Post-mortem cardiac magnetic resonance parameters in normal and diseased conditions

Background

Post-mortem cardiac magnetic resonance (CMR) is a non-invasive alternative to conventional autopsy. At present, diagnostic guidelines for cardiovascular conditions such as hypertrophic cardiomyopathy have not been established. We correlated post-mortem CMR images to definite conventional autopsy findings and hypothesed that elevated T2-weighted signal intensity and RV to LV area ratios can identify myocardial infarction and pulmonary emboli respectively.

Methods

For this unblinded pilot sub-study, we selected cases from the original blinded study that compared post-mortem imaging to conventional autopsy in patients referred for coronial investigation between October 2014 to November 2016. Three groups of scans were selected based on the cause of death identified by conventional autopsy: non-cardiovascular causes of death with no structural cardiac abnormality i.e., control cases, acute/subacute myocardial infarction and pulmonary emboli. Left ventricular (LV) wall thickness, LV myocardial signal intensity and ventricular cavity areas were measured.

Results

Fifty-six scans were selected [39 (69.6%) males]: 37 (66.1%) controls, eight (14.3%) acute/subacute myocardial infarction and eleven (19.6%) pulmonary emboli. The median age was 61 years [Interquartile range (IQR) 50-73] and the median time from death to imaging and autopsy was 2 days (IQR 2-3) and 3 days (IQR 3-4). The septal and lateral walls were thicker {15 mm [13-17] and 15 mm [14-18]} on post-mortem CMR than published ante-mortem measurements. Areas of acute/subacute myocardial infarction had significantly higher T2-weighted signal intensity (normalised to skeletal muscle) compared to normal myocardium in those who died from other causes {2.5 [2.3-3.0.] vs. 1.9 [1.8-2.3]; P<0.001}. In cases with pulmonary emboli, there was definite RV enlargement with a larger indexed RV to LV area ratio compared to those who died from other causes {2.9 [2.5-3.0] vs. 1.8 [1.5-2.0]; P<0.001}.

Conclusions

We present potential post-mortem CMR parameters to identify important cardiovascular abnormalities that may be beneficial when conventional autopsy cannot be performed. In patients without cardiovascular disease, LV wall thickness was found to be unreliable in diagnosing hypertrophic cardiomyopathy without histological and/or genetic testing. Elevated T2 signal intensity and RV to LV area ratios may be useful markers for acute/subacute myocardial infarction and pulmonary emboli. Larger studies will be necessary to define cut-offs.

How often is autopsy contributory in cases of sepsis?

This study sought to determine how often a medico-legal (coronial) autopsy contributes by identifying the source of infection when there has been a clinical diagnosis of sepsis prior to death. Autopsy reports were retrieved in which it was documented there had been a clinical diagnosis of sepsis preceding death. The autopsy report was reviewed to determine if a source for sepsis had been identified. It was found the autopsy was contributory in this respect in less than one fifth of all cases (35 of 198, 18%). It was also determined if there was a post-autopsy diagnosis of sepsis or if sepsis was excluded by a definite alternative diagnosis. During the study, of the 198 cases, sepsis was excluded by an alternative diagnosis in 78 (39%). Thus, the autopsy may be of more application to confirming or excluding a diagnosis of sepsis than identifying a source for sepsis.

Comparison of conventional autopsy with post-mortem magnetic resonance, computed tomography in determining the cause of unexplained death

