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Biomedical subjects

W Lee

Publications and source records attributed to W Lee.

At least 307 records · Page 17Linked to original sources
PubMed1991

Clinical management of gravid women with peripartum cardiomyopathy.

Peripartum cardiomyopathy is an important cause for idiopathic heart failure associated with pregnancy. Current evidence suggests a potential role for myocarditis in the pathogenesis of this disease. About 3% to 4% of these patients present before delivery. Another group of patients with prior history of this disease request information about pregnancy prognosis. This article focuses on current concepts about peripartum cardiomyopathy and presents a reasonable approach to this clinical challenge during pregnancy.

Cardiomyopathies↗
PubMed1991

Maternal, uteroplacental, and fetoplacental hemodynamic and Doppler velocimetric changes during epidural anesthesia in normal labor.

Pulsed Doppler and M-mode maternal echocardiography were combined with uterine and umbilical artery Doppler velocimetry to characterize the hemodynamic changes associated with fluid preload and epidural anesthesia in 12 normal laboring gravidas at term. Fluid preload alone was associated with significant (P less than .05) increases in heart rate (11%), stroke volume (10%), and cardiac output (20%), and a decrease in systemic vascular resistance (19%). There were no changes in mean arterial pressure (MAP) or ejection fraction during any stage of the study. Following placement of the epidural block, stroke volume and cardiac output returned to values not significantly different from baseline, whereas heart rate remained elevated and systemic vascular resistance remained decreased. There were no changes in uterine or umbilical artery systolic-diastolic (S-D) ratios during any stage of the study. We conclude that fluid preload and epidural anesthesia cause significant changes in maternal cardiac output, heart rate, stroke volume, and systemic vascular resistance without affecting MAP. These maternal changes do not correlate with any changes in uterine or umbilical artery S-D ratios following epidural anesthesia in the normal laboring gravida.

Anesthesia, Epidural↗
PubMed1990

Enhanced expression of ganglioside GD3 in human and rat hepatocellular carcinoma cells and NIH 3T3 cells transfected with human tumor DNAs.

The gangliosides of human hepatoma biopsies, human hepatoma cell lines, and diethylnitrosamine-induced rat hepatomas were examined. These malignant tissues all expressed increased content of disialolactosylceramide (GD3) with respect to their normal counterparts. During the induction of rat hepatoma by diethylnitrosamine, an increase in GD3 levels appeared as early as 12 wk after initiation of diethylnitrosamine, concurrent with the appearance of precancerous hepatocytes. GD3 levels gradually increased to a peak of 4 times that of normal rat liver at 20 wk. CMP-NeuAc:GM3 sialyltransferase, the enzyme that synthesizes GD3 by transfer of sialic acid to GM3, also had tumor-associated elevation during the course of diethylnitrosamine-induction of rat hepatomas. To investigate the relationship of oncogene transformation and changes in ganglioside biosynthesis, NIH 3T3 cells transfected DNAs from human hepatoma or nasopharyngeal carcinoma were studied. The transfectants each expressed the same ganglioside composition, including a detectable level of GD3, as well as enhanced activity of CMP-NeuAc:GM3 sialyltransferase. A correlation between the tumor DNA transfection and the augmentation of GD3 in malignant cells is discussed. Because of the early appearance of GD3 in hepatoma and its possible relationship to oncogene activation, GD3 may be a potentially useful early tumor marker.

Animals↗
PubMed1990

Translation of c-myc mRNA is required for its post-transcriptional regulation during myogenesis.

During the differentiation of C2 myoblasts into differentiated myotubes, there is a marked decrease in the abundance of c-myc mRNA. c-myc transcription initiation and elongation do not change significantly, but the turnover of c-myc transcripts appears to be accelerated during differentiation. We examined the expression of several recombinant c-myc genes introduced into C2 cells by stable transfection and found that mRNAs containing the c-myc protein-coding region of exons 2 and 3 are appropriately regulated; the upstream c-myc sequences, the long leader sequence encoded by c-myc exon 1, and the 3' untranslated region are dispensible for proper regulation. Regulation appears to affect c-myc transcripts that are bound to polyribosomes, and the mRNA from a gene with a point mutation in the translation initiation codon is no longer properly regulated. We conclude that down-regulation of c-myc expression during myogenesis is post-transcriptional and requires the presence of sequences encoding the c-myc protein in a form that can be translated.

Animals↗
PubMed1990

Effect of germanium on 1,2-dimethylhydrazine-induced intestinal cancer in rats.

