Fluorescence microscopy in the detection of early myocardial infarction

Novel use of fluorescent microscopy in determining basement membrane integrity in ambiguous cases

Indistinct basement membrane due to inflammation always poses a problem to the pathologists for commenting on micro-invasive squamous cell carcinoma. In such a situation, even a special stain would not be able to correctly demonstrate the basement membrane, which is necessary for estimating the depth of invasion. In this paper, we have proposed a novel fluorescent microscopy assisted visualization of basement membrane in such difficult situations. To further validate this approach, we then retrospectively investigated twenty such cases under a fluorescent microscope and could able to repeat the same result. As routine hematoxylin and eosin stained sections are required for evaluation, it is technically less demanding and less time-consuming.

Acridine Orange: A Review of Novel Applications for Surgical Cancer Imaging and Therapy

Introduction: Acridine orange (AO) was first extracted from coal tar in the late nineteenth century and was used as a fluorescent dye. In this paper, we review emergent research about novel applications of AO for fluorescence surgery and cancer therapy. Materials and methods: We performed a systematic search in the MEDLINE, PubMed, Cochrane library, Google Scholar, Embase, Web of Science, and Scopus database using combinations of the term "acridine orange" with the following: "surgical oncology," "neuropathology," "microsurgery," "intraoperative fluorescence," "confocal microscopy," "pathology," "endomicroscopy," "guidance," "fluorescence guidance," "oncology," "surgery," "neurooncology," and "photodynamic therapy." Peer-reviewed articles published in English were included in this review. We have also scanned references for relevant articles. Results: We have reviewed studies on the various application of AO in microscopy, endomicroscopy, intraoperative fluorescence guidance, photodynamic therapy, sonodynamic therapy, radiodynamic therapy. Conclusion: Although the number of studies on the clinical use of AO is limited, pilot studies have demonstrated the safety and feasibility of its application as an intraoperative fluorescent dye and as a novel photo- and radio-sensitizator. Further clinical studies are necessary to more definitively assess the clinical benefit AO-based fluorescence guidance, therapy for sarcomas, and to establish feasibility of this new approach for the treatment of other tumor types.

Repeated inspiratory occlusions acutely impair myocardial function in rats

Repeated episodes of hypoxia and sympathetic activation during obstructive sleep apnoea are implicated in the initiation and progression of cardiovascular diseases, but the acute effects are unknown. We hypothesized that repeated inspiratory occlusions cause acute myocardial dysfunction and injury. In 22 spontaneously breathing pentobarbital-anaesthetized rats, inspiration was occluded for 30 s every 2 min for 3 h. After approximately 1.5 h, mean arterial pressure started to fall; heart rate between occlusions was stable throughout, consistent with only transient increases in sympathetic activity during each occlusion. Three hours of occlusions resulted in ventricular diastolic dysfunction (reduced peak rate of change of ventricular pressure and slower relaxation). Post-occlusions, the left ventricular contractile response to dobutamine was blunted. After 1 h of recovery, left ventricular pressure generation had returned to values no different from those in sham animals in 5 of 9 of the animals. Cardiac myofibrils from rats subjected to occlusions had depressed calcium-activated myosin ATPase activity, indicating myofilament contractile dysfunction that was not due to breakdown of contractile proteins. Haematoxylin and eosin-stained cross-sections revealed multifocal areas of necrosis within the septum and both ventricles. Repeated inspiratory occlusions, analogous to moderately severe obstructive sleep apnoea, acutely cause global cardiac dysfunction with multifocal myocardial infarcts.

Application of fluorescence microscopy on hematoxylin and eosin-stained sections of healthy and diseased teeth and supporting structures

Destruction of dental tissue and supporting structures is usually microscopically assessed by routine hematoxylin and eosin (HE)-stained sections. This short communication is concerned with the potential role of fluorescence microscopy of HE-stained sections to study morphological aspects of intact and pathological teeth in dental research. This methodology improves the visualization of the anatomical structures of the intact teeth, especially anatomical features and periodontal ligament spatial distribution. This technique also improves the visualization of the root and bone resorption and the delineation of the periapical lesion extension. The fluorescence microscopy technique of HE-stained sections is an easy, reliable and inexpensive method that seems to be a useful tool for evaluating morphological aspects of intact and pathological teeth in dental research.

