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S W Han

Publications and source records attributed to S W Han.

89 records · Page 5Linked to original sources
PubMed1991

Vibrational structure of the formyl group on heme a. Implications on the properties of cytochrome c oxidase.

Resonance Raman spectra have been recorded for heme a derivatives in which the oxygen atom of the formyl group has been isotopically labeled and for Schiff base derivatives of heme a in which the Schiff base nitrogen has been isotopically labeled. The 14N-15N isotope shift in the C = N stretching mode of the Schiff base is close to the theoretically predicted shift for an isolated C = N group for both the ferric and ferrous oxidation states and in both aqueous and nonaqueous solutions. In contrast, the 16O-18O isotope shift of the C = O stretching mode of the formyl group is significantly smaller than that predicted for an isolated C = O group and is also dependent on whether the environment is aqueous or nonaqueous. This differences between the theoretically predicted shifts and the observed shifts are attributed to coupling of the C = O stretching mode to as yet unidentified modes of the heme. The complex behavior of the C = O stretching vibration precludes the possibility of making simple interpretations of frequency shifts of this mode in cytochrome c oxidase.

Electron Transport Complex IV↗
PubMed1991

Evidence for gamma-melanocyte stimulating hormone containing nerves and neutrophilic granulocytes in the human skin by indirect immunofluorescence.

gamma-melanocyte stimulating hormone (gamma-MSH)-like immunoreactivity has been found by indirect immunofluorescence in nerve fibers and terminals as well as in neutrophilic granulocytes of normal human skin. A preferential localization to sensory nerves was seen; abundant nerve fibers displaying gamma-MSH immunoreactivity were observed as free nerve endings in the basal layer of the epidermis and in the upper dermis, close to the Merkel cells, in Meissner's corpuscles, around the external root sheath of the lower part of the hair follicles, and in nerve bundles of the deeper parts of the dermis. Very few fibers were seen to be associated with sweat glands and most blood vessels, although arterioles were densely innervated. Thus, gamma-MSH should be considered for possible role as a sensory or axon-reflex chemical messenger. Furthermore, the presence of gamma-MSH in neutrophilic granulocytes raises the possibility that gamma-MSH may play a role in the genesis of post-inflammatory hyperpigmentation, nevi, and melanomas.

Adult↗
PubMed1990

Primary intermediate in the reaction of oxygen with fully reduced cytochrome c oxidase.

The primary intermediate in the reaction of oxygen with cytochrome c oxidase was generated by photodissociating carbon monoxide in a continuous flow rapid mixing apparatus. The presence of the primary intermediate was confirmed by a comparison of the iron-dioxygen stretching frequency with that obtained in the reaction of oxygen with the mixed-valence enzyme. For both of these preparations, the Fe-O2 stretching mode is detected at 568 cm-1, the same frequency as that found in oxyhemoglobin and oxymyoglobin. These data illustrate that the primary intermediate may be generated and detected at room temperature in the fully reduced enzyme and that the oxidation state of cytochrome a does not affect the structure of the iron-dioxygen complex. By following the changes in the intensity of the Fe-O2 stretching mode in the resonance Raman spectrum as a function of time, the first-order rate constant for the decay of the primary intermediate was found to be 3.5 x 10(4) s-1 (t1/2 = 20 microseconds).

Carbon Monoxide↗
PubMed1990

The specificity and cellular origin of phenylethanolamine N-methyltransferase (PNMT)-like immunoreactivity in psoriatic skin.

Phenylethanolamine N-methyltransferase (PNMT)-like immunoreactivity has been found in psoriatic skin and in this study, PNMT-like immunoreactivity was investigated in the involved and uninvolved skin of six patients with lichen planus and four patients with lichen simplex. No PNMT immunoreactivity was observed in these diseases. Studies were carried out using cultured fibroblasts from two patients with psoriasis from uninvolved and involved areas of skin and from two controls using antibodies to PNMT, as well as antibodies to the chemical messengers somatostatin, substance P, parathyroid hormone and peptide histidine isoleucine amide. No immunoreactivity to these substances was found, and fibroblasts are unlikely to be the cellular origin of the PNMT-like immunoreactivity as seen in psoriatic skin.

