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Biomedical subjects

C J Lee

Publications and source records attributed to C J Lee.

At least 127 records · Page 7Linked to original sources
PubMed1995

Functional expression of the tachykinin NK1 receptor by floor plate cells in the embryonic rat spinal cord and brainstem.

1. The floor plate is a ventral mid-line structure that plays a pivotal role in the organization of the developing vertebrate central nervous system. Previous studies have demonstrated that the floor plate may provide signals that induce neuronal differentiation and guide axons; however, it is not known whether the floor plate can itself respond to signals that derive from surrounding tissue. 2. The peptide substance P is one of the first transmitters to be expressed in the developing spinal cord. To determine whether the floor plate may respond to substance P we have examined the expression of the principal substance P receptor (the tachykinin NK1 receptor) by floor plate cells of the rat embryonic spinal cord using immunocytochemistry, in situ hybridization and fura-2 calcium imaging. 3. Immunocytochemistry demonstrated selective expression of the NK1 receptor by cells at the ventral mid-line of the spinal cord. Double immunofluorescence labelling with the specific floor plate marker FP3 indicated that NK1 receptor expression is confined to cells in the lateral region of the floor plate. 4. In order to confirm the specificity of the NK1 receptor immunoreactivity we performed in situ hybridization histochemistry using antisense cRNA probes directed against the NK1 receptor. In situ hybridization demonstrated selective expression of NK1 receptor mRNA by floor plate cells. 5. The ontogeny of NK1 receptor protein and mRNA expression in the floor plate was defined. NK1 receptor expression occurred in a rostrocaudal progression that begins at embryonic day 10-11 (E10-E11) and is complete by E12-E14. The restriction of NK1 receptor expression to the lateral part of the floor plate was conserved throughout embryonic development. 6. NK1 receptor signalling was assessed by monitoring substance P-evoked changes in the intracellular concentration of calcium ions ([Ca2+]i) of acutely dissociated cells from the floor plate region. Application of substance P (5 nM) elevated [Ca2+]i in 10% of cells examined. 7. Selective neurokinin agonists were used to identify the receptor subtype involved in the substance P-evoked elevation of [Ca2+]i. Acetyl-[Arg6,Sar9,Met(O2)11]-substance P(6-11) (5 nM) and [Sar9,Met(O2)11]-substance P (5 nM), two highly selective NK1 receptor agonists, both elevated [Ca2+]i in floor plate cells that responded to substance P. [beta-Ala8]-neurokinin A(4-10) (50 nM) and senktide (50 nM), selective agonists respectively of NK2 and NK3 receptors, had no effect on [Ca2+]i.

Amino Acid Sequence↗
PubMed1995

Efficacy of intravenous delta-aminolaevulinic acid photodynamic therapy on rabbit papillomas.

Endogenously induced protoporphyrin IX (PPIX), a metabolite of delta-aminolaevulinic acid (ALA), has been evaluated as a photosensitising agent for destruction of papillomas in cottontail rabbit papillomavirus-infected Dutch belted and New Zealand rabbits. Three factors were evaluated: (1) relative retention ratio of drug in normal tissue, papilloma and plasma over time; (2) tissue tolerance to treatment factors; and (3) efficacy of treatment protocol. Three drug doses of ALA were examined: 50, 100 and 200 mg kg-1. Actual PPIX concentrations in tissue and plasma were determined spectrophotofluorometrically. The optimal treatment time occurred 3-6 h post ALA injection. The highest PPIX concentration ratio between papilloma and normal skin was 6:1. Different light doses were investigated, using an injection to exposure interval of 3 h and an irradiance of 100 mW cm-2 at a wavelength of 630 nm. Efficacy without risk of significant damage to normal skin was obtained using 100-200 mg kg-1 ALA and 40-60 J cm-2. A long-term (3 months) cure rate of 82% was obtained with a single treatment, provided that papilloma depth did not exceed 8 mm, volume was not more than 1000 mm3 and the plasma concentration of PPIX immediately before exposure was above 500 micrograms ml-1. The short time between injection and treatment and high efficacy, together with PPIX disappearance from plasma and tissue within 24 h, make injected ALA a highly attractive drug for photodynamic therapy.

