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Biomedical subjects

A M Lee

Publications and source records attributed to A M Lee.

At least 73 records · Page 4Linked to original sources
PubMed1989

In ovo growth hormone alters growth and adipose tissue development of chickens.

The effect of in ovo administration of ovine growth hormone (oGH) on growth and adipose tissue development of chickens was investigated. Unlike mammalian species, exogenous growth hormone has not been previously shown to increase growth of aves. In trial 1, fertilized eggs were injected with vehicle (.03 M NaHCO3 in .15 M NaCl, pH 8.3), 0.25, 2.5, 25 or 250 micrograms oGH on day 11 of embryogenesis. In trial 2, fertile eggs were injected with vehicle or 250 micrograms oGH. In contrast to previous studies in which GH was administered to growing birds, oGH injected in ovo in the present study increased body weights, skeletal growth and feed efficiencies of male broilers. Growth rate was not altered in females. Adipose cellularity data from both trials indicated that in ovo oGH also altered adipose tissue development of broilers. Seven-week-old male and female broilers treated with oGH during embryogenesis exhibited larger adipocytes with correspondingly less cell per gram of tissue. Additionally, adipocytes from oGH-treated broilers exhibited decreased sensitivity to glucagon, cholera toxin or theophylline-induced lipolysis responsiveness to dcAMP in ovo. Cholera toxin plus theophylline improved the lipolytic response of oGH-treated birds; thus, in broilers injected with oGH cAMP-mediated lipase activation may be reduced by a mechanism of increased phosphodiesterase activity. The results of this study indicate that growth and tissue development of chickens have been altered by mammalian GH in ovo.

Adipose Tissue↗
PubMed1987

The sugar-specific adhesion/deadhesion apparatus of the marine bacterium Vibrio furnissii is a sensorium that continuously monitors nutrient levels in the environment.

Our earlier studies on cell adhesion to immobilized carbohydrates are extended here to a marine bacterium, Vibrio furnissii. Apparently one lectin mediates the binding of these cells to glycosides of N-acetylglucosamine, mannose, and glucose covalently linked to Agarose beads. Kinetic studies show that protein synthesis is required for initiating and for maintaining adhesion to the glycosides. Furthermore, a pro- mutant binds to GlcNAc-beads at Pro concentrations insufficient to support cell growth. Expression of the functional lectin therefore predominates under conditions of limiting protein synthesis. Thus, cells adhere to the sugars in an environment compatible with protein synthesis, and deadhere when depleted of any required nutrient, presumably to migrate to a more favorable locale. The adhesion-deadhesion apparatus thereby permits constant monitoring of the surrounding environment, comprising a "nutrient sensorium".

Acetylglucosamine↗
PubMed1987

Cervical carcinoma DNA content, S-fraction, and malignancy grading. I. Interrelationships.

The flow cytometric measured DNA content (i.e., DNA index), S-fractions, and histopathologic malignancy grades were studied for ninety uterine cervical squamous cell carcinomas using tissue biopsies taken prior to radiotherapy. The DNA aneuploidy frequency for low S-phase tumors (%S less than 14) was only 9/29 (31%) compared to 22/30 (73%) for intermediate (%S 15-23) and 30/31 (97%) for high (%S greater than 24) tumors. An overall mean %S of 20 +/- 7 (range 2-45%) was observed for these cervical cancers, with the S-fraction significantly increasing (P = less than 0.01) from 12 +/- 5, to 18 +/- 8, and 26 +/- 7 for diploid/near diploid, low-degree DNA aneuploidy, and high-degree DNA aneuploidy tumors, respectively. Broad heterogeneity was observed for the microscopic scored malignancy grades within DNA index and the cell-cycle S-fraction subgroups. Generally, multifactorial histopathology scoring was not significantly correlated with either the tumor DNA index or %S variables. Based on statistical analysis, the malignancy grades more closely reflected the tumor proliferative activity than the DNA index, with nuclear polymorphism, mitotic frequency, and the invasion pattern showing the lowest P values (which were not significant at P = 0.05). High tumor S-fraction was associated with high malignancy grade, as evidenced by 19/25 (75%) of high S-fraction, high degree DNA aneuploidy tumors having greater than average malignancy grade compared to only 2/14 (14%) low to moderate S-fraction tumors having similar DNA index. The results indicate that more reliable identification of biologically different cervical cancers can be achieved by evaluating the tumor DNA index in relationship to the cell-cycle %S and malignancy grading.

