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Biomedical subjects

J Hsu

Publications and source records attributed to J Hsu.

At least 55 records · Page 3Linked to original sources
PubMed1998

Decreased citrate improves iron availability from infant formula: application of an in vitro digestion/Caco-2 cell culture model.

We have applied an in vitro digestion/Caco-2 cell culture model to the assessment of iron availability from human milk and a generic cow's milk-based infant formula. Experiments were designed to determine the availability of iron from human milk relative to infant formula and whether known promoters of iron absorption would increase Caco-2 cell iron uptake and availability from the infant formula. In addition, we sought to determine if decreasing the citrate concentration in the infant formula would increase the iron uptake. Although approximately twice as much iron was in solution from digests of the infant formula relative to that of human milk, smaller or equal amounts of iron were taken up from the infant formula relative to the human milk digest. These results are qualitatively similar to in vivo studies. Addition of known iron uptake promoters to infant formula did not enhance Caco-2 cell iron uptake from the infant formula digest, indicating that the iron in the infant formula existed predominantly in a tightly bound unavailable form(s). Enzymatic pretreatment of the infant formula with citrate lyase and oxalacetate decarboxylase decreased the citrate concentration by 67% and resulted in a 64% increase of iron in solution, which corresponded to a 46% increase in the cell iron uptake. Iron uptake from the "low citrate" formula plus cysteine was 102% greater relative to the nontreated formula. The results indicate that too much citrate can reduce iron uptake, particularly if it is present at concentrations greater than promoters such as ascorbic acid and cysteine.

Animals↗
PubMed1997

Technology evaluation report: obtaining pulse oximeter signals when the usual probe cannot be used.

We studied the function of four different monitoring probes used with the Satlite pulse oximeter (Datex, Helsinki). The aim was to evaluate ease of use and compare the function of the probes and their attachment methods in different locations (finger, toe, ear, thumb web, instep, wrist, and ankle). Two similar pulse wave oximeters were used in the study. To select the best signal we determined the absolute height of the plethysmographic waveform for each probe. Probes were compared on awake normal adult volunteers (N = 13), in anesthetized adult patients (N = 12), and in neonates weighting 500-1000 g (N = 8). In all the adult trials, the clip-on finger probe was used as a reference, and probes taped or clipped onto the finger provided adequate signal from the ear or from the thumb web, however. In the neonates, taped-on probes were most satisfactory.

Adult↗
PubMed1997

Regulation of vascular endothelial growth factor expression by insulin-like growth factor I.

Insulin-like growth factor I (IGF-I) and vascular endothelial growth factor (VEGF) levels are correlated with retinal ischemia-associated intraocular neovascularization in humans. Since VEGF is required for iris and retinal neovascularization in animal models of retinal ischemia, we tested whether IGF-I could act as an indirect angiogenic factor by increasing VEGF gene expression. IGF-I increased retinal pigment epithelial (RPE) cell VEGF mRNA in a concentration-dependent manner with an EC50 of 7 nmol/1 (53.6 ng/ml). RPE and bovine smooth muscle cells exposed to 50 nmol/l (383 ng/m1) IGF-I achieved peak VEGF mRNA expression within 2 h. IGF-I-treated RPE cells increased VEGF protein levels in conditioned media and stimulated capillary endothelial cell proliferation. Blockade of the IGF-I receptor with a neutralizing antibody abrogated the VEGF increases in RPE cells. Further, hypoxia-mediated and IGF-I-mediated increases in VEGF mRNA and protein levels were additive in RPE cells, and the hypoxia-induced VEGF increases were independent of endogenous IGF-I. VEGF promoter activity was enhanced by IGF-I in RPE cells, but VEGF transcript half-life was unaltered. In summary, the supplementation of RPE and smooth muscle cell cultures with IGF-I at 5-100 nmol/l increased VEGF mRNA and secreted protein levels. The VEGF increases in RPE cells occurred primarily through enhanced transcription of the VEGF gene and via the IGF-I receptor. Elevated IGF-I levels may promote neovascularization through increased retinal VEGF gene expression.

Animals↗
PubMed1995

Coronary artery aneurysms after angioplasty and atherectomy.

Coronary artery aneurysm formation after percutaneous transluminal coronary angioplasty and directional coronary atherectomy is unusual. We report the case of a left anterior descending coronary artery aneurysm that formed in such a patient. The left anterior descending coronary artery was bypassed and the aneurysm was plicated with the aid of coronary angioscopy. The English-language medical literature on the topic of coronary artery aneurysms is reviewed.

