Endothelial cell proliferation associated with lesions of murine systemic candidiasis.

Neovascularization is associated with tumor growth and some inflammatory diseases but has not been reported to be induced by infectious agents. In a mouse model of systemic Candida albicans infection, extensive endothelial cell proliferation was seen in the periphery of brain abscesses and in the areas of fungal pyelonephritis in the kidney. This finding is important for an understanding of the pathogenesis of fungal infections and may contribute to an analysis of the mechanisms of angiogenesis.     

Oval cell proliferation and the origin of small hepatocytes in liver injury induced by D-galactosamine.

Oval cells may function as facultative liver stem cells and tumor progenitors in liver carcinogenesis. The authors determined whether oval cells proliferate and if small hepatocytes might be generated from epithelial cell progenitors in noncarcinogenic liver injury. The authors found that oval cells similar to those detected in early carcinogenesis proliferate in response to D-galactosamine (GaIN). Oval cells expressed gamma-glutamyl transpeptidase activity, bile duct-type cytokeratins and peanut agglutinin binding. Two unusual types of hepatocytes also appeared after injury: small hepatocytes (less than or equal to 16 microns in diameter) and hepatocytes lining atypical ductlike structures. In situ hybridization studies showed that the fetal form of alphafetoprotein mRNA was expressed by many oval cells, some bile duct cells, and occasional hepatocytes. By following the fate of epithelial cells labeled early after GaIN administration, the authors conclude that duct cells can generate both oval cells and small hepatocytes in response to GaIN.     

Oval cell proliferation in early stages of hepatocarcinogenesis in simian virus 40 large T transgenic mice.

In transgenic mice bearing the Simian Virus 40 large T antigen under the control of the human antithrombin III regulatory sequences, a stepwise progression toward hepatocellular carcinoma is observed. We have used two monoclonal antibodies (A6 and G7) developed against a surface antigen expressed in oval cells from dipin-treated mice, to analyze the emergence of such preneoplastic populations in the livers of antithrombin III Simian Virus 40 T transgenic mice. We show that a unique population of small heterogeneous epithelial cells, which probably corresponds to oval and/or transitional cells according to their morphological features, consistently appears at approximately the 10th week after birth and proliferates thereafter. This oval cell-like population stained positively for A6 and G7 monoclonal antibodies. Furthermore, different subpopulations usually recognized as possible precursors of carcinoma cells including hyperplastic foci and neoplastic nodules as well as carcinoma cells, were also positive for A6 but not G7 monoclonal antibodies. Stimulation of cell proliferation by partial hepatectomy performed at the time of emergence of the oval-like cells resulted in a rapid increase in the number of oval/transitional A6-positive cells. Our findings support the view that a common mechanism may be involved in the development of carcinomas that are induced by chemical carcinogens and in transgenic mice expressing a potent oncogene under the control of a hepatic specific promoter. In addition, our findings demonstrate a specific precursor-product relationship between the appearance of the oval/transitional cells and the development of neoplastic hepatocytes in this transgenic model.     

A simple reliable system for studying antigen-specific murine T cell proliferation.

Antigen-specific T cell proliferation can be readily elicited from the popliteal lymph node cells of mice which have received immunizations of antigen in the hind footpads. The advantages of our system over other published methods are (i) simplicity in method and materials, (ii) much improved reproducibility, (iii) negligible concomitant B cell proliferation, (iv) large degrees of antigen specific proliferation with very low background, and (v) complete dependence of the response on accessory cells or macrophages. These results were brought about by proper immunization procedures for mice and judicious choice of culture conditions. Our data show that the system is very suitable for the study of macrophage-T cell interaction in the induction of T cell proliferation as well as the genetic basis of responsiveness or non-responsiveness to protein and polypeptide antigens.     