Biopsy↗
PubMed1987

Natal teeth and steatocystoma multiplex: a newly recognized syndrome.

A Chinese family is reported in which five generations have exhibited natal teeth and generalized multiple steatocystomas. This autosomal dominant condition is not similar to the two reported types of pachyonychia congenita, because nail lesions, palmoplantar keratosis and hyperhidrosis, follicular keratosis, and oral leukokeratosis were not observed. Therefore, it is suggested that this family exhibits a newly recognized syndrome.

Epidermal Cyst↗
PubMed1986

Self-association and phospholipid binding properties of iodinated apolipoprotein A-I.

Kinetic turnover studies of apolipoprotein metabolism often utilize radioiodinated tracers. These studies rely on the "tracer assumption" that the modified tracer is physiologically and metabolically identical with the native unmodified tracer. This paper addresses the validity of this assumption on the basis of the examination of the state of self-association and binding properties with egg yolk phosphatidylcholine small unilamellar vesicles of native and iodinated apolipoprotein A-I (apoA-I). Human apoA-I was iodinated to the extent of 1.0 and 3.7 mol of nonradioactive iodine/mol of protein. At concentrations from 0.013 to 0.8 mg/mL, iodinated apoA-I underwent concentration-dependent self-association similar to that of native apoA-I as evidenced by circular dichroism and gel filtration. At all concentrations, however, the iodinated preparations were more highly self-associated as judged by gel filtration in relation to the extent of iodination. Scatchard analysis of fluorometric titrations of apoA-I/vesicle interactions demonstrated that the binding capacity of vesicles for apoA-I increased and apoA-I binding affinity decreased upon iodination. In addition, the kinetics of apoA-I binding to vesicles was enhanced by iodination. The affinity, capacity, and kinetics of apoA-I binding were each altered 2-3-fold dependent on the extent of iodination. Since the dynamic interactions of apoA-I are perturbed by iodination, one may legitimately question whether the "tracer assumption" is valid for 125I-apoA-I under all experimental conditions.

Apolipoprotein A-I↗
PubMed1985

Effects of electrical stimulation and an intracellular calcium chelator on calcium movement in suspensions of isolated myocardial muscle cells.

The procedure of Haworth RA, Hunter DR and Berkoff HA (J Mol Cell Cardiol, 1980; 12:715-23) for the isolation of myocardial muscle cells from rat hearts has been modified by the addition of a step which involves centrifugation of the cells through a Percoll gradient. This increased the proportion of rod-shaped cells from 47 +/- 2.2 to 80 +/- 1.3% (mean +/- SEM, n = 7). In the absence of electrical stimulation but in the presence of 1.3 mmol . litre-1 Ca2+ less than 2% of the cells beat spontaneously. This number was not increased by addition of the Ca2+-selective ionophore A23187. A method in which isolated myocytes suspended in a cyclindrical incubation chamber are stimulated to beat by electrical impulses is described. At 1.3 mmol . litre-1 extracellular Ca2+, electrical stimulation increased by 30% the amount of 45Ca2+ exchanged in the period 0.25 to 3 min following addition of 45Ca2+. For myocytes subjected to electrical stimulation, the amount of 45Ca2+ exchanged increased as the concentration of extracellular Ca2+ increased. At 0.5 mmol . litre-1 extracellular Ca2+ verapamil reduced the amount of 45Ca2+ exchanged by 15% while La3+ reduced the amount of 45Ca2+ exchanged by 80%. Incubation of myocytes with the acetoxymethyl ester of the intracellular Ca2+ chelating agent bis (o-aminophenoxy)-ethane-N,N,N'N'-tetraacetic acid (BAPTA) for 45 min led to an inhibition of contraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Metabolic activation of procarcinogens to genotoxic products in cultured rat liver cells.

