Degree Of Tissue Differentiation Research Articles

Prognostic analysis of hepatocellular carcinoma on the background of liver cirrhosis via contrast-enhanced ultrasound and pathology.

The aim of this study was to analyze the correlation between the quantitative parameters of contrast-enhancement ultrasound for primary hepatocellular carcinoma (HCC) and biological manifestations of tumor (Ki-67), and to explore the related risk factors of primary hepatocellular carcinoma, so as to provide the theoretical basis for the further study on contrast-enhancement ultrasound manifestations, clinical features and prognosis of HCC. The patients with HCC confirmed by operation or puncture were collected, and those with the background of liver cirrhosis and immunohistochemical staining for tumor sample sections were selected. H&E staining sections of pathological tissues of tumor samples were observed, whether there was any microvessel invasion (MVI) was recorded, the microvessel density (MVD) was counted and the recurrence situations after liver cancer operation was followed up. The change in size of tumor at arterial phase in contrast-enhancement ultrasound, enhancement mode and form at arterial phase, and whether there were tortuous vessels inside or not, and the enhancement intensity, extinction time and extinction intensity at portal phase were observed. The relationship between the parameters of contrast-enhancement ultrasound and Ki-67, AFP, MVD, MVI, tissue differentiation degree of tumor samples and recurrence was analyzed. Under the background of liver cirrhosis, there were significant differences in different enhancement modes and quantification parameters of contrast-enhancement ultrasound for HCC with different expression of Ki-67. Those with obvious tumor enlargement, inhomogeneous enhancement at arterial phase and irregular enhancement form at arterial phase after contrast-enhancement ultrasound had a high incidence of positive Ki-67 and a high early recurrence rate. The inhomogeneous enhancement at arterial phase might predict the proliferative activity and recurrence time of tumor cells; irregular enhancement form at arterial phase might indicate tumor MVI; and the low enhancement of tumor at portal phase may predict a lower degree of tissue differentiation, a higher tumor malignancy and poor prognosis. The incidence of positive Ki-67 under the background of liver cirrhosis is high, indicating poor prognosis. The enhancement mode and parameters of contrast-enhancement ultrasound for HCC may help evaluate the clinical biological manifestations of HCC and predict the postoperative recurrence of HCC.

Degree of Tissue Differentiation Dictates Susceptibility to BRAF-Driven Colorectal Cancer

Oncogenic mutations in BRAF are believed to initiate serrated colorectal cancers; however, the mechanisms of BRAF-driven colon cancer are unclear. We find that oncogenic BRAF paradoxically suppresses stem cell renewal and instead promotes differentiation. Correspondingly, tumor formation is inefficient in BRAF-driven mouse models of colon cancer. By reducing levels of differentiation via genetic manipulation of either of two distinct differentiation-promoting factors (Smad4 or Cdx2), stem cell activity isrestored in BRAFV600E intestines, and the oncogenic capacity of BRAFV600E is amplified. In human patients, we observe that reduced levels of differentiation in normal tissue is associated with increased susceptibility to serrated colon tumors. Together, these findings help resolve the conditions necessary for BRAF-driven colon cancer initiation. Additionally, our results predict that genetic and/or environmental factors that reduce tissue differentiation will increasesusceptibility to serrated colon cancer. These findings offer an opportunity to identify susceptible individuals by assessing their tissue-differentiation status.

Expression of Slug gene and E-cadherin gene in human hepatocellular carcinoma and its relationship with the clinicopathological features of hepatocellular carcinoma

