Tay-sachs disease. Detection of heterozygotes and homozygotes by serum hexosaminidase assay.
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Adult↗
Biomedical subjects
A Chen
Publications and source records attributed to A Chen.
Segmental hemorrhagic infarction of testis associated with epididymitis.
Testicular infarction is most commonly associated with acute testicular torsion. We present the sonographic findings in a case of segmental testicular infarction associated with epididymitis. The gray-scale abnormalities included a round, well-defined, hypoechoic intratesticular mass and heterogeneity and enlargement of the epididymis. Color Doppler sonography demonstrated only minimal blood flow in the intratesticular mass and increased flow in the epididymis. Recognition of acute testicular segmental infarction as a complication of epididymitis may prevent unnecessary orchiectomy.
Adult↗
Application of the multiple antigenic peptides (MAP) strategy to the production of prohormone convertases antibodies: synthesis, characterization and use of 8-branched immunogenic peptides.
Antiserum against an N-terminal sequence of murine prohormone convertase-1 (mPC1) incorporating the sequence immediately following the junction between the putative pro-region and the active enzyme was obtained. This was accomplished using the multiple antigenic peptide (MAP) approach whereupon an 8-branched polylysine core to which are grafted multiple copies of a 16 amino acid peptide representing the N-terminal sequence of mPC1 (positions 84-99) was synthesized by solid-phase Fmoc chemistry. The ensuing peptide was purified and fully characterized by RP-HPLC, 1H-NMR, amino acid composition, peptide sequencing and ion-spray mass spectrometry. The immunological properties of the resulting antibodies in detecting recombinant PC1 in both crude and purified preparations were compared with antibodies raised against a similar N-terminal segment of PC1 but using the conventional method of peptide-carrier protein conjugation and also developed against a C-terminal fusion protein of PC1. Our data indicate that the MAP antibody was as efficient as both the amino and carboxy-terminal antibodies in qualitative as well as quantitative analysis of PC1 encoded protein by radioimmunoassay. Following an identical approach, antibodies against other prohormone convertases like furin, PC5/6 and PACE4 were also developed and subsequently applied to a number of biochemical and immunological studies. In each case, the case of preparation and high immunogenicity of the MAP approach were confirmed and reside in the simplicity and rapidity with which a potent and useful antiserum is obtained.
Amino Acid Sequence↗
Scanning electron microscopy studies of protein-functionalized atomic force microscopy cantilever tips.
Protein-functionalized atomic force microscopy (AFM) tips have been used to investigate the interaction of individual ligand-receptor complexes. Herein we present results from scanning electron microscopy (SEM) studies of protein-functionalized AFM cantilever tips. The goals of this study were (1) to examine the surface morphology of protein-coated AFM tips and (2) to determine the stability of the coated tips. Based on SEM images, we found that bovine serum albumin (BSA) in solution spontaneously adsorbed onto the surface of silicon nitride cantilevers, forming a uniform protein layer over the surface. Additional protein layers deposited over the initial BSA-coated surface did not significantly alter the surface morphology. However, we found that avidin-functionalized tips were contaminated with debris after a series of force measurements with biotinylated agarose beads. The bound debris presumably originated from the transfer of material from the agarose bead. This observation is consistent with the observed deterioration of functional activity as measured in ligand-receptor binding force experiments.
Adsorption↗
Thermodynamic stability of bovine alpha-crystallin in its interactions with other bovine crystallins.
Light scattering measurements were performed on dilute solutions of alpha-crystallin mixed with different combinations of beta H, beta L and gamma-fractions of bovine lens crystallins. Light scattering intensities were obtained as a function of scattering angle, concentration and temperature. The temperature dependence of the second virial coefficients was used to obtain partial molar enthalpy and end entropy of solutions. The difference between the thermodynamic parameters of the crystallin mixtures and those of the weighted averages of the individual components yielded the excess enthalpy and entropy functions of the solutions. Both the excess enthalpy and entropy functions indicated that thermodynamic stability of alpha-crystallin is progressively enhanced by its interactions with gamma [symbol: see text] (beta H + gamma) [symbol: see text] (beta H + beta L + gamma) crystallins. The last two combinations showed negative values both for excess enthalpy as well for excess entropy of solutions. Other combinations demonstrated increasing positive values. This implies that the combination of all four crystallins in the vertebrate lens enables the best solvation property as well as the best packing as opposed to any other single or combinatorial arrangements of crystallins. Similar conclusions have been obtained in the past from water and other vapor sorption studies.
