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At least 721 records · Page 40Linked to original sources
PubMed2003

Haploinsufficiency of Anx7 tumor suppressor gene and consequent genomic instability promotes tumorigenesis in the Anx7(+/-) mouse.

Annexin 7 (ANX7) acts as a tumor suppressor gene in prostate cancer, where loss of heterozygosity and reduction of ANX7 protein expression is associated with aggressive metastatic tumors. To investigate the mechanism by which this gene controls tumor development, we have developed an Anx7(+/-) knockout mouse. As hypothesized, the Anx7(+/-) mouse has a cancer-prone phenotype. The emerging tumors express low levels of Anx7 protein. Nonetheless, the wild-type Anx7 allele is detectable in laser-capture microdissection-derived tumor tissue cells. Genome array analysis of hepatocellular carcinoma tissue indicates that the Anx7(+/-) genotype is accompanied by profound reductions of expression of several other tumor suppressor genes, DNA repair genes, and apoptosis-related genes. In situ analysis by tissue imprinting from chromosomes in the primary tumor and spectral karyotyping analysis of derived cell lines identify chromosomal instability and clonal chromosomal aberrations. Furthermore, whereas 23% of the mutant mice develop spontaneous neoplasms, all mice exhibit growth anomalies, including gender-specific gigantism and organomegaly. We conclude that haploinsufficiency of Anx7 expression appears to drive disease progression to cancer because of genomic instability through a discrete signaling pathway involving other tumor suppressor genes, DNA-repair genes, and apoptosis-related genes.

Animals↗
PubMed2001

H+,K+-ATPase is not involved in endolymph pH homeostasis.

In endolymph, the calculated electrochemical gradients suggest the presence of active transport of H+ and K+. The presence of H+,K+-ATPase, an active transporter that mediates the exchange of intracellular H+ for extracellular K+, was investigated using reverse transcription-polymerase chain reaction on rat microdissected inner ear tissues. Distal colon and kidney were used as positive controls. The two H+,K+-ATPase colonic or gastric isoforms were not detected in the rat cochlea and endolymphatic sac. This result suggests that H+,K+-ATPase is not involved in H+ and K+ endolymph homeostasis.

Acid-Base Equilibrium↗
PubMed2004

Effects of human immunodeficiency virus type 1 on astrocyte gene expression and function: potential role in neuropathogenesis.

Neurodegeneration and dementia caused by human immunodeficiency virus type 1 (HIV-1) infection of the brain are common complications of acquired immunodeficiency syndrome (AIDS). Introduction of highly active antiretroviral therapy (HAART) reduced the incidence of HIV-1-associated dementia, but so far had no effect on the high frequency of milder neurological disorders caused by HIV-1. This indicates that some neuropathogenic processes persist during limited HIV-1 replication in the central nervous system (CNS). The authors are evaluating the hypothesis that interaction of HIV-1 with astrocytes, which bind HIV-1 but support limited productive HIV-1 infection, may contribute to these processes by disrupting astrocyte functions that are important for neuronal activity or survival. Using laser-capture microdissection on brain tissue samples from HIV-1-infected individuals, we found that HIV-1 DNA can be detected in up to 1% of cortical and basal ganglia astrocytes, thus confirming HIV-1 infection in astrocytes from symptomatic patients. Using rapid subtraction hybridization, the authors cloned and identified 25 messenger RNAs in primary human fetal astrocytes either up-regulated or down-regulated by native HIV-1 infection or exposure to gp120 in vitro. Extending this approach to gene microarray analysis using Affymetrix U133A/B gene chips, the authors determined that HIV-1 alters globally and significantly the overall program of gene expression in astrocytes, including changes in transcripts coding for cytokines, G-coupled protein receptors, transcription factors, and others. Focusing on a specific astrocyte function relevant to neuropathogenesis, the authors showed that exposure of astrocytes to HIV-1 or gp120 in vitro impairs the ability of the cells to transport L-glutamate and the authors related this defect to transcriptional inhibition of the EAAT2 glutamate transporter gene. These findings define new pathways through which HIV-1 may contribute to neuropathogenesis under conditions of limited virus replication in the brain.