Angioplasty, Balloon, Coronary↗
PubMed1995

Cerebral ocular Whipple's disease: a 62-year odyssey from death to diagnosis.

A 47-year-old white man with dementia, supranuclear ophthalmoplegia, and myoclonic ocular and facial jerks died in 1931. The case report in 1936 by Ford and Walsh diagnosed encephalitis. In 1993, we made a clinical diagnosis of Whipple's disease on the basis of the 1936 publication. We restudied the pathologic material and found, in addition to extensive encephalitis, PAS-positive material in only the eye, brain, spinal cord, and pituitary. Electron microscopy demonstrated free and intracytoplasmic microorganisms in the eye and brain. We review the history of cerebral ocular Whipple's disease and the implications from this case, which occurred before the development of antibiotics.

Astrocytes↗
PubMed1994

The helix-loop-helix protein Id-2 enhances cell proliferation and binds to the retinoblastoma protein.

Cell growth and differentiation are usually antagonistic. Proteins of the basic helix-loop-helix (bHLH) family bind DNA and play important roles in the differentiation of specific cell types. Id proteins heterodimerize with bHLH transcription factors, blocking their activation of lineage-specific gene expression and thereby inhibiting cellular differentiation. To examine the effect of Id-2 on cell proliferation, we overexpressed Id-2 in the human osteosarcoma cell line U2OS. Id-2 expression in U2OS reduced the serum requirement for growth and stimulated cellular proliferation by shortening the doubling time and increasing the percentage of cells in S phase. We demonstrated that Id-2 expression was able to reverse the inhibition of cellular proliferation and the block in cell cycle progression mediated by the product of the retinoblastoma tumor suppressor gene pRB. This effect was not associated with changes in the state of pRb phosphorylation in transfected cells. In vitro, unphosphorylated pRb from cell lysates specifically bound Id-2 but was not able to bind a mutated form of Id-2 lacking the HLH domain that also did not antagonize the growth arrest by pRb. In vitro-synthesized pRb containing mutations within the E1A/large T-binding pocket did not bind Id-2. However, wild-type pRb was able to bind to a region of Id-2 corresponding to only the HLH domain. In vivo, a physical association between Id-2 and pRb was seen in cross-linked extracts from SAOS-2 cells transfected with Id-2 and pRb. Our data identify a role for Id-2 in the regulation of cellular proliferation and suggest that the interaction between Id-2 and pRB is a molecular pathway over which synchronous changes in growth and differentiation are mediated in vivo.

Base Sequence↗
PubMed1994

The bovine papillomavirus type 1 genome contains multiple loci of static DNA bending, but bends are absent from the functional origin of replication.

Twenty-four overlapping restriction fragments spanning the entire bovine papillomavirus type 1 (BPV-1) genome were analyzed by electrophoresis to determine the extent of static DNA bending in the BPV-1 genome. Thirteen of 24 fragments contained static bends. Based on known locations of previously mapped bend loci and the overlapping pattern of these 13 fragments, we estimate that there are 8-11 distinct static bend loci in the BPV-1 genome. The bend loci were not uniformly distributed on the genome and with one exception, were clustered from nucleotides 5816 to 2621 on the BPV-1 map. This portion of the BPV-1 genome contains most of the transcriptional regulatory sequences as well as the origin of replication. The concordance between the genomic distribution of DNA bends and cis-active elements is consistent with the possibility that bent sequences may contribute to the function of at least some of these elements. However, unlike SV40, there was no static bend at that functional origin of replication for BPV-1. The nearest bends to the origin were approximately 120 bp to the 5' side and 300 bp to the 3' side. As both of these bends were outside of the sequences required for origin function, it is unlikely that static bending plays a critical role in BPV-1 replication.

Base Sequence↗
PubMed1994

Open complex formation by DnaA initiation protein at the Escherichia coli chromosomal origin requires the 13-mers precisely spaced relative to the 9-mers.

The 245 bp chromosomal origin, oriC, of Escherichia coli contains two iterated motifs. Three 13-mers tandemly repeated at one end of the origin and four 9-mers in a nearby segment of oriC are highly conserved in enteric bacteria, as is the distance separating these two sequence clusters. Mutant origins were constructed with altered spacing of the 9-mers relative to the 13-mers. Loss or addition of even a single base drastically reduced replication, both in vivo and in vitro. Spacing mutant origins bound effectively to DnaA protein but failed to support efficient open complex formation. These results suggest that interaction with the 9-mers positions at least one subunit of DnaA to recognize directly the nearest 13-mer for DNA melting.

Bacterial Proteins↗
PubMed1994

Heat-treatment-induced reduction in the apparent solubility of human dental enamel.

