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Biomedical subjects

J Lo

Publications and source records attributed to J Lo.

At least 37 records · Page 2Linked to original sources
PubMed1996

Correlation of DNA ploidy and histologic diagnosis from prostate core-needle biopsies: is DNA ploidy more sensitive than histology for the diagnosis of carcinoma in small specimens?

DNA ploidy has been shown to have prognostic value in adenocarcinoma of the prostate. While occasional benign lesions of the prostate may be associated with a DNA aneuploid status, most aneuploid epithelial proliferations of the prostate are carcinomas. Because of the relationship between aneuploidy and malignancy, DNA ploidy analysis might improve detection of adenocarcinoma in small core-needle biopsy specimens. In this study, DNA ploidy analysis was performed on 186 fresh core biopsies from 32 patients who had undergone transrectal, ultrasonographically directed core-needle biopsies. Ploidy level was determined by Feulgen staining and image analysis with a CAS 200 image analyzer (Becton Dickinson-Cellular Imaging Systems, San Jose, CA). The resultant DNA ploidy levels were compared with the initial histologic diagnosis and subsequent clinical and pathologic follow-up. Nondiploid DNA patterns correlated with a diagnosis of carcinoma on core biopsy in 11 of 16 nondiploid cases and with a final diagnosis of malignancy in 13 of 16 nondiploid cases. Two patients with biopsy proven carcinoma had DNA diploid tumor patterns. Ploidy analysis had a sensitivity of 86.6% and a specificity of 73.7% in predicting the final diagnosis of malignancy. One case interpreted as DNA tetraploid by image analysis revealed seminal vesicle tissue on both the cytologic preparations and the core biopsy. Two DNA aneuploid specimen associated with cores initially read as benign or atypical demonstrated adenocarcinoma either on review of the original core biopsy or the prostatectomy specimen. The final DNA aneuploid specimen revealed acute prostatitis in the core biopsy. DNA ploidy analysis of core biopsy specimens appears to have relatively good specificity and sensitivity for the detection of prostatic carcinoma. Sampling errors appear to be the major cause of false negative results. Inappropriate measurement of seminal vesicle tissue and acute prostatitis can result in false positive results.

Adenocarcinoma↗
PubMed1996

Morin hydrate inhibits azo-initiator induced oxidation of human low density lipoprotein.

We demonstrated that the flavonoid morin hydrate at 75-100 microM protects against the oxidation of low density lipoprotein (LDL) by free radicals produced by 2,2'-azo-bis(2-amidinopropane) dihydrochloride. Morin hydrate reduces the relative electrophoretic mobility, malondialdehyde equivalents and lipid peroxide level of oxidized LDL. On the other hand, Trolox (an analogue of vitamin E) showed less protective effect in the present system. Since free radical mediated oxidation of LDL is implicated to be a cause of atherogenesis, morin hydrate may be a candidate chemotherapeutic agent herein.

Amidines↗
PubMed1996

Establishment of Schwann cell lines from normal adult and embryonic rat dorsal root ganglia.

Schwann cells, an important component of the peripheral nervous system, interact with neurons to mutually support growth and replication in the embryo and survival and differentiated function in the adult. The ability of adult Schwann cells to re-enter the cell cycle after nerve injury is crucial to their role in nerve repair. This ability suggests that it should be possible to obtain non-transformed, cell lines which maintain the characteristics of proliferating adult Schwann cells in vivo, as well as obtaining Schwann cells from rapidly dividing embryonic tissues. One approach to obtaining normal functionally differentiated cell lines has been to start primary cultures in serum-free medium containing growth factors and attachment proteins specifically selected to favor the replication of the cell type of interest. By culturing dispersed dorsal root ganglia on laminin, in serum-free medium with hormones and growth factors, we repeatedly generate homogenous Schwann cell cultures which yield normal Schwann cell lines from the dorsal root ganglia (DRG) of both embryonic and adult rats. These cells maintain the phenotype of Schwann cells as determined by morphology and staining for GFAP, S100, p75 NGF receptor, laminin, and MAG production in co-culture with DRG neurons.

Animals↗
PubMed1995

Delineation of an immunodominant and human T-cell lymphotropic virus (HTLV)-specific epitope within the HTLV-I transmembrane glycoprotein.

Antibody reactivity to the transmembrane region of human T-cell lymphotropic virus type I (HTLV-I) envelope, gp21, is observed in virtually all individuals infected with HTLV-I or HTLV-II. Recombinant proteins encoding selected portions of gp21 are described and used to define two immunogenic regions. The first epitope (designated GD21-I) contains amino acids 361 to 404 of the HTLV-I envelope and reacted with all of 54 sera from HTLV-I- and HTLV-II-infected individuals. The second epitope (designated BA21) expresses amino acids 397 to 430 of the HTLV-I envelope and was recognized by 33 of 54 HTLV antisera. To determine the specificity of GD21-I and BA21, sera from 17 HTLV-negative individuals with nonspecific reactivity to p21E were tested. None of these sera reacted with GD21-I, but 16 of 17 sera reacted with BA21. With virtually complete reactivity to sera from HTLV-infected individuals and no reactivity to sera from p21E-reactive uninfected individuals, GD21-I will be useful in immunoassays for the detection of HTLV infection.