AIDS Dementia Complex↗
PubMed2002

Molecular techniques for studying gene expression in carcinogenesis.

Many genes and signaling pathways controlling cell proliferation, death, differentiation, and genomic integrity are involved in cancer development. Various methods are available for detection and quantification of messenger RNA. Older methods such as Northern blots, nuclease protection, plaque hybridization, and slot blots suffer from being inherently serial, measure a single mRNA at a time, or being difficult to automate. New techniques for analysis of gene expression include: (a) comprehensive open systems such as serial analysis of gene expression (SAGE), differential display (DD) analysis, RNA arbitrarily primer (RAP)-PCR, restriction endonucleolytic analysis of differentially expressed sequences (READS), amplified restriction fragment-length polymorphism (AFLP), total gene expression analysis (TOGA), and use of internal standard competitive template primers (CTs) in a quantitative multiplex RT-PCR method [StaRT-(PCR)], and (b) focused closed systems such as: high density cDNA filter hybridization (HDFCA) analysis, suppression subtractive hybridization (SSH), differential screening (DS), several forms of high-density cDNA arrays, or oligonucleotide chips, and tissue microarrays. Sometimes, a combination of these systems is used to enhance the sensitivity and specificity of the assays. While closed systems are excellent for the initial screening of large number of sequences, the value of the information generated is generally limited to an often arbitrarily chosen known sequence. On the other hand, only the open system platform has the potential to evaluate the expression patterns of tens of thousands of genes that have not yet been cloned or partially sequenced in a quantitative manner. A cost analysis of the most commonly used expression technologies is provided. A method for purifying tumors from surrounding stroma and normal tissue employing laser microdissection, and subsequent RNA isolation/amplification from few cells employing sensitive kits are also discussed.

Cell Transformation, Neoplastic↗
PubMed1996

Relative contribution of T and B cells to hypermutation and selection of the antibody repertoire in germinal centers of aged mice.

The immune system of aged individuals often produces antibodies that have lower affinity and are less protective than antibodies from young individuals. Recent studies in mice suggested that antibodies produced by old individuals may be encoded by distinct immunoglobulin (Ig) genes and that the somatic hypermutation process in these individuals is compromised. The present study employed Ighb scid mice reconstituted with normal lymphocytes from young (2-3-mo-old) and aged (20-25-mo-old) donors and immunized with a protein conjugate of the hapten (4-hydroxy-3-nitrophenyl)acetyl (NP) to determine whether the molecular changes in antibody repertoire reflect senescence in the B cells or whether they are mediated by the aging helper T lymphocytes. The NP-reactive B cells from splenic germinal centers (GC) were recovered by microdissection of frozen tissue sections and their rearranged Ig heavy chain variable region (VH) genes of the V186.2/V3 families were sequenced. It was found that the VH gene repertoire of the GC B cells was strongly influenced by the source of the CD4+ T cells. When T cells were donated by young mice, the anti-NP response in GC was dominated by the canonical V186.2 gene, even if the responder B cells came from aged donors. However, when the mice were reconstituted with T cells from aged donors, the expression of the V186.2 gene by young B cells was diminished and the response was dominated by the C1H4 gene, another member of the V186.2/V3 family. In contrast, the somatic hypermutation process in the GC B cells followed a different pattern. The mutation frequencies in the animals that were reconstituted with both B and T cells from young donors (1/50 to 1/150 bp) were comparable to the frequencies previously reported for NP-immunized intact young/adult mice. However, when either lymphocyte subset was donated by the aged mice, the mutation frequencies declined. Thus, mice reconstituted with T cells from the aged and B cells from the young had severely compromised mutational mechanism. Likewise, the recipients of aged B and young T cells had diminished mutations even though the repertoire of their anti-NP response was dominated by the canonical V186.2 gene. It appears that the change in germine-encoded repertoire and the decrease of somatic hypermutation represent distinct mechanisms of immunosenescence and that the aging of helper T cells plays a pivotal role in both of these processes.