Holcomb and Young (1980) have shown a significant increase in human dental enamel (HE) structural order resulting from heat treatment in the temperature range of from 275 to 400 degrees C. Also, previous work in our laboratory had shown dramatic decreases in the initial dissolution rates (IDRs) of both carbonated apatite (CAP) heated at similar temperatures (from 300 to 500 degrees C) and HE exposed to CO2 laser irradiation for which calculated surface temperatures were in this same range. We hypothesize that thermal treatment shifts the apparent solubility distribution profile of HE toward lower apparent solubilities, paralleling the observed increased in crystal structural order and the decrease in IDRs. Powdered HE was heated in a furnace at temperatures ranging from 150 to 500 degrees C for 24 hours. The apparent solubility distributions of both heated and unheated HE powders were measured by equilibration for 24 hours in a series of partially saturated solutions simulating various amounts of HE dissolved in a pH 4.5 dissolution medium. The apparent solubility distribution for the unheated HE showed a peak at KHAP [the ion activity product based on the Ca10(PO4)6(OH)2 stoichiometry] of 10(121.0). Heat treatment shifted the apparent solubility distribution to lower solubilities. The peak KHAP values were approximately 10(124.8) at 200 degrees C; approximately 10(127.8) at 300 degrees C; and approximately 10(-129.1) from 400 to 500 degrees C. This approximately 8 orders of magnitude decrease in KHAP for HE heated at from 400 to 500 degrees C correlates with the previously observed reduction in the IDR driving force for laser-treated HE experiencing a similar surface temperature.(ABSTRACT TRUNCATED AT 250 WORDS)

Apatites↗
PubMed1994

Annexin II marks astrocytic brain tumors of high histologic grade.

Annexin II is highly expressed in glioblastoma multiforme [Reeves, S. A.; Chavez-Kappel, C.; Davis, R.; Rosenblum, M.; Israel, M. A. Developmental regulation of annexin II (lipocortin 2) in human brain and expression in high grade glioma. Cancer Res. 52:6871-6876; 1992] and is a likely second messenger in mitogenic pathways known to be important for the growth of these tumors. We have examined tumor tissue from patients diagnosed with low-, intermediate-, or high-grade astrocytic tumors for expression of annexin II by immunohistochemistry, and found that annexin II levels varied significantly among these three tumors (P < 0.0005). Levels were highest in glioblastoma multiforme, intermediate in anaplastic astrocytomas, and lowest in astrocytomas. In contrast to the usual cytoplasmic localization of annexin II, distinct nuclear staining was found in many of the specimens. Reactive astrocytes found in gliotic brain also stained with anti-annexin II antibody. We examined matched specimens for a correlation between annexin II staining intensity and the bromodeoxyuridine labeling index and found that, while tumors with the most intense annexin II staining had highest bromodeoxyuridine labeling indexes, there was not a strong association between these two parameters. The association between annexin II staining and histologic grade in astrocytic malignancies indicates that annexin II may be an important marker of high-grade glial tumors, and suggests that this marker may be useful for the pathologic classification of glial tumors and the clinical evaluation of brain tumor patients.

Adult↗
PubMed1994

Mechanochemical synthesis of bioactive material: effect of environmental conditions on the phase transformation of calcium phosphates during grinding.

The effect of environmental conditions on the crystalline transformation of metastable calcium phosphates during grinding was investigated using X-ray diffractometry and fourier transformed infrared spectroscopy. A mixture of CoA and dicalcium phosphate anhydrate (DCPA, CaHPO4) did not transform after grinding in air. On the other hand, CaO and dicalcium phosphate dihydrate (DCPD, CaHPO4 2H2O) were converted into a noncrystalline solid. Mixtures of DCPD and Ca(OH)2 transformed into low-crystallinity hydroxyapatite after grinding in air. When ground under N2, a mixture of Ca(OH)2 and DCPD did not transform into hydroxyapatite, whereas that of DCPD: Ca(OH)2: CaCO3 = 1:0.8: 0.2 did. The results of X-ray diffraction of FT-IR spectra suggested that the presence of carbon dioxide in the grinding system was necessary for transformation from metastable calcium phosphates to hydroxyapatite.

Air↗
PubMed1993

Hydroubiquinone-cytochrome c2 oxidoreductase from Rhodobacter capsulatus: definition of a minimal, functional isolated preparation.