Amino Acid Sequence↗
PubMed1995

Modes of photodynamic vs. sonodynamic cytotoxicity.

We compared effects of ultrasound-induced vs. photodynamic cytotoxicity in cell culture. The photodynamic effects mediated by mesoporphyrin caused a delayed toxic reaction, the presence of a "shoulder" on the dose-response curve, indicating the capacity for limited repair of photodamage. In contrast, ultrasound-induced loss of viability resulted from rapid cell destruction and was proportional to the time of sonication. Photodynamic damage to cells before exposure to ultrasound potentiated cell breakage but did not affect the clonogenicity of the surviving cell population. Photodamage after exposure to ultrasound decreased the viability of cells which had survived ultrasonic treatment.

Animals↗
PubMed1994

2-Deoxyglucose uptake patterns in response to pure tone stimuli in the aged rat inferior colliculus.

The tonotopic map of the inferior colliculus (IC) of aged rats (25 months old) was examined to determine whether age-related changes known to occur in the cochlea are reflected in the 2-deoxyglucose (2-DG) uptake pattern of the IC. Because aged animals have hearing losses, auditory brainstem response thresholds were measured. Animals with threshold shifts of no greater than 30 dB relative to young animals were used. Animals were injected with radiolabeled 2-DG and stimulated with continuous pure tones presented at 70 dB above the behavioral thresholds for young animals at either 1, 4 or 32 kHz for one hour in a sound attenuated booth. The stimulus sound pressure levels were chosen to achieve comparable sensation levels between the young and aged animals. The tonotopic map of the IC in aged rats was different from that reported previously for young animals (Ryan et al., 1988), in that, the regions stimulated by 1 and 4 kHz were shifted towards the higher frequencies and the uptake areas were twice as broad for the aged animals as for the young animals. The observed 2-DG uptake patterns are consistent with an activation pattern of a high intensity stimulus and a loss of responsive elements in the cochlear apex. Similar broad and shifted bands of activated tissue may contribute to difficulties in auditory perception in aged humans with increased thresholds and sound amplification.

Acoustic Stimulation↗
PubMed1993

Human T-cell leukemia virus type II infection frequently goes undetected in contemporary US blood donors.

Serologic screening for human T-cell leukemia virus type I (HTLV-I) infection was begun in US blood banks with the licensure of enzyme-linked immunosorbent assays (ELISA) in December 1988. We examined the donation histories of the first 60 Western blot (WB)-confirmed HTLV-I/II positive donors to one blood center and found 8 had made 16 previous donations that scored negative on the screening ELISA. All 16 donations had ELISA absorbance below the cutoff for a positive assay, but still well above that of the average donation (17.6% +/- 5.7% of the cutoff). In a more extensive study, 17 donations from a total of 61,752 at six blood centers were both ELISA-positive and WB-positive for HTLV-I (4) or HTLV-II (13), and 218 samples had ELISA absorbance greater than 50% of the ELISA cutoff. One hundred seventy-eight of the 218 were tested further by WB and 11 were found positive. All 11 positives were confirmed by polymerase chain reaction; 10 had HTLV-II and 1 had HTLV-I. Thus, the HTLV-I-based screening ELISA missed at least 10 of 23, or 43% (95% confidence interval, 23% to 66%), of HTLV-II infections, compared with 1 of 5, or 20%, of HTLV-I infections.

Blood Donors↗
PubMed1992

Chromium-51 labeling of sheep red blood cells.

The failure of sheep red blood cells (RBCs) labeled with Chromium-51 (Cr-51) using the ascorbic acid technique to act as a suitable intravascular marker of blood volume in a septic sheep model prompted us to investigate the technique of radiolabeling sheep erythrocytes with this isotope. Consequently, we studied thirteen sheep in which the labeling efficiency of Cr-51 as sodium chromate and hemoglobin typing was determined for each animal. Mean Cr-51 labeling efficiency of sheep RBCs was 67.5% (n = 13). Although 5 of the 13 sheep were discovered to have two types of hemoglobin (Hb) as determined by electrophoresis, overall labeling efficiency of sheep RBCs was determined to be independent of the type of hemoglobin present. However, when two types of Hb were present (Hb-A and Hb-B), Cr-51 had a higher affinity for Hb-B (80%) than Hb-A (20%) even though both Hb types are present in similar proportions (Hb-A = 53%, Hb-B = 46%). The results of this study indicate that sheep RBCs express a lower labeling efficiency for Cr-51 than do human RBCs and that Cr-51 has a higher affinity for Hb-B than for Hb-A when both hemoglobin types are present. This difference is noteworthy when interpreting Cr-51 RBC data in experimental sheep models. Furthermore, caution should be exercised when extrapolating established human protocols to animal models.

Animals↗
PubMed1991

Rapid skin edge elevation using the OCT compound droplet technique to obtain horizontal microsections in Mohs micrographic surgery.