Fluorescence of hematoxylin and eosin-stained histological sections of the human spleen

A major problem in the morphometric evaluation of human spleen is the simple but reliable determination of the border between T-cell and B-cell dependent areas, and other structures of the spleen. It was investigated whether cryostat sections of frozen surgical specimens of the human spleen and sections of paraffin-embedded specimens could be used for this purpose after being stained with haematoxylin and eosin and mounted in autofluorescence-free medium for fluorescence microscopical evaluation. Comparison was made with sections that were immunohistochemically-stained for fibronectin and collagens type II and type IV. Both in cryostat sections and paraffin sections, fluorescence was found in circumferential reticulum of periarterial lymphatic sheets, arterial terminals, arterial walls and walls of red pulp sinuses in the spleen. Evaluation was hindered by fluorescence of erythrocytes in paraffin sections but not in cryostat sections. Results were similar as those obtained with immunohistochemical fibronectin staining and are sufficient for morphometric evaluation or orientation in the tissue in case of neoplasia.

Analysis of ionic ratios in myocardial tissue and their relation to cardiac damage

The authors evaluated the usefulness of the postmortem biochemical analysis of ionic ratios in different parts of the heart and their relation to cardiac damage caused by chest trauma, as observed by anatomopathologic study. Fifty-nine 59 cases were studied, selected from routine necropsies, and samples were taken from different sites of cardiac tissue. The cause of death was trauma in 40 cases and nontraumatic causes in 19 cases. The object of this study was to analyze the levels of Na+, K+, Ca+2, Mg+2, and Zn+2 in different zones of the heart, and the relationship between intracellular and extracellular ion ratios and the different causes of death and any anatomopathologic alterations observed. The biochemical tests revealed a possible relation between the ionic values and cause of death. Alterations in cell membrane permeability and corresponding modification of the ionic ratios were produced earlier than histologic alterations, which need longer to establish themselves whether or not they follow a traumatic process.

Is immunohistochemistry a useful tool in the postmortem recognition of myocardial hypoxia in human tissue with no morphological evidence of necrosis?

Myocytes in the border zone of myocardial infarction are under severe hypoxia without characteristic morphology of necrosis, and show ultrastructural features similar to those seen within the first hours after coronary occlusion. This study was carried out to evaluate the possibility that immunohistochemical methods could be used for the early diagnosis of myocardial infarction by detecting areas of hypoxia. Nineteen human sections of formalin-fixed paraffin-embedded myocardial samples showing a necrotic area and its border were submitted to immunohistochemical staining with the markers antimuscle actin, antimyoglobin, antitroponin T, antifibronectin, and anticomplement component C9. Sections were also subjected to azan trichrome and hematoxylin-basic fuchsin-picric (HBFP) staining techniques. Immunohistochemistry and azan trichrome showed that in the border zone there was a pattern of reaction intermediate between the infarcted area and the normal myocardium. The HBFP failed to distinguish these two areas. In conclusion, immunohistochemistry and azan trichrome can recognize myocardial hypoxia. Because hypoxia is an invariable condition in infarction, these techniques can be used to confirm suspected cases of myocardial infarction in which necrosis is not yet evident. However, considering that agonal states may be associated with generalized hypoxia, further studies are needed to confirm the reliability of this procedure in the earlier phases of myocardial infarction.