Aging↗
PubMed1995

Allele-specific loss in chromosome 9p loci in preneoplastic lesions accompanying non-small-cell lung cancers.

BACKGROUND: Carcinogenesis is a multistep process, which may begin as a consequence of chromosomal changes. Deletions in the short arm of chromosome 9 (9p) have been observed in lung carcinomas. In addition, morphologically recognizable preneoplastic lesions, frequently multiple in number, precede onset of invasive carcinomas. PURPOSE: We tested for deletions and loss of heterozygosity (LOH) at 9p loci in preneoplastic and neoplastic foci in lungs of patients with non-small-cell lung carcinomas (NSCLCs). METHODS: Seven archival, paraffin-embedded, surgically resected NSCLC specimens were selected. They were predominantly from patients with adenocarcinomas and contained multiple preneoplastic lesions, including hyperplasia, metaplasia, dysplasia, and carcinoma in situ (CIS). Fifty-three histologically identified preneoplastic and malignant lesions present in bronchi, bronchioles, and alveoli were precisely microdissected from stained tissue sections with a micromanipulator. Stromal lymphocytes were used to determine constitutional heterozygosity. The specimens were analyzed for LOH using polymerase chain reaction-based assays for polymorphism in dinucleotide repeats (microsatellite markers) in interferon alfa (IFNA) and D9S171 loci on 9p. RESULTS: All seven cases were constitutionally heterozygous for one or both microsatellite markers. Five of seven cases had LOH at one or both 9p loci in the invasive primary cancers (doubly informative cases). Four of these five cases also revealed LOH in preneoplastic foci. In the doubly informative cases, LOH was detected in five (38%) of 13 foci of hyperplasia, four (80%) of five foci of dysplasia, and three (100%) of three CIS lesions. LOH was detected in preneoplastic lesions from all regions of the respiratory tract, including bronchi, bronchioles, and alveoli, and involved five different cell types. The identical allele was lost from both the preneoplastic lesions and the corresponding tumors (12 of 12 lesions, 17 of 17 comparisons), a phenomenon we have referred to as "allele-specific mutation." Statistical analyses employing a cumulative binomial test demonstrated that the probabilities of such findings occurring by chance are 2.4 x 10(-4) and 7.6 x 10(-6), respectively. From comparisons with the previously published data on other chromosomal abnormalities in the same tissue specimens, it appears that LOH at 3p and 9p loci occurred early in the hyperplasia stage, but the ras gene point mutations were relatively late, at the CIS stage. CONCLUSIONS: LOH at 9p loci occurs at the earliest stage in the pathogenesis of lung cancer and involves all regions of the respiratory tract. LOH in NSCLC is not random but targets a specific allele in individuals. Studying preneoplastic lesions may help identify intermediate markers for risk assessment and chemoprevention.

Adenocarcinoma↗
PubMed1997

Prevalence of activating K-ras mutations in the evolutionary stages of neoplasia in intraductal papillary mucinous tumors of the pancreas.

