Forensic application of three interstitial pneumonia markers: search for new pneumonia markers in dead bodies.

In forensic cases, detailed identification of pneumonia is important. Our objective was to statistically determine the applicability of three interstitial lung disease (ILD) markers for forensic diagnosis using serum collected from dead bodies with various postmortem intervals (PMIs). We retrospectively analyzed the levels of postmortem serum Krebs von den Lungen-6 (KL-6) and pulmonary surfactant-associated proteins A and D (SP-A and SP-D) using 221 samples obtained during forensic autopsy at our facility from 2019 to 2023. We evaluated the diagnostic efficacy of ILD markers for various pneumonias against the pathological diagnosis, and examined the assessment of the severity of ILD. When comparing the ILD group with bacterial pneumonia (BP) versus the control group, there was a significant increase in KL-6 in the ILD group. When comparing the severe ILD (SILD) group with the mild ILD (MILD) group, there was a significant increase in KL-6 and SP-D in the SILD group. The optimal cutoff values for differentiating SILD were 607.0 U/mL for KL-6, 55.5 ng/mL for SP-A, and 160.0 ng/mL for SP-D, and the sensitivity/specificity (%) of KL-6, SP-A, and SP-D for SILD were 84.1/95.2, 55.6/85.7, and 66.7/74.6, respectively. This is the first study to examine KL-6 in postmortem serum in forensic medicine. By analyzing dead bodies with various PMIs, our results confirmed statistically that postmortem serum KL-6 specifically detects ILD, postmortem serum SP-A has high sensitivity to lung injury, and postmortem serum SP-D is potentially useful in assessing the severity of ILD.

A suicide case of liquid nicotine intoxication.

A man in his 50 s, who was found vomiting and in a disturbed state when the emergency medical team arrived, then went into cardiopulmonary arrest during transport and died without responding to resuscitation. The hospital initially suspected that the death may have been caused by internal causes, but since the deceased had previously been transported to the hospital in a suicide attempt, the hospital called police regarding suspicions of unnatural death. The police investigation revealed two empty bottles of nicotine liquid for e-cigarettes in his house and a search history of "nicotine suicide" on his cellphone. In a forensic autopsy, he was found to be highly obese, and abundant fat deposits were observed in his organs. A stent was placed in the aorta, but no abnormality was found. There was no obvious stenosis or obstruction in the coronary arteries. Drug screening using liquid chromatography tandem mass spectrometry (LC-MS/MS) was performed on cardiac blood, urine, and stomach contents collected at autopsy, which revealed the presence of some medical products such as aripiprazole, nicotine, and cotinine. Further quantitative testing revealed high concentrations of nicotine in all samples. The left and right femoral venous blood concentrations were above the lethal dose, suggesting that arrhythmia or respiratory failure due to nicotine intoxication was the cause of death. With the widespread use of e-cigarettes, high concentrations of nicotine are readily available, and case reports of serious nicotine addiction are increasing. It is important to always consider addiction when conducting forensic evaluations in the medical field.

Bioprotective role of platelet-derived microvesicles in hypothermia: Insight into the differential characteristics of peripheral and splenic platelets.

BACKGROUND: Most platelets are present in peripheral blood, but some are stored in the spleen. Because the tissue environments of peripheral blood vessels and the spleen are quite distinct, the properties of platelets present in each may also differ. However, no studies have addressed this difference. We previously reported that hypothermia activates splenic platelets, but not peripheral blood platelets, whose biological significance remains unknown. In this study, we focused on platelet-derived microvesicles (PDMVs) and analyzed their biological significance connected to intrasplenic platelet activation during hypothermia. METHODS: C57Bl/6 mice were placed in an environment of -20 °C, and their rectal temperature was decreased to 15 °C to model hypothermia. Platelets and skeletal muscle tissue were collected and analyzed for their interactions. RESULTS: Transcriptomic changes between splenic and peripheral platelets were greater in hypothermic mice than in normal mice. Electron microscopy and real-time RT-PCR analysis revealed that platelets activated in the spleen by hypothermia internalized transcripts, encoding tissue repairing proteins, into PDMVs and released them into the plasma. Plasma microvesicles from hypothermic mice promoted wound healing in the mouse myoblast cell line C2C12. Skeletal muscles in hypothermic mice were damaged but recovered within 24 h after rewarming. However, splenectomy delayed recovery from skeletal muscle injury after the mice were rewarmed. CONCLUSIONS: These results indicate that PDMVs released from activated platelets in the spleen play an important role in the repair of skeletal muscle damaged by hypothermia.