Primary study of vascular endothelial growth factor immunohistochemical staining in the diagnosis of early acute myocardial ischemia

The expression of vascular endothelial growth factor (VEGF) in the model of rat early acute myocardial ischemia was studied by Strept-Avidin-Biotin-Peroxidase Complex (SABC) immunohistochemical staining. After ligating the anterior descending branch of the left coronary artery, an initial rapid (30min) positive expression of VEGF in myocardial ischemic areas was observed, the intensity of positive expression of VEGF increased with the continuation of myocardial ischemia. After 5h infarction, the strongly positive myocytes of SABC-VEGF staining were predominantly limited to perimyocardial infarction areas. No positive expression of VEGF was found in the control group. These findings suggested that SABC-VEGF method could give a sensitive, specific, simple and objective morphologic evidence to the diagnosis of sudden cardiac death caused by acute early myocardial ischemia.

Evaluation of cardiac troponin I immunoreaction in autopsy hearts: a possible marker of early myocardial infarction

Postmortem diagnosis of early myocardial infarctions is an ever recurrent problem in pathology. In the present study we determined the troponin I expression in 46 autopsy hearts using an immunohistochemical technique. Troponin I has, as a specific cardiac muscle protein, become a widespread used marker in testing patients with acute chest pain. The hearts were divided into three groups based on the macroscopical findings: definite signs of infarction, possible signs of infarction and no signs of infarction. All 14 cases of definite myocardial infarction showed a well-defined area with loss of troponin I. Twenty-three of 24 cases of possible myocardial infarction also showed a well-defined area with loss of troponin I. None of the eight non-cardiac death controls showed loss of troponin I expression. The results suggest troponin I expression as a sensitive test in diagnosis of early myocardial infarction.

The application of selected histochemical and immunohistochemical markers and procedures to the diagnosis of early myocardial damage

Histochemical (= HIS) methods (haematoxylin-eosin, luxol fast blue, chromotrope aniline blue) and various immunohistochemical (= IH) markers (myoglobin, desmin, fibrinogen, complement C5b-9) were applied in parallel to test the efficiency, specificity and sensitivity for the recognition of early ischemic myocardial damage. The whole series was subgrouped into cardiac deaths (N = 35) and controls (N = 13). Cardiac deaths were sub-divided into 3 groups: 1. infarction visible in gross examination (N = 15), 2. coronary thrombosis without infarction (N = 11), 3. stenosing coronary atherosclerosis without infarction (N = 9). The control group (group 4) consisted of unnatural deaths with presumed short agonal periods (N = 13). Group 1 cases usually exhibited extended coagulation necrosis of the diffuse type and the contraction type in combination (1 exception). Group 2 showed mainly a patchy type of coagulation necrosis and contained 1 cases where all methods failed to react and 3 more cases where only the HIS methods failed to react. Group 3 and 4 were associated with a disseminated type of single and/or grouped fibre necrosis. In addition, the average reaction strengths showed a decrease from group 1 to group 4 which was more pronounced in the HIS reactions compared with the IH reactions. One case in group 1 showing negative IH reactions cannot be explained. Positive IH reactions observed in a few cases in group 2 contrasting with negative HIS reactions would indicate a greater sensitivity of this methodology and this interpretation also applies to groups 3 and 4. From pathophysiological considerations, the positive cases in groups 3 and 4 can be well explained.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunocytochemical study with anti-muscle actin antibody (HHF35) on myocardial ischaemia and reperfusion injury in rats

Myocardial ischaemia and reperfusion injury in 16 anaesthetized Sprague-Dawley rats, eight of which were pretreated with morphine (5 mg/kg, intraperitoneally) to prevent arrhythmias, were studied immunocytochemically with anti-muscle actin specific monoclonal antibody (HHF35). Eight cases of simple ischaemia and eight cases of sham-operated rats were used as controls. With HHF35 ABC immunocytochemical method, the left ventricular myocardium in the reperfusion group (without morphine) showed large areas of staining loss, but no loss of staining was seen in controls. No significant changes were seen with H&E stain in all hearts. Compared with HBFP, acridine orange (AO), eosin-fluorescence, HHF35 ABC staining best demonstrated myocardial reperfusion injury. The results indicate that the degree of myocardial damage may be related to the arrhythmias.

