Telomerase recruitment to telomeres.

The ability of most cancer cells to grow indefinitely relies on the presence of functional telomerase to maintain telomeres, thus circumventing normal cellular senescence. A key feature of telomerase functionality is the localization of the enzyme complex to telomeres, a process which is highly regulated. A number of recent studies have reported data with significant implications for our understanding of telomerase recruitment to telomeres. A picture is emerging that this process is governed by a number of factors including telomeric binding proteins, structural features of the enzyme complex, cell cycle regulated processes such as DNA replication, and components of the DNA damage response pathway. In this review we summarize recent findings relating to this fundamental process in eukaryotes.

Diminished calcium homeostasis and increased susceptibility to excitotoxicity of JS 3/16 progenitor cells after differentiation to oligodendroglia.

JS 3/16, derived from passaged oligodendroglial cultures prepared from rat cerebral white matter, differentiate from progenitors (OP) into complex process-bearing, galactocerebroside-positive but myelin basic protein-negative immature oligodendrocyte-like cells (ImO) after withdrawal of trophic factors. We found that JS 3/16 ImO are markedly more susceptible than OP to cell death after sustained alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate glutamate receptor (AMPA-GluR) activation. This excitotoxicity is preceded by loss of intracellular Ca(2+) homeostasis, which is more marked in ImO than OP. We identified three factors likely to contribute to the diminished Ca(2+) homeostatic capacity of ImO. First, signal intensities of immunoreactive GluR2, GluR3, and GluR4 AMPA-GluR subunits are increased 1.3- to 2.2-fold in ImO over OP without comparable changes in RNA editing and alternative splicing. Second, transcriptional levels of genes encoding Na(+)-Ca(2+) exchanger proteins and a plasma membrane ATPase (PMCA1), which are necessary for Ca(2+) extrusion across the plasma membrane, are lower in ImO than in OP. Third, ImO have more depolarized basal mitochondrial membrane potential (Delta Psi) than OP, and Delta Psi collapses within 15 min after onset of AMPA-GluR activation in almost all ImO, but not in the majority of OP. This Delta Psi collapse limits the capacity of ImO mitochondria to buffer the rise in intracellular Ca(2+) caused by AMPA-GluR activation. The JS 3/16 line provides a valuable system for analysis of intracellular Ca(2+) homeostasis and AMPA-GluR-mediated excitotoxicity in the oligodendroglial lineage.

Invasive cervical carcinoma: role of MR imaging in pretreatment work-up--cost minimization and diagnostic efficacy analysis.

PURPOSE: To examine the cost and efficacy of diagnostic work-up in patients with invasive cervical cancer. MATERIALS AND METHODS: In 246 patients with invasive cervical cancer, all diagnostic tests performed before treatment were recorded. Patients were divided into two groups: those who underwent magnetic resonance (MR) imaging as the initial study (n = 105) and those who did not (n = 141). A list of 1995 Medicare global payments was used to measure cost. Bayesian analysis (likelihood ratios derived from a literature search) was performed for bladder, rectal, parameterial, and nodal involvement in stage Ib disease. RESULTS: Significantly fewer procedures and fewer invasive studies were performed in the MR imaging group. Net cost savings for the MR imaging group was $401 for all patients and $449 for patients with stage Ib disease. For stage Ib disease, the 0% pretest probability of bladder or rectal invasion does not justify the routine use of barium enema examination, cystoscopy, or proctoscopy. The increase in predictive values for parameterial and nodal disease was highest for MR imaging when tumor size was at least 2 cm. CONCLUSION: Guidelines for the pretreatment work-up of clinical stage Ib cervical cancer need revision. MR imaging should be used as an adjunct to clinical evaluation.

Phlorotannin-protein interactions.

