Biomedical subjects

J McClintock

Publications and source records attributed to J McClintock.

8 recordsLinked to original sources

PubMed2006

Activators of viral gene expression in polarized epithelial monolayers identified by rapid-throughput drug screening.

Epithelial polarity and tight junction formation limit the ability of adenovirus, retrovirus and adeno-associated virus (AAV) to deliver and express virally encoded genes. Using an extended half-life luciferase assay and high-throughput luminometry, we screened 23 000 compounds and natural product extracts as potentiators to overcome this barrier. Seven strong activators were discovered (up to several hundred fold above control) and two of these exhibited spectrum of activity in multiple cell types (HeLa (human cervical carcinoma), cystic fibrosis bronchial epithelial (human bronchial), HT29 (human colonic carcinoma), Calu3 (airway serous glandular)). Enhanced transduction by unrelated gene transfer vectors (adenovirus, lentivirus, AAV, liposomal) was also observed. These results establish a strategy for identifying compounds that improve viral gene transfer to resistant cell types, and provide new tools for examining epithelial defense against viral infection. The compounds should have broad usefulness in experimental therapies for cancer and genetic diseases.

Adenoviridae↗

PubMed2001

Müller cell differentiation in the zebrafish neural retina: evidence of distinct early and late stages in cell maturation.

The vertebrate neural retina is mainly composed of cells of neuroectodermal origin. The primary cell types found in all vertebrate retinas are several categories of neurons and the archetypical retina glial cell the Müller cell. Although the neurons and the single glial cell type of the retina are specialized for very distinct functions, they all have a common developmental origin within the tissue. How the distinctions between cell types, in particular between neurons and glia, arise during embryonic development remains a central issue in neurobiology. In this report, we examine the genesis of Müller glial cells during zebrafish (Danio rerio) eye development. Particular emphasis is placed on the expression of the Müller cell maturation markers carbonic anhydrase and glutamine synthetase. In addition, we report that the HNK-1 monoclonal antibody, which identifies a particular glycoconjugate frequently found on cell surface recognition molecules, also identifies zebrafish retina Müller cells early in development. The expression patterns of these three markers clearly show that the Müller cells mature in stages: HNK-1 labeling and glutamine synthetase arise earlier than carbonic anhydrase expression. In addition, the embryonic zebrafish neural retina is characterized by the presence of amoeboid, carbonic anhydrase-positive microglial cells even before the genesis of retinal neuroectodermal glia. The stepwise maturation of the glia is likely to be indicative of an overall retinal maturational program in which cell differentiation and the expression of certain phenotype-defining gene products may be separately regulated.

Animals↗

PubMed1996

Isolation of 20 glycosides from the starfish Henricia downeyae, collected in the Gulf of Mexico.

Thirteen new (1-13) and seven known (14-20) steroid glycosides were isolated from Henricia downeyae, collected from the offshore waters of the northern Gulf of Mexico. Ethanolic extracts of these starfish caused growth inhibition in bacteria and fungi, potent antifouling activity against barnacle and bryozoan larvae, and feeding deterrent activity against a marine fish. The known compounds are typical glycosides found in several species of the family Echinasteridae, i.e., Echinaster sp. and Henricia laeviuscola. One of the new compounds belongs to this group, whereas the remaining 12 new compounds represent a novel series of steroid glycosides which have aglycons with structural similarities to the "asterosaponins". They possess a delta 9(11) 3 beta, 6 alpha-dihydroxysteroidal aglycon with 23-oxo or 22,23-epoxy functionalities and often a 20-hydroxyl group in the side chain. The sulfate is located at C-6 and the saccharide moiety at C-3, in contrast with the asterosaponins which have the sulfate at C-3 and the oligosaccaride moiety at C-6. All the new compounds contain a glucuronic acid unit, which is uncommon among steroid glycosides from echinoderms. The structures of the new compounds, isolated in amounts ranging from 3.4 to 0.9 mg, were determined by interpretation of their spectral data and by comparison with spectral data of known compounds.