Adolescent↗
PubMed1989

Evidence for a hydroxide intermediate in cytochrome c oxidase.

A transient intermediate of cytochrome c oxidase has been generated by exposing the enzyme to a laser beam in the presence of oxygen. This intermediate develops when the enzyme is simultaneously reduced photoreductively and oxidized chemically, thereby forcing it to turn over. Under these conditions a form of the enzyme is generated with a line at 477 cm-1 in the resonance Raman spectrum, which we attribute to an Fe-OH stretching mode based on oxygen and hydrogen isotopic substitution. This hydroxide intermediate relaxes back to the resting state of the enzyme upon removal from the laser beam. Hydroxide intermediates have been postulated many times in the past in proposed catalytic mechanisms. The data reported here supply the first evidence for the existence of such an intermediate and a method for stabilizing it.

Animals↗
PubMed1989

Expression of hepatitis B core antigen gene in recombinant vaccinia virus.

Plasmid pMM2066 was digested with EcoRI restriction enzyme and an 870 bp fragment separated; it was located 12 bp upstream from the ATG codon of the antigen C structural gene. This DNA fragment was then inserted into shuttle vector pGJP-5 just downstream from the P7.5 promoter, producing recombinant vector p5-C2066. Three TK- recombinant vaccinia viruses expressing HBcAg were isolated by plaque assay, using homologous recombination in TK- 143 cells in the presence of BUdR. The supernatant from cells infected with recombinant virus (in dilutions of up to 1:64) still gave significant positive ELISA results. HBeAg activity titer was about the same. The HBcAg particles (26.6 nm) were visualized by electron microscopy. The influence of infection multiplicity, cell type, and culturing temperature on HBcAg expression was also investigated.

Animals↗
PubMed1989

Acid phosphatase (EC 3.1.3.2) synthesis by phosphorus regulatory mutant strains of Neurospora crassa.

1. Even though altered forms of acid phosphatase II were synthesized by the mutant strains nuc-1A and nuc-2A of N. crassa, their synthesis was independent of exogenous phosphate concentrations. 2. Synthesis of acid phosphatase I by nuc-2A was also insensitive to exogenous phosphate concentrations. When nuc-1A was grown on a low-phosphate medium, it also produced a heat-labile acid phosphatase in addition to a I-like acid phosphatase. I-like acid phosphatase was not detected in the mycelium of the pregc mutant strain grown on low-phosphate medium. 3. These results are consistent with the participation of the nuc-2, preg and nuc-1 genes in regulating the transport and/or secretion of acid phosphatase and probably other phosphatases by Neurospora crassa.

Acid Phosphatase↗
PubMed1989

[Estrogen and progesterone receptors in human ovary and ovarian tumors].

Ovarian specimens from 159 different patients were analyzed for estrogen and progesterone receptor (ER and PR) content with the Dextran-coated Charcoal method. The results indicated that the contents of ER and PR in malignant ovarian tumors were not correlated with the menstrual cycle of the patient, clinical stage and differentiation of the tumor. Among malignant ovarian tumors, the mean ER and PR concentrations in sex-cord stromal tumors and endometrioid carcinomas were higher than those in other malignant ovarian tumors (P less than 0.05, P less than 0.025). This suggests the possibility of endocrine therapy for these patients with the hope for a better prognosis.

Adenocarcinoma↗
PubMed1989

[Comparative study on human chorionic gonadotropin receptor in normal human ovary with ovarian tumors].