We describe a technique to quickly raise the skin edges when mounting flat tissue specimens on cryostat discs used in Mohs micrographic surgery. The technique consists of placing a drop of OCT compound on the superficial surface of the tissue before the specimen is mounted bottom-side-up on the cryostat object disc. When the Mohs tissue layer is transferred to the disc, the droplet spreads out underneath the tissue to support the bottom and to prevent the skin edges from dropping below the horizontal plane of the tissue. This technique assures that the skin edge and bottom surface of the tissue are on the same plane so that a complete section of the undersurface of the flat specimen is taken when the tissue is cut with the microtome. The technique is relatively simple to perform, requires no special instrumentation, and provides consistent microsections with complete skin edge.

Humans↗
PubMed1989

Control of intractable spasticity with intrathecal morphine sulfate.

Three years ago we reported our preliminary results regarding treatment of intractable spasticity with use of intrathecal morphine. This paper is a follow-up report of 12 patients who underwent implantation of a pump or reservoir for delivery of intrathecal morphine sulfate for control of spasticity. Our primary concern initially was that patients would ultimately become drug tolerant and lose the beneficial effect of the morphine. Only one of these 12 patients has developed drug tolerance. The longest follow-up period has been 4.3 years, and this patient has maintained excellent control of his spasticity with a stable dose of 2 mg of morphine daily.

Drug Tolerance↗
PubMed1987

Isolation of a retrovirus from the American bison and its relation to bovine retroviruses.

Tissue samples were removed at necropsy from five American bison (Bison bison) with clinical signs of a disease resembling malignant catarrhal fever (MCF). Using cell-associated virus techniques, attempts were made to isolate viruses from these tissues by culturing them directly or by co-culture with bovine fetal cells. Among the viruses isolated was one which was syncytiogenic and multiplied in bovine fetal spleen cells and remained highly cell-associated. The presence of reverse transcriptase activity indicated that it was a retrovirus. Also, it had antigenic cross activity with bovine syncytial virus, but not with bovine leukemia or bovine maedi-like retroviruses. We do not attribute a direct causative role of this retrovirus to MCF, but indirect relationships are possible.

Animals↗
PubMed1985

Protein adsorption on hydrogels. II. Reversible and irreversible interactions between lysozyme and soft contact lens surfaces.

Lysozyme was adsorbed on spin cast and lathe cut soft contact lenses of poly-2-hydroxyethylmethacrylate (PHEMA) and on poly-HEMA-methacrylic acid (PHEMA/MAA). The in vitro adsorption process was followed by ATR-FTIR. Lysozyme adsorbs both, reversibly and irreversibly, on the surfaces. While the reversible bound lysozyme experiences only minor changes in its secondary structure, conformational changes occur for the irreversibly adsorbed protein. The type and extent of structural changes depend on the degree of protein coverage on the lens surface, as well as the chemical structure and surface morphology of the lenses. PHEMA/MAA lenses adsorbed thirty times more lysozyme than either of the PHEMA lenses. Fabrication processes appear to induce different adsorption behaviour, PHEMA lathe cut lenses adsorb twice the amount of protein compared with PHEMA spin cast lenses.

Adsorption↗
PubMed1984

Surface analysis of biomedical polymers by attenuated total reflectance-fourier transform infra-red.

An infra- red approach has been developed to characterize hydrophilic biomaterials, particularly contact lenses. Water was utilized as the optical coupling agent between the sample and the ATR element. This method enables the study of hydrophilic polymers in their natural aqueous environment and simultaneously solves the optical contact problem that usually arises when the ATR technique is used. Some studies were made utilizing this approach: dry and hydrated samples were structurally compared; also, a depth profiling study and a surface comparison were made on soft contact lenses fabricated by different industrial processes. Finally, the three dimensional orientation of one hydrated structure was characterized.

Biocompatible Materials↗
PubMed1984

Characterization of protein adsorption on soft contact lenses. I. Conformational changes of adsorbed human serum albumin.

Adsorption of human serum albumin on three different soft contact lens surfaces (lathe cut and spin cast crosslinked PHEMA and spin cast PHEMA/MAA) was studied. Using ATR--FTIR spectroscopy the spectra of the adsorbed protein were obtained at different times of adsorption. Structural changes were detected, initially characterized by an increase in hydrogen bonding and after that by involvement of the protein hydrophobic side chain residues. At long adsorption times, the protein becomes denatured, its alpha-helix content is drastically reduced and the amounts of random coil and beta-sheet conformations are increased. ATR-FTIR and circular dichroism studies of albumin solutions reveal similar conformational changes to those experienced by the adsorbed protein. Differences in the adsorption behaviour for the hydrogel surface, indicate the importance of the hydrophilicity, surface regularity and the chemical composition of the contact lens surfaces as the controlling parameters in the protein adsorption phenomena.

Adsorption↗
PubMed1983

Gastric duplication in an adult.

Congenital alimentary duplications occur most commonly in relation to the ileum and are rare in the region of the stomach. A case of gastric duplication presenting in an adult and visualized on computed tomography is reported.

Adult↗