Immunomodulation of vascular endothelium: effects of ultraviolet B irradiation on vein allograft rejection

Prosthetic grafts of vein allografts are inadequate as small-diameter vessel substitutes. We have applied ultraviolet B (UVB) irradiation to modulate the immunogenicity of vein allografts to avoid immunologic injury. The veins of male ACI rats were irradiated with UVB (60 mJ/cm2) in situ and transplanted to male ACI rats (autografts) and female Lewis rats (allografts). Nonirradiated veins served as controls. At 4, 7, 14, and 28 days, all grafts were patent and were studied for morphologic changes by scanning electron microscopy and for immunogold labeling of major histocompatibility complex class II antigen expression. In autografts, scanning electron microscopy demonstrated minimal endothelial loss after grafting, regardless of UVB irradiation. Untreated allografts showed severe endothelial injury 4, 7, and 14 days after transplantation. UVB irradiation of veins protected allografts from injury to the endothelium and basement membrane. Major histocompatibility complex class II-positive endothelial cells were not seen in autografts but were seen in 40% of cells 4 days after transplantation in untreated allografts. UVB-treated allografts showed MHC class II antigen expression labeling of 20% of the endothelial cells. Barr body analysis demonstrated the donor origin of these endothelial cells. UVB irradiation of rat vein allografts prolongs endothelial survival while decreasing endothelial surface expression of class II antigens. These data suggest that modification of vein immunogenicity with UVB irradiation may permit functional survival of small-vessel allografts without chronic immunosuppression.     

Ultrastructural changes in feline arterial endothelium following subarachnoid hemorrhage

Scanning electron microscopy of feline basilar arterial endothelium 4 hours, and 1, 3,5, and 7 days after subarachnoid hemorrhage (SAH) showed longitudinal furrows that correlated with angiographically demonstrated vasospasm. These ridges persisted after fixation at physiological pressure, and probably reflected medial contraction with undulation of the underlying elastic lamina. No change in endothelial cell morphology or thrombogenesis was observed as long as 7 days after SAH. There is no evidence from this study to suggest that ischemia from vasospasm is a product of thromboembolism from damaged endothelial surfaces.     

Ultrastructural changes in rat peripheral nerve following pneumatic tourniquet compression

The sciatic nerves of 12 male rats were examined in the electron microscope 14 days after pneumatic tourniquet compression. Tourniquet pressure was maintained at 300 mmHg for varied lengths of time (30 minutes to 3 hours). Nerves compressed for 30 minutes showed very mild fissuring of the myelin without axonal degeneration. Examination of nerves compressed for 1 to 3 hours showed progressively more varied and extensive damage. Changes included splaying of myelin lamellae, axonal shrinkage with periaxonal edema. Schwann cell hypertrophy, and an increase in the number of microtubules and mitochondria per unit area. The myelin sheaths of some fibers, compressed for more than 2 hours, were completely ruptured. These changes resemble nerve lesions which could be induced by a variety of experimental procedures. Ultrastructural changes produced by tourniquet compression are apparently time-related and affect large-diameter nerves more profoundly than smaller-diameter nerves. The data reported provide an explanation for delayed muscle rehabilitation experienced by patients who have undergone extremity surgery with pneumatic tourniquet application. The evidence presented suggests that the incidence of tourniquet palsy may be far greater than previously recognized.     

Ultrastructural changes in human skeletal muscles following tendon and nerve injuries. I. Ultrastructural changes following tendon injuries]

During reconstructive procedures performed 4-16 weeks after the tendon lesion the specimens obtained from the injured muscle have been examined by the authors. It was found that after the tendon injury inactivity atrophy develops and a condition of equilibrium could be observed at this time. The most important changes in the fine structure were seen in the contractile elements: these were atrophied, homogenized, fragmentated and ragged independently from the functional unities. The number of the mitochondria was considerably decreased, the sarcoplasmic reticulum was increased, and the difference between the originally red and white muscular fibres was indistinct. The glycogen content of the musculature was decreased, or it disappeared completely. No pathologic changes have been observed in the sarcolemma, the cell nuclei and the motor nerve end-organs.     