Tannins are one of the most broadly distributed types of plant secondary compounds, and have been the focal point for many studies of plant/herbivore interactions. Tannins interact strongly with proteins, so that the fate and effects of ingested tannins are in part dependent on the mode of interaction of the tannin with dietary and endogenous proteins in an herbivore's gut. We investigated the factors affecting the precipitation of proteins by phlorotannins from three species of marine brown algae:Carpophyllum maschalocarpum, Ecklonia radiata, andLobophora variegata. Phlorotannins were precipitated by proteins in a pH-dependent and concentration-dependent fashion. Precipitation also varied as a function of the presence of reducing agent, the type of phlorotannin or protein used, and the presence of organic solvents such as hydrogen bond inhibitors. Of particular significance was the ability of some phlorotannins to oxidize and form covalent bonds with some proteins. In contrast, under similar experimental conditions three types of terrestrial tannins (procyanidins, profisetinidins, and gallotannins) apparently did not form covalent complexes with proteins. Our results suggest several ways in which the biological activity of phlorotannins may vary as a function of the properties of the gut environment of marine herbivores. Moreover, we identify specific structural characteristics of phlorotannins which affect their tendency to oxidize, and thus, their potential effects on marine herbivores.

A new assay for quantifying brown algal phlorotannins and comparisons to previous methods.

Quantitative measurement of phlorotannins (polyphenolics) in brown algae (Phaeophyta) by colorimetric assays can be confounded because: (1) most such assays also react to nonphlorotannin substances (interferences) and (2) the appropriate reference compound for such assays is not always clear, although phloroglucinol is typically used. We developed a new assay in which 2,4-dimethoxybenzaldehyde (DMBA) reacts specifically with 1,3-and 1,3,5-substituted phenols (e.g., phlorotannins) to form a colored product. This new assay, as well as eliminating the problem of measuring interferences, is inexpensive, rapid, and can be used with small sample volumes. We recommend it for all assays of phlorotannins from one or a set of closely related species where the structural types of phlorotannins present are likely to be similar among samples. It is also appropriate for broader surveys of phlorotannin levels across many species, but in this case a reference must be chosen with care. We also compared the DMBA assay to existing assays, including the Folin-Denis [both before and after the samples were mixed with polyvinylpolypyrrolidone (PVPP)] and the Prussian blue assays. PVPP was not 100% efficient (and often much less) at removing phlorotannins from solution, and its effectiveness varied among different phlorotannins. Thus, in contrast to previous studies, measuring phenolic levels in extracts before and after treatment with PVPP will not necessarily result in an interference-free measure of phlorotannins. Based on an analysis of reactive substances in red and green algae (which do not contain phlorotannins) in the Folin-Denis and Prussian blue assays, we estimate that the average level of interferences (nonphlorotannins) in brown algae measured in these two assays is on the order of 0.5% by dry weight.

Ovarian cancer: staging with CT and MR imaging.

PURPOSE: To evaluate ovarian cancer staging and tumor resectability with computed tomography (CT) or magnetic resonance (MR) imaging. MATERIALS AND METHODS: Eighty-two women underwent CT (n = 43) or MR imaging (n = 50); eleven of these 82 underwent both. Imaging was performed within 4 weeks of surgical staging. Radiologic, surgical, and histopathologic findings were compared. RESULTS: Overall staging accuracy was similar for CT and MR imaging (77% [33 of 43] vs 78% [39 of 50]). Evaluation of pelvic cancer extent was better with MR imaging than with CT. There was no difference in detection of abdominal disease. Most mesenteric and small-bowel implants were not detected with either CT or MR imaging. For CT, the positive predictive value for cancer nonresectability was 100% (three of three patients); the negative predictive value was 92% (37 of 40 patients). The positive and negative predictive values for MR imaging were 91% (10 of 11 patients) and 97% (38 of 39 patients). CONCLUSION: While the staging accuracy of both CT and MR imaging is only moderate, prediction of tumor resectability is excellent.

Ovarian cancer recurrence: value of MR imaging.