Conventional autopsy is the gold standard for identifying unexplained death but due to declines in referrals, there is an emerging role for post-mortem imaging. We evaluated whether post-mortem magnetic resonance (PMMR) and computed tomography (PMCT) are inferior to conventional autopsy. Deceased individuals ≥ 2 years old with unexplained death referred for coronial investigation between October 2014 to December 2016 underwent PMCT and PMMR prior to conventional autopsy. Images were reported separately and then compared to the autopsy findings by independent and blinded investigators. Outcomes included the accuracy of imaging modalities to identify an organ system cause of death and other significant abnormalities. Sixty-nine individuals underwent post-mortem scanning and autopsy (50 males; 73%) with a median age of 61 years (IQR 50-73) and median time from death to imaging of 2 days (IQR 2-3). With autopsy, 48 (70%) had an organ system cause of death and were included in assessing primary outcome while the remaining 21 (30%) were only included in assessing secondary outcome; 12 (17%) had a non-structural cause and 9 (13%) had no identifiable cause. PMMR and PMCT identified the cause of death in 58% (28/48) of cases; 50% (24/48) for PMMR and 35% (17/48) for PMCT. The sensitivity and specificity were 57% and 57% for PMMR and 38% and 73% for PMCT. Both PMMR and PMCT identified 61% (57/94) of other significant abnormalities. Post-mortem imaging is inferior to autopsy but when reported by experienced clinicians, PMMR provides important information for cardiac and neurological deaths while PMCT is beneficial for neurological, traumatic and gastrointestinal deaths.

Determining a sampling regime for PCR detection of respiratory tract viral infection at coronial post-mortem examinations

Death due to respiratory infection is commonly encountered at autopsy. With only one opportunity to obtain samples for identification of a causative agent, it is important to ensure that sampling regimes are optimized to provide the greatest detection, without the expense and redundancy that can arise from over-sampling. This study was performed retrospectively using data from Coronial autopsies over the period 2012–2019 from which swabs from the nasopharyngeal region, trachea and lung parenchyma, in addition to samples of lung tissue, had been submitted for multiplex PCR detection of respiratory pathogens. From 97 cases with all four samples, there were 24 with at least one positive result for viral infection. Some cases had multiple positive results and a total of 27 respiratory tract viruses were identified, of which rhinovirus, influenza A virus and respiratory syncytial virus were the most common. Seventeen of the 27 viral infections (63%) were identified in all four samples. However, in nearly all cases (96%) the nasopharyngeal swab detected the infective agent when the multiplex PCR panel had detected infection in any of the four sample types. A nasopharyngeal swab is considered to be an optimal sample for detection of respiratory tract viral infection. As the samples analyzed were acquired before the appearance of the COVID-19 virus, the applicability of this finding for COVID-19 screening is not established.

Firearm fatalities in Western Sydney 1994-2003

This study reviews firearm-related deaths (homicidal, suicidal and accidental) from 1994 to 2003 in the Western Sidney area, Australia, serviced by the Westmead Department of Forensic Medicine, in order to document the features of the cases and to assess the effect of the introduction of the NSW Firearms Act in 1996. There were 211 fatalities involving firearms (1.8% of all of the Coroner's cases for the period); firearm deaths were classified as homicide (75), suicide (134) or accidental (2). There was a clear peak of homicide deaths by firearm in the 20-29 age group, whereas the suicide peak was broad, spanning the ages 20-69 years. More suicides occurred at home than homicides and a higher proportion of suicides were by rifle than homicides, which favoured hand guns. Entry wounds in suicides mostly involved the head, with the chest being the commonest entry site in homicides. The only statistically significant trend was for an increase in the number of firearm-related suicides in males, comparing the number of deaths pre- and post-firearm law introduction. The study includes reports of two suicides by unusual weapons: a home-made pipe gun and a spear gun.

A Prospective Study of Sudden Cardiac Death among Children and Young Adults

BACKGROUND

Sudden cardiac death among children and young adults is a devastating event. We performed a prospective, population-based, clinical and genetic study of sudden cardiac death among children and young adults.

METHODS

We prospectively collected clinical, demographic, and autopsy information on all cases of sudden cardiac death among children and young adults 1 to 35 years of age in Australia and New Zealand from 2010 through 2012. In cases that had no cause identified after a comprehensive autopsy that included toxicologic and histologic studies (unexplained sudden cardiac death), at least 59 cardiac genes were analyzed for a clinically relevant cardiac gene mutation.

