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Biomedical subjects

S Hsu

Publications and source records attributed to S Hsu.

At least 127 records · Page 7Linked to original sources
PubMed1987

Circuit for the electromanipulation of plant protoplasts.

An electric circuit for plant protoplast manipulation is described. The circuit used readily available materials and was designed for use in teaching. This integrated circuit can be placed in a single small box with controls for the aligning voltage, the aligning frequency, the pulse voltage, and the pulse timing. The circuit can be supplied by any suitable source of dc power and can be easily altered for individual requirements. The circuit, as presented here, can be assembled for less than $250.

Cell Fusion↗
PubMed1987

Glottic and tracheal stenosis in spinal cord injured patients.

Between 1965 and 1985, 47 cases of glottic and/or tracheal stenosis were diagnosed at the Rocky Mountain Regional Spinal Cord Injury System. A retrospective review of medical records identified associated injuries, pulmonary and other medical complications in this patient population. Radiographic and endoscopic reviews utilised a grading system to classify the severity of stenosis. The clinical symptoms of stenosis were multiple, including dysphonia, aspiration, dysphagia, odynophagia, dyspnea and excessive secretions. The wide spectrum of treatment modalities included endoscopy with excision and/or dilation, general medical management, steroids, radiation therapy, intubation, stent insertion and surgical repair of the stenotic area. Outcome status was reviewed and suggestions provided for the early diagnosis and treatment of this potentially life-threatening condition.

Adult↗
PubMed1987

Expression of A9 antigen and loss of blood group antigens as determinants of survival in patients with head and neck squamous carcinoma.

The murine monoclonal antibody (A9), raised to the human squamous cell carcinoma (SCC) cell-line UM-SCC-1, defines a squamous cell antigen associated with aggressive biologic behavior of SCC cell lines in vivo and in vitro. In the present investigation, A9 antigen was detected in tissue sections from 37 consecutive, previously untreated patients with SCC of the head and neck. All tumors were positive for A9 binding, although three distinct patterns (reflecting different intensities of A9 expression) were identified. The intensity of A9 expression was independent of primary tumor site, tumor differentiation, keratinization, or growth pattern. The frequency of high expression (Pattern 1) grew with increasing T class, N class, and tumor stage, and was associated with loss of blood group expression in the tumor and with low levels of lymphocyte infiltration in the tumor. Strong A9 expression had a statistically significant association with low nuclear grade (i.e., tumors with more mature and fewer enlarged nuclei, P = 0.019), low vascular/stromal response (i.e., patchy response rather than continuous, P = 0.014), and impaired in vitro lymphokine production by peripheral blood leukocytes (P = 0.0011). Of greatest interest, however, was the strong association of high A9 expression with shortened disease-free interval (DFI) (P = 0.085) and survival (P = 0.081) relative to patients with weak A9 tumor staining (Patterns 2 and 3). Similarly, the loss of blood group antigen expression was strongly associated with decreased DFI (P = 0.038) and survival (P = 0.062). While neither Pattern 1 A9 expression nor loss of blood group reach statistical significance in prediction of survival, the combination of Pattern 1 A9 expression and loss of blood group expression in primary tumors was significantly associated, both with decreased disease-free interval (P = 0.017) and with decreased overall survival (P = 0.011) (median length of follow-up = 22 months). The length of follow-up (LFU) ranged from 2 to 38 months, with a median LFU of 22 months. While the number of patients (37) is small, the significant association between the expression of these cell-surface markers with relapse and survival indicates that immunohistologic staining of the primary tumor will be an important prognostic indicator useful in identification of individual patients at greatest risk of recurrence or early death from head and neck cancer, independent of tumor size, site, or stage at presentation. These markers may thus provide means of selecting patients who should receive adjuvant therapy and more intensive monitoring for the early detection of recurrent disease.

ABO Blood-Group System↗
PubMed1987

Self-renewal of pulmonary alveolar macrophages: evidence from radiation chimera studies.

Radiation-induced chimeric mice were used to study the origin of pulmonary alveolar macrophages. Unlike in other studies, these radiation chimeras were prepared by using a special fractionated irradiation regimen to minimize the killing of alveolar macrophage colony-forming cells, putative local stem cells. For this study CBA mice with or without T6 chromosome marker were used. Under this experimental condition, the majority of alveolar macrophages in mitosis are of host origin even after 45 weeks. These data suggest that alveolar macrophages are a self-renewing population under normal steady-state conditions.

Animals↗
PubMed1986

Modulation of tissue mononuclear phagocyte clonal growth by oxygen and antioxidant enzymes.

