in liquid and semi-clotted fractions were directly counted. Platelets aggregated on clot surfaces were observed by scanning electron microscopy. A higher centrifugal force increased the numbers of platelets and platelet aggregates in the liquid red blood cell fraction and the semi-clotted red thrombus in the presence and absence of the anticoagulant, respectively. Nevertheless, the calculated platelet counts in A-PRF/CGF preparations were much higher than expected, rendering the currently accepted subtraction method inaccurate for determining platelet counts in fibrin clots. To ensure the quality of solid types of platelet concentrates chairside in a timely manner, a simple and accurate platelet-counting method should be developed immediately.

Basic characteristics of plasma rich in growth factors (PRGF): blood cell components and biological effects

Platelet-rich plasma (PRP) is widely used in regenerative medicine because of its high concentrations of various growth factors and platelets. However, the distribution of blood cell components has not been investigated in either PRP or other PRP derivatives. In this study, we focused on plasma rich in growth factors (PRGF), a PRP derivative, and analyzed the distributions of platelets and white blood cells (WBCs). Peripheral blood samples were collected from healthy volunteers (N = 14) and centrifuged to prepare PRGF and PRP. Blood cells were counted using an automated hematology analyzer. The effects of PRP and PRGF preparations on cell proliferation were determined using human periosteal cells. In the PRGF preparations, both red blood cells and WBCs were almost completely eliminated, and platelets were concentrated by 2.84-fold, whereas in the PRP preparations, both platelets and WBCs were similarly concentrated by 8.79- and 5.51-fold, respectively. Platelet counts in the PRGF preparations were positively correlated with platelet counts in the whole blood samples, while the platelet concentration rate was negatively correlated with red blood cell counts in the whole blood samples. In contrast, platelet counts and concentration rates in the PRP preparations were significantly influenced by WBC counts in whole blood samples. The PRP preparations, but not the PRGF preparations, significantly suppressed cell growth at higher doses in vitro. Therefore, these results suggest that PRGF preparations can clearly be distinguished from PRP preparations by both inclusion of WBCs and dose-dependent stimulation of periosteal cell proliferation in vitro.

Growth factor and pro-inflammatory cytokine contents in platelet-rich plasma (PRP), plasma rich in growth factors (PRGF), advanced platelet-rich fibrin (A-PRF), and concentrated growth factors (CGF)

Background

The development of platelet-rich fibrin (PRF) drastically simplified the preparation procedure of platelet-concentrated biomaterials, such as platelet-rich plasma (PRP), and facilitated their clinical application. PRF’s clinical effectiveness has often been demonstrated in pre-clinical and clinical studies; however, it is still controversial whether growth factors are significantly concentrated in PRF preparations to facilitate wound healing and tissue regeneration. To address this matter, we performed a comparative study of growth factor contents in PRP and its derivatives, such as advanced PRF (A-PRF) and concentrated growth factors (CGF).

Methods

PRP and its derivatives were prepared from the same peripheral blood samples collected from healthy donors. A-PRF and CGF preparations were homogenized and centrifuged to produce extracts. Platelet and white blood cell counts in A-PRF and CGF preparations were determined by subtracting those counts in red blood cell fractions, supernatant acellular serum fractions, and A-PRF/CGF exudate fractions from those counts of whole blood samples. Concentrations of growth factors (TGF-β1, PDGF-BB, VEGF) and pro-inflammatory cytokines (IL-1β, IL-6) were determined using ELISA kits.

Results

Compared to PRP preparations, both A-PRF and CGF extracts contained compatible or higher levels of platelets and platelet-derived growth factors. In a cell proliferation assay, both A-PRF and CGF extracts significantly stimulated the proliferation of human periosteal cells without significant reduction at higher doses.

Conclusions

These data clearly demonstrate that both A-PRF and CGF preparations contain significant amounts of growth factors capable of stimulating periosteal cell proliferation, suggesting that A-PRF and CGF preparations function not only as a scaffolding material but also as a reservoir to deliver certain growth factors at the site of application.