Objective To investigate the expression of Slug gene and E-cadherin gene in hepatocellular carcinoma (HCC) and its relationship with the clinicopathological characteristics of HCC. Methods Immunohistochemical and reverse transcriptase-polymerase chain reaction (RT-PCR) methods were performed to detect the expression of Slug and E-cadherin proteins, and Slug and E-cadherin mRNA in 50 cases of HCC tissues and adjacent tissues. Results (1) The expression of Slug protein (64.0%) and Slug mRNA (0.560±0.030) in HCC was significantly higher than that in paracancerous tissues (12.0% and 0.230±0.020, P<0.05). The expression of E-cadherin (42.0%) and E-cadherin mRNA (0.144±0.018) in HCC tissues was significantly lower than that in paracancerous tissues (92.0% and 0.319±0.043, P<0.05). (2) The expression level of Slug protein in HCC tissues was related to the differentiation degree (P<0.05), tumor diameter (P<0.05), tumor pathological stage (P<0.05), portal vein invasion (P<0.05) and the expression level of alpha fetal protein (AFP, P<0.05). The expression level of E-cadherin in HCC tissues was also related to the degree of tumor differentiation (P<0.05), tumor diameter (P<0.05), tumor pathological stage (P<0.05), portal vein invasion (P<0.05) and the expression level of AFP (P<0.05). (3) Slug protein expression was negatively correlated with E-cadherin expression in HCC tissues (r=0.478, P<0.05). Conclusion The high expression of Slug and E-cadherin proteins in HCC tissues suggest that they may have a certain role in the occurrence and development of HCC. The levels of Slug and E-cadherin proteins have relationships with the HCC stage, the degree of tissue differentiation, the diameter of tumor and the expression level of AFP. Key words: Carcinoma, hepatocellular; Slug; E-cadherin; Immunohistochemistry; Reverse transcription-polymerase chain reaction

Expression of Cullin7 in breast invasive ductal carcinoma and its clinical significance

Objective To explore the expression of Cullin7 protein in breast invasive ductal carcinoma and its relationship with the clinicopathological factors.Methods The expression of Cullin7 protein was detected in 13 cases of normal breast tissues,20 cases of benign breast tumor,68 cases of breast cancer and 32 cases of axillary lymph node metastasis of breast cancer tissue samples by immunohistochemical streptavid-in-peroxidase (SP) method.Results The positive expression rate of Cullin7 in normal breast tissue,benign breast tumor,breast invasive ductal carcinoma and axillary lymph node metastases of breast cancer was 0,30.0％,55.9％,and 78.1％ respectively.The positive expression rate of Cullin7 in the axillary lymph node metastases of breast cancer was significantly higher than the other three kinds of tissue samples (P ＜ 0.05).Cullin7 protein expression had no obvious correlation with the menopausal status,tumor size,clinical stage or pathological type P ＞ 0.05),but had a significant correlation with tissue differentiation degree and axillary lymph node metastasis (P ＜ 0.05).Cullin7 protein expression in breast cancer tissue was significantly negatively correlated with estrogen receptor (ER,P ＜ 0.05),but not with progesterone receptor (PR),and human epidermalgrowth factor receptor-2 (Her-2,P ＞ 0.05).Conclusion Cullin7 may play an important role in the development,invasion and metastasis of breast cancer. Key words: Breast carcinoma ; Transfer; Cullin7

Exploration of the Mechanism of Colorectal Cancer Early Metastasis Based on Differential Expression Gene

Colorectal cancer is a common malignant tumor of digestive tract. Tumor metastasis is the leading cause of death in colorectal cancer patients. Clarifying the key genes in the early colorectal cancer metastasis-associated molecular events has great significance for diagnosis and treatment of colorectal cancer. From the colorectal cancer gene expression profile data, we screen the differentially expressed genes and use real-time PCR to prove the screened result. We analyze the key role of differentially expressed genes in the early metastasis of colorectal cancer. Through the above research, 16 differentially expressed genes which are related to the early metastasis of colorectal cancer are screened. Nine genes among them have up-regulated expression. They are VSNL1 , PSAT1 , KIAA1199 , ABHD7 , MMP7 , JUB , CLDN1 , KRT23 , and FOXQ1 . Seven genes among them have down-regulated expression. They are SFRP1 , SLC4A4 , CHGA , GCG , GUCA2B , CLDN8 , and CD177 . It is found that some genes are related to tissue differentiation degree, such as PSAT1 and JUB, and some genes are related to the tumor stage, such as VSNL1 and MMP7 . We find VSNL1 , PSAT1 , CLDN1 , SLC4A4 , and GCG are conservative genes among the differentially expressed genes. In conclusion, the nine up-regulated differential expression genes and seven down-regulated differential expression genes may play important roles in the molecular mechanism of colorectal cancer metastasis. Because their specificities are high in colorectal cancer, they may become the molecular signatures for the combined diagnosis.