Effects of total body irradiation on the vascular endothelium

Total body irradiation (TBI) is used as conditioning for stem cell transplantation. We studied its effects on the vascular endothelium in 55 consecutive patients undergoing stem cell transplantation with TBI (TBI group n=35) or without TBI (non-TBI group: n=20). Fifty patients underwent bone marrow transplantation and five underwent peripheral blood stem cell transplantation. The levels of thrombomodulin, plasminogen activator inhibitor-1, and cyclic GMP were measured before and after TBI. At both times, the thrombomodulin and plasminogen activator inhibitor-1 levels were within the normal range in all patients from the two groups, without any significant differences between the groups. The cyclic GMP level was increased after TBI in six of 35 patients. Five of these six patients died as a result of complications of transplantation, while one patient survived in whom the cyclic GMP level rapidly returned to normal. In contrast, the cyclic GMP level remained normal in all patients not receiving TBI. These results suggest that conditioning with TBI stimulates vascular endothelial cells, even if it does not cause immediate direct injury. Such stimulation may be related to vascular endothelial dysfunction, the development of which may be mediated by nitric oxide.     

Immunomodulation of vascular endothelium: induction of Ia antigen expression in rejecting venous allografts

MHC class II antigens (Ia) are important to the primary transplantation response. The present study investigates the kinetics of expression of Ia antigens on endothelial cells of rat vein autografts and allografts. The superficial epigastric veins of 15 ACI rats were anastomosed to the femoral artery of Lewis recipients using standard microsurgical technique. Eighteen Lewis-to-Lewis or ACI-to-ACI autografts served as controls. Veins were studied for Ia expression at 1, 4, and 7 days after grafting using the immunogold electron microscopic technique. All grafts remained patent for the duration of the experiment. Endothelial cells from control grafts did not demonstrate labeling of Ia antigens on their cell surfaces. Similarly, few mononuclear-adventitial cells in control grafts were Ia positive. When endothelial cells from vein allografts were studies for Ia antigen expression, 40% of the endothelial cells showed labeling for Ia at 4 days after transplantation. At 1 week following grafting, endothelial survival was inadequate for study because of cell loss secondary to rejection. In comparison to autografts, rejecting vein allografts showed numerous Ia-positive mononuclear cells permeating the vessel adventitia. Expression of Ia antigens by vascular endothelium may enable these cells to perform tasks traditionally ascribed to monocytes or dendritic cells. Effort to alter Ia expression may suggest an approach to long-term vein allograft survival.     

Meningioma following irradiation for vascular nevus. A case report

A case of meningioma that developed 37 years after irradiation therapy for vascular nevus of the scalp over the right frontoparietal region was reported. A 49-year-old male was admitted to the hospital of Gifu University on October 26, 1979, because of a generalized seizure. He had been born with a vascular nevus affecting the right frontoparietal scalp, for which he began receiving local irradiation at the age of 12. The total dose was not known because the only source of information regarding this treatment was the patient's memory. From the age of 17, the suffered from occasional attacks of dysesthesia in the left side of his body without consciousness disorder. He otherwise remained well for the intervening 37 years. Upon admission, he had a vascular nevus remaining with post irradiation skin changes over the right frontoparietal region. General and neurological examination were not remarkable. Right carotid angiogram and CT scan disclosed the presence of a right frontal tumor. A right frontotemporal craniotomy was performed on December 4, 1979 and a hard tumor was found firmly attached to the dura and bone at the right site. All visible tumor and involved bone were completely removed without difficulty. Histological examination of the surgical specimen showed the characteristic features of a transitional meningioma. There was no evidence of malignancy in the sections examined. Since Mann et al reported a malignant meningioma following irradiation therapy for optic nerve glioma, there have been many reports, over seventy cases of so-called radiation-induced meningioma. However, a meningioma following irradiation therapy for vascular nevus of scalp or face is exceedingly rare.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ultrastructural study of the vascular endothelium of patients with spontaneous rupture of hepatocellular carcinoma

BACKGROUND: Spontaneous rupture of hepatocellular carcinoma (HCC) is common in Asia and Africa, although the mechanism is unclear. In our previous study, we found that vascular injury exemplified by collagenase synthesis and collagen degradation in small arteries was related to the HCC rupture. METHODS: In this study, transmission electron microscopy was used to study 22 specimens from ruptured HCC and non-ruptured HCC. RESULTS: In nine specimens of ruptured HCC, there was evidence of vascular injury with fewer cell junctions and larger fenestrae in vascular endothelial cells. The phenomenon of increased endothelial protein synthesis was also present. In the specimens of non-ruptured HCC, evidence of vascular injury was found in only two cases (p < 0.01). Fewer cell junctions and larger fenestrae could increase the permeability of the vascular wall. Increased protein synthesis in endothelial cells correlates with the phenomenon that more collagenase is expressed in these cells. The resulting breakdown of collagen could render the blood vessels weak; hence, these blood vessels are more prone to splitting/breakage. CONCLUSION: We conclude from our study that this vascular injury may result in HCC rupture.     