A classification of juxta-dural ring aneurysms with reference to surgical anatomy

We report a subgroup of internal carotid artery (ICA) aneurysms located near the carotid ring which we call juxtadural ring aneurysms. These aneurysms are classified into three types: paraclinoid intradural, carotid cave and infraclinoid extradural aneurysms. The paraclinoid intradural aneurysms arise from the ICA distal to the origin of the ophthalmic artery and are close to the dural ring, which may include some so-called carotid-ophthalmic aneurysms. The carotid cave aneurysms are located in the carotid cave which is seated in the infraclinoid carotid groove and proximal to the origin of the ophthalmic artery. They are located at the angiographical genu and in the intradural space anatomically. The infraclinoid extradural aneurysms are located close to the dural ring extradurally in the infraclinoid carotid groove sinus, a peripheral venous space of the cavernous sinus. The infraclinoid extradural aneurysms should be differentiated from aneurysms in the cavernous sinus, because they are located in the infraclinoid carotid groove sinus.

Traumatic carotid artery occlusion following blunt cervical injury

Two cases of overlooked, traumatic unilateral occlusion of the carotid artery are reported. Postmortem revealed occlusion of the internal carotid artery in one case and that of the common carotid artery in another. The progression of the morbid state, along with the management with emphasis on the significance of the carotid angiogram and follow-up repeated computed tomography are mentioned. Although traumatic occlusion of the common carotid artery is not as common as that of the internal carotid artery, both entities are well known to produce morbidity and mortality.

Computer-generated microsurgical anatomy of the paraclinoid area

To represent multiple microstructures, including perforators, dura, and cranial nerves, and to allow understanding of the three-dimensional relations of the paraclinoid area, we made a computer graphics model. The source of the input data is a variety of publications showing the detailed anatomy of the paraclinoid area. To produce the model, we traced such data, input selected points for each structure, smoothed the lines with a spline program, and added depth using wire-framing and color alterations. The computer graphic model of the paraclinoid area showing perforators, dural ring, optic nerve, and so forth, was made using a paint method for hidden line removal. It can be rotated and viewed from any direction and thus allows understanding of the relations of the area. Using our method, it may be possible to obtain a more detailed model of various anatomies including the skull base, and such data would be useful for preoperative simulation to understand relative regional relations for a specific case and as a new navigational system for open microneurosurgery. Concepts and technical details of the method are described.

Valacyclovir neurotoxicity: clinical experience and review of the literature

Valacyclovir (VACV) is used increasingly to treat herpes zoster, although neuropsychiatric symptoms [VACV neurotoxicity (VAN) or acyclovir neurotoxicity], may accompany use of this drug. To promote awareness of this rare condition, we describe here two clinical cases of VAN we previously reported and review 20 cases from the literature. In all cases, chronic or acute renal failure preceded VAN. The symptoms of VAN varied, but disturbances of consciousness and hallucination occurred most commonly. When acute renal failure was due to the drug, recovery from both the disturbance of consciousness and renal failure followed within several days after discontinuation of VACV. Early recognition and diagnosis will ensure effective treatment of VAN.

Embolization of Arteriovenous Malformation. Efficacy and Safety of Preoperative Embolization Followed by Surgical Resection of AVM

SUMMARY

Treatment options for cerebral arteriovenous malformation (AVM) are still controversial due to the recent result of stereotactic radiosurgery and the improved result of microsurgical resection. We investigated previously treated AVM cases and discussed the efficacy and safety of preoperative embolization especially for microsurgical resection of high-grade AVM in the Spetzler-Martin grading. Efficacy of preoperative embolization was evaluated based on 126 previously treated AVM cases at Shinshu University Hospital during the last 25 years. The safety of embolization was evaluated based on our previously-embolized 58 AVM cases (91 procedures) in the last 11 years after introduction of preoperative embolization for AVM. In all 126 cases, 82 were treated before introduction of embolization and 44 were treated after introduction of embolization. In 82 cases of the pre-embolization era, 63 lesions were removed totally in 63 AVMs (77%), partially resected in 11 (13%) and untreated in eight (10%). In 74 surgically removed cases, 11 (15%) cases showed severe intra/postoperative bleeding. In 44 cases of the embolization era, lesions were removed totally in 29 AVMs (66%), disappeared only with embolization in one (2%), disappeared with radiosurgery in seven (16%) and were untreated in five (11%). In 32 surgically removed cases, only one (2%) case showed severe intra/postoperative bleeding. In all 58 embolized cases, 44 were surgically removed, six were treated with radiosurgery, one was eliminated with embolization alone and six were partially obliterated and followed up for their location. In 91 procedures for 58 cases, two haemorrhagic and three ischemic complications occurred, three were transient and two remained having neurological deficits. The introduction of preoperative embolization improved the total removal rate and reduced the intra/postoperative bleeding rate in surgical removal of AVM. The total risk of embolization is low and well-designed preoperative embolization makes surgical resection safer even in high-grade AVM in the Spetzler-Martin grading.