OBJECTIVE: The purpose of the study was to determine the prevalence of activating K-ras mutations in the pancreas of patients with intraductal papillary mucinous tumors (IPMT) and to analyze their relation to the degree of site-specific histopathologic abnormality. BACKGROUND: Intraductal papillary mucinous tumors of the pancreas have a biologic behavior that is significantly different from pancreatic ductal adenocarcinoma. Activating K-ras mutations, which may be important events in a multistage process of carcinogenesis, have been reported in IPMT. METHODS: Forty-six different histologic specimens (comprising normal pancreatic ducts, hyperplasia, low-grade dysplasia, high-grade dysplasia-carcinoma in situ, and carcinoma) from 16 patients with IPMT and 9 specimens from patients with pancreatic ductal adenocarcinomas were designated by a pathologist. Genomic DNA was extracted from paraffin-embedded tissue sections after microdissection. The K-ras gene was amplified by polymerase chain reaction and subjected to DNA sequencing. RESULTS: The K-ras mutations were detected in at least one specimen in 13 (81.2%) of 16 patients with IPMT. All mutations were found in codon 12. No codon 13 mutations were detected. The relative frequency of K-ras mutations in the different stages of IPMT was 16.7% in normal epithelium and papillary hyperplasia, 28.6% in low-grade dysplasia, and 57.1% in high-grade dysplasia-carcinoma in situ and invasive carcinoma. The K-ras mutations were detected in 6 (66%) of 9 pancreatic ductal adenocarcinomas. CONCLUSIONS: The K-ras codon 12 point mutations are as frequent in IPMT as in ductal adenocarcinoma. A stepwise increase in the frequency of codon 12 mutations correlated with the stage of neoplastic evolution to cancer. This finding is consistent with an important role of K-ras gene mutations in the transformation from normal epithelium to invasive carcinoma in the majority of patients with IPMT.

Carcinoma, Ductal, Breast↗
PubMed1997

Measurement of adenylylcyclase activity in the AV nodal region of the canine heart: evidence for inhibition by adenosine and acetylcholine.

Although it is essential to cardiac conduction, little is known about the biochemistry underlying postreceptor adrenergic, cholinergic and purinergic processes in the AV node. To study these mechanisms, we adapted a new and highly sensitive fluorometric assay for cyclic adenosine monophosphate (AMP) to characterize regional adenylylcyclase activity (cyclic AMP production in pmol/min/mg of protein) in membrane preparations made from 20-50 pieces of freeze-dried, 20-microm thick, microdissected samples of tissue from canine right atrium, the AV nodal region, and left ventricle. Basal and NaF-stimulated adenylylcyclase activity (mean +/- SEM, n = 6) were 7.2 +/- 0.4 and 72.4 +/- 7.5 in atrial, 15.6 +/- 1.3 and 58.8 +/- 4.7 in AV nodal, and 6.4 +/- 0.9 and 66.7 +/- 5.0 in ventricular tissues, respectively. Isoproterenol (10(-7)-10(-4) M) increased adenylylcyclase activity in a dose-dependent fashion in three different regions. The isoproterenol (10(-6) M)-stimulated adenylylcyclase activity (n = 6) was 14.4 +/- 1.3 in atrial, 21.9 +/- 1.6 in AV nodal and 13.4 +/- 1.4 in ventricular tissues. Adenosine (10(-3) M) and carbachol (10(-5) M) inhibited isoproterenol (10(-6) M)-stimulated adenylylcyclase activity to 10.1 +/- 1.1, 12.9 +/- 1.3 in atrial, 15.1 +/- 1.6, 15.5 +/- 1.2 in AV nodal, and 7.5 +/- 0.7, 11.9 +/- 1.2 in ventricular tissues, respectively. The results demonstrate that there are regional differences in adenylylcyclase activity under basal conditions and after adrenergic, purinergic, and cholinergic stimulation in the heart. Unlike adenosine, the inhibitory effects of cholinergic stimulation appear to be more specific for the AV node.

Acetylcholine↗
PubMed2002

Preferential loss of Fhit expression in signet-ring cell and Krukenberg subtypes of gastric cancer.