Aminolevulinic Acid↗
PubMed1995

Variable distributions of Ca(2+)-permeable and Ca(2+)-impermeable AMPA receptors on embryonic rat dorsal horn neurons.

1. By measuring the apparent reversal potential (aErev) of kainate- and alpha-amino-3-hydroxyl-5-methyl-4-isoxazole propionic acid (AMPA)-evoked currents associated with changes in extracellular Ca2+ concentration ([Ca2+]e), we have been able to identify embryonic dorsal horn neurons grown in tissue culture that express Ca(2+)-permeable non-N-methyl-D-aspartic acid (NMDA) receptors. 2. The relative expression of Ca(2+)-permeable and Ca(2+)-impermeable non-NMDA receptors varies from cell to cell. This was evident from the range of a ErevS observed for kainate-evoked currents in a 0 mM [Na+]e, 10 mM [Ca2+]e bath. Under these conditions, aErev ranged from -96 to -21 mV, suggesting that the percentage of the non-NMDA receptors on each neuron that are Ca(2+)-permeable is variable. 3. To determine the extent to which the variability in aErev is due to variable receptor expression rather than experimental variability, we compared the effects of changes in [Ca2+]e on kainate-evoked currents and NMDA-evoked currents on the same cells. Assuming that all of the NMDA receptors on each neuron have a similar Ca2+ permeability, this approach provides an index of the sensitivity of our assay system. The reversal potential of NMDA-evoked currents in 10 mM [Ca2+]e ranged from -30 to -7 mV, whereas on the same population of neurons, the aErev of kainate-evoked currents ranged from -92 to -40 mV. 4. The rectification properties of the non-NMDA currents were generally linear or outwardly rectifying in normal bath solution. When the PCa/PCs ratio in 0 mM [Na+]e, 10 mM [Ca2+]e bath solution was assessed as a function of the rectification index in standard bath, a poor correlation was found between Ca2+ permeability and the rectification index. 5. The aErev of kainate-evoked currents was similar to that of cyclothiazide-enhanced AMPA-evoked currents observed on the same cells (-66.5 +/- 18.4 and -64.0 +/- 13.9 mV, mean +/- SD, respectively). This suggests that kainate is primarily activating the AMPA receptor and that the majority of non-NMDA receptors on embryonic dorsal horn neurons in culture are high-affinity AMPA receptors. 6. Immunocytochemical evidence suggests that the AMPA receptor subunits GluR1-4 are expressed to a variable degree from cell to cell in our cultures. We found evidence for low levels of expression of the kainate receptor subunits GluR5-7. The immunocytochemical observations support the physiological data indicating that much of the kainate-evoked current recorded in our experiments can be accounted for by kainate activation of AMPA receptors.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1995

A rheological equation to express the relations among hemoglobin contents, hematocrits, and viscosity of hemosome.

The relations among hemoglobin contents, hematocrit and viscosity of hemosome at a fixed shear rate have been studied. These relations can be well fitted by a rheological equation with internal viscosity of hemosome, (Tk)h, as a parameter. Where, (Tk)h are correlated (r = 0.996) with logarithm of hemoglobin content of hemosome by an equation: (Tk)h = 0.315 ln (hemoglobin contents of hemosome) + 0.435. The correlation can serve as an alternative way to predict hemoglobin content of hemosome instead of Benesch's method. The results of this study serve as a reference to determine an optimal conditions for in vivo tests of hemosome.

Animals↗
PubMed1995

Chondromyxoid fibroma of the femur: a case report with intra-cortical location.

Chondromyxoid fibroma (CMF) is the least common benign cartilaginous tumor, comprising less than 0.5 to 1% of all skeletal neoplasms. This subject was a 16-year-old female with a three-year history of pain involving the distal femoral metaphysis. This case showed an unusual feature: it was intracortical in location. Radiologic differential diagnosis included metaphyseal fibrous defect, periosteal chondroma, simple or aneurysmal bone cyst, and cortical abscess. On operation, the lesion filled the intracortical defect with whitish myxoid soft tissue, bulging into the adjacent soft tissue. Microscopically, it showed typical features of chondromyxoid fibroma composed of mainly myxoid nodules and peripheral fibrous elements with focal chondroid differentiation.