Effects of ultraviolet B irradiation on fetal pig islet-like cell clusters

Abstract: Ultraviolet B (UV-B) irradiation of donor islets has previously been shown to result in the prolongation of their survival when transplanted into rodents. This study examined the in vitro and in vivo effects of UV-B irradiation on fetal pig islet-like cell clusters (ICCs), which like adult islets are being transplanted to reverse diabetes. Under control conditions, fetal pig ICCs were able to stimulate both human and pig peripheral blood mononuclear cells (PBMC) in mixed islet lymphocyte culture (MILC). Exposure of the ICCs to UV-B irradiation significantly reduced their ability to stimulate PBMC of both species in MILC when 600 J/m² but not lower doses (300 and 400 J/m²) of irradiation were applied. In contrast, all doses of UV-B irradiation were effective in inhibiting the ability of pig and human PBMC to stimulate human PBMC in a mixed lymphocytes culture (MLC). This demonstrates that UV-B irradiation is effective in reducing xeno immunogenicity of pig antigens. A toxic effect of all doses of UV-B irradiation on ICCs was demonstrated in vitro with a reduction in ³H-thymidine incorporation of 57, 71, 64, and 80% at 150, 300, 450, and 600 J/m², respectively. Toxicity of UV-B irradiation was also demonstrated when treated ICCs were transplanted beneath the renal capsule of SCID mice. The insulin content of the ICCs, 6 weeks after transplantation, was significantly reduced in the 600 J/m² group ( P <0.05). ICCs treated with UV-B irradiation (300 J/m²) in vitro and then transplanted beneath the renal capsule of BALB/c mice were rejected within 2 weeks as were untreated ICCs. Injection of cyclosporine (12.5 mg/kg/day) into these mice did not alter the results. It is concluded that UV-B irradiation is toxic to fetal pig ICCs and, in low dose, unable to prevent their rejection when transplanted into mice.     

同种异体血管移植内膜形态和功能的研究

采用冷冻，干燥和辐照法，制备犬的股动、静脉段后，作异体相应血管移植。观察３２周，移植段均通畅，静脉和动脉植段的内膜，分别于术后１６周和２４周修复完全，组织增生不明显，吻合口无狭窄，内皮细胞结构正常；静脉和动脉移植内膜前列环素的生成量，亦分别于术后１６周和２４周恢复到正常水平，与内膜修复的时间相一致。     

Ultrastructural changes of human dentin after irradiation by Nd:YAG laser

BACKGROUND AND OBJECTIVE: The use of Nd:YAG laser has been proposed for endodontic treatment. However, its ability to reduce dentin permeability, which is important for the success of root canal treatment, remains controversial. STUDY DESIGN/MATERIALS AND METHODS: Nd:YAG laser irradiation was performed in pulsed mode on human dentin. The parameters were: pulse energy (100 mJ), rate (10 pps), and total irradiation time (4 seconds). The crystalline phases, electron diffraction patterns, morphology, and microstructure of specimens after laser irradiation were observed by dark-field emission transmission electron microscope (TEM). RESULTS: Three ultrastructural zones could be delineated in the dentin: (1) an outer zone with an ordered columnar structure composed of hydroxyapatite and beta-tricalcium phosphate, (2) an intermediate zone composed of an amorphous substance (about 40-70 nm in diameter), and (3) an inner zone of well-crystallized hydroxyapatite grains. These three zones were free of pores or voids. CONCLUSIONS: Our study demonstrated that laser-irradiation might be used to reduce dentin permeability.     

Ultrastructural changes of the basilar artery following experimental subarachnoid haemorrhage

Summary Recent experimental studies have shown, that the endothelium of cerebral vessels undergoes significant changes after subarachnoid haemorrhage which may lead to biochemical changes at the endothelial surface with disturbance of the delicate homeostasis of vasodilating and vasoconstricting mechanisms which are thought to be responsible for preservation of the tones of the cerebral vasculature. Ultrastructural studies incorporating different forms of microscopic observations of the endothelium after SAH representing a prerequisite for further investigations on the pathogenesis of cerebral vasospasm are scarce. This experimental study was performed in order to investigate and define more precisely the pathomorphological changes at the endothelial surface of the basilar artery of dogs after experimental SAH.Two separate injections of autologous blood into the cisterna magna within 72 hours resulted in extensive angiographic narrowing of the diameter of the basilar artery of all animals. Histological studies of the basilar artery including light microscopic, transmission electron microscopic, scanning electron microscopic and freeze cracking microscopic examinations demonstrated severe pathomorphological changes at the endothelial surface. These consisted mainly of infolding and corrugation of the endothelium, disorientation and desquamation of endothelial cells as well as of vacuolation and ingrowth of fibrous tissue between the endothelial and muscular layer. No pathomorphological changes could be observed in the muscular layer.As the described post-haemorrhagic ultrastructural changes of the endothelium of cerebral vessels in spasm are likely to represent the morphological basis of the delayed form of cerebral vasospasm future research on its pathogenesis should primarily focus on the structural and biochemical changes taking place at the endothelial surface of the cerebral vasculature after SAH.     