RESULTS

A total of 490 cases of sudden cardiac death were identified. The annual incidence was 1.3 cases per 100,000 persons 1 to 35 years of age; 72% of the cases involved boys or young men. Persons 31 to 35 years of age had the highest incidence of sudden cardiac death (3.2 cases per 100,000 persons per year), and persons 16 to 20 years of age had the highest incidence of unexplained sudden cardiac death (0.8 cases per 100,000 persons per year). The most common explained causes of sudden cardiac death were coronary artery disease (24% of cases) and inherited cardiomyopathies (16% of cases). Unexplained sudden cardiac death (40% of cases) was the predominant finding among persons in all age groups, except for those 31 to 35 years of age, for whom coronary artery disease was the most common finding. Younger age and death at night were independently associated with unexplained sudden cardiac death as compared with explained sudden cardiac death. A clinically relevant cardiac gene mutation was identified in 31 of 113 cases (27%) of unexplained sudden cardiac death in which genetic testing was performed. During follow-up, a clinical diagnosis of an inherited cardiovascular disease was identified in 13% of the families in which an unexplained sudden cardiac death occurred.

CONCLUSIONS

The addition of genetic testing to autopsy investigation substantially increased the identification of a possible cause of sudden cardiac death among children and young adults. (Funded by the National Health and Medical Research Council of Australia and others.).

The use of incinerated pig head in dental identification simulation

PURPOSE

The aim of this exercise was to simulate a disaster victim identification scenario to allow training in documentation of postmortem incinerated remains and reconciliation of dental data.

METHOD

Varying number of restorations were placed in ten pig heads. The teeth and restorations were charted, with the restorations radiographed and documented, creating an ante-mortem data set. The following day the heads were cremated. Following cooling and recording they were transported for a post-mortem examination by trained specialist odontologists who were not involved in the initial antemortem phase. Recordings included the charting of teeth, restorations, lost teeth, and radiographs to simulate a post-mortem examination. A reconciliation of postmortem to antemortem information was attempted.

RESULTS

There was an unacceptable amount of error in the postmortem examination of the heads. The errors related mainly to avulsed teeth and incorrect opinion of which charted surfaces the restorations were placed upon. Also noted were a considerable number of root fractures occurring beneath the crestal bone. This observation does not mimic the evidence observed in human incinerated teeth where the crowns tend to fracture off the roots at the dentin-enamel junction.

CONCLUSION

The use of incinerated pig (Sus Scrofa) heads is not an ideal model for forensic odontology training in disaster victim identification. Differences in both anatomy and behavior following exposure to heat were shown to hamper documentation and subsequent comparison to antemortem data.

The utilization of a commercial gloss spray in stabilization of incinerated dental structures

PURPOSE

Incinerated human remains may require dental comparison to establish identity. The remains are often fragile and minor forces can damage teeth and facial bones, disrupting anatomical relationships, and impairing the ability to compare with antemortem records. This study evaluated the ability of a commercially available gloss spray to stabilize teeth in incinerated remains.

METHODS

Lower anterior teeth of scavenged sheep mandibles were incinerated in a furnace at a temperature of 500 °C for 35 min. Before a series of vibration tests, the left side of each sample was treated with the spray, with the right side acting as a control.

RESULTS

Significant retention of dental data was achieved utilizing the spray in comparison to the non-stabilized sides.

CONCLUSION

This study showed that a commercial clear gloss spray did not affect the ability to document or perform radiographic assessment of restorations, and statistically improved the stability and anatomical relationships of incinerated dental remains in scavenged sheep mandibles. Commercial products, such as the one tested in this study, are readily available and could be deployed at a mass disaster situation. However, the spray should not be used if there is any suspicion that accelerants might be involved at the scene.

Cochlear implants in the forensic identification process

PURPOSE

Decedents who are severely decomposed, skeletonized or incinerated present challenges for identification. Cochlear implants aid hearing and bear unique serial numbers that can be used to assist with identification of bodies that are not visually identifiable. The purpose of this paper was to highlight companies that have or had manufactured cochlear type implants and demonstrate the appearance of the implants to assist crime scene investigators, pathologists, anthropologists and odontologists.

METHOD

Investigation of cochlear implants was conducted on the internet and companies were contacted for information regarding their implants.