Submucosal glycerol injection-assisted laser surgical treatment of oral lesions

Recently, we modified laser surgery for superficial lesions in the oral cavity by using submucosal glycerol injection. This procedure was based on a technique for endoscopic mucosal resection (EMR) in the gastrointestinal tract. The aim of this study was to evaluate the effectiveness of the modified laser surgery assisted by a submucosal glycerol injection. Eleven superficial oral lesions in ten patients were treated with diode laser (continuous wave mode, 3 W) after a submucosal injection of glycerol solution. Injection of glycerol solution created mucosal expansion, which enabled the procedures to be done without bleeding, over cutting, over coagulation and unintended irradiation. The surface of the wounds showed little carbonization, resulting in good healing. Submucosal glycerol injection for laser treatment in the oral cavity is a promising technique for treating superficial oral lesions by virtue of less invasion and good results.

Ionic Pair Complexes with Well-Separated Columnar Stack Structure Based on [Pt(mnt)2]-Ions Showing Unusual Magnetic Transition: Syntheses, Crystal Structures, and Magnetic Properties

Three ion pair complexes, [4-R-benzylpyridinium][bis(maleodinitriledithiolato)platinum(III)] (abbreviated as [RBzPy][Pt(mnt)(2)]; R = Cl (1), Br (2), or NO(2) (3)), have been synthesized. The cations and anions stack into well-separated columns in the solid state, and the Pt(III) ions form a 1-D zigzag chain within a [Pt(mnt)(2)](-) column through Pt...S, S...S, and Pt...S...Pt interactions. The chain is uniform in 1 and 2, while it alternates in 3. Unusual magnetic phase transitions from paramagnetism to diamagnetism were observed in these three complexes at approximately 275 K for 1, approximately 269 K for 2, and approximately 184 K for 3. These phase transitions were also found in DSC measurements for 1 and 2. The overall magnetic behaviors for 1-3 indicate the presence of antiferromagnetic exchange interactions in the high-temperature phase and spin-gapped systems in the low-temperature phase. Below 50 K, 2 exhibits weak ferromagnetism. The spontaneous moments are nearly repressed by a field of 1.0 T. The crystal structure of 2 at 173 K reveals that there are two crystallographically independent [Pt(mnt)(2)](-) entries in an asymmetric unit. These two crystallographically independent [Pt(mnt)(2)](-) entries satisfy the spin-canting condition, and the EPR spectra measured at room temperature exhibit anisotropic character. Therefore, the weak ferromagnetic behavior in the low-temperature region for 2 can be attributed to the spin-canting phenomenon.

Isocentric head fixation for microscopic neurosurgery

The significance of isocentering in head fixation during micro-neurosurgery is described. The approach angle to the lesion could be changeable without adjusting the focus and placement of the operating microscope by rotating the head holder when the lesion is fixed at the isocenter of the rotatable.

How to make a three-dimensional surgical illustration of cerebral vessels with a personal computer: technical note

OBJECTIVE

To introduce a method of making three-dimensional (3-D) illustrations of cerebral vessels with a personal computer.

METHODS

We generated the 3-D images from only two views of conventional angiograms (anteroposterior and lateral views) with a personal computer, two commercial software programs, and an image scanner.

RESULTS

This method was applied to 10 consecutive cases of cerebral aneurysms. 3-D images were made in a few hours, and they contributed to assessing vascular structures of an aneurysm complex.

CONCLUSION

This method is useful for discussing surgical strategies preoperatively. Our method may be used in any facility where conventional angiography, personal computers, and 3-D software are available.

Skull base techniques for multiple aneurysms in the internal carotid juxta-dural ring region

The aneurysm located in the internal carotid juxta-dural ring region is difficult to surgically obliterate. At surgery, careful drilling of the anterior clinoid process is mandatory, especially when a laterally projecting aneurysm protrudes to or inside the anterior clinoid process.In this paper, treatment procedures using the skull base techniques with intravascular coil embolisation are described by showing a case.