High titers of infectious SARS-CoV-2 in corpses of patients with COVID-19.

OBJECTIVES: The prolonged presence of infectious SARS-CoV-2 in deceased patients with COVID-19 has been reported. However, infectious virus titers have not been determined. Such information is important for public health, death investigation, and handling corpses. The aim of this study was to assess the level of SARS-CoV-2 infectivity in the corpses of patients with COVID-19. METHODS: We collected 11 nasopharyngeal swabs and 19 lung tissue specimens from 11 autopsy cases with COVID-19 in 2021. We then investigated the viral genomic copy number by real-time reverse transcription-polymerase chain reaction and infectious titers by cell culture and virus isolation. RESULTS: Infectious virus was present in six of 11 (55%) cases, four of 11 (36%) nasopharyngeal swabs, and nine of 19 (47%) lung specimens. The virus titers ranged from 6.00E + 01 plaque-forming units/ml to 2.09E + 06 plaque-forming units/g. In all cases in which an infectious virus was found, the time from death to discovery was within 1 day and the longest postmortem interval was 13 days. CONCLUSION: The corpses of patients with COVID-19 may have high titers of infectious virus after a long postmortem interval (up to 13 days). Therefore, appropriate infection control measures must be taken when handling corpses.

Post-traumatic cerebral infarction caused by thrombus in the middle cerebral artery.

A woman in her 80s was found unconscious after being hit by a car while crossing a road. After admission to hospitals, computed tomography (CT) scans revealed traumatic brain injury (TBI), and the patient was treated symptomatically. However, despite improvement of TBI in CT images, she died unexpectedly. Postmortem CT demonstrated cerebral infarction in the territory of the right middle cerebral artery (MCA). Histopathological examination revealed lumen-obstructing thrombosis and intimal injury upstream of the thrombosis in the right MCA. These findings suggested that the intimal injury in the MCA had led to thrombus formation, and thromboembolism in the region distal to the injury leading to post-traumatic cerebral infarction (PTCI). Both postmortem CT and autopsy were able to reveal the final condition of the deceased, which had not been fully anticipated by the clinicians who had treated her after the accident. The longitudinal antemortem to postmortem course revealed by multiple CT images and the histopathological examination provided crucial clues to the pathogenesis of PTCI in this case.

Prevalence of blood-borne infections in forensic samples: Epidemiology in areas of Chiba, Japan.

OBJECTIVES: To statistically clarify the prevalence and risk factors of infections in forensic autopsy cases in Chiba Prefecture, Japan. The aim was to improve preventive measures against infection in forensic autopsies. METHODS: We retrospectively investigated the positive detection rates of five infections (hepatitis B, HBV; hepatitis C, HCV; human immunodeficiency virus, HIV; human T-lymphotropic virus, HTLV; Treponema pallidum, TP) using 1491 samples obtained in forensic autopsy at our facility from 2014 to 2018. In addition, risk factors related to infection such as methamphetamine and tattoos were analyzed. Pearson's chi-square test was used for statistical analysis, and the difference was judged to be significant at p < 0.05. RESULTS: Among our samples, 9.0% of cadavers tested positive for infection, and the prevalence rates for HBV, HCV, HIV, HTLV, and TP were 1.0%, 6.7%, 0.3%, 0.7%, and 1.1% respectively. Statistically, cadavers linked to information about methamphetamine use had a 7.2 times higher rate of infection, and those with tattoos had a 5.6 times higher rate of infection, with HCV being the predominant cause. CONCLUSIONS: To limit the risk of infection among autopsy workers, cadavers and samples should be handled on the presupposition that the bodies are at risk of infections. It is also important to obtain as much information as possible about the medical history and potential illegal drug use to help assess the risk of infection in a patient during forensic autopsy. We propose that all autopsy cases should be screened for infections whenever possible.

Multidirectional analysis for a colchicine poisoning case revealed detail cause of death and its mechanism.