The use of arm veins for infrainguinal bypass in end-stage peripheral vascular disease

Thirty-six infrainguinal bypass grafts were performed in 33 patients with the use of autologous arm vein. Indications for operation were ischemic rest pain or tissue loss in all patients. The average age of the patients was 70.0 years-27% were diabetic and 66% were smokers. Sixty-five percent of the grafts were performed as secondary reconstructions. Follow-up ranged from three weeks to six years, with a mean of 12.1 months. Life-table primary and secondary patencies for all grafts are 73% and 82% at one year, respectively. Simple (noncomposite) arm vein grafts had primary and secondary patencies of 75% and 85%, respectively. The limb salvage rate was 86%. No grafts required thrombectomy for early occlusion (less than 30 days), and no graft failures have occurred beyond nine months (n = 18). Arm vein bypass grafts demonstrate excellent patency rates and provide the preferred conduit in the absence of autologous saphenous vein.     

Ultrastructural changes in pneumocyte type II cells following traumatic brain injury in rats.

OBJECTIVE: We aimed to demonstrate the time-dependent ultrastructural changes in pneumocyte type II cells following brain injury, and to propose an electron microscopic scoring model for the damage. METHODS: Forty Wistar-Albino female rats weighing 170-200 g were used. The rats were allocated into five groups. The first group was the control and the second was the craniotomy without trauma. The others were trauma groups. Weight-drop method was used for achieving head trauma. Samples were obtained from the right and left pulmonary lobes at 2-, 8-, and 24-h intervals after transcardiac perfusion. An electron microscopic scoring model was used to reveal the changes. RESULTS: There were no ultrastructural pathological findings pointing to lung injury in any rat of the control groups. There was intense intracellular oedema in type II pneumocyte and interstitial oedema in the adjacent tissue in trauma groups. Oedema in mitochondria and dilatation in both smooth endoplasmic reticulum and Golgi apparatus was more evident in the 8- and 24-h trauma groups. The chromatin dispersion was disintegrated in the nucleus in all trauma groups. Scores of all trauma groups were significantly different from the controls (P<0.05). All trauma groups were different from each other at significant levels (P<0.05 for each trauma groups). CONCLUSIONS: The data suggested that ultrastructural damage is obvious at 2 h and deteriorates with time. The electron microscopic scoring model worked well in depicting the traumatic changes, which were supported by lipid peroxidation. Further experiments are needed to determine the exact outcome after brain death model.     

Ultrastructural changes of bladder cancer cells following methylene blue-sensitized photodynamic treatment

The cytotoxic efficacy of methylene blue-sensitized photoinactivation of bladder cancer cells has been proved in vitro and in vivo in our previous work. The ultrastructural changes of MBT-2 murine bladder cancer cells following methylene blue-sensitized phototherapy have been evaluated by scanning and transmission electron microscopy. MBT-2 cells were pretreated with 0.1% methylene blue, and then exposed to ordinary light for different durations from 1 to 60 min. Both electron microscopic examinations showed that changes in tumor cells occurred at 5 min of illumination with fenestration and minipore formation on the cell membrane and mitochondrial disintegration. At 30 min, cleavage and cracking of the cell membrane with ribosomal lysis were noted. Finally, fragmentation with decomposition of the membrane and chromosomal condensation and lysis resulted at 60 min. This study showed that the cytotoxic effect induced by methylene blue phototherapy is initiated in the cell membrane and intracellular mitochondria in the early phase.     

Fibrinolytic activator in the endothelium of the veins of the lower limb.

The local fibrinolytic acitivity of the femoral, popliteal and soleal veins has been studied using a histochemical technique. The results suggest that the fibrinolytic activity in the soleal veins may be low when compared with that in the femoral and popliteal veins. This may be an aetiological factor responsible for the high incidence of thrombi occurring in the soleal veins.