Adolescent↗
PubMed1995

Surgical treatment of second primary lung cancer: report of eight cases.

Of 312 patients undergoing resection for lung cancer at National Taiwan University Hospital during 1980 to 1990, eight presented with second primary lung cancer. One patient had synchronous and seven patients had metachronous primaries. There were five males and three females with ages ranging from 41 to 77 years. In the metachronous group, two patients had a different histology between the first and the second tumor, and the intervals between the two tumors varied from 12 to 60 months. The initial resections included pneumonectomy in one and lobectomy in six patients. At the second operation, the surgical procedures included lobectomy in three, completed pneumonectomy in one, segmentectomy in another, and wedge resection in two patients. There was no operative mortality and all patients were regularly followed up from 6 months to 6 years after the second operation. Two patients died, one from repeated respiratory tract infection and the other from brain metastasis. Kaplan-Meier analysis showed 2-year and 3-year survivals of 80% and 60%, respectively. It can be concluded that surgical resection for second primary lung cancer is justified, as it can prolong the patient's survival. Lobectomy can be performed for patients with a second primary lung cancer and sufficient lung reserve, but limited resection should be chosen for patients with poor lung reserve.

Adult↗
PubMed1995

Do immunosuppressants cause posttransplant diabetes mellitus?

BACKGROUND: Posttransplant diabetes mellitus (PTDM) was originally described by Starzl in 1964. The incidence is around 3-46%, according to several reports. Etiologies and risk factors of PTDM have been discussed after it was described and recognized as a complication of renal transplantation. METHODS: Twenty-five consecutive renal transplants in 24 recipients were reviewed, and 3 cases of posttransplant diabetes mellitus were found. Cyclosporine A (CsA), Azathioprine (Aza) dose and maintenance dose of Prednisolone (Pred.), rejection episodes, total dosage of steroid used at the time of acute rejection were carefully recorded and analyzed. RESULTS: The mean age of 3 living-related and 22 cadaveric transplant recipients was 32.7 +/- 7.5 and 33.5 +/- 6.8 years in PTDM and non-PTDM patients, and the onset of PTDM was, on the average, 11.3 +/- 10.6 months. Comparative studies between non-PTDM and PTDM groups showed that age, rejection episodes, total dose of methylprednisolone used in acute rejection, CsA level, and dosage of CsA, Aza and prednisolone at 1,6,12 and 24 months were not significantly different from one another. CONCLUSIONS: No significant risk factors or definitive mechanism involved in the development of PTDM were identified in this study. It is suggested that immunosuppressants are involved in the occurrence of PTDM, and probably neither a single factor is responsible nor is dose dependency involved.

Adult↗
PubMed1995

Postnatal development of GABAA receptor function in somatosensory thalamus and cortex: whole-cell voltage-clamp recordings in acutely isolated rat neurons.

GABAergic inhibition synchronizes oscillatory activity in the thalamocortical system. To understand better the role of this neurotransmitter in generation of thalamocortical rhythmicity, the postnatal development of GABAergic function mediated through activation of GABAA receptors was studied in thalamus and cortex. GABA-evoked chloride currents were recorded in dissociated rat cortical and thalamic neurons during postnatal development. Kinetic fits of GABA concentration/response relationships revealed developmental and regional alterations in the potency of GABA. Early in postnatal development (p5-p8), both thalamic and cortical neurons exhibited reduced potency of GABA (27-31 microM KD). Potency increased by p18-p25 in thalamic and cortical neurons (19-22 microM KD), to a level maintained in adult thalamic neurons. Adult cortical neurons exhibited reduced potency of GABA (40 microM KD). Benzodiazepine modulation of GABAA currents was also studied. Kinetic analyses of benzodiazepine augmentation of GABAA currents were best fitted assuming two effective sites with different affinities for clonazepam. The high-affinity site (KD of 0.05-0.27 nM) showed little variation with development in cortical neurons, contributing about 16-23% potentiation at all postnatal ages. Developing thalamic neurons (p5-p25) showed similar potency and efficacy of the high-affinity benzodiazepine site to cortical neurons. High-affinity benzodiazepine effects disappeared in adult thalamic neurons. A lower-affinity benzodiazepine site (25-50 nM KD) was greater in efficacy in cortical neurons compared to thalamic neurons at all ages, with efficacy ranging from 50% to 110% in cortex and from 20% to 60% in thalamus. Knowledge of developmental and regional alterations in GABAA receptor function may aid in understanding mechanisms involved in generation and control of normal and pathological thalamocortical rhythms.

