Search PubMed⌕ Search

Biomedical subjects

K Lee

Publications and source records attributed to K Lee.

At least 739 records · Page 41Linked to original sources
PubMed1990

Clonal growth of bladder cancer cells in a double layer soft agar assay: needles addition of multiple culture supplements.

The necessity of multiple culture supplements, characteristic of Hamburger and Salmon (H&S) soft agar assay (1977), for the clonal growth of bladder cancer cells was systematically investigated. One murine and 6 human cell lines were cultivated in different culture supplemented conditions based on the H&S method. All cell lines successfully formed colonies in the absence of supplements. The inclusion of 2-mercaptoethanol to supplement-free medium stimulated the clonal growth of murine (MBT-2) cells, whereas it did not affect the growth of human cell lines. DEAE-dextran suppressed the clonal growth of 5 out of 7 lines. Tryptic soy broth stimulated the growth of 2 human cell lines, whereas it suppressed the other 2 cell lines. The chemosensitivity of MBT-2 cells was not affected by these supplements.

Animals↗
PubMed1990

Non-everted oxygenated rat intestinal segments as a measure of neutral detergent fiber effects on iron absorption.

Iron absorption in the presence of varying amounts and sizes of dietary fiber was measured. A method using non-everted rat intestinal segments perfused in oxygen was refined. Neutral detergent fiber (NDF), a component of dietary fiber, was extracted from cooked pinto bean (Phaseolus vulgaris). The NDF did not affect iron absorption in intestinal segments from iron replete rats. However, 4 and 6 mg of NDF/ml significantly decreased iron absorption in the intestinal segments from anemic rats. NDF with a smaller particle size of 0.125 mm increased iron absorption relative to that absorbed with 0.180 mm particles. Histological examination validated using non-everted intestinal segments perfused with oxygen as a method for studying dietary effects on iron absorption. Segments which are not everted are less prone to damage. Perfusion with oxygen maintained metabolic activity in the tissue during the experiment.

Journal Article↗
PubMed1990

Evolutionary conservation of antigen recognition: the chicken T-cell receptor beta chain.

T cells play important regulatory roles in the immune responses of vertebrates. Antigen-specific T-cell activation involves T-cell receptor (TCR) recognition of a peptide antigen presented by a major histocompatibility complex molecule, and much has been learned about this antigen-recognition process through structural and genetic studies of mammalian TCRs. Although previous studies have demonstrated that avian T cells express cell-surface molecules analogous to the mammalian TCR heterodimers, TCR genes have not been identified in nonmammalian species. We now report the cloning of a cDNA that encodes the beta chain of the chicken TCR. Southern blot analysis using this TCR beta cDNA probe demonstrated that the chicken TCR beta locus was clonally rear-ranged in chicken T-cell lines. TCR beta mRNA was expressed in cells isolated from the thymus but not in cells from the bursa of Fabricius where B cells are generated. Sequence analysis of six additional TCR beta cDNAs suggested the existence of at least two variable (V) region families, three joining (J) elements, and single diversity (D) and constant (C) elements. As in mammals, considerable nucleotide diversity was observed at the junctions of the variable, diversity, and joining elements in chicken TCR beta cDNAs. Genomic V beta and J beta elements were also cloned and sequenced. Both elements are flanked by classical heptamer/nonamer recombination signal sequences. Although the chicken and mammalian TCR beta chains displayed only 31% overall amino acid sequence identity, a number of conserved structural features were observed. These data indicate that (i) the chicken TCR beta repertoire is generated by combinatorial and junctional diversity and (ii) despite divergent evolution at the level of nucleotide sequence, important structural features of the TCR beta polypeptide are conserved between avian and mammalian species.

Amino Acid Sequence↗
PubMed1990

The provision of urethral catheters: an equipment audit.