Sudden death due to cardiac sarcoidosis in a case of suspected homicide

In a case of suspected homicide death due to natural causes--cardiac death (SCD)--was found at autopsy. Despite an extensive replacement of myocardial tissue by sarcoid granulomata there was no history of cardiac dysfunction or preceding symptoms. The transmurally infiltrating granulomata and the concomitant fibrosis were predominantly confluent. They occupied vast areas within the interventricular septum and the adjacent posterior wall of the left ventricle. The only other organs involved were mediastinal lymph nodes, which appeared macroscopically normal.

Necropsy study of association between sudden death and cardiac enzymes

AIMS

To determine if cardiac enzymes measured at necropsy could be used to predict early myocardial infarction.

METHODS

Cardiac enzyme activities were measured in body fluids at necropsy. Coroners' necropsies were grouped by gross and microscopic findings into cases of definite myocardial infarction, cases with occlusive coronary artery atheroma but no identifiable myocardial infarction, and non-cardiac cases. Pericardial fluid, peripheral venous blood, and blood from the right atrium were collected. Total creatine phosphokinase, creatine phosphokinase isoenzymes, aspartate aminotransferase and hydroxybutarate dehydrogenase activities were measured and the results analysed by logistic regression.

RESULTS

The values of creatine phosphokinase and its isoenzymes were raised in those who had died of cardiac disease and were most discriminatory. Cases of early myocardial infarction without evidence of infarction on routine histological examination could be identified from enzyme activities.

CONCLUSIONS

Measurement of cardiac enzymes in blood and pericardial fluid at necropsy can provide valuable additional information in cases of sudden death as a result of myocardial ischaemia which have occurred before macroscopic or microscopic evidence of myocardial infarction.

Sudden cardiac death: a comparative study of morphological, histochemical and biochemical methods

The study deals with the comparison of morphological, histochemical and biochemical methods applied to the detection of myocardial infarction in 150 medico-legal autopsies performed at the Institute of Forensic Pathology in Copenhagen. The study also included an NBT (formazan) test of cardiac cross-sections, and light microscopy and fluorescence microscopy of acridine orange-stained specimens from four different sites of the cardiac musculature. Specimens of myocardium from the same four sites and pericardial fluid were analysed biochemically at the Institute of Legal Medicine in Granada. The K+/Na+ ratio was determined in the myocardial tissue and total creatine phosphokinase activity, creatine phosphokinase isoenzymes (MM, MB and BB) and myoglobin were assayed in pericardial fluid. When the results from Copenhagen and Granada were compared, there was absolute concordance in 96 cases, discrepancy in 53 and one case was inconclusive. After studying the circumstances of death, the number of discrepancies were reduced to 20, so that concordance was reached in 86% of all the cases. The results show that the combination of different methods leads to a diagnosis of myocardial infarction in far more cases than with morphological or biochemical methods alone.

Quantitation of early myocardial ischemia using acridine orange fluorescence--an experimental study

It has been observed in the present investigation that ischemic myocardium consistently produces bright green fluorescence after Acridine Orange (AO) staining. The area of ischemia in the left ventricular myocardium at different time intervals after onset of experimental ischemia has been calculated by use of this AO fluorescence technique. Zonal distribution of ischemia in the epicardial, middle, and endocardial zones has also been evaluated quantitatively from ten minutes to six hours after ligation of the anterior descending branch of the left coronary artery in the Wistar strain of albino rats. No similar study was available for comparison from the literature reviewed. The total area of left ventricular ischemia showed an increase with the prolongation of duration of coronary ligation from 13.39 +/- 2.69 mm2 at ten to twenty-five minutes to 32.99 +/- 5.69 mm2 at six hours after ligation. Statistical analysis of the zonal area of ischemia has shown that ischemia in the middle and endocardial zones was greater than that in the epicardial zone at all time intervals recorded. Middle zone ischemia extended over a larger area than that over the endocardial zone at all intervals except at intervals II (30-45 min), IV (2-2 1/2 hrs) and V (3-4 hrs). The results of this experimental investigation are significant for these point to the value of Acridine Orange fluorescence in detecting early myocardial ischemia and in demarcating zonal differences in ischemia. The authors have successfully utilized the method in a few human cases of clinically suspected myocardial infarction and recommend the technique for routine use to detect early human myocardial ischemia.