The appearance of Meadow saffron (Colchicum autumnale), which contains colchicine, closely resembles Alpine leek (Allium victorialis), a popular edible wild vegetable in Northern Japan. This often results in the accidental ingestion of Meadow saffron and acute colchicine poisoning deaths. Here, we report on a case of acute colchicine poisoning death caused by the accidental ingestion of Meadow saffron. A man in his 70 s had been given wild vegetables from his neighborhood, which were then cooked and eaten by himself and his wife. Several hours later, they suffered from abdominal pain, vomiting, and diarrhea. They immediately went to the hospital and received routine treatment. While his wife made a full recovery, he died at home two days after consumption of the vegetables. A forensic autopsy was conducted five days after ingestion of the Meadow saffron and a lethal concentration (21.5 ng/mL) of colchicine in the peripheral blood sample was detected by liquid chromatography-tandem mass spectrometry. Distribution of colchicine in body fluids, tissues and gastrointestinal contents was also investigated. Some of the plants he had eaten were identified as Alpine leek or Meadow saffron by genetic analysis of his stomach contents. Histopathological examination showed apoptotic cells and cell cycle arrest at the metaphase in the intestinal crypts and testis. In addition, we detected high concentrations of endotoxins and tumor necrosis factor-α in his blood, indicating that intestinal mucosal injury induced by colchicine poisoning had allowed endotoxins to invade the body, causing death by endotoxin shock.

Hypoxia-induced nuclear translocation of ß-catenin in the healing process of frostbite.

Frostbite occurs when the skin is exposed to localized low temperatures. The main causes of frostbite are thought to be direct cell injury due to freezing of cells and tissue ischemia due to abnormal blood circulation. However, the molecular mechanism of frostbite has not been elucidated. This study aims to explain the molecular dynamics of frostbite using a mouse frostbite model and keratinocyte cell culture. Comprehensive gene expression analysis performed on mouse skin samples revealed that ß-catenin signaling is activated by frostbite. Immunohistochemistry showed nuclear translocation of ß-catenin in the skin of frostbite model mice that was not observed in mice subjected to a mechanical skin damage model induced by tape stripping. Tissue hypoxia, as detected by pimonidazole staining, coexisted with nuclear expression of ß-catenin. In keratinocyte cell cultures, nuclear translocation of ß-catenin was induced by hypoxia, but not by low temperature. Hypoxia induced epithelial-mesenchymal transition - an important biological event in the healing process of skin - and in vitro wound-healing activity, both of which were suppressed by ß-catenin inhibition. Our results suggest that during frostbite, impaired blood flow causes hypoxia, which in turn activates ß-catenin that promotes keratinocyte motility and tissue repair.

SmartAmp method can rapidly detect SARS-CoV-2 in dead bodies.

Rapid and accurate detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in dead bodies is essential to prevent infection among those working with dead bodies. This study focused on the Smart Amplification (SmartAmp) method, which has a short examination time (approximately an hour), is simple to perform, and demonstrates high specificity and sensitivity. This method has already been used for clinical specimens; however, its effectiveness in dead bodies has not been reported. This study examined the SmartAmp method using 11 autopsies or postmortem needle biopsies performed from January to May, 2021 (of these, five cases tested positive for SARS-CoV-2 by quantitative real-time polymerase chain reaction (qRT-PCR) and six cases tested negative). Swab samples were collected from the nasopharynx, oropharynx, or anus and the SmartAmp and qRT-PCR results were compared. For the nasopharynx and oropharynx samples, the same results were obtained for both methods in all cases; however, for the anal swabs, there was one case that was positive according to qRT-PCR but negative according to the SmartAmp method. The SmartAmp method may therefore be less sensitive than qRT-PCR and results may differ in specimens with a low viral load, such as anal swabs. However, in the nasopharynx and oropharynx specimens, which are normally used for testing, the results were the same using each method, suggesting that the SmartAmp method is useful in dead bodies. In the future, the SmartAmp method may be applied not only during autopsies, but also in various situations where dead bodies are handled.

Soluble thrombomodulin ameliorates aberrant hemostasis after rewarming in a rat accidental hypothermia model.