Aging↗
PubMed1994

Photodynamic therapy using m-tetra(hydroxyphenyl) chlorin. An animal model.

OBJECTIVE: To evaluate the potent photosensitizer m-tetra (hydroxyphenyl) chlorin (m-THPC) by using rabbits with cottontail rabbit papillomavirus-induced tumors and the canine larynx as model systems. DESIGN: Nonrandomized control trial. SETTING: Division of ear, nose, and throat research at a tertiary care teaching hospital. MATERIALS: Rabbits were used for relative retention ratio studies and tissue tolerance tests. Studies on the swelling of normal tissues in the larynx after photoactivation were done with canines. INTERVENTION: Animals were injected with 0.3 mg/kg of m-THPC. At varying intervals, tissues were exposed to 652 nm of light. OUTCOME MEASURES: Outcome measures consisted of four elements: (1) decay of plasma concentration over time, (2) interval to and duration of maximal ratio between drug concentration in normal tissue and tumor, (3) maximal permissible light exposure to normal tissue (skin and laryngeal mucosa) at an optimal interval, and (4) efficacy--number of tumors with partial and complete response. RESULTS: The largest papilloma to skin ratio (10:1) occurred 4 to 8 days after drug injection. The rabbit skin damage threshold was 40 to 60 J/cm2 at 6 days. The canine laryngeal edema and erythema thresholds were 50 to 70 J. A 75% cure rate of papillomas was achieved with tumors that were less than 100 mm2 in area at light doses that ranged from 25 to 75 J/cm2. CONCLUSIONS: m-THPC shows efficacy in treating papilloma virus-induced tumors. We present a protocol for rapid optimization of the factors required for tumor destruction with minimal normal tissue damage, thus permitting determination of an optimal therapeutic protocol for any photosensitizer.

Animals↗
PubMed1994

Adjuvant immunotherapy with intrapleural Streptococcus pyogenes (OK-432) in lung cancer patients after resection.

A prospective randomized study to evaluate the effect of adjuvant intrapleural OK-432 immunotherapy after resection of lung tumor was conducted in 93 patients with primary lung cancer. Among them, 46 patients had had intrapleural OK-432 injection, 47 had not. In the meantime, serial measurements of serum immunosuppressive acidic protein, of serum interleukin-2 receptor and of the subpopulation of the peripheral blood cells and lymphocytes were performed in all these patients. Patient characteristics in these two groups (sex, age, histological type, pathological stage, type of operation, and performance status) were compatible. The results showed that adjuvant intrapleural OK-432 injection after resection had no beneficial effect on a patient's survival time. Patients who received intrapleural OK-432, had an increase in blood leukocytes, granulocytes and monocytes and serum immunosuppressive acidic protein level. But the cell numbers of total T cells, suppressor/cytoxic cells, helper/inducer cells and natural killer cells of peripheral blood were decreased in the OK-432 positive group. Over half of the patients had transient 1- or 2-day febrile reactions after intrapleural OK-432 injection. It was concluded that neither clinical observation nor immunological monitoring of peripheral blood could demonstrate a beneficial effect from intrapleural OK-432 immunotherapy after complete resection of the tumor.

Adjuvants, Immunologic↗
PubMed1994

Protection of infant mice from challenge with Streptococcus pneumoniae type 19F by immunization with a type 19F polysaccharide--pneumolysoid conjugate.

