Validation of the quality of histological images obtained of fresh and formalin-fixed specimens of esophageal and gastric mucosa by laser-scanning confocal microscopy

BACKGROUND AND STUDY AIMS

We have previously reported the success of a method of virtual histology using laser-scanning confocal microscopy (LCM) in vitro on untreated fresh specimens obtained from the gastrointestinal mucosa. In the present study, we aimed to apply LCM to both fresh and formalin-fixed specimens, without additional treatment, in order to validate and compare the quality of the images obtained.

METHODS

We obtained 18 specimens from 11 patients, either by endoscopic biopsy or following surgical resection. First, we observed the fresh, saline-immersed specimen with LCM using the Fluroview microscope (Olympus Co. Ltd., Tokyo, Japan). We then fixed the specimen with formalin and obtained further LCM images 1 hour, 3 hours, and 24 hours after fixation. Three independent observers observed the images and were asked to assess the origin of the samples, the treatment of the samples, the time after formalin fixation, and whether they showed benign or malignant lesions. We used kappa statistics to compare the agreement among the three observers in each of these four areas of interest.

RESULTS

Between January and March 2003, we obtained 191 LCM images from 18 specimens. Thirty images were randomly selected for observation. The overall accuracy for differentiating between esophagus and stomach specimens was 96.6 %. The accuracy of differentiating normal from cancerous lesions was 92.2 %. The differentiation between saline-immersed and formalin-fixed specimens was 59.7 % accurate and the assessment of the time interval after formalin fixation was only 37.3 % accurate. The kappa statistics showed that there was strong interobserver agreement on the differentiation of specimen origin and of cancerous from benign lesions. However, there was no agreement among the observers on the method of specimen preparation or on the estimated time interval after formalin fixation.

CONCLUSIONS

We concluded that images obtained from fresh specimens using LCM were of a quality good enough to make an accurate diagnosis of upper gastrointestinal carcinoma.

Development of virtual histology and virtual biopsy using laser-scanning confocal microscopy

The aim of this project is to acquire a direct image of histology from in vivo gastrointestinal mucosa. In other words, the task of 'endo-microscope' is to observe the cellular architecture of tissue in vivo during routine endoscopic examination. As the first step to completing this study, resected fresh specimens from the oesophagus. stomach and colon were examined by laser-scanning confocal microscopy (LCM) (Fluoview, Olympus, Tokyo). Fresh untreated mucosal specimens obtained by endoscopic pinch biopsy, polypectomy or endoscopic mucosal resection were collected and placed in normal saline and examined by LCM, collecting the reflective light of a 488-nm wavelength argon laser beam. As the second step, a probe-type LCM 'endo-microscope' was designed and applied to observe the human oral-cavity mucosa. The probe has 4.5-mm outer diameter and 20-cm length, which enables easy access to oral cavity mucosa. The estimated special resolution of the probe is 1-5 microm. A real-time microscopic image directly from ex vivo fresh specimens was acquired. The acquired LCM images corresponded well with the conventional H-E light microscopic images. Cell wall, nucleus and cytoplasm were simultaneously visualized by LCM scanning. This novel method enables serial imaginary microscopic sections on fresh specimens. In addition, a probe-type LCM 'endo-microscope' was designed and was applied to observe human oral cavity mucosa. Virtual histological images from the living oral squamous cell were successfully obtained. LCM images from ex vivo fresh specimens demonstrated the features of the H-E staining histological image. In the next step to accomplish our project, we developed a LCM probe with 4.5-mm outer diameter to obtain a virtual image of human oral cavity mucosa.

Cooperative Ca2+ removal from presynaptic terminals of the spiny lobster neuromuscular junction

Stimulation-induced changes in presynaptic free calcium concentration ([Ca2+]i) were examined by fluorescent imaging at the spiny lobster excitor motor nerve terminals. The Ca2+ removal process in the terminal was analyzed based on a single compartment model, under the assumption that the Ca2+ removal rate from the terminal cytoplasm is proportional to nth power of [Ca2+]i. During 100 nerve stimuli at 10-100 Hz, [Ca2+]i reached a plateau that increased in a less-than-linear way with stimulation frequency, and the power index, n, was about 2. In the decay time course after stimulation, n changed with the number of stimuli from about 1.4 after 10 stimuli to about 2 after 100 stimuli. With the change of n from 1.4 to 2, the rate became larger at high [Ca2+]i (>1.5 microM), but was smaller at low [Ca2+]i (<1 microM). These results suggest that a cooperative Ca2+ removal mechanism of n = 2, such as mitochondria, may play an important role in the terminal. This view is supported by the gradual increase in the [Ca2+]i plateau during long-term stimulation at 20-50 Hz for 60 s and by the existence of a very slow [Ca2+]i recovery process after this stimulation, both of which may be due to accumulation of Ca2+ in the organelle.