Gastric cancer of youth is predominantly a disease of women, usually of the signet-ring cell subtype, with a predilection for metastasizing to the ovaries. The metastatic ovarian tumor is named a Krukenberg tumor. However, the characteristic genetic alterations between the primary gastric cancer and its metastatic ovarian tumor have not been studied. We used laser capture microdissection to procure tissues from 7 patients with gastric cancer who had ovarian metastases (Krukenberg tumor) and tissues from 14 patients with gastric cancer without ovarian metastases. Loss of heterozygosity (LOH) analysis was performed by use of 16 polymorphic markers, which are mapped to the FHIT, APC, p16, BRCA2, E-cadherin, p53, BRCA1, and DPC4 loci. Immunohistochemical staining with anti-Fhit antibody was performed in 7 Krukenberg tumors and 92 gastric cancers without ovarian metastases. LOH at the FHIT locus was observed in six (85.7%) of the seven Krukenberg tumors. In contrast, the gastric cancers without ovarian metastases showed a lower frequency (28.6%, 4/14) of LOH at the FHIT locus (p < 0.05, odds ratio = 1/15). Anti-Fhit antibody showed that expression of Fhit was lost in each of the 7 (100%) Krukenberg tumors but in only 41 (44.6%) of the 92 patients who had gastric cancer without ovarian metastases (p < 0.05; odds ratio = 1/18.614). Further analysis showed that loss of Fhit expression is highly associated with signet-ring cell type gastric cancer (p < 0.0001, odds ratio = 62.5) but is not correlated with prognosis. Alteration of the FHIT gene is a characteristic of signet-ring cell type gastric cancer and Krukenberg tumor.

Acid Anhydride Hydrolases↗
PubMed2005

Absence of human papillomavirus infection in minimal deviation adenocarcinoma and lobular endocervical glandular hyperplasia.

The human papillomavirus (HPV) is basically always detected in squamous cell carcinoma of the cervix and its precursors; a high incidence of HPV also has been reported in adenocarcinoma and adenocarcinoma in situ of the uterine cervix. Lobular endocervical glandular hyperplasia (LEGH) was first described by Nucci in 1999. It is difficult to differentiate minimal deviation adenocarcinoma (MDA) from LEGH preoperatively or postoperatively by clinical and pathologic features. The relationships between HPV and MDA or LEGH have not been studied well because of the rare incidence of the two diseases. To our knowledge, the HPV status in LEGH has not been reported. This study was designed to investigate HPV infection in MDA and LEGH, using the polymerase chain reaction (PCR) technique. Tumor tissue lesions were microdissected and the detection of HPV and its typing were analyzed by PCR-based assay. As the control, HPV DNA was detected in all cases of squamous cell carcinoma and three of five cases of adenocarcinoma. However, no HPV DNA was detected in any of the 10 cases of LEGH or in the 3 cases of MDA. These results suggest that MDA and LEGH are probably not related to HPV infection.

Adenocarcinoma↗
PubMed1999

Genetic alterations in ulcerative colitis-associated neoplasia focusing on APC, K-ras gene and microsatellite instability.

The status of genetic alterations in ulcerative colitis (UC)-associated neoplasia (UCAN) was investigated focusing on microsatellite instability (MSI) which is seen in a certain fraction of colorectal carcinomas, and adenomatous polyposis coli (APC) gene and K-ras gene, in which mutations occur in the early stage of sporadic colorectal tumorigenesis. Thirty-one UCAN from 15 UC patients who had undergone colorectal resection at our institution were investigated. There were 8 lesions of invasive carcinoma, 15 high-grade dysplasia (HGD) and 8 low-grade dysplasia (LGD). DNA was extracted from each neoplastic lesion and corresponding non-neoplastic tissue by a microdissection method. MSI status at 9 microsatellite loci, loss of heterozygosity (LOH) at the APC locus, and K-ras codon 12 point mutation were examined. As for MSI, 4/31 (13%) UCAN (carcinoma: 1/8 (13%), HGD: 2/15 (13%), LGD: 1/8 (13%)) were MSI-high (3 or more unstable loci) and 12/31 (39%) UCAN (carcinoma: 3/8 (38%), HGD: 6/15 (40%), LGD: 3/8 (38%)) were MSI-low (1 or 2 unstable loci). LOH at the APC locus was not found in 9 UCAN from 6 informative (heterozygous) cases. The K-ras mutation rate of UCAN was 3/31 (9.7%) (carcinoma: 2/8 (25%), HGD: 1/15 (7%) and LGD: 0/8). MSI is relatively common in UCAN and is present at the early stage of tumorigenesis of UCAN, while the involvement of genetic alterations of the APC gene and K-ras gene is small. MSI may be one of the mechanisms of the increased neoplastic risk in UC, and UCAN may develop through a different carcinogenic pathway from sporadic carcinomas.