Pineal cavernous angioma presenting with Parkinsonism

Cavernous angioma of the pineal region is rare, as is brain tumour coincident with Parkinsonism. The authors describe the case of a 55 year old woman with a pineal region cavernous angioma, who subsequently developed Parkinsonism after her increased intracranial pressure was relieved. The cause of Parkinsonian syndrome is unclear, but compression of the posterior thalamus and upper mid-brain with congestion of the deep venous system may have caused vascular disturbance of the nigro-striate-pallidal system. Her symptoms gradually improved after total excision of the lesion.

Surgery of a cavernous angioma making a tunnel between the fourth ventricle and tubercle

We removed a cavernous angioma, making a tunnel between the fourth ventricle and tubercle using the traction-dissection method. Cavernous angioma with such a distribution is extremely rare, and we manipulated the mass differently to minimize surgical damage. Intraoperative findings and technical considerations are made.

Specific characteristics and management strategies of cerebral artery aneurysms: report of eleven cases

Owing to the deep location of the posterior cerebral artery (PCA) and its close relationship with the brainstem and surrounding vital structures, surgical treatment of aneurysms in this region is complex. This study was undertaken in an attempt to better delineate the surgical risks of PCA aneurysms. A retrospective analysis was undertaken in 11 patients with PCA aneurysm surgically treated between 1988 and 1996 at Shinshu University and its affiliated hospitals. Data regarding surgical strategy, surgical complications and outcomes were analysed. Seven aneurysms were saccular (including one mycotic) and the other four were fusiform, dissecting, thrombosed and an infundibular dilatation. The locations of the aneurysms were at the P1 segment in two patients, P1-P2 junction in two, P2 segment in six and P3 segment in one. Six saccular non-mycotic aneurysms were treated with neck clipping and the other five aneurysms were treated each with proximal occlusion of the parent artery, excision of the aneurysm or wrapping. All aneurysms were satisfactorily exposed except one large saccular aneurysm. Surgical outcomes were either good recovery or moderate disability in 10 patients, and severe disability in one patient with a large aneurysm due to temporal lobe contusion. In conclusion it is the responsibility of the surgeon dealing with rare PCA aneurysms to be aware of these specific characteristics and to appreciate which surgical technique is appropriate for each patient.

Remission of hemifacial spasm after proximal occlusion of vertebrobasilar dissecting aneurysm with coils: case report

Intracranial aneurysm is a rare cause of hemifacial spasm and most of the previously reported cases are treated with surgical microvascular decompression. Authors report a case of hemifacial spasm caused by a dissecting aneurysm located at the vertebrobasilar junction which improved after endovascular obliteration of the affected vertebral artery with coils. The patient was a 69-year-old man with 20 months' history of left hemifacial spasm. A vertebral angiogram showed an irregular dilatation of the right vertebral artery associated with aneurysmal dilatation at the vertebrobasilar junction. Endovascular obliteration of the abnormally dilated right vertebral artery proximal to the vertebrobasilar junction was performed. The hemifacial spasm gradually improved after the embolisation and disappeared 6 months later. Endovascular proximal obliteration of the vertebral artery may have changed the hemodynamic force inside the aneurysm and eliminated the vascular compression at the root exit zone of the facial nerve.

Intraoperative angiography for emergency cerebrovascular surgery using an exclusively developed radiolucent Sugita head frame and fixation

Intraoperative angiography during emergency cerebrovascular surgery, clipping operation for acute aneurysmal subarachnoid hemorrhage, is reported. For acquisition of intraoperative angiography, an exclusively developed radiolucent version of a Sugita head frame, made of engineering plastics for angiography, and an ordinary fluoroscopic unit were installed. In a radiolucent head frame, all the parts of the ordinary metallic Sugita multipurpose head frame, fixation and its accessories were made of high-molecular polymer plastics in the same size. In emergency cerebrovascular surgery, the radiolucent Sugita frame enabled us to carry out meticulous dissection and precise retraction control as the ordinary metallic system and to perform the intraoperative angiography if needed.

Strategic embolisation for successful resection of a large cerebral arteriovenous malformation

The risks accompanied by the treatment of cerebral arteriovenous malformation (AVM) are still cumulative despite recent progress in available treatment options. Pre-operative embolisation is one such option, however, it seldom makes the surgical resection difficult. The excessive embolised nidus makes the surgical resection difficult because it cannot be compressed during the resection surgery and embolised nidus as a 'glue ball' with marginal hypervascular territory is most difficult to remove. The aim of pre-operative embolisation for successful surgical resection is to put glue into the marginal part of the nidus so as to make a cleavage between the surrounding normal tissues. Remaining feedings via the dilatated leptomeningeal anastomoses from surrounding normal cortical arteries do not interfere with the resection and can be eliminated easily by coagulating the pia matter around the nidus. Strategic planning with regard to the systemic course of treatment, including the manner of resection, is important for effective pre-operative embolisation.

