Use of a Spray Device to Locate Touch DNA on Casework Samples

The use of a fluorescent dye to visualize cellular material on surfaces offers a targeted sampling approach for locating touch DNA on casework items. However, the current application of such dye is not feasible for examination of relatively large items. As a result, development of an efficient dye application system is required to translate this approach into practice. Here, the spray pattern (area covered, intensity, and evenness) of 15 different commercial spray devices was examined visually using food coloring. From this, five devices were selected to apply Diamond Nucleic Acid Dye (DD) to three substrates (glass slide, plastic sheet, and brown packing tape) seeded with saliva and touch DNA. The cellular material was visualized using the Dino-lite Microscope and Polilight. The inhibitory effects of DD afforded by each spray device were examined using Identifiler Plus^® DNA profiling kit and a DNA input of 800 pg. The two most promising devices were further tested on a range of mock casework items seeded with touch DNA. The results presented demonstrate the feasibility of a spray system to apply DD to large surfaces and subsequently detect cellular material at both micro and macroscale. Specifically, the data suggest that a pressurized continuous-spray system is favorable and that droplet size influences the intensity of fluorescence and surface coverage. Furthermore, this study indicates that full STR profiles can be obtained following spraying with DD solution, even with excessive application, which is essential for the widespread use of these devices in casework.     

The Analysis of 3D Printer Dust for Forensic Applications,,

3D printers are becoming increasingly efficient and economical, and thus more widespread and easily accessible to consumers and businesses. They have been used to print nefarious objects such as guns and suppressors. Previous research has documented the release of dust particles during the printing process; however, little has been written about the morphology and chemical features that define the dust emitted by these printers. This study was undertaken to recover, analyze, and identify the dust produced during the printing process in the context of forensic trace evidence analysis. Samples were collected from a variety of 3D fused deposition modeler printers, representing both consumer and commercial grade models. This work focused on printers that use thermoplastic filaments composed of acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA), two of the most commonly used filament polymers. Swabs were used to collect dust within the printer chamber and then processed to isolate the dust particles. Particles produced from ABS filaments are most easily recognized via light microscopy through a combination of color, morphology, and fluorescence. The composition of these particles can be confirmed through analysis by either FTIR or Raman microspectroscopy. These methods can also be used to identify ABS fillers and pigments within the printer dust particles. In contrast, dust from PLA printers consistently contained finer, submicron-sized particles that could be observed by field emission scanning electron microscopy. Because the size of the particles precludes their identification using vibrational spectroscopy methods, pyrolysis-GC-MS was used to confirm the presence of PLA.     

Ethylene glycol poisoning

A 40-year-old man was admitted to the emergency department after a suicide attempt. The patient was found at home unconscious, with an open bottle of antifreeze near him. The patient was in a coma on admission, but neurological examination excluded intracranial changes. Results of initial urine and serum toxicological screening tests were negative. Laboratory values indicated metabolic acidosis, leukocytosis, urinalysis revealed hematuria and unrecognized crystals. Osmolality and osmol gap were not determined on patient admission. Treatment with ethanol as an antidote and hemodialysis were started because of metabolic acidosis, anamnestic data and clinical status of the patient, and subsequently led to improvement of his condition. Further toxicological analyses of glycolic and oxalic acids in serum and urine samples were performed by ion-chromatography (IC) method and showed high values in spot urine and serum ultrafiltrate at admission, but during therapy the values progressively decreased. Treatment of poisoned patient for 3 weeks resulted in complete recovery.     

Inhalant abuse detection and evaluation in young Tunisians

Occupational exposure biological monitoring techniques were applied for the diagnosis of inhalation abuse and for the evaluation of the levels of exposure to benzene, toluene, ethylbenzene, xylenes, and n-hexane, in 44 Tunisian adolescents and children suspected for volatile substance addiction. Urinary trans,trans-muconic acid, hippuric acid (HA), mandelic acid, and methylhippuric acids determinations were performed by high performance liquid chromatography with a photodiode array detector, and urinary o-cresol (o-Cr) and 2,5-hexanedione (HD) were extracted simultaneously and measured using gas chromatography with a flame ionization detector. Given the high linearity ranges, HD and o-Cr occupational exposure monitoring techniques could be applied without modification. However, urinary sample dilution was necessary before HA analysis. Concentrations were compared with the maxima of normal values (MNVs) in the general population and to the biological exposure indices (BEIs) used in occupational toxicology. Values as high as 6610-fold the MNV and 68 times the BEI were registered. The subjects showed high exposure to toluene and hexane. Measured metabolites HA and/or o-Cr and HD enabled the easy detection and evaluation of exposure levels. The problem of inhalant abuse should be given more attention and treated through an effective prevention strategy.     