PURPOSE: To assess magnetic resonance (MR) imaging in depiction of ovarian tumor recurrence and for identification of patients who may not benefit from surgical reexploration. MATERIALS AND METHODS: In a prospective study, 34 patients (mean age, 57.07 years) with surgically staged ovarian cancer underwent MR imaging before reexploration. Findings at MR imaging and surgery were correlated. MR imaging tumor depiction was correlated with tumor size, presence of ascites, and CA-125 levels. RESULTS: Tumor recurrence was identified in 29 patients at surgery. MR imaging depicted tumor in 20 patients. Accuracy for lesions smaller than 2 cm was 35% and increased to 82% for lesions larger than 2 cm (P < .01). MR imaging had low sensitivity for depiction of implants in the peritoneum and mesentery. Ascites improved depiction of smaller lesions (< 2 cm). MR imaging in combination with CA-125 levels improved detection of recurrent disease (CA-125 measurement alone 53% vs CA-125 measurement and MR imaging 75%, P = .048). CONCLUSION: MR imaging is a useful adjunct to the clinical examination to identify patients with recurrent disease and those in whom reexploration may not be beneficial.

Cervical carcinoma: computed tomography and magnetic resonance imaging for preoperative staging.

OBJECTIVE: To assess the accuracy of computed tomography (CT) and magnetic resonance imaging (MRI) in the evaluation of invasive cervical cancer. METHODS: Seventy-nine women with untreated cervical cancer underwent pre-treatment MRI (n = 71) and/or CT (n = 37) within 4 weeks of surgical evaluation. Twenty-nine women had both MRI and CT. Images were evaluated for tumor detection, size, stromal invasion, local extension, and nodal metastases. RESULTS: Tumor size was evaluated accurately by MRI, with a correlation coefficient of 0.93. Magnetic resonance estimates of tumor size were within 0.5 cm of the surgical sample in 64 of 69 women (93%). Magnetic resonance was 88% accurate evaluating the presence of stromal invasion and 78% accurate for depth of stromal invasion. Computed tomography could not evaluate tumor size or stromal invasion because it could not distinguish cancer from the surrounding normal cervical tissue. In evaluating stage of disease, MRI had an accuracy of 90%, compared with 65% for CT (P < .005). Magnetic resonance imaging was more accurate than CT (94 versus 76%, P < .005) in assessing parametrial invasion. Both modalities were comparable in evaluating lymph node metastases (86% each). In determining operative candidates (stage I and minimal IIA), MRI was 94% accurate, compared with 76% for CT (P < .005). CONCLUSION: Compared with CT, MRI offered significantly improved evaluation of tumor size, stromal invasion, and local and regional extent of disease in pre-treatment imaging for cervical cancer.

Desmoplastic small cell tumor of the ovary: a unique polyphenotypic tumor with an unfavorable prognosis.

Desmoplastic small cell tumor (DSCT) is a recently described intraabdominal neoplasm of uncertain histogenesis that occurs predominantly in boys and young men. We report a case in a young woman that presented clinically as bilateral ovarian tumors with extensive pelvic and abdominal dissemination. The patient had cytoreductive surgery followed by combination chemotherapy. She had a complete clinical remission, but tumor recurrence was detected 1 year after diagnosis and the patient died of her disease 18 months after presentation. DSCT has a distinctive histologic appearance and a unique immunophenotype. It can present as an ovarian neoplasm and must be considered in the differential diagnosis of small cell tumors of the ovary.

Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors mediate excitotoxicity in the oligodendroglial lineage.