RESULTS

The functional appearance of a cochlear implant is explained, brands of implants are tabulated and pre and post-incineration images are presented.

CONCLUSION

The prevalence of cochlear implants is predicted to increase, thus they are likely to become relevant to the identification process. Company brand and serial markings can be retrieved from post-incineration implants making them a valuable aid in identification when other identifiers that may be present are not useful because they are heat-sensitive.

Using the Excess Heat Factor (EHF) to predict the risk of heat related deaths

Extremes of climate are not uncommon in Australia and heatwaves are not infrequent. Periods of high ambient temperature may result in clusters of heat related deaths, which may place strain on forensic facilities. This paper describes the formulation of the Excess Heat Factor using meteorological data to provide a means of predicting death resulting from periods of extreme heat stress. The 2009 South Australian heatwave had the highest ranked Excess Heat Factor in Adelaide's records. There were 58 heat related deaths, with the bulk of the heat related deaths following the peak Excess Heat Factor value (144 °C(2)). The 2008 heatwave had a lower peak Excess Heat Factor value (36 °C(2)); there was only one heat related death, which followed the peak in the Excess Heat Factor. It is proposed that calculation of the Excess Heat Factor from meteorological data could provide a means to predict and identify heat related deaths resulting from extreme weather conditions.

Fatal aortobronchial fistula

Aortobronchial fistula is a rare condition characterized by the development of a communication between the aorta and a branch of the bronchial tree that results from processes that arise within the aorta, in the tissues of the mediastinum, or in the adjacent thoracic organs. Three cases are reported to demonstrate characteristic features. Case 1: An 82-year-old woman was found collapsed with blood clot in her mouth. At autopsy an atherosclerotic thoracic aortic aneurysm was found which had eroded into the underlying left main bronchus with filling of the larynx, trachea and main bronchi with fluid blood. There was no evidence of dissection. Case 2: A 30-year-old woman collapsed and died. At autopsy, coarctation of the thoracic aorta was found with a saccular aneurysm distal to this which was joined to the left main bronchus by a mass of necrotic tissue. The bronchus contained a cast of blood; blood was also present within the trachea and within the distal airways of the left lung. Case 3: A six-year-old girl collapsed with massive airway haemorrhage following bronchoscopy. At autopsy coarctation of the thoracic aorta was identified with a saccular aneurysm distal to this. A transverse tear of the thinned aneurysm wall communicated with a mass of necrotic friable tissue that extended through the wall of the left main bronchus. Distal airways were filled with fluid blood. All three deaths were due to haemorrhage from aortobronchial fistulas. The pathogenesis of aortobronchial fistulas involves a variety of mechanical, infective and neoplastic processes. Many cases will not be diagnosed until autopsy examination is performed.

An assessment of the usefulness of routine histological examination in hanging deaths

A retrospective study was carried out on 100 randomly selected medico-legal autopsies of victims who had committed suicide by hanging. All cases had undergone full police and coronial investigation. Complete external and internal examinations had been carried out including routine histological examination of organs. The age range of victims was 15-94 years (average, 41.7 years) with a male-to-female ratio of 7:1. External and internal injuries were consistent with the reported events. Diagnoses based purely on histology included hepatic steatosis (n = 16), asthma (n = 3), lymphocytic thyroiditis (n = 2), and pulmonary and cardiac sarcoidosis (n = 1). A large cell carcinoma of the lung and a rectal adenocarcinoma were confirmed. Histological evaluation was, however, of limited usefulness in contributing to the medico-legal evaluation of cases, with careful scene, external and internal examinations providing the most relevant information. The results of histological examination of tissues were all incidental to the cause, mechanism, and manner of death.