Animals↗
A rat model to study the role of STn antigen in colon cancer.
Expression of the mucin-associated sialyl-Tn (STn) antigen has been associated with a decreased survival in patients with colorectal, gastric, and ovarian cancer. To better understand the role of STn antigen in tumor biology, we developed STn(+) (called LP) and STn(-) (called LN) clonal cell lines from a parental metastatic rat colon carcinoma cell line (LMCR). Both derivative cell lines exhibited identical proliferation rates in vitro. LP cells strongly expressed STn antigen both in vitro and in vivo, and were poorly tumorigenic when given to syngeneic rats. LN cells did not express STn antigen in vitro, but as in vivo tumors these cells rapidly acquired STn expression, readily formed tumors, and were highly lethal. When rats were given an otherwise lethal inoculum of i.p. LN cells, pre-immunization with synthetic STn antigen conjugated to keyhole limpet hemocyanin (STn-KLH) resulted in a 60% survival rate. When LN cells were injected subcutaneously in the presence of STn-KLH-sensitized lymphocytes, tumor growth was decreased. Distribution of STn antigen in normal organs of host rats is quite similar to that of humans. This model mimics human disease and should facilitate studies of mucin-associated antigens in tumor biology and the development of immunotherapeutic agents based on mucin-related antigens.
Animals↗
Primary B cell lymphoma of the penis: successful treatment with organ preservation.
Malignant lymphoma uncommonly manifests in the genitourinary tract. Primary penile lymphoma is extremely rare. A 77-year-old male presented with primary malignant B-cell lymphoma of the penis with the chief complaint of a painless and itching nodule on the penile glans for more than 2 months. The pathologic examination with immunohistochemical stain of penile biopsy revealed malignant B cell lymphoma, mixed cellular type. The physical examination and the computed tomography scan of chest, abdomen, and pelvis showed no evidence of superficial, thoracic, abdominal, or pelvic lymphadenopathy. This case was treated with local excision and systemic chemotherapy with good cosmetic and functional results. There was absence of recurrence 16 months after therapy.
Aged↗
The effect of certain variables on the tumor and tissue distribution of tracers: VI. False-carrier effect, Part III, Fe.
Previous work has shown that Fe3+, when administered in the proper dose and time sequence, increases the tumor uptake of gallium-67 (67Ga) while decreasing its uptake by normal tissues. The purpose of this series of experiments was to examine further the postulate that the false carrier effect is mediated at the cellular as well as the vascular level, determine the lowest concentration of ionic Fe3+ that will induce near maximum tumor/background ratios (T/Bkg), determine the best technique for its administration, and decide whether Benadryl and dexamethasone could be used to offset side effects of the Fe3+ without altering tumor and tissue kinetics. Fe3+ altered tissue levels of 67Ga prior to changes in the blood. The threshold for initiation of the false-carrier effect varied to some extent from one organ to another. Tumor uptake of 67Ga was either enhanced or unaltered at 4 hours after injection; 0.3 mg Fe3+/kg administered 0.5 hour before and 2 hours after the 67Ga enhanced 4-hour T/Bkg by a factor of about ten. Twenty-four-hour ratios were improved (to a lesser extent than 4-hour), but decreased concentrations of 67Ga occurred in the tumor. Dexamethasone and Benadryl did not alter the outcome of the experiment. This technique should be useful for imaging with gallium-68 and the PET camera.
Animals↗
In situ assessment of cell viability.