We have investigated the effects both of oxygen concentrations below that of ambient air in the gas phase and antioxidant enzymes on the clonal growth of various tissue mononuclear phagocyte colony-forming cells in vitro. The degree of enhancement in growth is dependent on the source of these colony-forming cells. Clonal growth of colony-forming cells from peritoneal exudate was enhanced both by lowering the oxygen tension and using three antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase). The optimal concentration of oxygen was 6%. Colony-forming cells from alveolar spaces failed to respond to either the reduction in oxygen tension or the addition of antioxidant enzymes to the culture dishes. The optimal concentration of oxygen for the clonal growth of blood monocytes was 6%. However, clonal growth was enhanced more in soft agar than in liquid culture. Our data also suggest that at least part of the growth-enhancing effect of hemolysate may be attributable to its ability to decrease oxygen toxicity.

Animals↗
PubMed1985

DNA content of human squamous cell carcinoma cell lines. Analysis by flow cytometry and chromosome enumeration.

Fifteen squamous cell carcinoma cell lines derived from nine patients were examined for DNA content by flow cytometry and chromosome counts. Using human peripheral blood leukocytes and nucleated trout and chicken red blood cells as standards, the DNA indexes of the squamous cell carcinoma cell lines were found to range from 1.1 to 3.3. The DNA content was a stable characteristic of individual cell lines in multiple passages over a seven-month period. Although flow cytometry could detect abnormal DNA content even in diploid tumor lines, the chromosome number correlated well with the DNA content by flow cytometry. In cases in which more than one cell line was established from the same patient, the individual cell lines were found to differ in their DNA content. The cell lines established from metastatic or recurrent tumors usually had a lower DNA content and chromosome number and exhibited a more aggressive in vitro growth pattern than the primary tumor or earlier recurrence. We hypothesize that "streamlined" and aggressive cell populations may evolve in vivo from more slowly growing hyperploid precursor tumor cell populations when in the course of random loss of DNA or chromosomes those that confer no growth advantage are lost, while those that do confer growth advantage are retained.

Animals↗
PubMed1985

Effects of dose rate and dose fractionation of irradiation on pulmonary alveolar macrophage colony-forming cells.

We have studied the effects of dose rate and dose fractionation on murine pulmonary alveolar macrophage colony-forming cells (AL-CFC). The dose-response curve of AL-CFC to ionizing irradiation has a Dq of about 100 rad, reflecting the cells' ability to repair sublethal damage. For comparison, we investigated the effect of dose schedule on the committed bone marrow stem cells for both granulocytes and monocytes (GM-CFC) since their dose-response curve has a very small shoulder. We compared the results of dose rates of 3 and 10 rad/min to those obtained with a dose rate of 85 rad/min. We determined survival after giving 100, 300, and 500 rad either in vivo or in vitro. A significant dose rate effect was observed. To study the effect of dose fractionation, a total of 600 rad was given either as a single fraction, three fractions of 200 rad on 3 consecutive days, or six fractions of 100 rad in 3 days. The most dramatic effect was seen in the group that received six 100-rad fractions. No reduction in the number of AL-CFC was seen in this group. In sharp contrast, only a minimal dose schedule effect was observed with GM-CFC.

Animals↗
PubMed1984

Effect of intravenous eicosapentaenoic acid on cerebral blood flow, edema and brain prostaglandins in ischemic gerbils.

Eicosapentaenoic acid is converted by cyclo-oxygenase to the prostacyclin, PGI3. Consequently eicosapentaenoic acid might protect the brain from the impairment in cerebral blood flow that follows temporary cerebral arterial occlusion. We studied the effect of 90% pure eicosapentaenoic acid, given intravenously, on cerebral blood flow, brain water and prostaglandins after ischemia in gerbils. Ischemia was produced by bilateral carotid occlusion for 15 min followed by reperfusion for 2 h. In experimental gerbils, 0.833 mg or 0.167 mg of eicosapentaenoic acid (Na salt) was given intravenously followed by a continuous infusion of 1 mg h-1. Control gerbils were given 0.167 mg of linoleic acid (Na salt) intravenously followed by a continuous infusion of 1 mg h-1 or a saline infusion. Regional cerebral blood flow was measured by the hydrogen clearance method and brain water by the specific gravity technique. Brain diene prostaglandins were measured by radioimmunoassay. In control gerbils cerebral blood flow decreased significantly during reperfusion and remained depressed after 2 h of reperfusion. In eicosapentaenoic acid treated gerbils blood flow decreased initially but after 2 h of reperfusion blood flow was significantly higher than in control gerbils. Brain edema and brain diene prostaglandins were not significantly different between control and experimental groups. Our study indicates that eicosapentaenoic acid, given intravenously, improves cerebral blood flow after ischemia and reperfusion. We speculate that this effect may be due to the formation of the prostacyclin, PGI3.

Animals↗
PubMed1984

Sodium 5-(3'-pyridinylmethyl)benzofuran-2-carboxylate (U-63557A) potentiates protective effect of intravenous eicosapentaenoic acid on impaired CBF in ischemic gerbils.