Adult↗
PubMed1982

An unusual type of cytokeratin filament in cells of a human cloacogenic carcinoma derived from the anorectal transition zone.

Epithelia-derived tumors (carcinomas) can be distinguished from mesenchymally derived tumors by the presence of intermediate-sized filaments of the cytokeratin type, which usually coincides with the absence of other types of intermediate-sized filaments such as vimentin filaments. In the course of diagnostic examinations of human tumors, using immunofluorescence microscopy, we have come across a case of an unusual carcinoma (Primary tumor and lymph node metastasis) positively stained not only with cytokeratin antibodies but also with immunoglobulins present in vimentin antisera. Therefore, this tumor, a cloacogenic carcinoma apparently derived from the rectal-anal transitional region, has been examined in greater detail using both immunofluorescence microscopy and immuno-electron microscopy as well as gel electrophoretic analysis of cytoskeletal polypeptides from total tumor tissue and from microdissected nodules enriched in carcinoma cells. The unusual reaction of the carcinoma cells with immunoglobulins present in seven different (rabbit or guinea pig) antisera raised against vimentin, has been found to be diminished after absorption on purified cytokeratin or total epidermal cytoskeletal material, but not after absorption on purified vimentin. Gel electrophoretic analysis of tumor cytoskeletons showed an unusual complex pattern of cytokeratin polypeptides containing relatively large (Mr 68,000 and Mr 58,000) neutral-to-slightly basic cytokeratins, as are typically found in epidermis and other stratified squamous epithelia, as well as several smaller acidic cytokeratins, including a Mr 40,000 polypeptide found in certain nonstratified epithelial such as colon and small intestine. Total tumor also showed the inclusion of some vimentin which, however, was significantly decreased in analysis of excised carcinoma nodules. Examining antibody binding to polypeptides separated by gel electrophoresis and blotted on nitrocellulose paper, we have found that antisera raised against vimentin contained not only vimentin antibodies but also immunoglobulins which specifically bound to the largest cytokeratin component. We conclude that the unusual reaction of immunoglobulins present in vimentin antisera with cytokeratin filament bundles does not represent specific binding to vimentin in these carcinoma cells, but is due to a component obviously widespread in vimentin antisera which binds specifically to a cytokeratin present in this type of tumor but not in most other carcinomas. It is proposed that use is made in diagnostic examinations of vimentin antisera or affinity-purified vimentin antibodies that have been pre-absorbed on cytokeratin protein, in order to eliminate such disturbing reactions.

Aged↗
PubMed1985

Different patterns of cytokeratin expression in the normal epithelia of the upper respiratory tract.