Relevance of tumor angiogenesis in occurrence and development of breast cancer

To detect the differential expression of vascular endothelial growth factor (VEGF) and microvessel density (MVD) count in benign and malignant breast lesions to clarify the correlation of VEGF expression with the occurrence and progression of breast cancer and angiogenesis. Immunohistochemistry (SP method) was used to examine the expression of VEGF and MVD count in 88 intra-operatively harvested samples of invasive ductal breast carcinoma, 25 samples of breast carcinoma in situ, 15 samples of atypical breast hyperplasia and 100 samples of benign breast lesions obtained. The positive rate of VEGF in invasive ductal breast carcinoma group was 70.5% and it was significantly higher than those of benign breast lesions, atypical breast hyperplasia and breast carcinoma in situ groups ( 22.0%, 33.3% and 56.0% respectively, P = 0.000). The positive rate of VEGF with lymph node metastasis was higher than that without lymph node metastasis (P = 0.015). The positive rate of VEGF in Stages II b- III was higher than that in Stages I - II a (P = 0.006). The positive rate of VEGF in C-erbB-2 positive group was higher than that in C-erbB-2 negative group (P = 0.016). An elevated expression of VEGF was observed as the tissue differentiation degree increased (P = 0.017). The MVD value of invasive ductal breast carcinoma group was 23 +/- 15 and it was significantly higher than those of benign breast lesions, atypical breast hyperplasia and breast carcinoma in situ groups (14 +/- 4, 18 +/- 4 and 20 +/- 6 respectively, P = 0.000). In invasive ductal breast carcinoma group, a significant higher MVD value was observed as the tissue differentiation degree increased (P = 0.006). The MVD value in VEGF positive group was higher than that in VEGF negative group (P = 0.000). In invasive ductal breast carcinoma, the MVD count increased significantly with the elevated expression of VEGF (P = 0.000). In invasive ductal breast carcinoma, angiogenesis and metastasis are mediated mainly by VEGF. The expressions of VEGF and MVD may be two of reference predictors for biological behaviors of breast carcinoma The occurrence and progression of breast cancer might be correlated with the expression of VEGF. The VEGF-targeting antiangiogenic therapy is expected to become a new therapeutic modality for C-erbB-2 positive patients.

Tissue specific response of Agrobacterium tumefaciens attachment to Sorghum bicolor (L) Moench

Agrobacterium mediated genetic transformation of plants have advantages over other methods, especially for making single copy transgenic plants with reduced chances of gene silencing and instability. However, monocotyledonous plant species could not utilize the full potential of this system because of possible limitations in Agrobacterium interaction with monocot plant cells. Agrobacterium attachment as a factor in genetic transformation was studied in the leaf, shoot apex, and leaf derived callus of sorghum (Sorghum bicolor (L) Moench). Pre-induction of Agrobacterium with acetosyringone was found necessary for Agrobacterium attachment to sorghum tissues. All the explants responded positively, with preferential Agrobacterium attachment and colonization around the tissues having actively dividing cells. Callus proved to be the best explant for Agrobacterium attachment as observed in scanning electron microscopy and transient GUS expression. Loss of Agrobacterium attachment was observed with an increase in the degree of tissue differentiation.