The hydroubiquinone-cytochrome c2 oxidoreductase (cyt bc1) from Rhodobacter capsulatus has been solubilized according to the dodecyl maltoside method and isolated, and its minimal functional composition has been characterized. We find the complex to be composed of three protein subunits corresponding to polypeptides of cyt b (44 kDa), cyt c1 (33 kDa), and 2Fe2S cluster (24 kDa). A fourth band sometimes discernable at 22 kDa appears to be an artifact of the polyacrylamide gel electrophoresis procedure. Its appearance is shown to be derived from the 2Fe2S cluster subunit by the similarity of the binding of subunit-specific monoclonal antibodies and the identical N-terminal sequence of the 24- and 22-kDa bands. The cofactors of cyt bc1, namely, cyt bH, cyt bL, cyt c1, and the 2Fe2S center, the Qos and Qow domains of the Qo site, and the Qi site appear intact as indicated by their optical and EPR spectral signatures, redox properties, and inhibitor binding. The electron paramagnetic resonance spectrum of the cyt bH heme is altered by antimycin, consistent with a change in the dihedral angle between the ligating histidine imidazoles, while the spectrum of the cyt bL heme is broadened by stigmatellin. The ubiquinone-10 content is variable, ranging from 0.8 to 3 molecules/cyt bc1. Activity studies define this three-subunit cyt bc1 complex as a minimal structure, equipped as the enzyme in the native state and capable of full catalytic activity.

Amino Acid Sequence↗
PubMed1993

Psychiatric complications of family reunion after four decades of separation.

OBJECTIVE: After four decades of separation due to civil war, many people who had migrated to Taiwan from mainland China had the unexpected opportunity to briefly visit their families in mainland China. A study was conducted to examine psychiatric complications associated with these family reunions following long involuntary separation. METHOD: Eighty subjects who made the journey were given semistructured interviews investigating their psychological experiences relating to the family reunion. The variables investigated were sociodemographic characteristics, the subject's previsit emotional condition, factors related to the family reunion experience, and stress encountered during the visit. RESULTS: The survey indicated that more than one-fifth of the subjects (22.5%) developed psychiatric complications, mainly depression, immediately after the visit. Determinants found to contribute significantly to the occurrence of emotional disorders were previous ways of expressing homesickness, family members seen during the reunion, family misfortunes that the subjects discovered, family conflict encountered at the reunion, and tactics for coping with such stressors. CONCLUSIONS: The study results suggest that family reunions after long-term separation can be trauma-repairing experiences for some but for others can lead to trauma reexperiencing and psychiatric complications requiring mental health intervention.

Adaptation, Psychological↗
PubMed1992

Autophosphorylation of skeletal muscle myosin light chain kinase.

Ca2+/calmodulin-dependent myosin light chain kinase phosphorylates the regulatory light chain of myosin. Rabbit skeletal muscle myosin light chain kinase also catalyzes a Ca2+/calmodulin-dependent autophosphorylation with a rapid rate of incorporation of 1 mol of 32P/mol of kinase and a slower rate of incorporation up to 1.52 mol of 32P/mol. Autophosphorylation was inhibited by a peptide substrate that has a low Km value for myosin light chain kinase. Autophosphorylation at both rates was concentration-independent, indicating an intramolecular mechanism. There were no significant changes in catalytic properties toward light chain and MgATP substrates or in calmodulin activation properties upon autophosphorylation. After digestion with V8 protease, phosphopeptides were purified and sequenced. Two phosphorylation sites were identified, Ser 160 and Ser 234, with the former associated with the rapid rate of phosphorylation. Both sites are located amino terminal of the catalytic domain. These results indicate that the extended "tail" region of the enzyme can fold into the active site of the kinase.

Adenosine Triphosphate↗
PubMed1992

The Vineberg procedure revisited: angiographic evaluation and coronary artery bypass surgery in a patient 21 years following bilateral internal mammary artery implantation.

A patient receiving bilateral internal mammary implantation (Vineberg's operation) in 1969 was symptom free for a period of 21 years. In 1990 he developed acute myocardial infarction followed by post-infarction angina. Cardiac catheterization revealed severe left main and three vessel disease and patency of both mammary implants which filled the left anterior descending and circumflex coronary arteries via collaterals. Coronary artery bypass surgery was indicated due to the native coronary artery disease and inability of the internal mammary grafts' blood flow to alleviate symptoms. The patient underwent direct coronary artery bypass grafting utilizing femoral vessels for cannulation and saphenous veins for grafting, while preserving the mammary implants. This unique case attests to the longevity of the internal mammary artery grafts. These grafts, even if directly implanted, can serve as a crucial source of blood to an otherwise severely underperfused myocardium. Strategy and technical aspects of surgical redo in patients who underwent Vineberg's operation are discussed.

Aged↗