Eicosapentaenoic acid (EPA) has been reported to improve postischemic cerebral blood flow (CBF). The present study was designed to determine whether sodium 5-(3'-pyridinylmethyl)benzofuran-2-carboxylate (U-63557A), a selective thromboxane synthetase inhibitor, could potentiate the effects of EPA on CBF in ischemic gerbils. Ischemia was produced by bilateral carotid artery occlusion for 15 minutes followed by reperfusion for 2 hours. Immediately after ischemia, gerbils were given either an intravenous bolus of 0.167 mg of EPA followed by a continuous infusion of EPA at 1 mg/hr, or U-63557A (10 mg/kg intraperitoneally), or U-63557A and EPA, or a saline infusion. Regional CBF was measured by the hydrogen clearance method, and brain water by the specific gravity technique. Brain prostaglandins were measured by radioimmunoassay. Preischemic CBF's ranged from 27.4 to 29.5 ml/100 gm/min for the four animal groups. After ischemia and 2 hours of reperfusion, CBF in the saline-infused gerbils was significantly decreased to 19.2 ml/100 gm/min. Gerbils treated with either EPA or U-63557A alone had a CBF of 23.7 and 21.6 ml/100 gm/min, respectively. Postischemic CBF in animals treated with both U-63557A and EPA was 30.0 ml/100 gm/min, significantly higher than in saline-infused gerbils. Brain levels of 6-keto prostaglandin (PG)F1 alpha (the metabolite of PGI2) were significantly higher in gerbils treated with U-63557A and EPA compared to gerbils given EPA alone. This study indicates that U-63557A potentiates the effects of EPA on postischemic CBF. This is probably due to the ability of U-63557A to increase prostacyclin formation in the vessel wall.

Animals↗
PubMed1984

Low-grade lymphomas. Expression of developmentally regulated B-cell antigens.

A series of low-grade B-cell lymphomas was analyzed for a battery of immunologic determinants by flow cytometry and immunohistochemistry. Histologically distinctive subclasses of these lymphomas, well-differentiated lymphocytic (WDL), intermediately differentiated lymphocytic (IDL), and follicular center cell (FCC) lymphoma, were found to be readily distinguishable by their expression of immunologic determinants that are known to be developmentally regulated in normal B cells. Although all cases expressed monoclonal surface immunoglobulin (sIg), HLA-DR, and the surface membrane proteins recognized by antibodies B1 (p32) and BA1, staining with other monoclonal antibodies revealed unique immunologic phenotypes for each subclass: WDL p65 (Leu 1)+, p24 (BA2)-; IDL p65+, p24+; FCC p65-, p24-. Additionally, the fluorescence intensities (number of determinants per cell) obtained for sIg, BA-1, and B1, but not HLA-DR, were significantly different among the three lymphoma subclasses. The relative fluorescence intensities of each of these three markers followed the same pattern: FCC greater than IDL greater than WDL. Taken together, these distinguishing features suggest that low-grade B-cell lymphomas represent arrested, and possibly sequential, stages of B-cell differentiation.

Antibodies, Monoclonal↗
PubMed1983

Enzyme-linked immunoadsorbent assay for detection of colony-stimulating factor (CSF-1).

An enzyme-linked immunoadsorbent assay (ELISA) has been developed for the quantitative measurement of L-cell colony-stimulating factor (CSF-1). According to this method, purified antigen (CSF-1) was allowed to adsorb to polystyrene or polyvinyl microtiter wells, which were then incubated with specific rat anti-CSF-1 antiserum with or without standard antigen or unknown test samples. The amount of antibody bound to the solid phase was then quantitated by enzyme (horseradish peroxidase)-conjugated rabbit anti-rat immunoglobulin antibody. This assay has a sensitivity comparable to that of the bioassay (approximately 5 U) and can be carried out in a single day.

Animals↗
PubMed1983

Tumor-promoting phorbol esters inhibit the binding of colony-stimulating factor (CSF-1) to murine peritoneal exudate macrophages.