Vascular endothelial growth factor expression in invasive ductal carcinoma of breast

To detect the expression of VEGF and MVD count in invasive ductal carcinoma of breast to clarify the association of VEGF expression and MVD count with the clinicopathologic features. The expressions of VEGF, ER, PR, C-erbB-2 and MVD count in 88 cases of invasive ductal carcinoma of breast were examined by immunohistochemistry staining (SP-method). Sixty-two out of the eighty-eight specimens of breast carcinoma (70.45%) showed positive expression of VEGF. The positive rate of VEGF in cases with lymph node metastasis was higher than that without lymph node metastasis (P<0.05). The positive rate of VEGF in stage IIb-III was higher than that in stage I-IIa (P<0.05). The positive rate of VEGF in C-erbB-2 positive group was higher than that in C-erbB-2 negative group (P<0.05). Higher expression of VEGF was observed in cases with higher tissue differentiation degree (P<0.05). Also, significant higher MVD count was observed in cases with higher tissue differentiation degree (P<0.01). The MVD count increased significantly with the increase of the expression of VEGF (P<0.01). The result of this study suggested that in invasive ductal carcinoma of breast, angiogenesis and metastasis were mediated mainly by VEGF. The expression of VEGF and MVD might be reference predictors for the biological behavior of breast carcinoma. The antiangiogenic therapy which used VEGF as a target would become a new method to treat patients who were C-erbB-2 positive in the future.

Diversity in the distribution of polysaccharide and glycoprotein epitopes in the cell walls of bryophytes: new evidence for the multiple evolution of water-conducting cells.

• Although histologically much simpler than higher plants, bryophytes display a considerable degree of tissue differentiation, notably in those groups that possess an internal system of specialized water-conducting cells (WCCs). Here, using a battery of monoclonal antibodies, we examined the distribution of cell wall polysaccharide and glycoprotein carbohydrate epitopes in the gametophyte of four hepatics and eight mosses, with special reference to water-conducting cells. • CCRC-M7, an antibody against an arabinogalactan epitope, gave a highly consistent and generally specific labelling of WCCs; more variable results were obtained with other antibodies. The labelling patterns indicate that bryophytes exhibit cell and tissue complexity with respect to cell wall components on a par with higher plants. • A remarkable diversity in the immunocytochemical characteristics of WCCs was observed not only when comparing major bryophyte groups but also within the relatively small and well-circumscribed moss order Polytrichales, indicating that the cell wall biochemistry of WCCs may have been finely tuned in response to specific evolutionary pressures. The immunocytochemical data strengthen the notion that the WCCs in Takakia are not homologous with the hydroids of other mosses nor with the WCCs in Haplomitrium and metzgerialean liverworts. • The presence of several carbohydrate epitopes in hydroid walls runs strongly counter to the notion that their maturation involves hydrolysis of noncellulosic polysaccharides.

McManus, M.T. and Veit, B.E. eds. Meristematic tissues in plant growth and development

McManus, M.T. and Veit, B.E. eds. Meristematic tissues in plant growth and development

Magnetic resonance imaging of congenital, inflammatory, and infectious soft-tissue lesions in children.

Magnetic resonance imaging has the advantages of multiplanar capability and high degree of tissue differentiation. It is useful for assessing the extent of soft-tissue abnormalities, such as vascular malformations, inflammatory and infectious processes, muscle disorders, and limb hypertrophy. Magnetic resonance imaging is sensitive to the presence of water and edema and is a good indicator for early diagnosis of inflammation and its level of activity. Fat-saturation techniques, including T2-weighted sequences and inversion recovery imaging, optimize diagnostic accuracy. T1-weighted images are good at defining the distribution and proportion of fat in the body, so they are useful in evaluating syndromes of the limbs, including vascular malformations, as well as lipoatrophy-lipodystrophy conditions. Magnetic resonance imaging provides guidance for efficient tissue biopsy. It allows comprehensive pretherapeutic assessment of soft-tissue vascular anomalies. It constitutes a good modality for following up the natural history of soft-tissue disorders during childhood.