We demonstrate by reverse transcriptase-polymerase chain reaction and Southern blotting that an immortalized rat oligodendroglial cell line (CG-4) expresses the non-N-methyl-D-aspartate (non-NMDA) glutamate receptor (GluR) genes GluR2-7, KA-1, and KA-2 and that nonimmortalized cells of the rat oligodendroglial lineage express the GluR1-3, GluR5-7, KA-1, and KA-2 genes. Lactic dehydrogenase release assays show that both immortalized and nonimmortalized cells of the oligodendroglial lineage are damaged by a 24-h exposure to 500 microM kainate or 5 mM L-glutamate, but not by a 24-h exposure to up to 10 mM alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA). Damage is prevented by the non-NMDA GluR channel inhibitor 6-cyano-7-nitroquinoxaline-2,3-dione and is also averted if Ca2+ is removed from the culture medium. Cyclothiazide, which blocks desensitization of AMPA-preferring GluRs, increases cytotoxicity of kainate as well as inducing toxicity of AMPA. We conclude that cells of the oligodendroglial lineage express a population of AMPA-preferring and possibly also kainate-preferring GluR channels that are capable of mediating Ca(2+)-dependent excitotoxicity and that AMPA-induced cytotoxicity is blocked by desensitization of AMPA-preferring GluRs.

Trophic effects of basic fibroblast growth factor (bFGF) on differentiated oligodendroglia: a mechanism for regeneration of the oligodendroglial lineage.

We have investigated the effect of basic fibroblast growth factor (bFGF) on the proliferation and phenotype of differentiated oligodendroglia. Using primary cell cultures enriched in oligodendrocytes but containing few O2A-oligodendrocyte progenitor cells, we demonstrate that bFGF treatment greatly increases the proportion of O2A cells while decreasing the proportion of galactocerebroside +(GalC+), myelin basic protein +(MBP+) oligodendrocytes, and the steady state levels of MPB mRNA. Complement mediated cell lysis experiments using the A2B5 antibody to deplete existing O2A cells or the R-Mab antibody to deplete existing oligodendroglia show that bFGF elicits a rapid increase in the number of O2A cells in cultures previously depleted of O2A cells, but does not cause an early increase in O2A cells in cultures from which oligodendroglia had been removed, indicating that the oligodendrocytes are the source of the newly recruited O2A cells. This bFGF-mediated transition from oligodendrocyte to O2A cells occurs with a time course similar to the bFGF-induced increase of the proliferation rate of the GalC+ oligodendrocytes. Studies with purified, passaged cells of the oligodendroglial lineage show that bFGF augments oligodendroglial dedifferentiation and proliferation in chronologically adult oligodendrocytes and in the virtual absence of other cell types. We have thus demonstrated that mature oligodendrocytes are induced by bFGF to dedifferentiate and proliferate, suggesting a mechanism for regeneration of the oligodendroglial lineage following demyelinating disease.

Carcinoma of the cervix: predictive value of clinical and magnetic resonance (MR) imaging assessment of prognostic factors.

PURPOSE: This retrospective study assesses the predictive value of magnetic resonance imaging (MRI) to identify high risk cervical cancer patients. METHODS AND MATERIALS: The MRI evaluation of morphologic risk factors in patients with invasive cervical carcinoma treated with definitive radiation therapy were correlated with clinical factors and with complete tumor regression (CTR) at 6 months, tumor local control (TLC), and patient outcome at 12 months after irradiation. Sixty-six patients, median age 44.5 years, with bulky Stage I or greater disease were included in the study. RESULTS: In univariate analysis, clinical International Federation of Gynecology and Obstetrics (FIGO) stage had significant correlation with patient outcome, but it correlated poorly with complete tumor regression and tumor local control. In contrast, MRI stage showed significant correlation with complete tumor regression, tumor local control, and disease-free survival at 12 months. When each stage was analyzed separately, the greatest difference was demonstrated between clinical and MRI assignment of stage Ib disease. MRI Stage Ib disease significantly correlated with all three categories analyzed, while clinical Stage Ib did not. Superiority of MRI assessment of low stage disease was also evident in the detection of lymph node metastasis. Significant risk for nodal metastasis was related to tumor size greater than 4 cm, invasion of the parametria and urinary bladder, and stage of the disease. CONCLUSION: The multivariate analysis demonstrated that the most related variables in order of significance were the presence of juxta-regional and paraaortic lymph nodes, patient age, tumor size, and MRI tumor stage. This study demonstrates the value of MR imaging as an adjunct to clinical assessment of bulky invasive cervical cancer, rendering more complete assessment of morphologic risk factors important in patient prognosis.