Human Chorionic Gonadotropin (HCG) is major physiological luteotropic factors for the human corpus luteum. The observations strongly suggest that the human ovary possesses a gonadotropin receptor in the cell membrane. We studied the HCG receptor in normal human ovary and ovarian tumors. Twenty-three human ovarian specimens and 16 ovarian tumor specimens were obtained from women patients having gynecological surgery. Ovaries were homogenized and sonicated. The homogenates were centrifuged at 2000 g for 15 min. After sucrose density gradient ultracentrifugation (78,000 g, 4 h), two fractions were collected from layer of 33% and interface between 33% and 37%. Thirty micrograms of ovarian protein, 8 ng 125I-HCG and unlabeled HCG in a final volume of 0.5 ml of 0.05 mol/L Tris buffer were incubated at 30 degrees C for 2 h. The results were shown in the table.

Binding Sites↗
PubMed1987

Regulation of synthesis and secretion of acid and alkaline phosphatases in Neurospora crassa.

We show that N. crassa represses the production of acid phosphatase at pH higher than 8.0, irrespective of the carbon source used, whereas production was stimulated by sucrose at slightly acidic pH. The same profile of acid phosphatase production was observed in the pho-2A, pho-3A, nuc-1A, nuc-2A and pregc mutant strains. We also show that acid phosphatase synthesized by the pregc mutant strain grown on high phosphate medium has pronounced differences when compared to the enzyme synthesized by the wild-type strain grown on low phosphate medium in terms of heat stability, steady-state kinetic properties and DEAE-cellulose chromatography. In addition, the synthesis and/or secretion of only phosphate-repressible alkaline phosphatase is affected by mutations in acu-1, and acu-5 and acu-7 genes. These results, which indicate distinct pathways for the synthesis and secretion of acid and alkaline phosphatases in N. crassa, contradict the dosage titration model proposed by Metzenberg et al. (1974) whereby the synthesis of these enzymes should occur through a single hierarchical regulatory circuit as a response to phosphate starvation.

Acid Phosphatase↗
PubMedDate not supplied

Thyrotoxic periodic paralysis in a Jamaican male.

Thyrotoxic periodic paralysis is a rare endocrine disorder most prevalent among individuals of Asian descent that presents as proximal muscle weakness, hypokalemia, and signs of hyperthyroidism. We present the case report of a patient with previously undiagnosed hyperthyroidism, protracted muscle weakness with transient exacerbations, and nocturnal onset of periodic paralysis affecting the upper and lower limbs.

Adult↗
PubMedDate not supplied

Heterologous expression of a Trypanosoma cruzi surface glycoprotein (gp82) in mammalian cells indicates the existence of different signal sequence requirements and processing.

Metacyclic trypomastigotes of Trypanosoma cruzi express a developmentally regulated 82 kDa surface glycoprotein (gp82) that has been implicated in the mammalian cell invasion. When the non-infective epimastigote stage of the parasite was transfected with a vector containing the gp82 gene, an 82 kDa surface glycoprotein, which was indistinguishable from the metacyclic stage protein, was expressed. In contrast, when the same gene was expressed in transfected mammalian cells, although a large amount of protein was produced, it was not imported into the endoplasmic reticulum and glycosylated. This blockage in targeting and processing could be partially compensated for by the addition of a virus haemagglutinin signal peptide to the amino terminus of gp82. Thus, the requirements for membrane protein processing are distinct in mammals and T. cruzi, and an intrinsic feature of the gp82 prevents subsequent sorting to the mammalian cell surface. These results could be useful in the development of new DNA vaccines against T. cruzi employing parasite genes encoding immunodominant surface glycoproteins.

Amino Acid Sequence↗
PubMedDate not supplied

Advanced nursing practice: an introduction to physical assessment.

Changing philosophies of clinical management and moves to reduce junior doctors' hours have led to increasing pressure upon nurses to take on the responsibility for assessing and initiating the management of acutely ill patients. Although nurses have been educated to assess, plan, and deliver care in a format known as the nursing process, this does not fully equip them for the demands of their rapidly developing roles. With increased responsibility comes the risk of increased stress and legal accountability, particularly where inadequate support is provided. In an effort to address this matter, this article briefly considers the theory of gaining clinical expertise, and describes a framework to facilitate physical assessment.

Clinical Competence↗