L-cell colony-stimulating factor (CSF-1) is a sialoglycoprotein of molecular weight 70,000 daltons that specifically stimulates macrophage colony formation by single committed cells from normal mouse bone marrow and by various classes of more differentiated tissue-derived mononuclear phagocyte colony-forming cells (Stanley et al., 1978). CSF-1 interacts with target cells by direct and specific binding to membrane receptors (CSF-1 receptors) that are present only on cells of the mononuclear phagocyte series and their precursors. We studied the effect of tumor-promoting phorbol esters on the binding of 125I-labeled CSF-1 (125I-CSF-1) to murine peritoneal exudate macrophages (PEM). Biologically active TPA (12-O-tetradecanoyl phorbol-13-acetate) inhibits the binding of 125I-CSF-1 to its receptor on PEM. This inhibition exhibits temperature, time, and concentration dependence. At 37 degrees C, maximum inhibition occurred at about 10(-7) M; inhibition was 50% at 5 X 10(-9) M. At 0 degrees C, the inhibitory activity of TPA is diminished. The action of TPA on PEM is transient. Treated cells recover their 125I-CSF-1-binding activity whether TPA is later removed or not. The process of recovering CSF-1-binding activity is completely blocked by the addition of cycloheximide. When several phorbol derivatives were tested for their inhibitory activities, only biologically active phorbol esters were found to possess such activities. Furthermore, the inhibitory activities of various phorbol esters are proportional to their tumor-promoting activities. Inhibition appears to be due to a reduction in the total number of available CSF-1 receptors rather than a decrease in receptor affinity.

Animals↗
PubMed1983

Lipopolysaccharide inhibits the binding of colony-stimulating factor (CSF-1) to murine peritoneal exudate macrophages.

These studies demonstrate the potent effect of bacterial endotoxin (LPS) on the inhibition of iodinated colony-stimulating factor- (125I-CSF-1) binding by murine peritoneal exudate macrophages (PEM) from C3H/An and C57BL/6 mice. As small an amount as 0.1 ng/ml LPS is sufficient to cause a significant inhibitory effect; this effect is temperature-, time- and concentration-dependent. LPS, however, causes minimal or no inhibition of 125I-CSF-1-binding by PEM from LPS-resistant C3H/HeJ mice. Inhibition of 125I-CSF-1-binding does not appear to be a result of a direct occupancy by LPS of CSF-1 receptors present on the cell membrane and is most likely due to a progressive loss of available CSF-1-binding sites. The effect can be neutralized by the addition of the antibiotic polymyxin B, which binds to the lipid A portion of LPS. The action of LPS on PEM is transient; treated cells recover their 125I-CSF-1-binding activity whether or not LPS is later removed. The restoration of 125I-CSF-1-binding activity can be blocked completely by the addition of cyclohexamide. These findings suggest the rapid, LPS-induced disappearance of CSF-1 receptors from the cell surface may be related to the activation of macrophages by LPS.

Animals↗
PubMed1982

Binding, internalization and degradation of colony-stimulating factor by peritoneal exudate macrophages.

Iodinated colony-stimulating factor produced by L-cells (125I-CSF-1) binds specifically to murine peritoneal exudate macrophages. At 37 degrees C, the cell-bound 125I-CSF-1 was internalized and degraded very rapidly, with the appearance of radioactive iodotyrosine in the medium. At 0 degree C, the cell-bound 125I-CSF-1 was not internalized and degraded, nor did it dissociate from the membrane. The internalization and degradation at 37 degrees C could be blocked or reduced by the presence of phenylglyoxal, methylamine and NH4Cl. The chemical nature of the CSF-1 binding site is polypeptide as judged by its sensitivity to trypsin treatment. After the binding and degradation of unlabeled CSF-1, the exudate cells were no longer able to rebind freshly added 125I-CSF-1, indicating the removal of CSF-1 binding site. The binding capacity of these cells, however, could be restored by prolonged incubation at 37 degrees C but not at 0 degrees C in culture medium containing fetal calf serum.

Animals↗
PubMed1981

Immunologic studies of cartilage-hair hypoplasia in the Amish.

The immunologic status of 18 Old Order Amish persons with cartilage-hair hypoplasia and 9 unaffected sibs was studied. Although none of the subjects had a history suggestive of persistent immune dysfunction, the subjects with cartilage-hair hypoplasia had significantly lower lymphocyte mitogenic and allogeneic cell stimulation responses when compared to unaffected sibs and unrelated control subjects. The abnormalities of cellular immune function found in the 18 affected subjects were similar to those reported in Finnish subjects with cartilage-hair hypoplasia.

Adolescent↗
PubMed1979

Effector localization and transfer of reactive inhibition.

An experimental test was made of Hull's (1943) notions that reactive inhibition is effector-specific and that it has primary negative motivational properties. Four groups of 20 subjects (10 males and 10 females in each) executed two segments of continuous right-hand practice on a mirror-tracking task. The two segments were separated either by 0 min rest, 5 min rest, 5 min continuous right-hand practice on rotary pursuit, or 5 min continuous left-hand practice on rotary pursuit. Effects of interpolated conditions were measured in terms of main-task reminiscence arid initial post-treatment performance. When interpolated practice was conducted with the right hand, reminiscence and post-treatment performance were significantly depressed relative to the rest effect, but not when interpolated practice was conducted with the left hand. Thus, Hull's views were supported, while competing views, such as the task specificity concept of lr and the consolidation theory of reminiscence, were impugned.

Journal Article↗