The distribution and type of cytokeratins present in the normal human epithelia of the nasopharynx, oropharynx, tongue, palatine tonsil, epiglottis, vocal cord, and laryngeal ventricle were studied using immunohistochemical techniques and by gel electrophoresis of cytoskeletal proteins microdissected from frozen tissues. Noncornifying stratified epithelia covering the oropharynx, tongue, surface of the palatine tonsil, pharyngeal surface of the epiglottis, and vocal cord were all found to contain cytokeratins nos. 4, 5, 6, 13, 14, and 15, together with minor amounts of cytokeratin no. 19, i.e., a pattern similar to that previously reported for esophageal epithelium. The immunohistochemical reaction with KA4, an antibody specific for cytokeratins nos. 14, 15, 16, and 19, revealed reactivity confined to the basal epithelial cells of the tongue, oropharynx, pharyngeal epiglottis, and two out of five samples of vocal cords. This same antibody reacted with the entire thickness of three out of the five true vocal cords which were shown by gel electrophoresis to also contain cytokeratins nos. 16 and 17. Gel electrophoresis revealed that the pseudostratified columnar epithelium covering the laryngeal ventricle was more complex, in that it contained cytokeratins nos. 5, 13, 14, 15, and 17, which are typical of stratified epithelia, as well as cytokeratins nos. 7, 8, 18, and 19, which are characteristic of simple epithelia. This pattern is similar to that found in bronchial epithelium. The laryngeal surface of the epiglottis exhibited cytokeratins nos. 4, 5, 7, 8, 13, 14, 15, 17, 18, and 19, i.e., a pattern combining features of both esophageal- and bronchial-type epithelia. The reaction of these epithelia containing columnar cells with antibody RGE-53, which is specific for cytokeratin no. 18, revealed a staining reaction confined to the superficial columnar cells, whereas KA1 stained only the basal cells of these epithelia. The results of our study make it possible to distinguish two types of noncornifying stratified squamous epithelium, namely the 'esophageal type' which covers the tongue, oropharynx, and pharyngeal surface of the epiglottis, and another type which overlies the vocal cords and the transitional zone between the pharyngeal and laryngeal surfaces of the epiglottis. Furthermore, there appear to be variants of pseudostratified columnar epithelium, i.e., the usual bronchial type lining the laryngeal ventricle, and a type with a thicker subcolumnar cell compartment that is found on the laryngeal surface of the epiglottis. The patterns of expression of cytokeratins in the respiratory tract are compared with those of other epithelia.

Antibodies, Monoclonal↗
PubMed1978

Immunoreactive vasopressin and oxytocin: concentration in individual human hypothalamic nuclei.

Individual hypothalamic nuclei were microdissected from brain tissue of ten human subjects who had died suddenly while in apparent good health. Appreciable amounts of vasopressin and oxytocin immunoreactivity were found by specific radioimmunoassay in six hypothalamic nuclei including supraoptic and paraventricular nuclei. Vasopressin and oxytocin are presumed to be synthesized in supraoptic and paraventricular nuclei for axonal transport to the posterior pituitary for storage and release. Vasopressin and oxytocin in other hypothalamic nuclei may be a part of this system of neurosecretion or may serve some other function.

Adolescent↗
PubMed1988

Complex physiological and biochemical action of aldosterone in toad urinary bladder and mammalian renal collecting duct cells.

Since the discovery of the steroid hormone aldosterone nearly 35 years ago, our knowledge on the cellular actions of aldosterone is still incomplete. Most of the present physiological and biochemical knowledge about the antinatriuretic action was revealed by investigations on amphibian tight epithelia, in particular the toad urinary bladder. Less biochemical information was obtained from mammalian tissue such as microdissected renal tubules and cultured cells. In our opinion, it is questionable whether de novo synthesis of cell proteins-induced by aldosterone-can explain all of the hormonal effects to increase the Na+ transport. In the present paper we try to analyze the wide and contradictory field of biochemical data about the action of aldosterone on the increase in Na+ transport in renal cells in an attempt to incorporate this information into an extended working hypothesis. We suggest distinguishing principally between an early and a late biochemical response phase. We speculate that aldosterone may act by a two-step mechanism: the early and late aldosterone-induced proteins.

Aldosterone↗
PubMedDate not supplied

Production of urea from arginine in pars recta and collecting duct of the rat kidney.