Although medical and nursing audit is attaining a high profile in UK hospitals, the development of objective measures remains a challenge. The availability and storage or urinary catheters was recorded by a point prevalence survey in a District General Hospital. A "long-term" and "short-term" catheter were provided in all areas, but seven further brands of catheter were found. Female length catheters were rarely available. With some limited exceptions there were no written or verbal policies concerning selection of catheters in the wards. Excess numbers of catheters were stored by wards responsible for their own ordering. Damage of catheters during storage was noted. The survey provided a simple, rapid and inexpensive method of audit to rationalise and improve the provision of catheters. The implementation of a policy incorporating the selection, ordering, storage and use of such equipment will both optimise patient care and maximise efficient budgeting.

Catheters, Indwelling↗
PubMed1990

Effects of choline administration on in vivo release and biosynthesis of acetylcholine in the rat striatum as studied by in vivo brain microdialysis.

The purpose of the present study is to clarify the effects of the administration of choline on the in vivo release and biosynthesis of acetylcholine (ACh) in the brain. For this purpose, the changes in the extracellular concentration of choline and ACh in the rat striatum following intracerebroventricular administration of choline were determined using brain microdialysis. We also determined changes in the tissue content of choline and ACh. When the striatum was dialyzed with Ringer solution containing 10 microM physostigmine, ACh levels in dialysates rapidly and dose dependently increased following administration of various doses of choline and reached a maximum within 20 min. In contrast, choline levels in dialysates increased after a lag period of 20 min following the administration. When the striatum was dialyzed with physostigmine-free Ringer solution, ACh could not be detected in dialysates both before and even after choline administration. After addition of hemicholinium-3 to the perfusion fluid, the choline-induced increase in ACh levels in dialysates was abolished. Following administration of choline, the tissue content of choline and ACh increased within 20 min. These results suggest that administered choline is rapidly taken up into the intracellular compartment of the cholinergic neurons, where it enhances both the release and the biosynthesis of ACh.

Acetylcholine↗
PubMed1990

Enhancement of in vivo tyrosine hydroxylation in the rat adrenal gland under hypoxic conditions.

We examined the effects of hypoxia (8% O2) on in vivo tyrosine hydroxylation, a rate-limiting step for catecholamine synthesis, in the rat adrenal gland. The hydroxylation rate was determined by measuring the rate of accumulation of 3,4-dihydroxyphenylalanine (DOPA) after decarboxylase inhibition. One hour after hypoxic exposure, DOPA accumulation decreased to 60% of control values, but within 2 h it doubled. At 2 h, the apparent Km values for tyrosine and for biopterin cofactor of tyrosine hydroxylase (TH) in the soluble fraction were unchanged, whereas the Vmax value increased by 30%. The content of total or reduced biopterin was unchanged, but the content of tyrosine increased by 80%. Tyrosine administration had little effect on DOPA accumulation under room air conditions but enhanced DOPA accumulation under hypoxia. After denervation of the adrenal gland, the hypoxia-induced increase in DOPA accumulation and in the Vmax value was abolished, whereas the hypoxia-induced increase in tyrosine content was persistent. These results suggest that in vivo tyrosine hydroxylation is enhanced under hypoxia, although availability of oxygen is reduced. The enhancement is the result of both an increase in tyrosine content coupled with increased sensitivity of TH to changes in tyrosine tissue content and of an increase in dependence of TH on tyrosine levels. The increase in the sensitivity of TH and in the Vmax value is neurally induced, whereas the increase in tyrosine content is regulated by a different mechanism.

Adrenal Glands↗
PubMed1990

Enhancement of dopamine release in vivo from the rat striatum by dialytic perfusion of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin.

We have previously reported that intracerebroventricular administration of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (6R-BH4), a cofactor for tyrosine hydroxylase, enhances biosynthesis of 3,4-dihydroxyphenylethylamine (dopamine) in the rat brain. In the present study, we have more precisely examined the effects of 6R-BH4 on dopamine release in vivo from the rat striatum using brain microdialysis. The amount of dopamine collected in striatal dialysates was determined using HPLC with electrochemical detection after purification with an alumina batch method. When the striatum was dialyzed with Ringer solution containing various concentrations of 6R-BH4 (0.25, 0.5, and 1.0 mM), dopamine levels in striatal dialysates increased in a concentration-dependent manner. Biopterin had little effect on dopamine levels in dialysates. The 6R-BH4-induced increase in dopamine levels in dialysates was abolished after pretreatment with tetrodotoxin (50 microM) added to the perfusion fluid, but after pretreatment with nomifensine (100 mg/kg, intraperitoneal injection), an inhibitor of dopamine uptake mechanism, a larger increase was observed. After inhibition of tyrosine hydroxylase by pretreatment with alpha-methyl-p-tyrosine (250 mg/kg, intraperitoneal injection), most of the increase persisted. These results suggest that 6R-BH4 has a dopamine-releasing action, which is not dependent on biosynthesis of dopamine.