Effects of alkali metal cations on the labellar water receptor cell of the fleshfly, Boettcherisca peregrina

Dose-response relationships of the labellar water receptor cells of the fleshfly, Boettcherisca peregrina, in response to alkali-metal ions were studied electrophysiologically. When cation concentration was raised, the frequency of spikes from the water receptor cells was decreased. We analyzed the data under the assumption that channels on the water receptor membrane open when stimulated with water and are closed by alkali cations or nonelectrolytes. Dose-response relationships of the water receptor for NaCl, KCl and LiCl were analyzed using the Hill equation. The Hill coefficients and the activities of salts eliciting the half maximal response differed considerably among these salts. It is concluded that the effectiveness of salts on the inhibition of the water receptor cell differs among alkali metal ions, and that alkali cations interact cooperatively with the receptor membrane.

Characterization of sulpiride-displaceable 3H-YM-09151-2 binding sites in rat frontal cortex and the effects of subchronic treatment with haloperidol on cortical D-2 dopamine receptors

We investigated the pharmacological properties of the sulpiride-displaceable binding sites labeled by 3H-YM-09151-2 in rat frontal cortex, compared to those in striatum. The IC50 value of ketanserin was 486 nM, which was apparently different from its affinity for the 5HT-2 receptor. Various dopamine antagonists showed almost the same inhibitory effects for binding site in frontal cortex and striatum. Sulpiride-displaceable 3H-YM-09151-2 binding sites were considered to be D-2 dopamine receptors. After subchronic treatment with haloperidol, the D-2 receptor density of frontal cortex (0.55 fmol/mg tissue) increased to the same extent (about 25%) as striatum without significant change in apparent affinity.

[Behavioral pharmacological investigation and clinical consideration of the inhibitory potencies of psychotropic drugs against the D-1 and D-2 dopamine receptors]

The potencies of various psychotropic drugs to antagonize stereotypes induced by a high dose of (-)-apomorphine (10 mg/kg) in rats have been investigated in a comparison with their inhibitory potencies against the D-1 and D-2 dopamine receptors binding sites in rat striatum labelled by 3H-cis-flupentixol and 3H-spiperone, respectively. cis-Flupentixol and fluphenazine, which had high affinities for D-1, showed about 10 times stronger inhibitory effects on the stereotypes than perphenazine and haloperidol, which had moderate or weak affinities for D-1, although these drugs had similar affinities for D-2. A D-1 selective antagonist, SCH 23390, showed manifest inhibitory effect. The D-2 selective antagonists tested, spiperone and YM-09151-2, also showed marked inhibitory effects on the stereotypes but their potencies were largely weakened by concomitant treatment with scopolamine (more than 20 times), whereas the potency of D-1 selective antagonist, SCH 23390, was little affected. Stereotypes induced by a high dose of (-)-apomorphine in rats may partly be mediated through D-1. Clinically, it is well known that D-2 antagonists are effective for the acute psychotic state, but not for the negative symptoms of chronic schizophrenia. On the basis of these laboratory and clinical findings, the possible roles of the D-1 receptor blocking property of some neuroleptic agents were discussed in terms of their clinical relevance.

Antibacterial and inducer activities for tetracycline resistance by its derivates and analogues

Antibacterial and inducer activities of thirteen TC derivates were investigated for tetracycline (TC) resistance in staphylococcus aureus. Four compounds of the TC derivatives were not able to induce the resistance to TC in Staphylococcus aureus MS3937 rms7 (TC) + harboring an inducible TC resistance determinant located on a plasmid. The 12a-hydroxy position seems to be essential for the inducer activity.