Stimulation of the DNA replication and murine bone marrow cell proliferation with exogenous zinc-metallothionein

It is shown that zinc-metallothionein from rat liver increases 1.5-fold thein vitro incorporation of³H-thymidine in murine bone marrow cells. The same concentrations of zinc chloride and a mixture imitating zinc-metallothionein (zinc, cysteine, and albumin) inhibit DNA synthesis. In mice receiving an intraperitoneal injection of zinc-metallothionein 10–15 min before γ-irradiation, the incorporation of³H-thymidine and the content of nucleated cells in the bone marrow is 1.5- to 2-fold higher than those in unprotected animals, the number of endogenous splenic colonies in pretreated mice being 2.7-fold higher. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 11, pp. 505–508, November, 1996     

Cell surface changes associated with mutation of visna virus in antibody-treated cell cultures.

Sheep cells inoculated with a portion of a plaque suspension of visna virus developed acute cytopathic changes and produced progeny virus which was antigenically identical to the parental strain. In contrast, cultures inoculated with other portions of the same suspension and maintained in medium containing specific viral antiserum developed cytopathic changes more slowly and yielded genetically stable mutant strains of virus which were poorly neutralized by the same antiserum. Scanning and transmission electron microscopy showed that, in the absence of antibody, cell surfaces of infected cells were covered diffusely with viral buds, whereas in the presence of antibody, viral buds were often grouped in caps and progressive aggregation of released virus occurred. Viral aggregates were strongly anchored to viral buds or long villi and sometimes became engulfed by infected cells. In addition, single maturing virions were continuously detected close to large aggregates. These morphological events suggest that selective replication of mutant virus in antibody-treated cells is favored by (1) elimination of parental virus through aggregation and endocytosis and (2) patching and capping of viral buds, which leave free cell surface areas for maturation of mutant virus.     

Sustained cell proliferation of renal epithelial cells in mice with inv mutation

A tubule system is an important component of the nephron, which is the structural and functional unit of the kidney. Expansion of renal tubules results in renal cysts. Hereditary forms of renal cystic diseases suggest that tubular size is determined genetically. The inv was discovered as a mutant with renal cysts and situs inversus. Inv/inv, inv deltaC::GFP (inv deltaC) mouse was created by the introduction of the inv gene lacking the C-terminus (inv deltaC) into inv/inv mice. The mouse develops multiple renal cysts without situs abnormality, giving us an opportunity to study inv function in renal tubular structure maintenance. In the present study, we showed that inv suppresses cyst progression in a dose-dependent manner and that the inv deltaC cystic kidneys showed increased cell proliferation and apoptosis. Cell cycle regulators for G1-S progression were activated in the cystic kidney. Furthermore, cDNA microarray and semiquantitative RT-PCR analysis showed that growth-related genes maintained a high level of expression in the cystic kidney at 4 weeks of age whereas they were decreased in control kidneys, suggesting that cells in inv deltaC kidney are still active in the cell cycle. One of the inv protein functions may provide a stop signal for renal epithelial cell proliferation.     

Normal immunosuppressive protein inhibition of human and murine lymphoblastoid cell line proliferation.

Normal immunosuppressive protein, prepared from human plasma by DEAE-cellulose chromatography, inhibits DNA synthesis in human cell lines of lymphocytes of both T and B origin. It also inhibits [3H]thymidine incorporation in mouse cell lines. Normal immunosuppressive protein was able to inhibit the proliferation of these cells, although they were already transformed and had a high rate of DNA synthesis. On the other hand, it does not inhibit myeloid cells or fibroblasts.     

T细胞稳态增殖与自身免疫

近年有关外周T细胞群体存活与稳态的深入研究发现：抗原活化前T细胞的存活需要自身肽-删c复合物的作用以提供适度的存活信号；在淋巴细胞急剧减少的状态下，T细胞一样通过与自身肽-MHC复合物的作用发生稳态增殖以恢复T细胞群体的正常规模，这种增殖后的T细胞具显著的自身反应性且兼具效应与记忆T细胞的功能。稳态增殖后的T细胞可能参与自身免疫疾病的发生；与此同时，稳态增殖的这种特性也可用来激发特异的抗肿瘤免疫，特别针对异常高表达的非突变肿瘤抗原或肿瘤相关抗原的自身免疫。     

Multifocal intrafollicular granulosa cell tumor of the ovary associated with an unusual germline p53 mutation.