Further evaluation of immunocytochemical staining in the diagnosis of early myocardial ischaemic/hypoxic damage

The pattern of immunocytochemical staining with antibodies to caeruloplasmin, myosin, myoglobin and C-reactive protein seen in myocardium taken from deaths with macroscopic evidence of myocardial infarction and/or significant coronary artery atherosclerosis and from deaths with neither of these lesions has been correlated with H&E, PTAH and HBFP staining of myocardium and circumstances of each death indicative of antemortem hypoxia and/or ischaemia. Loss of staining with these antibodies correlated well with fuchsinorrhagia and both techniques are more sensitive than H&E and PTAH staining in the detection of early ischaemic/hypoxic damage to myocardium. However, their sensitivity is such that they appear to detect agonal changes and, therefore, cannot be used for specific diagnosis of early myocardial infarction.

Diaphragmatic muscle fibre necrosis in SIDS

Observations of acute muscle fibre necrosis, as seen in 242 sudden infant death syndrome (SIDS) cases is described. The lesion is a focal acute anoxic muscle fibre coagulative necrosis in some cases followed by myocytolysis, central vacuolation, macrophage and phagocytic cell infiltrate, stromal condensation and scarring.

Evaluation of eosin-fluorescence in the diagnosis of sudden cardiac death

The diagnostic significance of the eosin-fluorescence method was evaluated and compared with the enzymehistochemical beta-hydroxybutyrate-dehydrogenase method (beta-HBDH) and the degree of hyperchromasia in 568 samples from 24 bets-HBDH-negative and beta-HBDH-positive sudden cardiac deaths (SCD) and 23 non-cardiac deaths as controls. The effect of autolysis was investigated separately on isolated human hearts at +4 degrees C and +22 degrees C. All samples were examined without any knowledge of clinical or autopsy data. Normal olive-green fluorescence was observed in only five individuals of the control group and two in the beta-HBDH-negative one. The frequency of the yellow-fluorescence and hyperchromasia increased from the control subjects towards the beta-HBDH-positive-ones. The difference in frequency distribution of fluorescence between the groups was statistically highly significant (P less than 0.001). The change in fluorescence did not correlate with the loss of beta-HBDH-reaction or the distribution pattern of hyperchromasia. Postmortem autolysis did not change the fluorescence significantly but the 78% wrong positive subjects in the control group render this method too sensitive and unreliable for medicolegal purposes.

Immunocytochemical diagnosis of early myocardial ischaemic/hypoxic damage

The sensitive and reliable dinitrophenyl (DNP) hapten sandwich staining (DHSS) procedure (B. Jasani et al., Virchows Arch (Pathol. Anat.), 406 (1985) 441-448) was used to study the distribution of immunoperoxidase staining seen with antibodies to seven protein markers in post-mortem heart tissue. This was obtained from 12 cases with macroscopic myocardial infarction and 17 cases without myocardial infarction (10 with and 7 without significant coronary artery atherosclerosis). The immunostaining patterns were compared with the appearances seen in adjacent sections stained by the routine haematoxylin and eosin (H & E) and phosphotungstic acid haematoxylin (PTAH) methods and a method previously recommended for the detection of early myocardial infarction, the haematoxylin basic fuchsin picric acid (HBFP) stain. Loss of immunostaining with an antibody to myoglobin was found to be a reliable and more objective marker of both early and established myocardial infarction compared with the histological stains. Antibodies to myosin, caeruloplasmin, C-reactive protein and pre-albumin gave similar but less reliable results, whilst those to complement factor C3b and alpha-1 anti-trypsin gave the least reliable results for early myocardial ischaemic/hypoxic damage. The immunocytochemical results are considered sufficiently encouraging to extend the work to a large number of sudden death cases in order to establish a new, more reliable approach to the detection of histologically latent ischaemic/hypoxic damage in the myocardium.