Animals↗

PubMed1995

Chemical and biological investigation of the polar constituents of the starfish Luidia clathrata, collected in the Gulf of Mexico.

Ten new [1-10] and three known [11-13] polyhydroxysteroids were isolated, along with four known asterosaponins [14-17], from the starfish Luidia clathrata, collected from the offshore waters of the northern Gulf of Mexico. The EtOH extracts of this starfish showed feeding-deterrent properties against marine fish, and inhibited the settlement of larvae of barnacles and bryozoans, as well as the growth of several bacteria. The structures of the new compounds were determined by interpretation of their nmr spectral data and by comparison with the spectral data of known compounds. The assignment of the configurations of the side-chain stereogenic centers of compounds 1 and 3-10 were based on the comparison of their nmr data with those of the stereoisomeric model compounds after derivatization with the chiral auxiliary MTPA reagent. Larval settlement assays conducted on ten isolated compounds revealed they are all potent inhibitors of settlement. Two of these isolated compounds inhibited the growth of several bacteria.

Animals↗

PubMed1995

Chromophobe cell carcinoma of the kidney. A clinicopathologic study of 21 cases.

The clinicopathologic features in a series of 21 chromophobe cell carcinomas are reviewed. Patients' ages ranged from 30 to 83 years (mean, 53 years), and the number of men and women was roughly equal. Major presenting complaints included hematuria, flank pain, and flank mass. All but two tumors were staged as tumor node metastasis (TNM) T2N0M0. Histologically, the carcinomas were composed of large cells with variably reticulated, translucent cytoplasm. The tumor cells could be divided into three types according to the extent and distribution of reticulated cytoplasm. Ultrastructurally, these reticulated areas were characterized by the presence of large numbers of microvesicles, which appeared to be unique to chromophobe cell carcinomas because ultrastructural examination of 20 clear cell carcinomas and six granular cell carcinomas failed to reveal similar structures. The origin of the vesicles appeared to be from saccular outpouchings from the outer mitochondrial membrane. Immunohistochemical studies revealed that all the tumors were variably positive for cytokeratins 8, 18, and 19, and epithelial membrane antigen but negative for vimentin. Flow cytometric DNA analysis of eight carcinomas revealed slightly hypodiploid cell populations in seven tumors. Of these, four also contained hyperdiploid cell populations. Follow-up (6-108 months) of 16 patients revealed all these patients to be alive and well. These findings further confirm the concept that chromophobe cell carcinoma is a special subtype of renal cell carcinoma in which the presence of microvesicles is a characteristic morphologic feature. Furthermore, loss of chromosomal DNA may also be a frequent, perhaps unique, feature of chromophobe cell carcinoma.

Adenocarcinoma↗

PubMed1994

Neuroendocrine differentiation in prostatic adenocarcinoma and its relationship to tumor progression.

BACKGROUND: Neuroendocrine differentiation has been demonstrated by immunohistochemical preparations in many cases of acinar type prostatic adenocarcinoma (CAP). Some studies have suggested that this differentiation may indicate an adverse prognosis. METHODS: Tissue samples from 38 consecutive patients with clinical Stage II (AJCC) CAP who underwent radical retropubic prostatectomy (RRP) were studied after preparations were made with antichromogranin (ChA) and neuron-specific enolase (NSE). All patients were followed for at least 4 years post-RRP or until disease progression was documented by rising serum prostate specific antigen concentration, X-ray evidence of recurrence, or a positive tissue biopsy. RESULTS: Nine of the 38 RRP specimens (24%) were positive for NSE, and 11 (29%) were positive for ChA. Neither of these neuroendocrine markers showed a significant correlation with tumor progression. Neuroendocrine differentiation in needle biopsy specimens from these same patients (when available) did not correlate with tumor progression either. Of the patients with tumor progression, 9 of 11 (82%) had pathologic Stage III disease after RRP; of those with no progression of CAP, only 7 of 27 (26%) had pathologic Stage III disease. CONCLUSIONS: Neuroendocrine differentiation, as demonstrated by NSE and ChA preparations, was not helpful in predicting tumor progression of CAP.