Through recent research, the trace element, germanium, was found to have an anticancer effect. The purpose of this research was to determine the effect of germanium on 1,2-dimethylhydrazine-induced intestinal cancer in rats. Ninety-six 8-week-old Sprague-Dawley male rats were divided into 4 groups, with 24 rats in each group. All received dimethylhydrazine, 20 mg/kg body weight, subcutaneously, once a week for 20 weeks. Except for one control group, the other three groups were subdivided into six groups and administered three different kinds of germanium (inorganic germanium, organic germanium, and natural organic germanium) one month before and during dimethylhydrazine treatment, and during dimethylhydrazine treatment, respectively. Twenty-four weeks after carcinogen exposure, all surviving animals were sacrificed and examined for intestinal tumors. The number and location of the tumors were recorded and the pathology examined. The incidence of intestinal cancer in the control group (dimethylhydrazine only) was 91 percent; in groups provided with inorganic germanium one month before and during dimethylhydrazine treatment, and during dimethylhydrazine treatment only, it was 91 and 78 percent; in groups provided with organic germanium one month before and during dimethylhydrazine treatment, and during dimethylhydrazine treatment only, it was 64 and 64 percent; in groups provided with natural organic germanium one month before and during dimethylhydrazine treatment and during dimethylhydrazine treatment only, it was 50 and 45 percent. From these results, the authors conclude that natural organic germanium has the best prevention effect for intestinal cancer in this animal model (P less than 0.01), followed by organic germanium (P less than 0.05). Inorganic germanium has no effect. However, there is no difference in the cancer prevention effect of germanium provided one month before and during dimethylhydrazine treatment, and during dimethylhydrazine treatment only.

1,2-Dimethylhydrazine↗
PubMed1990

Cyanotic maternal heart disease in pregnancy.

Cyanotic heart disease has major implications for maternal and fetal well-being during pregnancy. This article reports six patients with cyanotic congenital heart disease recently managed at our institutions. Although the maternal condition deteriorated to some extent during each pregnancy, it was the fetal condition that ultimately dictated delivery in each case.

Adolescent↗
PubMed1990

High-level transcription from the adenovirus major late promoter requires downstream binding sites for late-phase-specific factors.

The adenovirus major late promoter (MLP) is active during both the early and late phases of infection. During the early phase the activity of the MLP is similar to those of the other early viral promoters, but during the late phase the rate of transcription from the MLP becomes much greater by comparison. We report here that sequence-specific binding proteins are induced during the late phase which interact with three regions in the first intron of the MLP transcription unit from positions +37 to +68, +80 to +105, and +105 to +125 relative to the transcription initiation site. To measure the significance of these binding sites for transcription during the late phase, we constructed MLP-beta-globin fusions and substituted them for early region 3 in adenovirus recombinants. Deletion of the binding sites caused significant reductions in the rate of transcription, specifically during the late phase of infection. Deletion of all three sites reduced the rate of transcription 25- to 50-fold and the accumulation of cytoplasmic MLP-beta-globin RNA 200-fold. These results indicate that the high rate of transcription from the MLP during the late phase of infection results from the interaction of virus-induced transcription factors with three binding sites in the first intron of the major late transcription unit.

Adenoviruses, Human↗
PubMed1990

Alterations in plasma volume and protein during cycle exercise throughout pregnancy.

The purpose of this investigation was to determine the effects of cycle exercise on maternal plasma volume (PV) and protein dynamics during pregnancy. Sixteen healthy gravidas (age = 23 +/- 4.6 yr) cycled for 5 min (75 W) at 4 wk intervals throughout term. Venous blood samples were drawn immediately prior to and during the last minute of exercise. Relative (percent) PV changes during exercise were calculated from hematocrit ratios and hemoglobin concentrations. Plasma was analyzed for total protein ([TP]) and albumin ([ALB]) concentrations and colloid osmotic pressure (COP). Resting blood volumes were also estimated (carbon monoxide rebreathing) so that absolute PV (ml) and TP and ALB contents (g) could be determined. COP increases (P less than 0.001) during exercise were similar at all gestational ages. Plasma volume, TP, and ALB decreased during exercise with significantly (P less than 0.001) greater losses occurring from 29-32 wk gestation. This may indicate an increase in capillary permeability to large molecules when vascular volume was highest.

Adult↗
PubMed1990

Interferon production from peripheral blood, synovial fluid, and synovial tissue lymphocytes in patients with rheumatoid arthritis and ankylosing spondylitis.