BACKGROUND: Accidental hypothermia (AH) sometimes leads to coagulation disorder, especially in severe AH. We previously demonstrated that intrasplenic platelet activation caused aberrant hemostasis and thrombus formation after rewarming in a murine AH model. However, no study has focused on the appropriate management of platelets causing coagulation activation after rewarming of AH. We investigated whether or not recombinant soluble thrombomodulin (rTM) can suppress thrombosis formation after rewarming using a rat AH model. METHODS: Wistar rats were exposed to an ambient temperature of -20 °C under general anesthesia until their rectal temperature decreased to 26 °C. The Hypo group rats (n = 5) were immediately euthanized, while the Hypo/Re group (n = 5) and rTM group rats (n = 5), which were administered rTM (1 mg/kg) via the tail vein, were rewarmed until the rectal temperature returned to 34 °C and then euthanized 6 h later. Tissue and blood samples were collected from all rats for histopathological and coagulation analyses at euthanasia. RESULTS: There was no significant change in the D-dimer level in the Hypo group rats, while the D-dimer level was significantly elevated at 6 h after rewarming in the Hypo/Re group rats (P = 0.015), and histopathology detected both fibrin and platelets in the renal glomerulus. However, the rTM group rats did not show any elevation of the D-dimer levels at 6 h after rewarming, and no fibrin was noted on histopathology. CONCLUSIONS: rTM may be useful as an appropriate anticoagulant in cases of aberrant hemostasis after rewarming of AH.

Treatment of hepatocellular carcinoma with autologous platelets encapsulating sorafenib or lenvatinib: A novel therapy exploiting tumor-platelet interactions.

Hepatocellular carcinoma (HCC) activates platelets through the action of adjacent sinusoidal cells. Activated platelets bind to tumor-associated endothelial cells and release growth factors that promote tumor progression. We hypothesized that platelets encapsulated with tumor inhibitors would function as drug carriers for tumor therapy. We propose a therapeutic strategy for HCC using autologous platelets encapsulating multiple tyrosine kinase inhibitors in a rat chemically induced HCC model. Sorafenib or lenvatinib was encapsulated in platelets isolated from tumor-bearing rats in vitro. The rats were divided into groups that received repeated intravenous injections (twice a week for 10 weeks) of the following materials: placebo, sorafenib (SOR), lenvatinib (LEN), autologous platelets, autologous platelets encapsulating sorafenib (SOR-PLT) and autologous platelets encapsulating lenvatinib (LEN-PLT). The therapeutic effect was then analyzed by ultrasonography (US) and histopathological analysis. Histopathological and US analysis demonstrated extensive tumor necrosis in the tumor tissue of SOR-PLT or LEN-PLT, but not in other experimental groups. By liquid chromatography-mass spectrometry, more abundant sorafenib was detected in tumor tissues after SOR-PLT administration than in surrounding normal tissues, but no such difference in sorafenib level was observed with SOR administration. Therefore, the use of autologous platelets encapsulating drugs might be a novel therapeutic strategy for HCC.

Splenic peliosis associated with spontaneous rupture and massive bleeding.

We report findings from an autopsy case who died from massive bleeding because of splenic peliosis. The case subject was an 80-year-old man who had diabetes mellitus and who was receiving hemodialysis and anticoagulant therapy. Postmortem computed tomography demonstrated massive intra-abdominal hemorrhage especially seen around the spleen. At autopsy, we found abundant hemorrhagic ascites, including a large number of clots, in the abdominal cavity. The spleen had several distinct dark red areas ranging in size from 1.5 to 2.5 cm and showed spontaneous rupture along with hematoma formation on the outside of the splenic capsule on the anterior side. From these findings, we concluded that the cause of death in this case was massive hemorrhage owing to spontaneous rupture of splenic peliosis. Although peliosis itself rarely causes death, but when it is destroyed, massive bleeding leads to death. Thus, it is necessary to know the histopathological characteristics of peliosis, in forensics.

Hypothermia causes platelet activation in the human spleen.