Animal-related fatalities--part I: characteristic autopsy findings and variable causes of death associated with blunt and sharp trauma

Animals may be responsible for an array of potentially lethal injuries. Blunt force injuries characteristically involve larger animals such as cattle or horses that may kick, crush, or trample a victim causing head and facial injuries. Farm workers in particular are at high risk of lethal injuries involving the head and torso. Significant blunt trauma may be found in vehicle occupants after collisions with large animals such as camels or moose. Rarely, zookeepers may be crushed by particularly massive animals such as elephants. Sharp force injuries usually involve carnivore bites, most often from dogs with a "hole and tear" pattern of wounding. Injuries from animals such as alligators and sharks may have a significant component of crushing. Incised wounds may result in death from exsanguination and air embolism. On occasion, blunt or sharp trauma from animal activity may be confused with postmortem damage or with inflicted injury from an assault.

Positive "water test"-an external indicator of base of skull hinge-ring fracture

Despite having significant internal injuries, victims of motor vehicle accidents may have surprisingly few external manifestations of trauma. The water test describes a technique whereby water placed in an upwardly facing ear results in drainage from the nose and opposite ear, thus demonstrating transcranial passage of water. This sign can be demonstrated in cases of blunt cranial trauma where there is a "hinge" fracture involving the petrous temporal bones bilaterally associated with a ring fracture extending around the foramen magnum posteriorly. Such a fracture results in separation of the posterior and middle cranial fossae providing a track for water to traverse. The water test provides a quick and noninvasive method for demonstrating the presence of a particular type of skull fracture.

Postmortem molecular analysis of KCNQ1 and SCN5A genes in sudden unexplained death in young Australians

The cause of sudden death in young people remains unknown in up to 50% of postmortem cases. Mutations in the ion channel genes are known to cause primary arrhythmogenic disorders such as long QT and Brugada syndromes, which can present with sudden cardiac death and a negative autopsy. In this study, 59 sudden unexplained deaths occurring in Australians aged </=35 years with a negative autopsy, from 1994-2002, were studied. Genomic DNA was extracted from paraffin-embedded tissues. Genetic analysis of the KCNQ1 and SCN5A genes was performed using denaturing high-performance liquid chromatography and direct DNA sequencing. Nine DNA sequence variants were identified in the KCNQ1 gene and 9 sequence variants were identified in the SCN5A gene. In total, 23 out of 59 cases were found to have at least one DNA variant in KCNQ1 or SCN5A, of which one, H558R in the SCN5A gene, caused an amino acid substitution. None of the DNA variants were determined to be disease causing as they were also identified in control populations. In conclusion, no disease-causing mutations were found in the KCNQ1 or SCN5A genes in this cohort. A more selective screening approach, including only individuals with a clinical or family history of arrhythmogenic disorders, may yield greater success in identifying disease-causing mutations in cohorts of young individuals who have died suddenly.

Applying visible hyperspectral (chemical) imaging to estimate the age of bruises

Hyperspectral (chemical) imaging collects spectroscopic data in a two-dimensional spatial format. The potential application for the determination of the age of bruises is demonstrated and compared to reflectance probe spectrophotometry as well as photography. Blood was deposited on white cotton cloth or injected subcutaneously into pig skin to simulate a 'fresh bruise'. A mixture of blood and bile was used to simulate 'old' bruises. On the cloth background all the photographic methods clearly separated the two groups of samples (i.e. 'blood only' from 'blood plus bile'). However, on the pig skin the two groups could be separated by one of the photographic methods only. Separation of blood from blood and bile mixtures was obtained on the cloth and skin backgrounds using spectrophotometry and hyperspectral imaging. In a test using serial dilutions of blood and bile mixtures, the hyperspectral system performed slightly better than the spectrophotometer. The former also had the advantage of imaging a wider area and providing spatial data. Hyperspectral (chemical) imaging and spectrophotometry are superior to photography for the detection of bilirubin on a background of skin (due to the presence of yellow chromophores); this technology combined with mathematical analysis of the spectral data warrants further investigation.