A recently established rat liver cell line, RL-12, exhibits an unusually high sensitivity to the genotoxic effects of a number of selected procarcinogens. Significant reductions in cell survival (D37%) and induction of sister chromatid exchanges were obtained with 1 X 10(-9) M benzo[a]pyrene and 2 X 10(-8) M 7,12-dimethylbenz[a]anthracene. This rat liver epithelial cell line may serve as a useful model system to study the metabolic activation of procarcinogens to their ultimate genotoxic form.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1983

Prostanoids can modify response to electrical stimulus and 45Ca2+ exchange in isolated myocardial muscle cells.

The effects of prostaglandins E1 and E2, prostacyclin and thromboxane B2 on electrically-induced contraction and 45Ca2+ exchange in isolated rat cardiac muscle cells were investigated. Low (10(-13) - 10(-11) M) and high (10(-5), 10(-4) M) concentrations of prostaglandin E2 produced a significant inhibition of contraction. The effects of prostaglandin E1 were less pronounced, with maximal inhibition observed at 10(-10), 10(-9) M and 10(-6) - 10(-4) M. Both prostacyclin (10(-9) - 10(-4) M) and thromboxane B2 (10(-12) - 10(-5) M) produced a transient inhibition of contraction 1 - 3 min after the addition of these agents to the cells. All four prostanoids increased the amount of 45Ca2+ exchanged by non-beating cells at 2 and 4 min after the addition of 45Ca2+. Maximal effects were observed at 10(-12) M prostaglandin E1, 10(-5) M prostaglandin E2 and prostacyclin, and at 10(-12), 10(-8) and 10(-4) M thromboxane B2. These results may be relevant to the involvement of prostanoids in cardiac function in normal and pathological situations.

Alprostadil↗
PubMed1983

Computer-tomographic appearance of branchial cleft and thyroglossal duct cysts of the neck.

The usefulness of computer tomography (CT) in the evaluation of a congenital neck mass has received little attention in the literature. We present the CT findings in two relatively common congenital neck masses - the thyroglossal duct cyst and the branchial cleft cyst. These cysts present a relatively common CT appearance of a mass with an enhancing capsule and a lucent center measuring between 20 and 35 Houndsfield Units. The branchial cleft cyst commonly occurs along the lateral border of the neck, anterior to the sternocleidomastoid muscle, while the thyroglossal duct cyst occurs along the midline of the neck. CT is excellent for determining the location, size, extent and character of these two common congenital neck masses.

Adolescent↗
PubMed1982

Project Burn Prevention: outcome and implications.

Project Burn Prevention was designed and implemented to determine the ability of a public education program to increase awareness about burn hazards and reduce the incidence and severity of burn injuries. Media messages were transmitted to residents of a large metropolitan area; separate school and community interventions were implemented in two demographically similar communities within the Standard Metropolitan Statistical Area (SMSA). A second metropolitan area and two of its communities served as control sites. Messages for specific, high-risk age groups emphasized flame burns because of their severity and scalds because of their frequency. Knowledge gains were demonstrable only as a result of the school program. Neither the school program nor the media campaign reduced burn incidence or severity; the community intervention may have brought about a moderate, temporary reduction in injuries. Multiplicity of messages, brevity of the campaign, and separation of the interventions are among possible reasons for the program's failure to significantly reduce burn injuries. Education for personal responsibility is not sufficient. Product modification and environmental redesign must be instituted through education and legislation for successful control of burn injuries.

Adolescent↗