BACKGROUND: Accidental hypothermia results in various dysfunctions in the human body. Additionally, coagulation disorder can lead to a life-threatening condition. We previously demonstrated that platelets stored in the spleen were activated and thus triggered coagulation disorder in a mouse model of hypothermia. In the present study, we wanted to investigate if this phenomenon in mice also occurs in humans as a reaction to hypothermia. METHODS: We analyzed splenic tissue collected from 22 deceased subjects who have died from hypothermia. These samples were compared with 22 control cases not exposed to cold environment. We performed immunohistochemical staining for CD61 (a marker of all platelets) and CD62P (a marker of activated platelets). We also evaluated the morphology of platelets in the spleen with scanning electron microscopy. RESULTS: Immunohistochemical analysis revealed no significant changes in the amounts of CD61-positive platelets between the hypothermia and control cases. However, the hypothermia cases contained abundant CD62P-positive platelets compared with those of the control cases. Immunohistochemical analysis also revealed that the activated platelets formed aggregates and adhered to splenic sinusoidal endothelial cells in the hypothermia cases. However, we observed no significant fibrin formation around the activated platelets. CONCLUSIONS: Hypothermia resulted in splenic platelet activation, which may be used as a postmortem marker of hypothermia. The release of activated platelets from the spleen into to circulation upon rewarming may promote coagulation disturbances.

Rewarming from accidental hypothermia enhances whole blood clotting properties in a murine model.

BACKGROUND: Hypothermia triggers coagulation, which can lead to the development of a life-threatening condition. We previously reported that hypothermia induces platelet activation in the spleen, resulting in microthrombosis after rewarming. However, the changes in whole blood clotting properties that occur remain unclear. Using thromboelastography, we investigated blood clotting activity and the effects of rewarming in a murine model of hypothermia. METHODS: C57Bl/6 mice were exposed to an ambient temperature of -20 °C under general anesthesia until their rectal temperature decreased to 15 °C. One group of mice was kept at 4 °C for 2 h and then euthanized. Another group was rewarmed, kept in normal conditions for 24 h, and then euthanized. Tissue and citrated whole blood samples were obtained from the mice for histopathological analysis, flow cytometry, and thromboelastography. RESULTS: Hypothermia induced the activation of platelets in the spleen; however, rewarming significantly reduced the number of activated platelets in the spleen while their numbers significantly increased in peripheral blood. In hypothermic mice not subjected to rewarming, no increase in activated platelets was observed in peripheral blood. Thromboelastography analysis showed that whole blood samples from the rewarmed mice displayed an enhanced clotting strength. CONCLUSIONS: Rewarming from hypothermia enhances whole blood coagulation activity accompanied by an increase in the number of active platelets in peripheral blood. This phenomenon may lead to formation of microthrombi and thrombotic disorders.

Low temperature induces von-willebrand factor expression via increased early growth response 1 transcriptional activity in splenic sinusoidal endothelial cells.

von Willebrand factor (vWF) is a large plasma glycoprotein that plays an important role in hemostasis by forming molecular bridges with platelets following vascular injury. Previously, we reported that hypothermia enhanced vWF production in the spleen, which resulted in the activation of the platelet pool in a hypothermia-induced murine model. However, the mechanisms that regulate vWF expression under hypothermic conditions remain unclear. In this study, we focused on vWF expression under hypothermic conditions in splenic endothelial cell culture. Human splenic endothelial cells (HSEC) were incubated at 20 °C for 1 h. Total RNA was extracted from the cells, and cDNA microarray gene expression analysis was performed. Genes that may be associated with vWF expression in low temperature culture conditions were then selected for further analysis. Gene expression analysis showed that low temperature conditions increased the expression of FOS and EGR1. We then hypothesized that these factors upregulate vWF mRNA expression in HSEC. The transcriptional inhibitors of EGR1 significantly inhibited vWF mRNA expression in HSEC cultured at a low temperature. Our analysis revealed that low temperatures enhance the gene expression of EGR1, which transcriptionally increases vWF expression. This acute-phase reaction may play an important role in platelet activation in the spleen during hypothermia.

Acute Colchicine Poisoning Causes Endotoxemia via the Destruction of Intestinal Barrier Function: The Curative Effect of Endotoxin Prevention in a Murine Model.

