‘How I Do It’: TEM for Tumors of the Rectum

Introduction  Transanal endoscopic microsurgery (TEM) has an established role in the management of benign rectal tumors. It also has an expanding role in the management of malignant tumors, which is more demanding for the clinician. It requires accurate histological and radiological assessment and draws on an expert understanding of the nature of local recurrence, metastasis, and the place of adjuvant therapies. Discussion  A multidisciplinary approach is recommended. This paper discusses our institutional approach to TEM for benign and malignant tumors and covers some of the current management controversies.     

Detection of TEM-induced reciprocal translocations in F1 sons of CD-1 male mice: comparison of sequential fertility evaluation and cytogenetic analysis

To determine the positive and negative classification error rates associated with the HTA in our laboratory, F1 sons of TEM-exposed CD-1 male mice were evaluated by the sequential fertility method with subsequent cytogenetic analysis. Males who sired three litters of size 10 or less when mated to primiparous females from either the B6C3F1 or the BCF1 strain were classified as partial steriles. When meiotic chromosome analyses revealed the presence of at least two cells containing multivalent figures, males were classified as translocation heterozygotes. When the fertility evaluation and the cytogenetic analysis were compared, normal fertility was observed on 5 of 83 (6.02%) translocation-bearing F1 males mated to B6C3F1 tester females and on 3 of 83 (3.61%) F1 males mated to BCF1 tester females. Thus, the false-negative error rates were 6.02% and 3.61% with these two tester strains. Multivalent figures were not observed in the meiotic chromosomes of 410 F1 males. Of these, 12 (2.93%) had reduced fertility when mated to the B6C3F1 tester strain as did 7 (1.71%) mated to the BCF1 strain. Thus, the false-positive error rates with these two tester strains were 2.93% for the B6C3F1 strain and 1.71% for the BCF1 strain. Our results indicate that non-zero error rates, both false-positive and false-negative, are associated with the sequential mating method HTA. In addition, the magnitude of these error rates was influenced not only by the tester female strain but also by the genotype of the F1 male.     

A model for the distribution of HAP crystallites in bone—an hypothesis

Summary Previous study of the velocity of sound in hard tissues led to the hypothesis that collagen is stiffened because the intermolecular links between collagen molecules are embedded in mineral by the mineralizing process. Recently published available high-resolution electron microscope studies of biological apatitic crystals frequently show periodic lattice images of the crystal basal plane. Some of these images from bone and dentin display a sequence of etch pits strung linearly along the midline indicating a chain of screw dislocations. These are interpreted to be the loci of the embedded connecting links required by the collagen stiffening hypothesis. The particular crystallites seen in the micrographs probably are from the interfibril region. Most important, the periodic lattice images show the axes of the links must be parallel to the c-axis of the crystallite. The location of the crystallites and their orientation in situ indicate that the c-axis of the crystallites must be perpendicular to the collagen axis. X-ray diffraction studies available in the literature for a long time indicate the c-axis of HAP crystallites are parallel to the collagen molecular axes. A model of the crystallite distribution is presented which reconciles the two types of crystallite orientation. It is assumed there is only one physical mineralization process for all apatitic crystallites. Additional data from several sources, particularly the distribution of mineral between intra- and interfibril spaces deduced by Katz and Li, are used to develop a first-order model of mineral in bone. Hole filling crystallites between ends of colinear collagen molecules have their c-axes parallel to the molecular axis. The other crystallites must have their c-axes perpendicular to the collagen molecular axis.     

Fusion of myogenic cells to the newly sealed region of damaged myofibres in skeletal muscle regeneration

In regenerating skeletal muscle, sarcoplasmic extensions containing variable numbers of nuclei, widely referred to as 'buds' or 'stumps', are formed at the ends of damaged myofibres. In this paper we investigated whether the nuclei seen in the buds results from fusion of myogenic cells or from migration of myonuclei to the sealed ends of damaged myofibres in murine muscle regenerating after crush injury. The fusion of mononuclear and multinucleate myogenic cells to the buds was demonstrated by transmission electron microscopy. In order to elucidate the frequency and kinetics of cytoplasmic continuity between myotubes and sealed myofibres, we labelled the damaged myofibres with carbocyanine dye DiI (which inserts into the lipid bilayer and travels down continuous membranes) and the samples were then examined by con-focal scanning microscopy. This technique showed that there was little fusion between myotubes and myofibres during the first 6 days after crush injury, but significant fusion had occurred by the tenth day especially at the newly sealed region of the damaged myofibre. A scheme for the repair of damaged skeletal muscle is presented.     

Genital Paget's disease: a transmission-, scanning-, and immuno-electron microscopic study

A case of genital Paget's disease examined by a transmission-, scanning-, and immuno-electron microscopy was reported. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) observations indicated that Paget cells had the characteristic features of glandular cells. In immunoelectron microscopy, carcinoembryonic antigen was found on the entire plasma membrane of Paget cells. Therefore, these observations may support the viewpoint that Paget cells are neoplasmic glandular cells.     

Mutagenic potential of cis-dichlorodiammine platinum II in rodents

The ability of cis-dichlorodiammine platinum II to cause chromosomal aberrations in rats and dominant lethaloty in mice was studied. Five daily intraperitoneal doses raging from 0.25 to 2.00 mg/kg/day failed to result in the observance of dominant lethal mutations in mice. Intraperitoneal doses of 0.13 and 0.52 mg/kg/day for 5 days in rats did, however, cause chromosomal aberrations in bone marrow cells collected and harvested 24 h after the last dose. The incidence of total aberrations obeserved at the 0.52 mg/kg/day dose level was 5.5-fold greater than that seen for the vehicle control group. Thus, cis-dichlorodiammine platinum II appears to be clastogenic in rats.     