Correction of recurrent dislocation of the mandible in elderly patients by the Dautrey procedure

Twelve patients with recurrent mandibular dislocation, 11 of whom were over 50 years old, were treated by the Dautrey procedure using a temporal approach. None experienced recurrence or developed complications such as restriction of mouth-opening, paresis of the facial nerve, or pain in the temporomandibular joint during a follow-up period that ranged from 1.5 to 8 years.

Computer generated microsurgical anatomy of the supraclinoid portion of the internal carotid artery

In this article we demonstrate a computer graphics model to represent the microsurgical anatomy of the supraclinoid portion of the internal carotid artery (ICA). The source of the input data is a variety of publications showing the detailed anatomy of the area. A computer graphics model of the supraclinoid portion of the ICA and relevant structures including perforators and cranial nerves was made under full colour shading using a Z-buffer algorithm. Complicated microstructures including perforators or cranial nerves are depicted in detail, and can be rotated and viewed from any direction, and thus allows understanding of the three-dimensional relations of the area. Using our method, it may be possible to represent more complicated models of various anatomies, and this methodological tool would be useful for teaching surgical microanatomy and pathology and in pre-surgical operative planning and preparation of the surgeon, introducing a new style navigational system for open microneurosurgery.

Endovascular treatment of basilar trunk aneurysm associated with fenestration of the basilar artery

Basilar trunk saccular aneurysms associated with fenestration are infrequent, especially in the middle or distal portion of the basilar artery. Surgical treatment of the basilar trunk aneurysm is difficult, due to its anatomical environment and the complicated surgical exposure. A 46-year-old woman presenting with Hunt and Kosnik grade II subarachnoid hemorrhage was found to have a ruptured aneurysm arising at the proximal corner of the associated fenestration in the middle portion of the basilar artery. Because of surgical difficulties anticipated in approaching the aneurysm, it was decided to treat it with endovascular embolization utilizing the Guglielmi detachable coil; and complete occlusion of the aneurysm was obtained. The efficacy of endovascular treatment for the basilar trunk aneurysm with associated fenestration is discussed from anatomical and embryological points of view, and relevant literature is reviewed.

Computer-generated microsurgical anatomy of the basilar artery bifurcation. Technical note

The authors' goal was to develop a computer graphics model to represent the microsurgical anatomy of the basilar artery (BA) bifurcation and surrounding structures to simulate surgery of a BA bifurcation aneurysm performed via the transsylvian approach. The source of the input data was a variety of publications that showed detailed anatomy of the area. A computer graphics model of the area near the BA bifurcation including relevant structures, such as perforating branches or cranial nerves, was depicted in detail. A BA bifurcation aneurysm was added to the computer graphics model and it was rotated to simulate the transsylvian approach. After the internal carotid artery was displaced using a virtual retractor, the aneurysm was exposed, thus providing an understanding of the three-dimensional surgical orientation of the area. Designing a standard anatomical model on the basis of data culled from a variety of publications and adding morphological changes by using a virtual retractor to displace structures that obstruct the view along a critical path at the base of the brain are useful strategies of computer manipulation for surgical simulation in open microneurosurgery. This methodological tool would be useful in teaching surgical microanatomy and in introducing a new navigational system for virtual reality. Both concept and technical details are discussed.