Bleomycin sclerotherapy of an intractable inguinal lymphocyst.

One of the complications of an inguinal lymphadenectomy is formation of a lymphocyst. The literature dealing with management of this complication is scant. In this report we present a patient who developed an inguinal lymphocyst which did not respond to percutaneous drainage, but was successfully treated with sclerotherapy using bleomycin. Based on our experience and review of the literature a scheme for the management of groin lymphocysts is presented.

The role of MR imaging in determining surgical eligibility for pelvic exenteration.

OBJECTIVE: The purpose of this study was to evaluate the role of MR imaging in the preoperative assessment of candidates for pelvic exenteration. Specifically, we sought to determine if MR imaging was reliable in selecting patients with pelvic cancer for surgical exenteration. MATERIALS AND METHODS: MR images of the pelvis were retrospectively evaluated in 23 patients with proved pelvic cancer. These images were analyzed for (1) presence and location of the primary or recurrent tumor; (2) tumor extension to the bladder, rectum, or pelvic sidewall; and (3) presence and location of lymphadenopathy. On the basis of the MR findings, we determined suitability for pelvic exenteration by using generally accepted contraindications to surgery (involvement of the pelvic sidewall muscles or metastatic lymphadenopathy). In addition, tumor involvement of the bladder or rectum was evaluated to help determine the type of exenteration indicated. Surgical and/or histologic confirmation was available in all 23 cases. RESULTS: The accuracy of MR imaging in selecting patients was 83% (19 of 23), with a positive predictive value of 56% and a negative predictive value of 100%. In evaluating tumor involvement of the pelvic sidewall and lymph nodes, the negative predictive values were 100% and 95%, respectively. Tumor extension into the pelvic sidewall was overestimated in four patients, in three of whom it was not possible to distinguish radiation changes from tumor on MR images. For assessing extension of these pelvic tumors into the bladder and rectum, MR imaging had an accuracy of 81% and 85%, respectively. CONCLUSION: MR imaging may provide an accurate means of selecting patients considered for pelvic exenteration. MR accurately determined which patients should undergo the surgery, by demonstrating absence of sidewall abnormalities or adenopathy. Radiation changes could not be reliably distinguished from tumor involvement in those patients with sidewall abnormalities, however, especially in the first 6 to 12 months after treatment.

Diffuse adenomatoid tumor of the uterus with a serosal papillary cystic component.

A 39-year-old woman undergoing immunosuppressive therapy following kidney transplantation for systemic lupus erythematosus presented with a uterine adenomatoid tumor that diffusely infiltrated the entire myometrium and contained a serosal papillary cystic component that resembled a cystic mesothelioma. This is the first reported case of an adenomatoid tumor showing both of these features. Although adenomatoid tumors are considered benign, the patient may be at risk for recurrence of the papillary cystic component (which is known to recur in 50% of cases) if this tumor reflects an inability to limit neoplastic processes.

Ovarian lesions: detection and characterization with gadolinium-enhanced MR imaging at 1.5 T.

Magnetic resonance (MR) imaging for detection and characterization of ovarian masses was assessed in 33 patients with a total of 60 lesions. Lesions were characterized prospectively as benign or malignant by using T2-weighted MR images and unenhanced and gadolinium-enhanced T1-weighted MR images. MR imaging findings were compared with results of surgical laparotomy performed for staging of lesions. When malignancy was suspected, staging with MR imaging was performed. MR imaging demonstrated 57 of 60 (95%) surgically proved ovarian masses (34 of 36 were benign, 23 of 24 were malignant). Five significant primary criteria and four ancillary criteria for malignancy were established. For all MR pulse sequences combined, characterization of either type of lesion was correct in 84% of cases (48 of 57) when the five primary criteria were used and 95% (54 of 57) were correct when the four ancillary criteria were added. With gadolinium-enhanced images, correct characterization of malignant lesions increased from 56% to 78% with use of the five primary criteria and from 83% to 100% with use of both sets of criteria. Malignancies were correctly staged with MR imaging in 12 of 16 patients. Staging accuracy was 63% with unenhanced images and 75% with the addition of enhanced images.