Animals↗
PubMed1990

Effects of hypoxia on the catecholamine release, Ca2+ uptake, and cytosolic free Ca2+ concentration in cultured bovine adrenal chromaffin cells.

The purpose of the present study is to clarify the effects of hypoxia on catecholamine release and its mechanism of action. For this purpose, using cultured bovine adrenal chromaffin cells, we examined the effects of hypoxia on high (55 mM) K(+)-induced increases in catecholamine release, in cytosolic free Ca2+ concentration ([Ca2+]i), and in 45Ca2+ uptake. Experiments were carried out in media preequilibrated with a gas mixture of either 21% O2/79% N2 (control) or 100% N2 (hypoxia). High K(+)-induced catecholamine release was inhibited by hypoxia to approximately 40% of the control value, but on reoxygenation the release returned to control levels. Hypoxia had little effect on ATP concentrations in the cells. In the hypoxic medium, [Ca2+]i (measured using fura-2) gradually increased and reached a plateau of approximately 1.0 microM at 30 min, whereas the level was constant in the control medium (approximately 200 nM). High K(+)-induced increases in [Ca2+]i were inhibited by hypoxia to approximately 30% of the control value. In the cells permeabilized by digitonin, catecholamine release induced by Ca2+ was unaffected by hypoxia. Hypoxia had little effect on basal 45Ca2+ uptake into the cells, but high K(+)-induced 45Ca2+ uptake was inhibited by hypoxia. These results suggest that hypoxia inhibits high K(+)-induced catecholamine release and that this inhibition is mainly the result of the inhibition of high K(+)-induced increases in [Ca2+]i subsequent to the inhibition of Ca2+ influx through voltage-dependent Ca2+ channels.

Adenosine Triphosphate↗
PubMed1990

Selective medium for isolation of Bacteroides gracilis.

A new medium selective for Bacteroides gracilis was developed. The medium is tryptic soy agar (Difco Laboratories, Detroit, Mich.) containing nalidixic acid, teicoplanin, sodium formate, sodium fumarate, and potassium nitrate. All 18 strains of B. gracilis tested grew with only minimal inhibition. Most of the other 214 organisms tested, including most Bacteroides species, other anaerobes, and a substantial number of facultative anaerobes, were significantly inhibited by the medium. In a diagnostic study of 49 clinical specimens (28 patients with intra-abdominal infection, mostly gangrenous or perforated appendicitis), four strains of B. gracilis were isolated (from 4 different patients) on B. gracilis selective agar but were not detected on standard media.

Agar↗
PubMed1990

Endotoxemia in patients on hemodialysis.

We examined endotoxins and limulus amebocyte lysate-reactive material (LAL-RM) in serum from 87 patients on hemodialysis, using the conventional chromogenic limulus test (CCLT) and a new specific endotoxin assay with factor G-free LAL (endotoxin-specific test: EST). All patients with regenerated cellulose dialyzers had increased CCLT values, whereas the EST values were not higher than in controls. This discrepancy can be explained by the LAL-RM which is cellulose-derived and cross-reacts with LAL via factor G. Using EST for measurements of endotoxin, 6 patients out of 87 had pathological endotoxemia and all of these patients were associated with either cirrhosis, infection, or malignancy. Some patients who had no complications showed fever before or during dialysis, but they did not have high endotoxin levels. EST is useful for the diagnosis of endotoxemia in patients on hemodialysis because of the presence of LAL-RM in serum. Endotoxemia is rare in patients on hemodialysis, if they are not associated with infection, cirrhosis, or other complications.