Transanal endoscopic microsurgery (TEM). Current situation and future expectations

Transanal endoscopic microsurgery (TEM) uses specific equipment that allows resection of large rectal adenomas and incipient malignancies in the rectal ampulla. TEM aims to provide an alternative to conventional abdominal surgery (low anterior resection or abdominoperineal amputations), which carries not inconsiderable morbidity and mortality. Application of the technique of endoanal excision is limited by the height and extension of the lesions. In this review, the authors present their own experience with this technique and that described in the literature. The protocol for selecting candidates for TEM, their preoperative preparation, equipment, characteristics of the surgical technique, postoperative complications, and follow-up are described. The collaboration of a multidisciplinary team is essential when developing this technique. TEM-associated morbidity is low and mortality is practically nil. TEM is the technique of choice in large rectal adenomas and malignant rectal tumors in stages pT1 localized in the rectal ampulla. The frequency of recurrence is similar to that in abdominal surgery. The technique does not cause complications of urinary or sexual dysfunction and fecal incontinence is minimal. In more advances stages of rectal cancer, the results of better patient selection and future studies on the possible application of neoadjuvant therapy associated with TEM are required.     

Post-mortem modifications of the ependyma of the lateral ventricular wall

Summary The ependymal lining of the lateral ventricles of the brain of rats, rabbits, and man was investigated at several times after death. In contrast to control material that was fixed by the aldehyde perfusing method, the following post-mortem (p.m.) changes were found.(1) Cytoplasmic protrusions of ependymal cells appear 15 min p.m. They are present up to several hours after death. (2) The formation of these protrusions causes the tufts of cilia to clump together and later to become integrated within the ependymal cell. This may simulate an unciliated surface. (3) Small porelike holes, which are present 15 min p.m. in the ependymal cell membrane, enlarge and in later stages produce a meshwork of fibers instead of a closed ependymal lining. (4) TEM observation shows that ependymal cells are separated from each other very soon after death by intercellular gaps. Cell junctions between ependymal cells resist separation over a longer p.m. period.In animal or human material that is fixed at any time after death, such modifications have to be considered very critically. In human p.m. autopsy material they are mostly the expression of a p.m. alteration.     

Morphological alterations and distribution of occludin in rat testes after bilateral vasectomy

The aim of study was to investigate the fate and the morphology of the cells which constitute the spermatogenic line, and to determine the distribution of occludin in the testis in adult vasectomized Wistar rats. The rats were divided into two groups: control group (sham-operated) and vasectomized group. One, 3 and 6 months after sham and vasectomy operations, testis samples were examined. The weight of the testes was found to be reduced 3 and 6 months after vasectomy. There was vacuolization in the seminiferous tubules one month after vasectomy. The tubules showed severe atrophy 3 and 6 months after vasectomy. The occludin immunolabeling in the 3- and 6-month groups was weak and diffuse, and the density of the protein was found to be decreased. The increase in the number of apoptotic cells was accompanied by a time-dependent decrease in the number of haploid, diploid and tetraploid cells. This study demonstrated that vasectomy causes degeneration in the seminiferous tubules with alterations in occludin distribution with a decrease in the number of spermatogenic cells. Moreover, these alterations increase in a time-dependent manner.     

Effects of ozone and fine particulate matter (PM2.5) on rat system inflammation and cardiac function

In order to understand the toxic mechanisms of cardiovascular system injuries induced by ambient PM_2.5 and/or ozone, a subacute toxicological animal experiment was designed with exposure twice a week for 3 continuous weeks. Wistar rats were randomly categorized into 8 groups (n = 6): 1 control group, 3 groups exposed to fine particulate matters (PM_2.5) alone at 3 doses (0.2, 0.8, or 3.2 mg/rat), 1 group to ozone (0.81 ppm) alone and 3 groups to ozone plus PM_2.5 at 3 doses (0.2, 0.8, or 3.2 mg/rat). Heart rate (HR) and electrocardiogram (ECG) was monitored at approximately 24-h both after the 3rd exposure and the last (6th) exposure, and systolic blood pressure (SBP) was monitored at approximately 24-h after the 6th exposure. Biomarkers of systemic inflammation and injuries (CRP, IL-6, LDH, CK), heart oxidative stress (MDA, SOD) and endothelial function (ET-1, VEGF) were analyzed after the 6th exposure. Additionally, myocardial ultrastructural alterations were observed under transmission electron microscopy (TEM) for histopathological analyses. Results showed that PM_2.5 alone exposure could trigger the significant increase of CRP, MDA, CK, ET-1 and SBP and decrease of heart rate variability (HRV), a marker of cardiac autonomic nervous system (ANS) function. Ozone alone exposure in rats did not show significant alterations in any indicators. Ozone plus PM_2.5 exposure, however, induced CRP, IL-6, CK, LDH and MDA increase, SOD and HRV decrease significantly in a dose–response way. Meanwhile, abnormal ECG types were monitored in rats exposed to PM_2.5 with and without ozone and obvious myocardial ultrastructural changes were observed by TEM. In conclusion, PM_2.5 alone exposure could cause inflammation, endothelial function and ANS injuries, and ozone potentiated these effects induced by PM_2.5.