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Biomedical subjects

B J Wagner

Publications and source records attributed to B J Wagner.

At least 73 records · Page 4Linked to original sources
PubMed1984

A synthetic endopeptidase substrate hydrolyzed by the bovine lens neutral proteinase preparation.

Lens neutral proteinase is thought to exhibit primarily endopeptidase activity. We have identified a synthetic endopeptidase substrate which is hydrolyzed by the bovine lens neutral proteinase preparation. Among 11 fluoro- and chromogenic endopeptidase substrates, only carbobenzoxy-glycylglycyl-L-leucyl-p-nitroanilide is effectively hydrolyzed. The activity hydrolyzing this substrate co-elutes with neutral proteinase activity upon gel filtration and specifically attacks the leucyl-p-nitroaniline bond. Optimal hydrolysis of the synthetic substrate is at neutral pH and high temperature (53 degrees C), analogous to the alpha-crystallin protein substrate obtained from lens. The rate of hydrolysis of the synthetic substrate increased proportionally with temperature between 20 and 60 degrees C, in contrast to alpha-crystallin. The rate of hydrolysis was linear for at least 1 h at 37 degrees C and there was no evidence of enzyme activation at high temperature.

Animals↗
PubMed1984

Characterization of lens proteins. IV. Analysis of soluble high molecular weight protein aggregates in human lenses.

Soluble proteins of individual human normal and nuclear cataractous lenses of 60-70-year-old subjects were collected for this investigation. The average wet weights of both the normal and nuclear cataractous lenses were found to be essentially identical, approximately 230 mg. When the lens proteins, either cortical or nuclear, were subjected to fractionation by Sephadex G-200 sf chromatography, six fractions (F-I to F-VI) were obtained and their respective molecular weights approximated. F-I, which contains alpha-crystallin and high molecular weight aggregates, was subsequently fractionated through a series of Bio-gel A chromatographic columns. The quantities of the proteins and the molecular weights of each fraction were obtained. All the proteins fractionated were subjected to SDS gel electrophoresis by which the molecular weights of the subunits were obtained. The distribution and molecular weights of proteins smaller than 0.2 X 10(6) showed certain changes, more noticeable in the nucleus than in the cortex, between the normal lens and nuclear cataractous lens. For the high-molecular-weight protein aggregates, the major fraction in the lens cortex was found to be in the 5-1.5 X 10(6) range, representing 10 and 12% of the total protein in the normal and cataractous lenses, respectively. The major fraction in the nucleus was found to be greater than 150 X 10(6), representing 11 and 19% for the normal and cataractous lenses respectively. The above data are presented for the first time to show the differences in distribution of the high-molecular-weight proteins in the cortical and nuclear regions, and their respective changes in cataractogenesis. Based upon these data, we are able to calculate the average molecular weights of (1) the soluble cortical and nuclear proteins and (2) the total soluble protein, in the normal and cataractous human lenses.

Aged↗
PubMed1984

Intervening with the adolescent involved in substance abuse.

The problem of drug abuse in the school and the detrimental effects of drug use on the student's ability to concentrate, to remain involved in school work, and to relate to others has been well documented. However, the identification of the problem is only part of the solution. Intervening once a student has been identified as a "user" of an illegal substance is the rest of the problem. Members of the school health team are in a pivotal position to intervene and provide alternatives for the student and the family.

Adolescent↗
PubMed1982

Decrease in the number of lower affinity (type II) nerve growth factor receptors on embryonic sensory neurons does not affect fiber outgrowth.

Nerve growth factor binds to two different specific receptors on responsive cells. The relationship of these two receptors is not fully understood at this time. We have studied the binding of labeled NGF to a different strain of white leghorn chicken embryo dorsal root ganglionic cells. The equilibrium dissociation constants for the two sites (KdI = 4.1 +/- 1.8 x 10(-11) M, KdII = 1.0 +/- 0.8 x 10(-9) M) are identical to those obtained previously. Also, the number of type I sites per cell (3.8 +/- 1.3 x 10(3)) is the same as that previously determined. However, the number of type II sites per cell (1.9 +/- 1.3 x 10(4)) is significantly different than that previously determined. This 2.5-fold decrease in the number of type II sites does not affect the concentration of NGF needed to obtain maximal fiber outgrowth from explanted sensory ganglia. The rate of association (1.2 +/- 0.2 x 10(7) M-1 sec-1 at 22 degrees C) of labeled NGF with receptors on sensory neurons from this different strain of chickens is identical to that previously obtained. The rate of association of NGF with its receptors on sensory neurons was also determined at 4 degrees C. This rate constant (2.1 +/- 1.1 x 10(6) M-1 sec-1) along with the rate constants obtained at 22 degrees and 37 degrees C were used to determine an activation energy for the binding of NGF to its receptors. The activation energy obtained (16.2 kcal/mole) suggests that binding is not a diffusion-controlled process.

Animals↗
PubMed1982

Sequestration requirements for the degradation of 125I-labeled beta nerve growth factor bound to embryonic sensory neurons.