Development and validation of the AmpFlSTR MiniFiler PCR Amplification Kit: a MiniSTR multiplex for the analysis of degraded and/or PCR inhibited DNA

DNA typing of degraded DNA samples can be a challenging task when using the current commercially available multiplex short tandem repeat (STR) analysis kits. However, the ability to type degraded DNA specimens improves by redesigning current STR marker amplicons such that smaller sized polymerase chain reaction (PCR) products are generated. In an effort to increase the amount of information derived from these types of DNA samples, the AmpFlSTR MiniFiler PCR Amplification Kit has been developed. The kit contains reagents for the amplification of eight miniSTRs which are the largest sized loci in the AmpFlSTR Identifiler PCR Amplification Kit (D7S820, D13S317, D16S539, D21S11, D2S1338, D18S51, CSF1PO, and FGA). Five of these STR loci (D16S539, D21S11, D2S1338, D18S51, and FGA) also are some of the largest loci in the AmpFlSTR SGM Plus kit. This informative nine-locus multiplex, which includes the gender-identification locus Amelogenin, has been validated according to the FBI/National Standards and SWGDAM guidelines. Our results demonstrate significant performance improvements in models of DNA degradation, PCR inhibition, and nonprobative samples when compared to the AmpFlSTR Identifiler and SGM Plus kits. These data support that the MiniFiler kit will increase the likelihood of obtaining additional STR information from forensic samples in situations in which standard STR chemistries fail to produce complete profiles.     

A new approach to amino acid racemization in enamel: testing of a less destructive sampling methodology

Aspartic acid racemization has been found to be an accurate measure of age at death for recent forensic material. This paper examines the practicality of using acid etching of the tooth surface to extract amino acids from the enamel for racemization analysis. By serial etching of the tooth and contamination of the teeth with bovine serum albumin prior to etching, the ability of etching to remove contamination was assessed. The destructiveness of the method was visualized and quantified using micro-computed tomography (micro-CT). By bleaching the teeth and by deeper etching it was possible to obtain more consistent values. While etching had little effect on the enamel at the macroscale, it did have an impact at the microscale. The quantities of enamel removed varied depending upon the tooth morphology, but were not large. Acid etching of enamel thus appears to be a promising new method for extracting proteins for amino acid racemization age estimation noninvasively.     

Assessing the Utility of Soil DNA Extraction Kits for Increasing DNA Yields and Eliminating PCR Inhibitors from Buried Skeletal Remains

DNA identification of human remains is often necessary when decedents are skeletonized; however, poor DNA recovery and polymerase chain reaction (PCR) inhibition are frequently encountered, a situation exacerbated by burial. In this research, the utility of integrating soil DNA isolation kits into buried skeletal DNA analysis was evaluated and compared to a standard human DNA extraction kit and organic extraction. The soil kits successfully extracted skeletal DNA at quantities similar to standard methods, although the two kits tested, which differ mechanistically, were not equivalent. Further, the PCR inhibitors calcium and humic acid were effectively removed using the soil kits, whereas collagen was less so. Finally, concordant control region sequences were obtained from human skeletal remains using all four methods. Based on these comparisons, soil DNA isolation kits, which quickened the extraction process, proved to be a viable extraction technique for skeletal remains that resulted in positive identification of a decedent.     

A Concentrated Hydrochloric Acid-based Method for Complete Recovery of DNA from Bone

The successful extraction of DNA from historical or ancient animal bone is important for the analysis of discriminating genetic markers. Methods used currently rely on the digestion of bone with EDTA and proteinase K, followed by purification with phenol/chloroform and silica bed binding. We have developed a simple concentrated hydrochloric acid-based method that precludes the use of phenol/chloroform purification and can lead to a several-fold increase in DNA yield when compared to other commonly used methods. Concentrated hydrochloric acid was shown to dissolve most of the undigested bone and allowed the efficient recovery of DNA fragments <100 bases in length. This method should prove useful for the recovery of DNAs from highly degraded animal bone, such as that found in historical or ancient samples.     

HPLC-DAD双波长法同时测定脑络欣通胶囊中阿魏酸及天麻素含量

目的 建立双波长同时测定脑络欣通胶囊中天麻素和阿魏酸含量的方法,为脑络欣通的质量控制提供依据。 方法 采用高效液相色谱-二极管阵列检测器和Welch Materials C8色谱柱（250 mm×4.6 mm,5 μm）。流动相：乙腈-0.01%磷酸;梯度洗脱（乙腈：0～10 min,6%;10～30 min,6%→35%）;流速：1.0 mL/min;柱温：35 ℃;检测波长：320 nm（阿魏酸）和222 nm（天麻素）。结果 在30 min内,实现了阿魏酸与天麻素双波长同时测定,二者含量分别在0.20～2.39 μg（r＝0.999 9）和0.20～2.41 μg（r＝0.999 8）范围内与峰面积呈现良好的线性关系,平均加样回收率分别为99.5%和99.1%（n＝6）。 结论 双波长检测对复方中阿魏酸与天麻素定量更准确,二者同时测定能有效提高分析效率,该方法可用于脑络欣通胶囊的质量控制。     

不同产地牵牛子生品及炒制品咖啡酸含量测定

目的 通过测定不同产地牵牛子生品及炒制品中咖啡酸含量,探讨产地和炮制方法对牵牛子质量的影响。方法 采用高效液相色谱法测定牵牛子生品及炒制品中咖啡酸的含量。色谱柱：Shim-pack ODS（4.6 mm×150 mm,5 μm）;柱温：30 ℃;流动相：乙腈-0.04%磷酸水溶液,梯度洗脱;检测波长为325 nm。结果 河南产牵牛子咖啡酸含量最高,山西产牵牛子咖啡酸含量最低,其他产地牵牛子咖啡酸含量居中,牵牛子炒制品较生品中咖啡酸含量均有不同程度的降低。结论 不同产地牵牛子咖啡酸含量不同,炮制后,咖啡酸含量降低,咖啡酸可作为牵牛子的评价指标之一。