Carcinoma of the uterus: use of gadopentetate dimeglumine in MR imaging.

This prospective study assessed the role of gadopentetate dimeglumine-enhanced magnetic resonance imaging in the detection and staging of carcinomas of the endometrium and cervix. Surgical-pathologic findings were used as the standard of reference. In the evaluation of endometrial carcinoma, contrast-enhanced imaging improved tumor detection and differentiation between viable tumor and retained debris. Use of contrast material significantly improved the staging accuracy. The ability to assess the depth of myometrial invasion was also improved. In the evaluation of cervical carcinoma, assessment of tumor location and size did not improve following contrast enhancement. Use of gadopentetate dimeglumine resulted in overestimation of stromal, parametrial, vaginal, and/or bladder wall invasion in eight patients. However, evaluation of intratumoral architecture and large lesions was easier with contrast-enhanced imaging. When only stage II and higher disease was analyzed, use of contrast material improved the evaluation of disease extent. The authors conclude that gadolinium enhancement adds to the accuracy of evaluation of endometrial carcinoma but is useful in only advanced cases of cervical carcinoma.

Preventing cervical conization by achieving satisfactory colposcopy with hygroscopic cervical dilators.

Eighteen women with abnormal cervical cytologic findings and unsatisfactory colposcopic examinations underwent cervical dilatation with Dilapan (Gynotech), a hygroscopic dilator. Dilatation exposed the entire squamocolumnar junction, converting an unsatisfactory colposcopic examination into a satisfactory one and avoiding cervical conization in 17 of the patients.

Cerebral white matter contains PDGF-responsive precursors to O2A cells.

Cells dissociated from the cerebral white matter of immature rats were maintained in monolayer culture. Treatment with platelet-derived growth factor (PDGF) caused a large increase in the numbers of "O2A" oligodendroglial precursor cells (which bind the monoclonal antibody A2B5) and subsequently in the numbers of galactocerebroside (galC)-positive oligodendroglia. A2B5-negative "pre-O2A cells" in cerebral white matter cultures in which O2A cells and oligodendroglia had been killed by antibody-dependent complement-mediated cytolysis were induced by PDGF to proliferate and to differentiate into O2A cells and subsequently into oligodendroglia and type 2 astroglia. The most mature pre-O2A phenotype in these cultures was a small, round, process-bearing cell which expressed vimentin but not glial fibrillary acidic protein or galC. Cells of this phenotype were not observed upon PDGF treatment of immature rat optic nerve monolayer cultures from which O2A cells and oligodendrocytes had been depleted, and PDGF also failed to elicit the accumulation of O2A cells and oligodendroglia in such cultures.

Salvage whole-abdominal irradiation following chemotherapy failure in epithelial ovarian carcinoma.

During the period 1977 to 1985, 12 patients with FIGO stage II and III epithelial ovarian carcinoma failed to achieve a pathologic complete response with chemotherapy and underwent salvage whole-abdominal irradiation (WAXRT). Six of these patients had gross residual disease present at the time of irradiation, and three (50%) were unable to complete the planned radiotherapy. All eventually failed in the treatment field; their 5-year actuarial survival and local control rates were zero. The other six were irradiated without residual macroscopic disease. Five of the six (83%) were able to complete WAXRT as planned without prolonged delays. The 5-year actuarial survival and local control rates for this group were 21 and 25%, respectively. The actuarial laparotomy rate to relieve bowel obstruction following WAXRT was 40% at 2 years. The results from this and other series indicate that salvage WAXRT is not effective for patients irradiated with macroscopic tumor. However, WAXRT appears to be potentially curative for a small but significant percentage of patients irradiated without gross disease, although the risk of significant complications is high.