The fungicide propiconazole interferes with embryonic development of the crustacean Daphnia magna

AbstractPropiconazole is a fungicide used in a variety of agricultural applications. Preliminary studies had suggested that embryos of the crustacean Daphnia magna are particularly susceptible to the toxicity of this chemical. The goals of the present study were to define endpoints of daphnid embryonic development that could be routinely used to assess the embryo toxicity of chemicals and to characterize definitively the embryo toxicity of propiconazole to daphnids. Daphnid embryonic development was characterized into six readily distinguishable stages based on the degree of tissue differentiation. Embryonic development could be monitored either in the brood chamber of the maternal organism or using embryos removed from the brood chamber and incubated ex vivo. Standard toxicity assessment revealed that propiconazole elicited no significant adverse effects on daphnid survival or fecundity during a 21‐d exposure to concentrations as high as 0.25 mg/L. Exposure to 0.25 mg/L propiconazole, however, caused a significant incidence of developmental abnormalities and embryonic death. Abnormalities were consistent with developmental arrest at later stages of embryonic maturation. Propiconazole elicited a steep concentration‐response curve with respect to embryo toxicity, with a 10% and a 90% incidence of embryo toxicity measured at 0.50 and 0.82 mg/L, respectively. Direct exposure of embryos to propiconazole resulted in toxicity, though the incidence and characteristics of developmental abnormalities were not consistent with that observed during chronic exposures. However, maternal exposure to propiconazole followed by transfer of early embryos to propiconazole‐free media resulted in embryo toxicity consistent with that observed during chronic exposure. These results indicate that propiconazole interferes with the later stages of daphnid embryonic development, and that this toxicity is manifested largely via maternal exposure to the fungicide.

The fungicide propiconazole interferes with embryonic development of the crustacean Daphnia magna.

Propiconazole is a fungicide used in a variety of agricultural applications. Preliminary studies had suggested that embryos of the crustacean Daphnia magna are particularly susceptible to the toxicity of this chemical. The goals of the present study were to define endpoints of daphnid embryonic development that could be routinely used to assess the embryo toxicity of chemicals and to characterize definitively the embryo toxicity of propiconazole to daphnids. Daphnid embryonic development was characterized into six readily distinguishable stages based on the degree of tissue differentiation. Embryonic development could be monitored either in the brood chamber of the maternal organism or using embryos removed from the brood chamber and incubated ex vivo. Standard toxicity assessment revealed that propiconazole elicited no significant adverse effects on daphnid survival or fecundity during a 21-d exposure to concentrations as high as 0.25 mg/L. Exposure to 0.25 mg/L propiconazole, however, caused a significant incidence of developmental abnormalities and embryonic death. Abnormalities were consistent with developmental arrest at later stages of embryonic maturation. Propiconazole elicited a steep concentration-response curve with respect to embryo toxicity, with a 10% and a 90% incidence of embryo toxicity measured at 0.50 and 0.82 mg/L, respectively. Direct exposure of embryos to propiconazole resulted in toxicity, though the incidence and characteristics of developmental abnormalities were not consistent with that observed during chronic exposures. However, maternal exposure to propiconazole followed by transfer of early embryos to propiconazole-free media resulted in embryo toxicity consistent with that observed during chronic exposure. These results indicate that propiconazole interferes with the later stages of daphnid embryonic development, and that this toxicity is manifested largely via maternal exposure to the fungicide.

Callus induction, somatic embryogenesis and organogenesis in Narcissus confusus : correlation between the state of differentiation and the content of galanthamine and related alkaloids

In vitro cultures from two strains of Narcissus confusus (Amaryllidaceae) initiated from mature seeds were screened for their ability to produce alkaloids. Protocols for callus induction, somatic embryogenesis and organogenesis were established. The alkaloid contents were determined by HPLC. Undifferentiated calli produced small amounts of galanthamine, which increased with the degree of tissue differentiation. Scanning electron micrographs of the cultures at different stages of development were made. Embryogenic friable calli were maintained in culture for more than 2 years, retaining a high regeneration capability. All regenerated plants showed normal morphological characteristics.

Regulation of cholinesterase gene expression affects neuronal differentiation as revealed by transfection studies on reaggregating embryonic chicken retinal cells.