A previous study demonstrated that interferon was present in the serum of 30% of the patients with systemic lupus erythematosus (SLE), which was significantly higher than the 4.5% found in normal controls. We also recently reported that interferon production was deficient from SLE mononuclear cells, which has been attributed to immunodeficiency of the lymphocytes. In this study, interferon measurement included lymphocytes obtained from peripheral blood (PB), synovial fluid (SF) and synovial tissue (ST) in patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS). PB from normal subjects (NS) was used as a control. The results showed with PHA stimulation, that the interferon level in PBL (L = lymphocyte) in NS (70.0 +/- 67.5) was significantly higher when compared with PBL in RA (27.9 +/- 21.6). However, there was no difference between PBL in NS and AS. With ConA stimulation, the interferon level was significantly higher in the PBL of NS (130 +/- 59) and as compared with the PBL in RA (83.6 +/- 53.5). The SFL in RA (67.8 +/- 31.1) and the STL in RA (77.2 +/- 93.2) were also significantly different. It is concluded that interferon production was deficient not only in PBL in RA, but also in SF and STL in RA. The reduced interferon production from PB, SF and ST lymphocytes in RA patients may be due to previous release or immunodeficiency. Lymphocyte interferon production was normal in AS, which suggests that the lymphocyte abnormality between RA and AS may be different.

Adult↗
PubMed1990

Ontogeny of cortical muscarinic receptor subtypes and muscarinic receptor-mediated responses in rat.

To determine the ontogenetic relationship of muscarinic receptor and effector systems in the central nervous system, the developmental time courses for binding sites with high (M1) and low (M2) affinity for pirenzepine as well as muscarinic receptor-mediated stimulation of phosphoinositide breakdown and inhibition of cyclic AMP accumulation were examined in rat cortex. M1 sites were 30% of adult levels at 1 week, 70% at 2 weeks, 90% at 3 weeks and equal to adult levels at 4 weeks postpartum. M2 sites, on the other hand, did not show a significant change between the ages of 1 and 6 weeks. Acetylcholine-stimulated phosphoinositide breakdown was detected at all ages tested (1, 2, 3, 4 and 6 weeks). The percentage of conversion of [3H] phosphoinositides to [3H]inositol phosphates, stimulated by 1 mM acetylcholine, increased with age until 3 weeks after birth and then decreased slightly at ages 4 and 6 weeks. Carbachol inhibition of [3H]cyclic AMP accumulation, on the other hand, was undetectable in tissues from 1- and 2-week-old rats, whereas in tissues from 3- and 4-week-old rats, the responses were at 6-week level. Thus, for carbachol inhibition of cyclic AMP accumulation, a time in development existed (2 weeks after birth) at which receptors appeared to be present but response to stimulation was absent. To examine indirectly the coupling of binding sites to second messenger systems via guanine nucleotide-binding regulatory proteins, the density of binding sites for the muscarinic receptor agonist, [3H]oxotremorine-M, was measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1990

Randomized controlled trial of doxycycline in prevention of recurrent periodontitis in high-risk patients: antimicrobial activity and collagenase inhibition.

82 patients with a recent history of periodontal abscesses and/or loss of gingival attachment (GAL) despite active periodontal therapy were enrolled in a double-blind, randomized, placebo-controlled trial. Clinical measurements and subgingival scaling were performed every 2 months. If any site exhibited greater than or equal to 2 mm loss of GAL or a periodontal abscess, patients were administered either 100 mg Doxycycline per day for 3 weeks or placebo. During 12 months of monitoring, 55 patients exhibited recurrent active disease and were then randomly assigned to either the Doxycycline or placebo groups. Clinical measurements of GAL and microbiological culture of subgingival bacteria were made at intervals between 1 week and 7 months after completion of the drug regime. Within 7 months, 15 out of 19 patients on placebo exhibited recurrent disease compared to 13 out of 29 patients on Doxycycline, a relative risk reduction of 43% (p less than 0.05) for Doxycycline compared to placebo. Minimal inhibitory concentrations of Doxycycline for subgingival plaque samples from active sites ranged between 25-100 micrograms/ml, which are several fold higher than reported crevicular fluid concentrations for this drug. However gingival crevicular fluid collagenase was inhibited in vitro at concentrations of 5-10 micrograms/ml Doxycycline. These data indicate that Doxycycline provides significant risk reduction of recurrent periodontitis in patients with active disease.

Adult↗
PubMed1990

Nutrition and the precontest preparations of a male bodybuilder.