Urea production from arginine was studied in vitro in the kidney of normal rats in tubule suspensions of the four different renal zones (cortex, outer and inner stripe of outer medulla, and inner medulla), and in individual microdissected nephron segments. Tissue was incubated with L-[guanido-14C]-arginine to measure cellular arginase activity. Addition of urease to the incubate freed 14CO2 from the 14C-urea formed by arginase and released from the cells. CO2 was trapped in KOH and counted. These experiments revealed that significant amounts of urea are produced in the outer stripe and in the inner medulla. This intrarenal urea generation takes place mainly in the proximal straight tubule and in the collecting duct, with increasing activity in these two structures from superficial to deep regions of the kidney. Urea is known to play a critical role in the urinary concentrating process. The fact that some urea can be produced in the mammalian kidney, and that the two structures showing this capacity are straight portions of the renal tubular system descending along the corticopapillary axis suggest that this urea production might play a role in the formation and/or maintenance of the medullary urea concentration gradient.

Animals↗
PubMed2002

KSHV- and EBV-associated germinotropic lymphoproliferative disorder.

Kaposi sarcoma-associated herpesvirus (KSHV) is known to be associated with 3 distinct lymphoproliferative disorders: primary effusion lymphoma (PEL), multicentric Castleman disease (MCD), and MCD-associated plasmablastic lymphoma. We report 3 cases of a previously undescribed KSHV-associated lymphoproliferative disorder. The disease presented as localized lymphadenopathy and showed a favorable response to chemotherapy or radiotherapy. Histologically, the lymphoproliferation is characterized by plasmablasts that preferentially involved germinal centers of the lymphoid follicles, forming confluent aggregates. They were negative for CD20, CD27, CD79a, CD138, BCL6, and CD10 but showed monotypic kappa or lambda light chain. Clusters of CD10(+)CD20(+) residual follicle center cells were identified in some of the follicles. The plasmablasts were positive for both KSHV and EBV, and most of them also expressed viral interleukin-6 (vIL-6). Unexpectedly, molecular analysis of whole tissue sections or microdissected KSHV-positive aggregates demonstrated a polyclonal or oligoclonal pattern of immunoglobulin (Ig) gene rearrangement. The plasmablasts showed somatic mutation and intraclonal variation in the rearranged Ig genes, and one case expressed switched Ig heavy chain (IgA), suggesting that they originated from germinal center B cells. We propose calling this distinctive entity "KSHV-associated germinotropic lymphoproliferative disorder."

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2007

Identification and characterization of multiple corticotropin-releasing factor type 2 receptor isoforms in the rat esophagus.

The rat esophagus shares some cellular features with skin squamous epithelium and striated muscle that express high levels of corticotropin-releasing factor type 2 (CRF2) receptors or their cognate ligand urocortin (Ucn) 1, 2, and 3. We investigated the expression and cell signaling of CRF2 receptors and ligands in the rat esophagus and lower esophageal sphincter (LES) by RT-PCR and quantitative PCR in normal and corticosterone-treated whole esophageal tissue, laser capture microdissected layers, and isolated esophageal cells. The expression of CRF2 receptor protein and intracellular cAMP and ERK1/2 responses to CRF agonists and CRF2 antagonist were determined in cultured esophageal cells and HEK-293 cells transfected with CRF2b receptors. CRF2 was abundantly expressed in the mucosa and longitudinal muscle layers of the esophagus and LES, whereas CRF1 expression was scarce. CRF2b wild-type transcript was predominantly expressed in the esophagus, and in addition, several new CRF2 splice variants including six CRF2a isoforms were identified. Expression of Ucn 1, Ucn 2, and to a smaller extent Ucn 3, but not CRF mRNA, was detected in the esophagus and LES. Ucn 1 and Ucn 2 stimulated dose-dependent cAMP production and ERK1/2 phosphorylation in the esophageal cells, whereas CRF and CRF1 agonist, cortagine, had less potent effects. In addition, Ucn 2-stimulated cAMP and ERK responses were blocked by the CRF2 antagonist, astressin2-B. These data established the presence of a prominent CRF2 signaling system in the esophagus and LES-encompassing multiple CRF2 receptor variants and Ucn, suggesting a functional role in secretomotor activity and epithelial and muscle cell proliferation.

Animals↗