Adult↗
PubMed1990

Oral premedication in children: a comparison of chloral hydrate, diazepam, alprazolam, midazolam and placebo for day surgery.

A double-blind study consisting of 339 randomly selected children investigated the effects of several premedicants on the preoperative and postoperative behaviour of children who underwent day-stay surgery. Patients were allocated into two groups. Group 1 consisted of 165 children aged between 6 and 47 months. Group 2 consisted of 174 children aged four years and older to a body weight of 50 kg. Each child received one premedicant. Both groups included alprazolam 0.005 mg/kg, midazolam 0.3 mg/kg and placebo. In addition Group 1 included chloral hydrate 40 mg/kg and Group 2 diazepam 0.25 mg/kg. Chloral hydrate produced superior conditions (more patients calm or asleep) at induction of anaesthesia. Postoperative behaviour and incidence of vomiting were similar for all drugs. No premedicant reduced anxiety in the older group. The time to awaken postoperatively with diazepam was longer than with placebo. Alprazolam and midazolam were unpalatable for children over four years and conferred no advantage over placebo.

Administration, Oral↗
PubMed1990

Episodic fluctuation in serum intact parathyroid hormone concentration in men.

To evaluate the temporal features of physiological fluctuation in serum PTH concentration, we sampled peripheral blood at 4-min intervals for 24 h from five normal men (32.8 yr; range, 26-40 yr) and measured serum PTH levels using a two-site immunoradiometric assay with the exquisite sensitivity and specificity for human PTH-(1-84) (intact PTH). The resultant 24-h time series of serum intact PTH levels were assessed by contemporary techniques in chronophysiology for rhythmic and episodic peak detection. Cosinor analysis disclosed a significant circadian rhythm in serum intact PTH concentrations in all five men, with the mean circadian amplitude and acrophase of 7.2 +/- 4.4 ng/L and 2305 +/- 401 h, respectively (mean +/- SD; n = 5). No apparent fixed ultradian periodicity was found by autocorrelation and spectral analyses. Evaluation of episodic intact PTH pulsatility by Cluster analysis revealed 23.0 +/- 4.4 discrete PTH pulses/24 h (P less than 0.01 vs. signal-free noise), which occurred at an interpulse interval of 61.6 +/- 11.1 min. The average duration of a serum intact PTH peak was 42.8 +/- 7.3 min, and its mean incremental amplitude was 12.6 +/- 1.3 ng/L, which corresponded to a 31.8 +/- 5.2% increase above the preceding nadir. Discrete PTH peaks were separated by nonpulsatile valleys which lasted for 17.9 +/- 4.4 min. Cross-correlation between the time series of serum intact PTH and whole blood ionized calcium (Ca2+) was at its maximum (-0.5) at concurrent time points in three subjects, while significant positive correlation between serum intact PTH and simultaneous serum inorganic phosphorus concentrations was observed in four of five subjects. There was no apparent correlation between the levels of serum intact PTH and serum magnesium. Our data show that serum levels of intact PTH, the only biologically active form of PTH in the blood, is characterized by a significant circadian periodicity, spontaneous episodic pulsatility with distinct peak properties, and a significant temporal coupling with Ca2+ and inorganic phosphorus concentrations. We conclude that PTH secretion, as judged by the temporal pattern of serum intact PTH levels, is pulsatile in normal men.

Adult↗
PubMed1990

Prophylactic oral naltrexone with intrathecal morphine for cesarean section: effects on adverse reactions and analgesia.