Aneurysm surgery in Asia--Japanese situation

This report is based on the results of the questionnaires conducted for the Japan Stroke Surgery Meeting 1996 (President: S. Kobayashi). The questionnaires were sent to all neurosurgical training institutions approved by The Japan Neurosurgical Society, numbering 959. The response rate was 54.2% (520 institutions). All statistics dealt with cases from January 1995 to December 1995. The total number of aneurysm surgery performed was 13,166. The average operative case number per institution during the year was 25. About 20% of the institutions exceeded 35 cases. Of all operative cases, 76.3% were ruptured aneurysms and 23.7% were nonruptured. Giant aneurysms were 2.9%; dissecting aneurysms 2.4%. Surgical procedures performed were clipping in 90.3%, wrapping in 5.2%, proximal ligation 1.6%, and bypass in 0.7%. Intravascular surgery was performed for 2.3% of the cases. Sugita clips were mainly used in 80.5% of the institutions, Yasargil clips in 6.6%, and both in 12.9%. For anterior communicating artery aneurysms pterional approach was mainly used in 81.0% of the institutions, interhemispheric in 7.2%, and both in 11.7%. For basilar terminal aneurysms, pterional approach was mainly used in 88.3% of the institutions, subtemporal approach in 6.6%, and both in 5.1%. The nonoperative cases included 24.9% of the ruptured aneurysms, 31.7% of the unruptured aneurysms, 38.4% of the giant aneurysms, and 52.1% of the dissecting aneurysms. The above statistics suggest that aneurysms are treated in Japan in most training institutions and that open surgical treatment is still the main procedure of choice.

Computer-generated surgical simulation of morphological changes in microstructures: concepts of "virtual retractor." Technical note

The authors' goal was to develop a computer graphics model to simulate the displacement and morphological changes that are caused by the retraction of fine intracranial structures. The authors developed an application program to interpolate the contour of models of an artery and a retractor. The center of the displacement was determined by spatial coordinates, and the shape of the displacement of the arterial model was calculated using a cosine-based formula with representation of a brain retractor. This computer graphics model was applied to the simulation of the displacement and morphological changes that occur when retraction is performed in the optic nerve. An illustrative case is presented, in which the optic nerve was displaced by a retractor to simulate the surgery performed in a carotid cave aneurysm of the internal carotid artery. The authors have named this methodological tool a "virtual retractor." This new navigational system for open microneurosurgery would be useful in teaching surgical microanatomy and in presurgical operative planning.

Monitoring of cerebral hemodynamics using near-infrared spectroscopy during local intraarterial thrombolysis: case report

BACKGROUND

The efficacy of continuous measuring of changes in regional cerebrovascular hemoglobin saturation during local intraarterial thrombolytic therapy for middle cerebral artery (MCA) occlusion is discussed.

METHODS

To obtain real-time data on changing cerebral hemodynamics, near-infrared spectroscopy (NIRS) was used during recanalization of an occluded MCA branch. Changes in regional cerebrovascular hemoglobin saturation of the affected left frontal lobe were observed immediately after intraarterial injection of urokinase (UK).

RESULTS

A steady increase in regional oxygen saturation (rSO2) was observed until recanalization was confirmed angiographically as a result of 300,000 IU of UK.

CONCLUSIONS

Monitoring of cerebrovascular hemoglobin saturation by NIRS is a simple, noninvasive technique suggesting its potential for intraoperative monitoring during interventional neuroradiologic procedures.

Periventricular enhancement following intraoperative CT cisternography in a patient with Dandy-Walker syndrome. Case report

The rare finding of strong periventricular enhancement was observed by means of intraoperative CT cisternography using Iotrolan in a one-month-old boy with Dandy-Walker syndrome associated with occipital cephalocele. Chronological findings of intraoperative CT scanning are demonstrated and etiological considerations are discussed.

Color Doppler ultrasound imaging in the emergency management of an intracerebral hematoma caused by cerebral arteriovenous malformations: technical case report

OBJECTIVE AND IMPORTANCE

Ruptured arteriovenous malformations (AVMs) are important causes of spontaneous intracerebral hemorrhages. This is a report of emergency hematoma removal, avoiding damage to the nidus of the AVM, using intraoperative color Doppler imaging.

CLINICAL PRESENTATION

A 38-year-old woman suddenly presented with coma. The patient underwent emergency surgery immediately after admission, without preoperative angiographic examination, because of progressive neurological deterioration caused by a massive hematoma in the right basal ganglia, as diagnosed with computed tomographic scanning.

INTERVENTION

A right frontotemporoparietal craniotomy was performed. Intraoperative ultrasound imaging with a color Doppler system (EUP-NS32, 5 MHz; Hitachi Medical, Tokyo, Japan) clearly demonstrated a nidus complex in the hematoma. Based on the imaging, effective decompression of the hematoma was performed without damage to the AVM complex.

CONCLUSION

Color Doppler imaging (with real-time availability) of an atypical hematoma provided significant information on the vascular lesion causing the hematoma and could reduce the surgical risks during emergency evacuation of large intracerebral hemorrhages resulting from ruptured AVMs.