Biomarkers, Tumor↗

PubMed1982

Lead staining in the Golgi complex.

Lead ions at similar concentrations to those used for Gomori type phosphatase localization stain some parts of the vacuolar system, particularly compartments of the Golgi complex (GC) and isolation envelopes (im) in a characteristic way in both vertebrates and invertebrates. After fixation in 2.5% glutaraldehyde, lead citrate in acetate or aspartate buffer (pH 5.5-7.2) leaves the contents of GC cisternal compartments with a fine particulate stippling. In the fat body of Calpodes ethlius and in mouse pancreas the staining is faint but definite without further enhancement of contrast, although it is easily overlooked after section staining. The distribution of lead stain differs from that of the lead phosphate precipitated after Gomori type acid phosphatase reactions. Whereas lead stain may be in all GC and im compartments, acid phosphatase is restricted to the innermost saccules and nearby vacuoles. The compartment specific staining by led also differs from the generalized staining in all compartments given by uranyl. Thus the contents of luminal membrane surfaces of some parts of the vacuolar system can be characterized by their ability to bind lead. In cells where protein synthesis has been blocked by cycloheximide, secretory vesicles are absent and the RER and GC from the generalized staining in all compartments given by uranyl. Thus the contents of luminal membrane surfaces of some parts of the vacuolar system can be characterized by their ability to bind lead. In cells where protein synthesis has been blocked by cycloheximide, secretory vesicles are absent and the RER and GC from the generalized staining in all compartments given by uranyl. Thus the contents of luminal membrane surfaces of some parts of the vacuolar system can be characterized by their ability to bind lead. In cells where protein synthesis has been blocked by cycloheximide, secretory vesicles are absent and the RER and GC cisternae are devoid of uranyl stainable material. However, lead staining and acid phosphatase activity in the GC continue. We presume that they mark the environment within these cisternae rather than the proteins passing through them. This environment is itself not static. Several observations suggest that the function of cisternae that is detectable by lead staining is temporally discontinuous and related to a stage of maturation or development. Only early stage ims stain: the staining ceases by the beginning of autophagy after hydrolytic enzymes are presumed to have been added. Condensing vacuoles cease to stain as the central core crystallizes out. Stain may be absent from one or two GC saccules at any position in the stack as though the phase of lead staining (or lack or it) can move progressively through the system. We conclude that in studies characterizing components of the vacuolar system it is necessary to separate those that mark transient occupants of a compartment from those that mark the compartment itself. Both may vary temporally independently from one another.

Acid Phosphatase↗

PubMed1982

Monocyte IgG-Fc receptors in myotonic dystrophy.

Myotonic dystrophy (MyD), an autosomal dominant neuromuscular disease with multisystem abnormalities, is associated with hypercatabolism of IgG. The hypercatabolism is not related to structural abnormalities of the IgG molecule in MyD but appears to be due to a derangement of the serum IgG concentration-fractional catabolic rate relationship. Since the catabolic pattern of IgG is governed by the Fc portion of the molecule, the possibility of Fc receptor dysfunction in MyD has been explored. We have observed that although MyD patients have normal numbers of Fc receptor bearing leucocytes in their peripheral blood, MyD monocytes express significantly (P less than 0.02) greater numbers of Fc receptors (47.9 +/- 21.2 X 10(3) receptors/monocyte) than do monocytes of healthy subjects (29.1 +/- 9.6 X 10(3) receptors/monocyte). The mean affinity constants of the Fc receptors was lower in the MyD group (1.5 +/- 0.7 X 10(8)/M) than the normal control group (2.4 +/- 0.9 X 10(8)/M) but this difference was not statistically significant. MyD monocytes showed a propensity to shed Fc receptors in culture at 37 degrees C whereas no significant shedding was observed with control monocytes. Thus MyD monocytes may shed Fc receptors at physiological temperatures but at the same time express more receptors per cell than normal monocytes. This suggests that MyD monocytes may have an abnormally high turn-over of Fc receptors.

Cells, Cultured↗