A 23-year-old woman presented with a 7 cm right multicystic mass in the ovary, which corresponded microscopically to an unusual lesion consisting of a multifocal granulosa cell tumor with intrafollicular ('in situ') growth involving two-thirds of mature follicles. Stromal invasion was found in only one area where neoplastic follicles coalesced. Granulosa cells had atypical, bizarre TP53 positive nuclei with hyperchromatism, abundant mitoses and numerous hyaline globules. The contralateral ovary was normal. From the age of 10 years, the patient had a complex medical history of multiple tumors, including telangiectatic osteosarcoma, typical and malignant phyllodes tumor, reticulohistiocytoma of skin, carcinomas of the breast and lipo- and leiomyosarcoma. The female genital tract also harbored myometrial leiomyomas and an early endometrial carcinoma. Retrospective histologic study of all mesenchymal neoplasms in this patient showed, the conspicuous presence of similar bizarre TP53 positive cells with hyaline globules in all the mesenchymal neoplasms. In the genetic study, a germline p53 gene mutation was detected in exon 10, codon 336, generating a stop codon in the oligomerization domain of the protein (E336X). A further p53 mutation was found in exon 7 in the granulosa cell tumor. Mutation occurred de novo since there was no history of tumors in any family members, all of whom had a wild-type p53. Although this patient shows a typical tumor phenotype of Li Fraumeni syndrome, the germline mutation corresponded to a highly unusual mutated domain, which is similar to the one found in childhood malignant adrenocortical tumor; also a rare neoplasm that originates in adrenocortical cells; which are closely related, both functionally and embryologically, to granulosa cells.     

Apoptosis and proliferation in the neonatal murine heart.

The spatial and temporal patterns of apoptosis and proliferation in timed fetal, neonatal, and adult murine hearts have been determined using an in situ end-labeling technique for detecting fragmented DNA, and bromodeoxyuridine immunofluorescence as a marker for DNA synthesis. Also, cardiac expression of apoptosis-related proteins was assessed by immunofluorescence. Prominent apoptotic labeling was found in the right ventricular subendocardium and the basal septum in the area of the developing conduction system. In the right ventricle, apoptotic labeling surged late in the first day postpartum, then declined to levels similar to the left ventricle by postpartum day 8.5. Apoptotic labeling at the basal septum was greatest peripartum and gradually declined to levels seen in the rest of the heart by postpartum day 8.5. Cessation of proliferation did not occur simultaneously throughout the neonatal heart. Through postpartum day 4.5, incorporation of BrdU was greater in the left ventricle than in the right ventricle, particularly in the subendocardium. Bax and Fas, proapoptotic proteins, were detected homogeneously throughout both ventricles in the neonate, while Bcl-2, an antiapoptotic protein, was not detectable. These data suggest that postnatal cardiac remodeling results from changes in both apoptosis and proliferation. Furthermore, the temporal and spatial pattern of these processes, coincident with the hemodynamic changes associated with parturition, suggests that both processes may be regulated by mechanical factors.     

Cell surface and cell cycle analysis of metal-induced murine T cell proliferation

The heavy metal cations Pb2+, Ni2+ and Zn2+ have previously been shown to induce T cell proliferation which required the presence of both T cells and Ia+ cells at the initiation of culture. This work has examined the ability of these metals to induce cell cycle entry as determined by acridine orange cell cycle analysis. Cell surface phenotype analysis, performed on splenocytes stimulated with optimum metal concentrations (100 microM), indicated that in vitro T cell recovery (growth and/or longevity) was enhanced by Pb2+, Ni2+, and Zn2+. Furthermore, simultaneous examination of cell surface phenotype and cell cycle progression (propidium iodide) indicated that the predominant cell type proliferating in response to these metals was Thy-1.2+. The metals differentially induced L3T4+ and Lyt-2+ cells to enter the cell cycle. The ability of various monoclonal antibodies to modulate metal-induced proliferation was examined. Anti-L3T4a, anti-I-A and anti-I-E blocked metal-induced proliferation. Anti-Lyt-2 only partially inhibited whereas anti-Lyt-1 was stimulatory. These results suggest that recognition of major histocompatibility complex-encoded class II molecules is required for the induction of proliferation by these metals (similar to the autologous mixed lymphocyte response).     