Brain spatula with transparent tip: technical note

A newly developed brain spatula with transparent tip for brain retraction is introduced. The high-molecular polymer plastic material is used only for the tip of the new spatula whilst rest of the spatula is made up of the ordinary malleable metal. The transparent nature of the spatula tip helps us in observing the retracted brain vessels and cranial nerves in continuity with the main operating area. The extent of distortion as a result of the retraction can be directly observed assisting in prevention of an inadvertent injury. The new brain spatula with transparent tip is helpful for microneurosurgery under high magnification. Various shapes and sizes of the spatula can be used.

Unexpected nerve gas exposure in the city of Matsumoto: report of rescue activity in the first sarin gas terrorism

This report describes the rescue activities and the exposure of rescue and hospital personnel from the first unexpected nerve gas terrorist attack using sarin (isopropyl methylphophonofluoridate) in the city of Matsumoto at midnight on June 27, 1994. The details of the emergency activities in the disaster were studied based on the records from emergency departments of the affiliated hospitals and records from the firehouse. About 600 people, including residents and rescue staff, were exposed to sarin gas. Fifty-eight residents were admitted to hospitals, and 7 died. Among 95 rescuers and the duty doctor from the doctor car, 8 had mild symptoms of poisoning. All the rescue activity took place without gas masks or decontamination procedures. In this case of unexpected mass exposure to sarin gas, the emergency rescue system for a large disaster in Matsumoto city, which had been established for a conflagration or a local earthquake, was effective.

Temperature dependence of structure parameters in natural magnetite: single crystal X-ray studies from 126 to 773 K

Structural parameters and their thermal changes in natural magnetite, Fe3O4, have been studied using the single-crystal X-ray diffraction method in the temperature range 126–773 K. The cell dimensions, oxygen coordinate and atomic mean square displacements (m.s.d.'s) reversibly change as a function of temperature. The coordinate of oxygen remains almost constant at x = 0.2549 (1) below ~600 K, but increases with increasing temperature above this temperature. This characteristic behavior of the oxygen coordinate with temperature indicates that the cation disordering over the tetrahedral (A) and octahedral (B) cation sites occurs above 600 K. All atomic m.s.d.'s increase monotonously with temperature rise. The m.s.d.'s of the B atom show a unique temperature dependence. At lower temperatures the B atom prefers to vibrate along [111], but this preference is reduced with a temperature rise up to 630 K, above which the m.s.d. normal to [111] becomes dominant.

Cadaveric Hands-on Workshop Using a Three-Dimensional High-Definition Television System

We report the introduction of a three-dimensional high-definition television system in cadaveric microneurosurgical hands-on workshops on skull base technique. The system was found to be a useful means of exact communication between the instructor and the participants and avoided congestion around the instructor's table. The instructions could be refayed to the multiple participants at one time and thus avoided repetitions. More participants could be accommodated in the workshops. The entire proceeding could be recorded three-dimensionally for later use and educational purposes.

[A case of severe sarin poisoning in the sarin attack in Matsumoto--one-year follow-up of clinical findings, and laboratory data]

A patient severely poisoned with sarin in the Sarin Attack in Matsumoto is described. A 19-year-old man was exposed to sarin at 23:00 on 27 June, 1994. At 1:00 of the following day, a rescue team found and brought him to the hospital. His blood pressure was 150-80mmHg and the heart rate was 120/min with frequent premature ventricular contractions (PVC). His respiration was shallow and copious salivation and excretion from the respiratory tract were observed. Consciousness disturbance, generalized convulsion, severe miosis and fasciculation of tongue, facial muscle and extremities were also marked. Serum cholinesterase was 21 U/l (normal 109-249) and acetylcholinesterase in erythrocyte (E-AchE) was 0.1U/l (normal 1.2-2.0). Electroencephalogram (EEG) 30 hours after exposure showed polispike and wave complexes. Ventilatory assistance, forced urination and injection of diazepam and atropin improved his general condition and he was discharged 18 days after exposure. Three months after exposure, E-AchE was normalized and there was no complaint. But one year after exposure, EEG showed epilecpic discharges during sleep, and Holter electrocardiogram showed frequent PVC. As no clinical cases of severe sarin poisoning like this patient was reported, a longterm follow-up of this patient is very important.