The immunogenicity and protective efficacy of a conjugate of Streptococcus pneumoniae type 19F polysaccharide and a genetically toxoided derivative of the pneumococcal toxin pneumolysin was investigated in an infant mouse model. The conjugate was administered to Balb/c mice during pregnancy and/or lactation, and to their offspring during early infancy. The anti-polysaccharide and anti-pneumolysin titres of the immunized infant mice were significantly higher than those of non-immunized controls. When the infant mice were challenged with type 19F pneumococci, the bacteria were cleared more effectively from the blood of immunized mice than from that of control mice. The survival rate for the immunized mice was also significantly higher than that for the control group. These results indicate that highly protective anti-pneumococcal responses can be induced in infant mice by immunization with the conjugate during gestation or early infancy, and suggest a possible role for pneumolysoid-polysaccharide conjugates as human vaccine components.

Animals↗
PubMed1994

Immune responses of young mice to pneumococcal type 9V polysaccharide-tetanus toxoid conjugate.

Pneumococcal type 9V polysaccharide (PS), contained in the current pneumococcal vaccine, induces only a weak antibody response in young children and therefore is not an effective vaccine for young children. To increase its immunogenicity, a conjugate of PS to a protein carrier, tetanus toxoid (TT), was prepared. To quantify the immune response, mouse anti-9V PS immunoglobulin G (IgG) and IgM reference standards were established. Young mice immunized at 2 weeks of age produced IgM antibody in response to 9V PS alone or 9V PS conjugated to TT. However, only the 9V PS-TT conjugate induced an IgG antibody response and an anamnestic effect. Thus, a covalent linkage between TT and 9V PS was required for isotype switching from IgM to IgG. 9V PS-TT adsorbed with aluminum hydroxide adjuvant resulted in a fivefold or greater increase in the IgG antibody level. We also studied the effect of maternal immunization on the immune response of young mice to 9V PS-TT. Maternal immunization before mating or before mating and during gestation primed 2-week-old progeny given two injections of 9V PS-TT to produce more IgM antibody than progeny from unimmunized mothers. The IgG antibody level of neonates at birth was similar to that observed in the mothers and was probably passive antibody. These results indicate that maternal immunization with an optimum dose of a PS-protein conjugate before and/or during pregnancy, followed by immunization of the offspring with the conjugate, could provide young children with an enhanced IgM antibody response to pneumococcal PSs.

Age Factors↗
PubMed1994

Adenosine deaminase and carcinoembryonic antigen in pericardial effusion diagnosis, especially in suspected tuberculous pericarditis.

BACKGROUND: Adenosine deaminase (ADA) and carcinoembryonic antigen (CEA) have been measured in pleural fluid to help distinguish malignant from benign effusions, especially in tuberculous pleurisy. We investigated ADA and CEA levels in patients with moderate to large pericardial effusions of different etiologies. METHODS AND RESULTS: We performed diagnostic and therapeutic pericardiostomy with drainage and biopsy. We measured ADA and CEA levels in the pericardial fluid in 26 patients with moderate to large pericardial effusion and 19 control patients. Patients were included in a prospective protocol from August 1991 to August 1993. Patients were grouped as follows: group 1, 9 patients with tuberculous pericarditis (TP) confirmed by bacteriologic culture or histology of pericardial biopsy; group 2, 5 patients with clinically strongly suspected TP; group 3, 12 patients with malignancy (8) and acute pericarditis (4); group 4, 19 control patients without pericardial disease. We treated patients with TP with isoniazid, rifampin, and either streptomycin or ethambutol for 12 months and pyrazinamide for 2 months. We observed for symptoms and signs of recurrent pericarditis or constrictive pericarditis on follow-up. In group 1 the ADA activity was significantly higher (101 +/- 14 U/L) than that in group 3 (22 +/- 5 U/L) or that in group 4 (17 +/- 2 U/L) (P < .05). There was no significant difference between ADA activity in group 1 (101 +/- 14 U/L) and that in group 2 (100 +/- 26 U/L). With a cutoff value for ADA activity of 40 U/L, sensitivity was 93% and specificity 97% in the diagnosis of TP. In benign diseases, the CEA level was significantly lower (1.0 +/- 0.3 ng/mL) than that in malignant diseases (135.1 +/- 79.7 ng/mL) (P < .05). With a cutoff value for CEA level of 5 ng/mL, sensitivity was 75% and specificity 100% in the diagnosis of malignant pericarditis. Follow-up study (mean, 12.9, 19.8, and 11.8 months in groups 1, 2, and 3, respectively, showed no symptoms or signs of constrictive pericarditis, except for 1 patient. CONCLUSIONS: Pericardial fluid ADA and CEA are useful for the differential diagnosis of pericardial effusion of various causes. They also have great value in early diagnosis of TP, particularly when the results of other clinical and laboratory tests are negative.