In the embryonic chicken neuroepithelium, butyrylcholinesterase (BChE) as a proliferation marker and then acetylcholinesterase (AChE) as a differentiation marker are expressed in a mutually exclusive manner. These and other data indicate a coregulation of cholinesterase expression, and also possible roles of cholinesterases during neurogenesis. Here, both aspects are investigated by two independent transfection protocols of dissociated retina cells of the 6-day-old chick embryo in reaggregation culture, both protocols leading to efficient overexpression of AChE protein. The effect of the overexpressed AChE protein on the re-establishment of retina-like three-dimensional networks (so-called retinospheroids) was studied. In a first approach, we transfected retinospheroids with a pSVK3 expression vector into which a cDNA construct encoding the entire rabbit AChE gene had been inserted in sense orientation. As detected at the mRNA level, rabbit AChE was heterologously overexpressed in chicken retinospheroids. Remarkably, this was accompanied by a strong increase in endogenous chicken AChE protein, while the total AChE activity was only slightly increased. This increase was due to chicken enzyme, as shown by species-specific inhibition studies using fasciculin. Clearly, total AChE activity is regulated post-translationally. As an alternative method of AChE overexpression, transfection of spheroids was performed with an antisense-5'-BChE vector, which not only resulted in the down-regulation of BChE expression, but also strongly increased chicken AChE transcripts, protein and enzyme activity. Histologically, a higher concentration of AChE protein (as a consequence of either AChE overexpression or BChE suppression) was associated with an advanced degree of tissue differentiation, as detected by immunostaining for the cytoskeletal protein vimentin.

Analysis of DNA ploidy using fresh frozen tissues of head and neck squamous cell carcinomas

The DNA ploidy of fresh frozen tissues of head and neck squamous cell carcinomas was determined by flow cytometry to investigate whether DNA ploidy is correlated with various clinical and pathological parameters. The subjects were 51 patients who had been treated radically by our department. The DNA ploidy pattern was classified into three types, diploid, single aneuploid and multiploid, according to the DNA index and the DNA histogram. This is our original classification. No particular correlation could be detected between the DNA ploidy pattern and sex, age, primary tumour site or disease stage. The degree of tissue differentiation tended to be poorer in aneuploid tissues than in diploid tissues. The efficacy of chemotherapy was higher in aneuploid cases than in diploid cases. The recurrence rate was significantly lower in diploid cases than in multiploid cases. When disease stage, degree of histological differentiation, efficacy of the chemotherapy and the DNA ploidy pattern were subjected to multivariate analysis for correlation with the prognosis, the DNA ploidy pattern showed the highest correlation. The results suggest that the DNA ploidy as analyzed by flow cytometry can be used as an important prognostic factor.

Analysis of DNA ploidy using fresh frozen tissues from head and neck squamous cell carcinomas

The DNA ploidy of fresh frozen tissues from head and neck squamous cell carcinomas was determined by flow cytometry, with the aim of investigating whether DNA ploidy correlates with various clinical and pathological parameters. The subjects were 51 patients who had undergone radical surgery in our department. The DNA ploidy pattern was classified into three types, diploid, single aneuploid and multiploid, according to the DNA index and the DNA histogram. This is our original classification. No particular correlation could be detected between the DNA ploidy pattern and sex, age, primary tumor site or disease stage. The degree of tissue differentiation tended to be poorer in aneuploid than in diploid tissues. The efficacy of chemotherapy was higher in aneuploid than in diploid cases. The recurrence rate was significantly lower in diploid than in multiploid cases. When disease stage, degree of histological differentiation, the efficacy of chemotherapy and the DNA ploidy pattern were subjected to multivariate analysis for correlation with prognosis, the DNA ploidy pattern showed the highest correlation. Our results suggest that the DNA ploidy, as analyzed by flow cytometry, can serve as useful prognostic factor.