BACKGROUND: Colchicine binds to intracellular tubulin and prevents mitosis. Colchicine is also used as an anti-inflammatory drug. Meanwhile, excess administration of medication or accidental ingestion of colchicine-containing plants can cause acute colchicine poisoning, which initially results in gastrointestinal effects that may be followed by multiorgan dysfunction. However, the mechanism of colchicine poisoning remains unclear, and there are no standard therapeutic strategies. AIMS: We focused on intestinal barrier function and attempted to reveal the underlying mechanism of colchicine poisoning using an animal model. METHODS: Colchicine was orally administered to C57Bl/6 mice. Then, we performed histopathological analysis, serum endotoxin assays, and intestinal permeability testing. Additionally, the LPS-TLR4 signaling inhibitor TAK-242 was intraperitoneally injected after colchicine administration to analyze the therapeutic effect. RESULTS: We observed villus height reduction and increased numbers of apoptotic cells in the gastrointestinal epithelium of colchicine-treated mice. Both intestinal permeability and serum endotoxin levels were higher in colchicine-treated mice than in control mice. Although colchicine-poisoned mice died within 25 h, those that also received TAK-242 treatment survived for more than 48 h. CONCLUSION: Colchicine disrupted intestinal barrier function and caused endotoxin shock. Therapeutic inhibition of LPS-TLR4 signaling might be beneficial for treating acute colchicine poisoning.

Overproduction of thrombopoietin by BRAFV600E-mutated mouse hepatocytes and contribution of thrombopoietin to hepatocarcinogenesis.

In hepatocarcinogenesis induced by diethylnitrosamine (DEN) in B6C3F1 mice, the BrafV637E mutation, corresponding to the human BRAFV600E mutation, plays a pivotal role. The livers of transgenic mice with a hepatocyte-specific human BRAFV600E mutation weighed 4.5 times more than that of normal mice and consisted entirely of hepatocytes, resembling DEN-induced preneoplastic hepatocytes. However, these transgenic mice spontaneously died 7 wk after birth, therefore this study aimed to clarify the causes of death. In the transgenic mice, the liver showed thrombopoietin (TPO) overexpression, which is associated with eventual megakaryocytosis and thrombocytosis, and activated platelets were deposited in hepatic sinusoids. TPO was also overexpressed in the DEN-induced hepatic tumors, and sinusoidal platelet deposition was observed in the hepatic tumors of humans and mice. Podoplanin was expressed in some of the Kupffer cells in the liver of the transgenic mice, indicating that platelet activation occurred via the interaction of podoplanin with C-type lectin receptor 2 (CLEC-2) on the platelet membrane. Additionally, erythrocyte dyscrasia and glomerulonephropathy/interstitial pneumonia associated with platelet deposition were observed. In the transgenic mice, aspirin (Asp) administration prevented platelet activation, reduced the liver/body weight ratio, decreased the platelet deposition in the liver, kidney, and lung, and prevented erythrocyte dyscrasia and ameliorated the renal/pulmonary changes. Thrombopoietin overproduction by BRAFV600E-mutated hepatocytes may contribute to hepatocyte proliferation via thrombocytosis, platelet activation, and the interaction of platelets with hepatic sinusoidal cells, while hematologic, renal, and pulmonary disorders due to aberrant platelet activation may lead to spontaneous death in the transgenic mice.

Hypothermia-induced activation of the splenic platelet pool as a risk factor for thrombotic disease in a mouse model.

BACKGROUND: Hypothermia, either therapeutically induced or accidental (ie, an involuntary decrease in core body temperature to <35°C), results in hemostatic disorders. However, it remains unclear whether hypothermia enhances or inhibits coagulation, especially in severe hypothermia. The present study evaluated the thrombocytic and hemostatic changes in hypothermic mice. METHODS: C57Bl/6 mice were placed at an ambient temperature of -20°C under general anesthesia. When the rectal temperature decreased to 15°C, 10 mice were immediately euthanized, while another 10 mice were rewarmed, kept in normal conditions for 24 hours, and then euthanized. These treatments were also performed in 20 splenectomized mice. RESULTS: The hypothermic mice had adhesion of CD62P-positive platelets with high expression of von Willebrand factor (vWF) in their spleens, while the status of the peripheral platelets was unchanged. Furthermore, the plasma levels of platelet factor 4 (PF4) and pro-platelet basic protein (PPBP), which are biomarkers for platelet degranulation, were significantly higher in hypothermic mice than in control mice, indicating that hypothermia activated the platelets in the splenic pool. Thus, we analyzed these biomarkers in asplenic mice. There was no increase in either PF4 or PPBP in splenectomized hypothermic mice. Additionally, the plasma D-dimer elevation and microthrombosis were caused in rewarmed mice, but not in asplenic rewarmed mice. CONCLUSIONS: Our results indicate that hypothermia leads to platelet activation in the spleen via the upregulation of vWF, and this activation causes hypercoagulability after rewarming.