Atypical melanocytic proliferation associated with squamous cell carcinoma in situ of the esophagus

We present the case of a 64-year-old woman who underwent a transhiatal esophagectomy subsequent to the presence of high-grade dysplasia of the esophageal squamous epithelium in repeated biopsies. In the resection specimen chronic esophagitis and multifocal carcinoma in situ of the squamous epithelium were diagnosed, associated with a diffuse intraepithelial proliferation of melanocytic cells. While melanocytic hyperplasia (melanocytosis) has previously been recognized as an occasional reactive lesion that can accompany esophageal inflammation and invasive squamous carcinoma, the present case was unusual because of its cytonuclear and architectural atypia in the melanocytic cell population, resembling features of a melanoma in situ in the absence of manifest invasive malignant melanoma. The disappearance of the melanocytic lesion during follow-up supports its nonneoplastic nature, however. This case illustrates that ’malignant features’ in esophageal melanocytosis should be interpreted with caution. Received: 10 December 1999 / Accepted: 6 March 2000     

Effects on murine T helper cell proliferation by DTH activated syngeneic epidermal cells.

Epidermal cells, obtained either from the site of a delayed type of hypersensitivity (DTH) reaction to 2,4-dinitro-1-fluorobenzene (DNFB) or from skin subjected only to painting with acetone: olive oil have been studied for their capacity to stimulate antigen specific T-lymphocyte proliferation. Small numbers of cells from the control, as well as from the DTH activated epidermis, presented collagen type II to a line of and a clone of collagen II specific T helper cells. Larger numbers of epidermal cells from DTH activated epidermis suppressed this T-cell proliferation compared to control epidermal cells. Phenotypic analysis showed an increased expression of Thy-1 antigen on epidermal cells from DTH lesions 3 days after provocation. It is suggested that epidermal cells may be involved in negative as well as positive feedback loops in conjunction with T-cell immunity. It would thus be of interest to study further whether the induced Thy-1 antigen expression on epidermal cells is of importance in a negative feedback system.     

Myofibroblast and endothelial cell proliferation during murine myocardial infarct repair

Granulation tissue formation is a critical step in infarct repair, however, the kinetics of cell replication and the molecules that regulate this process are poorly understood. In uninjured mouse hearts and at 2 days post-infarction, very little DNA synthesis (measured by incorporation of a BrdU pulse) was detected in any cell type. Four days after permanent coronary occlusion, the rates of myofibroblast (smooth muscle alpha-actin and BrdU double-positive) and endothelial cell (CD31 and BrdU double-positive) proliferation were 15.4 +/- 1.1% and 2.9 +/- 0.5%, respectively. Most proliferating cells were located at the interface of the infarct and viable tissue. By 1 week, fibroblast and endothelial cell proliferation declined to 4.1 +/- 0.6% and 0.7 +/- 0.1%, respectively. In the 2-week infarct, the remaining necrosis had been phagocytosed, and fibroblast and endothelial cell proliferation were <0.5%. Although leukocytes were abundant throughout infarct repair, no significant proliferation was detected at any time in cells expressing CD45 or mac-3. Infarct size at 4 days was 38 +/- 5% of the left ventricle and contracted to 20 +/- 4% by 4 weeks. After 4 days, the chamber dilated to four times that of the control hearts and remained so for the duration of the time course. The vascular density (per mm(2)) declined from 3643 +/- 82 in control hearts to 2716 +/- 197 at 1 week and 1010 +/- 47 at 4 weeks post-myocardial infarction (MI). The average percent area occupied by vessels did not change significantly between the groups but the area/vessel ( micro m(2)) increased from 14.1 +/- 0.3 in control hearts to 16.9 +/- 1.9 at 1 week and 38.7 +/- 7.9 at 4 weeks post-MI. These data indicate that mitogens for fibroblasts and endothelial cells peak within 4 days of infarction in the mouse heart. This provides the basis for identifying the responsible molecules and developing strategies to alter wound repair and improve cardiac function.