The influence of two different doses of oral naltrexone on the adverse effects and the analgesia associated with intrathecal morphine was compared in a double-blind, placebo-controlled study. Thirty-five patients undergoing cesarean section were provided postoperative analgesia by 0.25 mg intrathecal morphine. Sixty minutes later they were given 6 mg naltrexone, 3 mg naltrexone, or placebo as an oral solution. Pain relief was assessed by the Visual Analog Scale. Requirements for additional analgesics and side effects were recorded. Duration of analgesia was shorter in the 3- and 6-mg naltrexone groups than in the placebo group, 10.0 +/- 2.6, 12.4 +/- 2.6, and 19.2 +/- 4.5 h (mean +/- SEM), respectively, but values did not reach statistical significance. The incidence of pruritus and vomiting was significantly less in the 6-mg naltrexone group than in the other two groups (P less than 0.05). Somnolence was significantly less in the 3- and 6-mg naltrexone groups than in the placebo group (P less than 0.05). Naltrexone (6 mg) is an effective oral prophylactic against the pruritus and vomiting associated with intrathecal morphine for analgesia after cesarean section, but it is associated with shorter duration of analgesia.

Administration, Oral↗
PubMed1990

A case of idiopathic fibrosing pancreatitis.

We experienced a case of chronic fibrosing pancreatitis in an 18/12-year-old girl, which was idiopathic because there were no familial back ground, no cystic fibrosis of pancrease, no ductal anomalies and obstruction. The patient presented intermittent colicky abdominal pain and progressive obstructive jaundice, but T-tube drainage and removal of the lymph nodes around the common bile duct relieved her symptoms and disease process. This seems to be the first case reported in a Korean child. Idiopathic fibrosing pancreatitis should be considered in the differential diagnosis of abdominal pain with obstructive jaundice in children.

Abdominal Pain↗
PubMed1990

Aberrant breast tissue of the perineum--a report on two cases.

In this abstract we report on two cases of aberrant breast tissue of the perineum in a 41-year-old and a 42-year-old woman with the complaint of a slowly growing vulvar mass. The masses were not fixed, they were ovoid, rubbery firm and measured 3 x 2.5 and 4 x 3 cm in size. Microscopically, they revealed normal lobular architecture with focal papillomatosis in the former.

Adult↗
PubMed1990

Maximum acceptable weight of lift for side and back lifting.

A series of laboratory experiments were conducted to find maximum acceptable weights in front, side, and back lifting. Fifteen college students participated in the experiment. Experimental trials for each type of lifting were conducted for 10 min for each subject at a rate of 4 lifts/min. Psychophysical methodology was used to find the acceptable weight based upon their perceived feeling of stress in the lower back. It was found that subjects are willing to lift the heaviest load using back lifting (average maximum acceptable weight: 41.5 lbs). Front lifting was the close second with 39.4 lbs. Also, there was a significant difference in maximum acceptable weight of lift between side lifting (average maximum acceptable weight: 25.5 lbs) and the other two types of lifting. It was also found that leg strength was a limiting variable for maximum acceptable weight in front lifting. Composite strength and shoulder strength were found to be limiting variables in side lifting. Composite strength was the limiting variable in the back lifting.

Accidents, Occupational↗
PubMed1989

Production of interleukin 1 beta, a potent bone resorbing cytokine, by cultured human myeloma cells.

Supernatants of freshly isolated human myeloma cell cultures were examined both for bone-resorbing activity (BRA) in vitro using newborn mouse calvaria, and for identification of the causal substances of the BRA. Eight of 14 culture supernatants of myeloma cells had BRA. All of these BRA-positive supernatants were from patients with marked destructive bone lesions of multiple myeloma. The presence of interleukin 1 (IL-1), especially IL-1 beta, was demonstrated in seven of these BRA-positive supernatants but not in BRA-negative supernatants. The concentrations of IL-1 beta were high enough to induce bone resorption in the newborn mouse calvaria assay and the BRA was totally abolished by pretreatment of the supernatants with anti-IL-1 beta antibody but not with either anti-IL-1 alpha antibody or normal serum. Other bone resorbing cytokines such as tumor necrosis factor or lymphotoxin were not present in high enough concentrations to stimulate bone resorption and their levels did not correlate with the BRA. IL-1 beta mRNA was also identified in BRA-positive myeloma cells. These results demonstrate that IL-1 beta is the principal agent of BRA present in supernatants of myeloma cell cultures, and also identify a possible role of IL-1 beta in destructive bone lesions in patients with multiple myeloma.

Adult↗