Adenosine Deaminase↗
PubMed1994

Pneumococcal infection and immunization in children.

Pneumococcal infection persists as a major cause of pneumonia, bacteremia, and otitis media and is the important cause of meningitis in young children. Children less than 2 years of age show the highest incidence of pneumococcal diseases. Pneumococcal types 6A + 6B, 7F, 9V, 14, 18C, 19F + 19A, and 23F account for the large majority of disease isolates in the pediatric population. Bacterial clearance and antibody response were studied in young mice from mothers injected with pneumococcal type 9V polysaccharide (PS) conjugated with the inactivated pneumolysin to examine the protective immunity of young mice to pneumococcal infection. The injection of mice with pneumococcal PS-protein conjugate conferred the protective immunity to pneumococcal infection. The efficacy of pneumococcal vaccine might be enhanced by addition of inactivated pneumolysin in the form of PS-protein conjugate. The molecular size of pneumococcal type 19F PS or oligosaccharide used for preparing the PS-protein conjugate has a profound effect on the antibody response to the PS. The conjugate immunogen prepared from a large molecule of 19F PS produced a high antibody response to the PS in young mice. Development of a PS-protein conjugate vaccine for selected pneumococcal types will help in solving problems of poor immunogenicity of pneumococcal PS vaccine in young children.

Adolescent↗
PubMed1994

Application of aqueous two-phase systems in separation/purification of stroma free hemoglobin from animal blood.

Aqueous two-phase system (ATPS) is suitable for treatment of biological materials. It has been traditionally employed in the separation of product from fermentation broth, and in the extraction of large-molecule proteins from colloid solution. The separation method based on ATPS features simple, rapid and continuous operation with low equipment cost. A PEG/Salt aqueous two-phase system is studied, and developed for hemoglobin (Hb) separation from animal bloods. Stroma free hemoglobin (SFHb) was extracted from 200ml packed red blood cells by the two-stage aqueous two-phase system and subsequently was desalted and dialyzed by ultrafiltration. It took only 2.5hr to complete overall process to purify SFHb. The purity of SFHb was analyzed by HPLC and IEF (silver staining). Large partition coefficients of Hb have been observed with proper selection of PEG molecular weight, added concentrations of PEG and salt in each phase. The SFHb of very high purity which is free of other proteins (< 0.1% impurity) and phospholipids (< 2% impurities) may be obtained from human packed RBCs. A two-stage extraction design using ATPS separation concept is very simple and useful for purification of SFHb. The method may be further developed to offer potent technology for hemoglobin separation from animal blood and future production industry of blood substitutes.

Animals↗
PubMed1994

Treatment of renal artery stenosis after kidney transplantation by percutaneous transluminal angioplasty: report of two cases.

Graft renal artery stenosis is one of the causes of hypertension after kidney transplantation. Surgical angioplasty was the treatment of choice before the development of percutaneous transluminal angioplasty (PTA) in the 1970s. Surgical repair was associated with some morbidity and graft loss while PTA was reported to have controversial results in the treatment of this disease. This is a report of two cases of graft renal artery stenosis occurring four and seven months after kidney transplantation that were treated with PTA. The immediate and short-term results of PTA were excellent, but the long-term effects require further follow-up.

Adult↗