Characterization of the triacylglycerol crystal formation in adipose tissue during a vehicle collision

The unusual appearance of crystalline fat structures was observed during the postmortem examination of a motor vehicle accident victim. The crystal structures were characterized using Fourier transform infrared spectroscopy and x-ray diffractometry. The structures were found to be made of triacylglycerols, a dominant lipid structure found in human adipose tissue, capable of forming various polymorphic structures. The morphology of the crystalline material was found using both techniques to be predominantly the beta' form of triacylglycerols. The accelerated growth of such triacylglycerol morphology has been observed as a result of shear stresses in other studies involving edible fats. As a result of the findings of this study, it is proposed that increased shear forces may be responsible for the formation of the unusual fat structure found in the victim. An understanding of the effect of forces on the structure of body fat in high-impact collisions can potentially assist in verifying a high-velocity impact.

Causes of sudden cardiac death in young Australians

OBJECTIVES

To determine the causes of sudden cardiac death in people aged 35 years or younger.

DESIGN AND SETTING

A review of all autopsies performed between 1 January 1994 and 31 December 2002 at a major Sydney forensic medicine department serving an area with over 2 million people.

MAIN OUTCOME MEASURES

Incidence of various types of cardiac disease causing sudden death in those aged <or= 35 years; proportion of deaths in which no cause was found at autopsy.

RESULTS

There were 10 199 autopsies performed during the study period. Of these, 2986 (29.2%) deaths occurred in people aged <or= 35 years; 193 were classified as sudden cardiac deaths. The cause of sudden death in this group was not established in 60 (31%), and was presumed to be due to primary arrhythmogenic disorders. Coronary artery disease occurred in 46 (24%), hypertrophic cardiomyopathy/unexplained left ventricular hypertrophy in 29 (15%), and myocarditis in 23 (12%).

CONCLUSIONS

Unexplained deaths, presumed to result from sudden primary arrhythmogenic causes, occur in young Australians with structurally normal hearts. That underlying disease-causing genetic defects may be involved has clinical implications for family members.

Synthesis and cytotoxicity on sensitive and doxorubicin-resistant cell lines of new pyrrolo[2,1-c][1,4]benzodiazepines related to anthramycin

A new 7,8-methylenedioxy analogue (4) of (+)-porothramycin B (2) and its water-soluble sodium bisulfite derivative (15) have been synthesized in high yields and have been shown to exhibit high cytotoxic activities against several tumor cell lines. The new pyrrolo[2,1-c][1,4]benzodiazepine 4 was as effective against the resistant cell lines as against the doxorubicin-sensitive cell lines tested.

Regulation of bovine satellite cell proliferation and differentiation by insulin and triiodothyronine

Satellite cells activity contributes to postnatal muscle growth. Herein, we have studied the respective influence of insulin and triiodothyronine (T3) on the proliferation and differentiation of primary bovine satellite cells isolated from Semitendinosus muscle of Montbéliard steers. Under basal conditions, satellite cells proliferated until the fifth day of culture, began to fuse into myotubes and expressed differentiation markers such as connectin, myogenin, and myosin heavy chain (MHC) isoforms. Insulin behaved as an effective mitogen. Moreover, it promoted extensive myotube formation and enhanced differentiation as shown by an increase in the accumulation of differentiation markers. Maximal differentiation occurred with insulin physiological range concentrations. A delay in the stimulation of differentiation was registered with a high dose that promoted maximal proliferation. Conversely, T3 decreased cell proliferation in a dose-dependent manner. In addition, fusion and biochemical differentiation (accumulation of connectin, MyoD1, myogenin, and myosin heavy chain isoforms) were also enhanced. Bovine satellite cells seemed to respond differentially to insulin and T3 for proliferation. Interestingly, both hormones displayed a myogenic influence. Our observations suggest that both hormones could influence bovine satellite cells in vivo and contribute to the regulation of postnatal muscle growth.