Nerve growth factor interacts with responsive cells by binding to cell surface membrane receptors. There are two different receptors on both embryonic sensory and sympathetic neurons, a high-affinity (type I) receptor and a lower-affinity (type II) receptor. Sequestration, which we have defined as bound nerve growth factor that becomes inaccessible to the external milieu with time, occurs through the type I receptor on both sensory and sympathetic neurons. We describe here a process subsequent to sequestration involving internalization and degradation of bound nerve growth factor and showing that bound nerve growth factor is not degraded under the following conditions: (1) low temperature, ie 4 degrees C; (2) when a large excess of unlabeled nerve growth factor is added concomitantly with the labeled nerve growth factor and the temperature is raised from 4 degrees C to 37 degrees C; (3) when metabolic inhibitors sodium fluoride and dinitrophenol are added concomitantly with the labeled nerve growth factor and the temperature is raised from 4 degrees to 37 degrees C. On the other hand, conditions that allow bound nerve growth factor to be degraded are the following: (1) incubation of the sensory nerve cells at low temperature (ie, 4 degrees C) only in the presence of labeled nerve growth factor, then raising the temperature to 37 degrees C; (2) when sodium fluoride and dinitrophenol are added when the temperature is raised to 37 degrees C; (3) when excess unlabeled nerve growth factor is added when the temperature is raised to 37 degrees C. These studies are consistent with the idea that nerve growth factor has to bind to the cells in order to be degraded; however, binding is not sufficient for degradation to occur. Second, the bound nerve growth factor must be sequestered in order to be degraded. Third, the process of internalization of the bound nerve growth factor, unlike sequestration, is not an energy-dependent process. Thus, it seems reasonable to suggest the following steps for the interaction of nerve growth factor with responsive cells: binding to a cell surface membrane receptor, followed by sequestration of the bound nerve growth factor, and finally, internalization of the sequestered nerve growth factor.

Animals↗
PubMed1981

Sequestration of 125I-labeled beta nerve growth factor by embryonic sensory neurons.

Nerve growth factor (NGF) binds to two specific receptors on sensory nerve cells. These two receptors are characterized by different equilibrium dissociation constants. The higher affinity (type I) receptors have an equilibrium dissociation constant of 3.3 X 10(-11) M. The lower affinity (type II) receptors have an equilibrium dissociation constant of 1.7 X 10(-9) M. These two receptors are not a result of negative cooperativity, but apparently are different receptors. At 22 degrees C the rate of association is 1 X 10(7) M-1 S-1 and the rates of dissociation are 6.5 X 10(-4) S-1 (type I) and 3.2 X 10(-2) S-1 (type II). After binding, a time-dependent process occurs that makes that NGF inaccessible to the external milieu (sequestered). The sequestration process is energy-dependent, but apparently temperature-independent. The data suggest that only the type I receptors are involved in the sequestration process. This process is similar to that observed on sympathetic neurons and may be the first step in the internalization of NGF by responsive cells.

Animals↗
PubMed1980

Growth and differentiation of chicken embryos in simplified shell-less cultures under ordinary conditions of incubation.

The growth and differentiation of chicken embryos maintained in evaporating dishes as shell-less cultures were compared to that of control embryos in ovo under the same conditions of incubation. The development of cultured embryos appears to be indistinguishable from that of embryos in ovo up to 10 days of total incubation. Thereafter, the growth of shell-less embryos is significantly retarded as evidenced by morphological criteria of the Hamburger-Hamilton stages of development, body weight, tibia length, and total protein content. Cultured embryos are smaller in size than controls, but show normal morphological features including a fully-differentiated skeleton. Skeletal defects and other anomalies were not detected in any of the specimens studied. Limitations as to the use of the simplified method of culture are evaluated and discussed.

Animals↗
PubMed1973

Stimulation of lactic acid bacteria by a micrococcus isolate: evidence for multiple effects.

Growth of, and rate of acid production by, six cultures of lactic acid bacteria were increased in the presence of Micrococcus isolate F4 or a preparation of its capsular material. Concentrations of hydrogen peroxide found in pure cultures of the lactic acid bacteria were not detectable, or were greatly reduced, in mixed culture with Micrococcus isolate F4. The capsular material was not as effective as whole cells in preventing accumulation of H(2)O(2). Catalase stimulated growth of, and the rate of acid production by, the lactic acid bacteria, but not to the same extent as Micrococcus isolate F4 in some cultures. The existence of two mechanisms for micrococcal stimulation of the lactic acid bacteria is postulated. One mechanism involves removal of H(2)O(2); the other has not been characterized.

Animals↗
PubMedDate not supplied

Fibroepithelial polyps of the urinary tract.

BACKGROUND: Fibroepithelial polyps of the urothelium are rare but frequently mistaken for transitional cell carcinoma. To better define the demographics, urothelial distribution, and typical gross anatomic and radiologic appearances, we reviewed 41 pathologically proven cases. METHODS: We reviewed 41 cases of fibroepithelial polyps from the archives of the Armed Forces of Pathology. Data were collected from radiographic studies, gross anatomic pathology, and pathology and radiology reports and categorized by age, sex, clinical presentation, lesion size, location, and morphology. RESULTS: The mean patient age was 21 years, and 58% were male. Most presented with hematuria and/or flank pain (68%). Most polyps were located in the upper ureter or renal pelvis (87%). Posterior urethral and bladder polyps were present in children. Most polyps were single or bilobed (73%) and 1-6 cm. CONCLUSION: Because most urothelial tumors are malignant epithelial tumors, fibroepithelial polyps are commonly mistaken for transitional cell carcinomas. However, because fibroepithelial polyps and malignant urothelial tumors typically present in different patient populations, different locations in the urinary tract, and appear different radiographically, distinguishing features between these entities is helpful in determining the differential diagnosis of a urothelial mass. In the appropriate clinical setting, fibroepithelial polyps should be considered in the differential diagnosis, which will affect surgical treatment.

Adolescent↗