Discrimination of haplotype in mitochondrial DNA mixtures using LNA-mediated PCR clamping.

Locked nucleic acid (LNA) has been widely used for various genetic analyses, and has many benefits, in terms of the specificity or sensitivity of amplification, because LNA-containing primers/probes form more stable duplexes with template DNA than probes lacking LNA. Here, we developed a new method for discriminating HV1 haplotypes from mitochondrial DNA (mtDNA) mixtures by applying PCR clamping using LNA. PCR clamping is based on the selective inhibition of amplification using LNA-containing probes, which can discriminate single-nucleotide differences. Before designing probes, we selected 171 sequences with single-nucleotide variations from the HV1 region, and evaluated the specificity of LNA-containing probes for them by predicting Tm values. The differences of Tm between mismatched and exactly matched probe-template duplexes depended markedly on the type of LNA nucleotides for discriminating single-nucleotide differences, and the cytosine LNA nucleotide at the site of variations in the probes was most effective to discriminate these differences. For mixture analysis, each probe targeted one or two variations (16209C, 16217C, 16257A/16261T, 16297C/16298C, 16304C, 16362C, or 16362T) that are particularly common in the Japanese population, and seven designed probes completely inhibited the amplification of exactly matched templates. We prepared mixed samples by mixing DNA from two individuals at a ratio of 1:9, 1:4, 1:1, 4:1, or 9:1, and then performed Sanger sequencing analysis after PCR clamping with each probe. Our method distinguished each haplotype at lower ratios from two-person mixtures, and enabled sensitive detection at 12 pg of total DNA including 600 copies of mtDNA. Moreover, we analyzed three-person mixtures with representative sequences, and detected the minor haplotype of one individual present at a rate of 10% by adding two selected probes. The ability to discriminate haplotypes in mixed samples by using LNA-mediated PCR clamping indicates the potential value of mtDNA analysis in criminal investigations.

Assessment of DNA degradation of buccal cells under humid conditions and DNA repair by DOP-PCR using locked nucleic acids.

We analyzed the degradation level of DNA from buccal cells under humid conditions using quantitative PCR analysis. Gauze samples with buccal cells were incubated for up to 12 months under three different conditions (25 °C/dry, 25 °C/humid, or 40 °C/humid). The degradation was evaluated based on two degradation ratios (129:41 and 305:41 bp). DNA degraded slowly under the 25 °C/humid condition, and significant differences in the two degradation ratios were detected between 25 °C/dry and 25 °C/humid conditions after 12 months. Moreover, the degradation rapidly progressed under the 40 °C/humid condition, and the two degradation ratios in this condition were much lower than those from 25 °C/dry and 25 °C/humid conditions after a short incubation period (3 months). To evaluate the effect of DNA repair on low-copy degraded DNA, degenerate oligonucleotide-primed PCR (DOP-PCR) was performed before short tandem repeats (STR) genotyping. As a standard DOP-PCR, we used a 22-base primer with 10 degenerate sequences (5'-CTCGAGNNNNNNNNNNATGTGG-3'), and additionally designed DOP-PCR primers with 2, 4, 6, or 8 locked nucleic acids (LNAs). When slightly degraded DNA (305:41-bp ratio = 0.60) was used, DOP-PCR significantly increased the fluorescent intensity and success rate of genotyping using Identifiler and Globalfiler kits. In particular, the reaction with four LNAs produced the highest value. However, such benefits were not observed in the analysis of moderately degraded DNA (305:41-bp ratio = 0.13). Although the recovery rates of STR profiles by DOP-PCR were dependent on the degradation level of low-copy DNA, the effectiveness of DOP-PCR highlights the potential of LNA for degenerate sequences.