A 27-year-old male bodybuilder was studied during a 30-day precontest period when his goal was to lose fat and retain muscle mass. Weighted dietary intakes were obtained for each day of the study. The subject trained 6 days per week with weights and included an aerobic component on most days. Ergogenic drugs and a diuretic were self-administered. At the contest, the subject placed in the top three for his weight division. The strict diet enabled the subject to lose fat weight predictably in preparation for the contest. However, some weight lost was lean body tissue, suggesting the rate of loss was too fast. Blood chemistry studies revealed abnormalities, including hemoconcentration and alterations in cholesterol metabolism, which could have placed the subject at risk for thromboembolic phenomena because of increased blood viscosity. Those abnormalities could reflect the use of ergogenic drugs. For this subject, bodybuilding included diet, exercise, and drug regimens, which are common among competitive athletes.

Adult↗
PubMed1990

Cardiac output responses of primigravid women during exercise determined by the direct Fick technique.

We compared metabolic and cardiovascular responses to aerobic exercise with the direct Fick technique in women during and after pregnancy. Seven subjects were studied at 37 weeks' gestation and again 12 weeks postpartum. All were tested at rest and during four sequential exercise bouts consisting of 5 minutes at each of two cycle (50 and 75 W) and two treadmill (67 m x min-1 at 2.5 and 12% grade) protocols. Oxygen consumption (VO2) and heart rate were measured during the fifth minute of exercise. Arterial and mixed venous oxygen contents, obtained from catheters placed in the radial and pulmonary arteries, respectively, were used to calculate arterial-venous oxygen difference. Cardiac output and stroke volume were calculated from the Fick equation. Responses of VO2, cardiac output, and stroke volume were greater when exercise was performed at 37 weeks' gestation as compared with postpartum. In contrast, heart rate response (during cycling) and arterial-venous oxygen difference (during treadmill walking) were less when exercise was performed during pregnancy. Our results indicate that there is no compromise in maternal cardiac output during either cycle or treadmill exercise performed late in pregnancy as compared with postpartum conditions.

Adult↗
PubMed1990

Artificial orbit system for experimental surgery with enucleated globes.

A portable system for holding, accurately positioning, and restoring the physiologic integrity of enucleated globes during experimental anterior segment procedures and pars plana vitrectomy is described. A 0 to 500-mm Hg vacuum fixation ring and positioning apparatus mechanically locks globes into known spatial position while they are supported in a 2 to 6-mm Hg pressurized, pliable socket designed to match the size and pressure of a natural orbit. A gravity infusion system and an implantable piezoelectric pressure sensor in conjunction with a syringe and stopcock assembly allow for controlled inflation of globes to intraocular pressure (IOP) levels from 0 to 70 mm Hg, and to over 300 mm Hg. The fixation vacuum level, and intraocular and extraocular pressures are simultaneously monitored on 3-digit LED displays, and permanent records of each can be generated by routing data to storage devices. The anterior segment remains accessible at all times for surgical procedures and diagnostic measurements. The entire system is portable, allowing globes to be transported to multiple experimental stations, while all pressure settings and the position of the globe are maintained. To demonstrate applications of the artificial orbit system, we describe experiments using it to calibrate applanation tonometers, and to study the relationship between IOP and corneal curvature as well as the effect of trephination procedures and limbal vacuum fixation on IOP.

Animals↗
PubMed1989

Outbreak of coagulase negative staphylococcus highly resistant to ciprofloxacin in a leukaemia unit.

OBJECTIVE: To define an outbreak of bacteraemia due to coagulase negative staphylococci highly resistant to ciprofloxacin in a leukaemia unit, investigate the source and mode of spread of the outbreak strain, and assess control measures. DESIGN: The outbreak strain was characterised by five different typing methods. Surveillance of patients, staff, and environment was carried out during the outbreak and five months after control measures were introduced. SETTING: A unit with 10 beds for adults with leukaemia and patients receiving bone marrow transplants. The outbreak occurred during a trial of ciprofloxacin for empirical treatment of neutropenic fevers. INTERVENTIONS: Ciprofloxacin was withdrawn from use in the unit and daily bathing with chlorhexidine gluconate solution started. Main outcome measure--The absence of bacteraemia due to the outbreak strain for five months after control measures. RESULTS: During the study 49 patients developed 21 episodes of bacteraemia due to the outbreak strain, which was ciprofloxacin resistant (minimum inhibitory concentration greater than or equal to 128 mg/l), susceptible to phage 155 A9C, and SII biotype and had characteristic immunoblot and DNA fingerprint features. There was a high amount of colonisation of patients but not staff with this strain, which was also wide spread in the environment. The control measures led to rapid resolution of the outbreak and disappearance of the strain from the unit. CONCLUSIONS: In areas where coagulase negative staphylococcal infections are common doctors must be aware of the possibility of cross infection with single strain, and the availability of more discriminatory methods of typing will facilitate the identification and control of such episodes.

Cancer Care Facilities↗