NM23 gene product expression does not predict lymph node metastases or survival in young patients with colorectal cancer

NM23 gene product is a putative metastases suppressor gene which has structural homology to a nucleoside diphosphate kinase. Previous studies examining the relationship between NM23 gene product expression and survival in patients with colorectal cancer have revealed conflicting results. However, no study has focused on young patients with colorectal cancer. This study was carried out to determine if expression of the NM23 gene product was correlated with metastatic potential and survival in young patients (45 years and under) with colorectal cancer. Eighty- one patients with colorectal cancer were studied and the presence of the NM23 gene product (H1) was detected using standard immunohistochemical techniques. NM23 gene product expression did not correlate with tumour stage, lymph node involvement by tumour, presence of distant metastases, extramural vascular invasion or degree of tumour differentiation. Independent risk factors for overall survival were: Dukes' stage (p=0.00001) and extramural vascular invasion (p=0.003). NM23 expression was not an independent prognostic indicator (p=0.55). Therefore, NM23 expression does not correlate with existing indicators of tumour aggressiveness and behaviour nor is it an independent predictor of survival in young patients with colorectal cancer.

Expression of growth factor receptors is not a prognostic indicator in young patients with colorectal cancer

Growth factor receptor expression has been shown to be of prognostic significance in certain cancers, but its relevance in young patients with colorectal cancer is unknown. The aim of this study, therefore, is to determine the prognostic relevance of growth factor receptor expression [c-erbB-2, epidermal growth factor receptor (EGFR) and transforming growth factor beta receptor (TGF beta R)] in such patients. Ninety-two patients were evaluated. They were staged using the Jass staging system and the presence of metastases. The expression of EGFR and TGF beta R and the protein production of c-erbB-2 were detected using standard immunohistochemical techniques. The expression of EGFR and TGF beta R and the presence of the c-erbB-2 protein product were not identified as independent prognostic factors for survival. Furthermore, their expression did not correlate with established prognostic indicators such as Jass staging, the presence of extramural vascular invasion and the degree of tumour differentiation.

Circulating antibodies to mouse monoclonal immunoglobulins in normal subjects--incidence, species specificity, and effects on a two-site assay for creatine kinase-MB isoenzyme

With a two-site CK-MB assay, we screened serum samples from 1008 blood donors for the presence of antibodies to mouse monoclonal immunoglobulin. These antibodies were capable of cross-linking the labeled antibody with the solid-phase antibody in the two-site assay, thus generating a falsely high apparent CK-MB concentration. In 92 (9.12%) of the blood donors tested, apparent CK-MB concentrations of 10-1000 micrograms/L decreased to less than 3 micrograms/L when re-assayed with non-immune mouse serum (10 mL/L) included in the assay reagent. We tested the ability of non-immune sera from other animal species to lower the concentration of apparent CK-MB in 58 of the 92 samples. Bovine and ovine serum were almost as effective as mouse serum; feline, canine, and rabbit serum were less effective. Of the samples tested, 12% (1.1% of the original population screened) showed apparent CK-MB values that either were not depressed by bovine serum or were only partly depressed. We discuss the possible etiology of these antibodies in normal subjects and recommend that all mouse monoclonal two-site assays should contain non-immune mouse serum (or a suitable "irrelevant" mouse monoclonal antibody) to prevent false-positive results.

Circulating antibodies to mouse monoclonal immunoglobulins in normal subjects--incidence, species specificity, and effects on a two-site assay for creatine kinase-MB isoenzyme

With a two-site CK-MB assay, we screened serum samples from 1008 blood donors for the presence of antibodies to mouse monoclonal immunoglobulin. These antibodies were capable of cross-linking the labeled antibody with the solid-phase antibody in the two-site assay, thus generating a falsely high apparent CK-MB concentration. In 92 (9.12%) of the blood donors tested, apparent CK-MB concentrations of 10-1000 micrograms/L decreased to less than 3 micrograms/L when re-assayed with non-immune mouse serum (10 mL/L) included in the assay reagent. We tested the ability of non-immune sera from other animal species to lower the concentration of apparent CK-MB in 58 of the 92 samples. Bovine and ovine serum were almost as effective as mouse serum; feline, canine, and rabbit serum were less effective. Of the samples tested, 12% (1.1% of the original population screened) showed apparent CK-MB values that either were not depressed by bovine serum or were only partly depressed. We discuss the possible etiology of these antibodies in normal subjects and recommend that all mouse monoclonal two-site assays should contain non-immune mouse serum (or a suitable "irrelevant" mouse monoclonal antibody) to prevent false-positive results.