New data on multicellular thallophytes and fragments of cellular tissues from Late Proterozoic phosphate rocks, South China

Zhung Yun & Yuan Xun-lai 1992 01 15: New data on multiccllular thallophytes and fragments of cellular tissues from Late Proterozoic phosphate rocks. South China, Lethaia. Vol. 25. pp. 1–18. Oslo. ISSN 0024–1164. A fossil assemblage consisting of multicellular thallophytes. acritarchs. cyanophytes. bacteria and some forms of uncertain affinity were found in black phosphorites of the Late Protcrozoic Doushantuo Formation (upper Sinian) in Wengan Phosphate Mine. central Guizhou Province. South China. This paper reports new forms of multiecllular thallophytes and cellular tissue. Four new genera and seven new species are described. Cytomorphological-histomorphological study of these lossil tissues and comparison with modern rhodophyle Corallina sp. suggest that (I) most fossils described here are thalloid plants with a certain degree of tissue differentiation. Some of them may be hisiomorphologically comparable to modern rhodophytcs. but all are still of uncertain systematic position Some exhibit histomorphological features of mctazoan tissues. (2) The fossil cells appear to have undergone plasmolysis that might be due to osmosis caused by the high phosphate content in the sea water. (3) Most of the thallophytes were sessile benthos with recognizable basal and upper parts to the thallus. Forms with leafshaped or nodular thalli may have moved passively or ncuslonically. New fossil forms discovered from the local rock bed demonstrate the possible existence of a community with relatively high diversity in Wengan shallow sea. This confirms that an evolutionary radiation of mctaphylcs look place during Ediacaran time, shortly after the Nantuo glacial epoch. Multicellular tlhallophytes. mctaphytes. phosphate rocks, phosphorites. Late Proterozoic.

MHC antigens on human tumors

MHC class I antigens on tumor cells are expected to play an important role because they regulate the sensitivity to antitumoral immunological mechanisms. Overall or selective qualitative or quantitative changes in MHC molecules may modify the recognition of tumor cells by components of the immune system. It seems clear that MHC antigen expression on tumor cells is important in triggering the immune response by autologous lymphocytes. A deficiency in or lack of MHC class I antigens may have profound effects on T and NK cell activity. In experimental models, variation in the expression of MHC class I antigens has been shown to exert a decisive influence on local tumor growth and metastasis. However, there is little information about the influence of selective loss of individual locus products on the behavior of human tumor cells. Total and selective HLA losses have been found in a large variety of tumors, and different mechanisms have been shown to be responsible for these changes. In some examples, HLA losses are associated with a poor degree of tissue differentiation and poor prognosis. In other tumors, however, no such association has been found. We do not know whether HLA class II expression in neoplastic cells plays an immunological role, although, with the exception of melanoma, HLA class II expression is more frequently observed in tumors with a more favorable prognosis. Finally, there is no doubt that we need to learn more about how to manipulate the expression of MHC class I and II antigens in human tumors, in order to stimulate immune response.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunogold localization of pathogenesis-related protein P14 in tomato root cells infected by Fusarium oxysporum f. sp. radicis-lycopersici

The accumulation of soluble pathogenesis-related (PR) P14 protein in tomato plants has only been reported in green tissue. An antiserum raised against purified PR P14 protein was used to study the spatial and temporal distribution of this protein in tomato root tissues infected by Fusarium oxysporum f. sp. radicis-lycopersici . Within healthy root tissue, PR P14 protein was found to be present in variable amount in cell walls, depending apparently on cell age and on the degree of tissue differentiation. Cell walls of infected tomato root tissues were markedly enriched in PR P14 protein. Although differences in the timing of PR P14 protein accumulation were observed between susceptible and resistant cultivars, the spatial distribution of the protein was similar in both interactions. Its predominant accumulation in host primary and secondary cell walls contrasted with its lack of association with the middle lamella. Deposition of PR P14 protein was also noticeable in intercellular spaces and within wall appositions. Its absence in the fungal wall provides support for a possible role in plant cell wall modification. This is contrary to other extracellular PR proteins such as chitinases and β-1,3-glucanases which are found associated with walls of invading fungal pathogens.