Cryobiological studies of tissues often require the simultaneous assessment of tissue structure and in situ cellular function. Localization of damage during cryopreservation occurs as a consequence of tissue structure and morphology and as a result of biophysical constraints imposed by diffusion and heat transfer. This study used five experimental model tissue systems: cells in suspension, cells attached to a substrate, a monolayer of cells attached to a substrate, porcine corneas, and intact porcine articular cartilage to examine the efficacy of assessing cell recovery using a novel fluorescent stain (SYTO-13). A graded freezing protocol was used to induce varying degrees of tissue damage. Recovery was assessed in the different tissue model systems using SYTO with ethidium bromide, fluorescein diacetate (FDA) with ethidium bromide, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT). In each of the tissue model systems, the SYTO/EB assessment technique was shown to be equally effective as the existing techniques for the determination of cell recovery. In addition, the properties of fluorescence intensity and rate of release for SYTO were significantly better than those obtained using FDA. Assessment of in situ cell viability was clearly demonstrated using porcine corneas and articular cartilage. The SYTO/EB assay is superior to the existing techniques used for the localization of cell damage in tissues after cryopreservation.
Animals↗
An introduction to sequential electric acupuncture (SEA) in the treatment of stress related physical and mental disorders.
A method of sequential electrical stimulation to certain acupuncture loci was found to be effective in the treatment of stress related physical and mental disorders. Recent research found that cerebral serotonin has anti-depressant and analgesic effects. It was reported that cerebral serotonin can be released by the stimulation of certain acupuncture loci. Omura reported that the stimulation of ST36 and GB20 increased intracephalic blood flow. Increasing intracephalic blood flow may indirectly increase the quantity of serotonin released. The release of serotonin can be enhanced further by sequential stimulation of these acupuncture loci. A marked degree of mental relaxation by SEA was shown in this study of 85 clinical cases of chronic physical disorders, e.g. intractable pain, headache, with most disorders complicated by reactive depression. Some of the cases were psycho-somatic disorders. The percentage of improvement from slight to remarkable between mental disorders (78.8%) and physical disorders (77.1%) is about equal. The method of treatment and schematic of the SEA device are discussed and shown.
Adjustment Disorders↗
Cigarette smoking among Vietnamese immigrants in California.
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Adult↗
Inhibition of lung cancer proliferation by antisense cyclin D.
The growth and tumorigenicity of murine lung cancer cells transfected with an antisense cyclin D1 construct were evaluated in studies pertaining to mouse lung carcinogenesis. This antisense construct inhibited the expression of cyclin D in these cells, significantly reducing both their in vitro proliferation and tumorigenicity in nude mice relative to control cells. These data may have implications regarding the treatment of human neoplasms of aerodigestive tract origin that either overexpress the cyclin D oncogene or exhibit mutations that influence cell cycle progression via cyclin D-dependent mechanisms.
Animals↗
Performance of a fully automated in vitro allergy testing system.
BACKGROUND: Since the development of the radioallergosorbent test (RAST) for quantification of allergen-specific IgE, numerous non-radoisotopic methods have been devised which combine the proven cellulose disc technology with enzyme-linked immunoassay methods. The HY.TEC EIA (Hycor Biomedical, Inc. Irvine, CA) was compared with Pharmacia CAP with respect to overall system features and assay performance characteristics. METHODS: The HY.TEC EIA and Pharmacia CAP were compared with respect to calibrator range, sensitivity, type of detection, type of solid phase, throughput, and mode of operation. To determine the assay sensitivity and specificity for a variety of allergens, a total of 2,447 tests were performed on both CAP and HY.TEC EIA. The samples were scored positive in both cases using a cutoff of 0.35 IU/mL. RESULTS: The general features of the HY.TEC EIA system are comparable to Pharmacia UniCAP, with the added advantage of higher throughput. Intra-assay precision was 7% and inter-assay precision was 9-15%. Using CAP as a comparative method, HY.TEC EIA has a sensitivity of 94.0% and a specificity of 94.4%. CONCLUSIONS: The HY.TEC EIA demonstrates excellent agreement with the Pharmacia CAP system in the determination of allergen-specific IgE. With the automation necessary in today's clinical laboratory, we conclude that the HY.TEC EIA is a state-of-the-art tool for the diagnosis of allergic disease.
Allergens↗