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Biomedical subjects

J D Green

Publications and source records attributed to J D Green.

At least 73 records · Page 4Linked to original sources
PubMed1988

Fertilization envelope assembly in sea urchin eggs inseminated in Cl- deficient sea water: I. Morphological effects.

Elevation and hardening of the fertilization envelope (FE) occur within 15 min following insemination of the sea urchin egg. When chloride ions were replaced in the media with various anion substitutes, including methyl sulfonate, nitrates, bromide, and isethionate, the fertilization envelope failed to harden and collapsed back to the surface of the egg of Lytechinus variegatus, L. pictus, and Strongylocentrotus purpuratus. At the light microscopy level, the collapse of the envelope was accompanied by a decrease in birefringence, compared with controls. When examined with electron microscopy, the FEs of eggs inseminated in reduced Cl- solutions failed to transform from an amorphous layer into the more robust laminar structure observed around eggs incubated in normal sea water. Furthermore, in the case of S. purpuratus, the I-T transformation of the FE did not occur. When transfer of the inseminated eggs from the Cl- -deficient sea water to normal sea water was carried out before 10 min elapsed, the envelope did not collapse, and the birefringence of the envelope was similar to that of controls. Partial envelope collapse was also observed in a dose-dependent manner, varying with the concentration of the Cl- in the sea water solution. The results suggest that lack of Cl- in the media may interfere with proper fertilization envelope assembly. Possible mechanisms, including proper incorporation of the cortical granule exudate into the nascent envelope structure, are discussed.

Animals↗
PubMed1988

Tapetal changes in beagle dogs following oral administration of CGS 14796C, a potential aromatase inhibitor.

CGS 14796C, cis-1-[(4-[(1-imidazolyl)methyl]-cyclohexyl)methyl)imidazole succinate, has been evaluated as a potential aromatase inhibitor. As part of the safety evaluation program, a 3-month oral toxicity study was performed in which beagle dogs were administered CGS 14796C by gavage at 5, 15, or 50 mg/kg/day. Ophthalmoscopically, changes in the tapetum lucidum affecting dogs from the 15 and 50 mg/kg dose levels were diffuse areas of pigmentation varying in appearance from a brownish peppered or mottled to a more uniform brown similar to that of the nontapetal area of the fundus. Tapetal reflectivity was absent or markedly reduced. Within the pigmented area, multiple islets (yellow, green, or orange) of tapetal cells were visible, suggestive of destruction of the tapetum. In no instance was retinal destruction, edema, vascular changes, or detachment observed. Ophthalmoscopic examinations performed during recovery revealed changes of slight increase in tapetal islets, suggestive of a slight progression and organization within the tapetum followed by an arrest of the toxic insult within the tapetal tissue. At light and electron microscopic examination of the ocular tissues, the lesions were tapetal cell degeneration/atrophy. These results demonstrated that the taptetum lucidum was a target tissue of toxicity for CGS 14796C, and indicated that the findings are without toxicological significance in atapetal species, including man, whose globes do not have this structure.

Administration, Oral↗
PubMed1988

Developmental expression of adenosine deaminase in placental tissues of the early postimplantation mouse embryo and uterine stroma.

In this study, we have investigated the distribution of adenosine deaminase (ADA) in embryonic, extra-embryonic, and decidual tissues of the developing mouse embryo. ADA catalyzes a key step in purine metabolism converting adenosine to inosine. ADA specific activity (nmol/min/micrograms protein) was present at low levels in the embryo-decidual unit during the first 2 days of postimplantation development but then increased starting late on Day 6 of gestation (Day 0 plug). By Day 9, ADA specific activity was 80-fold higher than on Day 6. A histochemical staining method for ADA activity was applied to cryostat sections of the implantation site. The developmental increase localized primarily to the trophoblast/antimesometrial decidua interface between Days 7 and 9 of gestation, and decidua basalis and the metrial gland by Day 11. Immunofluorescent staining with sheep anti-mouse ADA antiserum confirmed the presence of ADA antigenicity in tissues forming the maternal/fetal interface. ADA specific activity was 19-fold higher in homogenates of the Day 11 decidua/parietal yolk sac than in the thymus, a tissue generally thought of as ADA-rich. High levels of ADA activity and immunoreactivity were also detected in the embryonal plasma during organogenesis, but the embryo proper showed only low levels. These results indicate that ADA is tightly regulated within tissues forming the maternal/fetal interface during early postimplantation stages of development.

Adenosine Deaminase↗
PubMed1988

Neoplasms of the vagus nerve.

A tumor of the vagus nerve often is discovered unexpectedly at operation. We report 36 of these rare neoplasms in 35 patients. The majority of the tumors presented as a mass in the upper cervical or parapharyngeal region. Usually the mass was asymptomatic. The following types and frequencies of neoplasms of the vagus nerve were noted: paragangliomas, 50%; neurilemmomas, 31%; neurofibromas, 14%; and neurofibrosarcomas, 6%. Surgical resection, with preservation of the vagus nerve when possible, is the treatment of choice. The clinical features, diagnosis, management, and prognosis of the tumors are presented. Special problems that occur with vagal neoplasms include postoperative dysfunction, catecholamine secretion, and intracranial or skull-base extension.

Adolescent↗
PubMed1986

Detection of femtomole quantities of proteases by high-performance liquid chromatography.

Small amounts (femtomoles) of proteases, as might be present in cell extracts or secretions, were detected using reverse-phase high-performance liquid chromatography. Carboxymethylated lysozyme and cytochrome c were incubated with trypsin and chymotrypsin. Peptide peaks were present in the column elution profiles (as detected by absorbance, 206 nm) from incubations with as little as 0.1 fmol of chymotrypsin and 5 fmol of trypsin. In addition, the disappearance of the substrate peak or the increase in peptide peaks could be quantitated by integrating the areas under the peaks. In this way estimates of relative enzyme concentrations or duration of incubation can be determined. However, when [14C]lysozyme was used as a substrate and the radioactivity of collected peaks was measured, the assay was less sensitive than that using uv absorbance. This finding probably is related to the selective radiolabeling of the substrate, in contrast to uv detection, which should detect all the peptides. The technique reported in this paper should prove to be a sensitive indicator of proteolytic activity in cell or tissue preparations where the use of synthetic ester or amide substrates might lead to erroneous conclusions regarding the nature of the enzymatic activity present. Furthermore, by the collection of the peptides generated, one would have the ability to determine amino acid compositions or sequences and thus ascertain the specificity of enzymatic cleavage.

Chromatography, High Pressure Liquid↗
PubMed1985

A 53,000-Da esterase in Strongylocentrotus purpuratus semen is derived from phagocytic cells, not sperm.

Semen from the sea urchin Strongylocentrotus purpuratus contains sperm and a small volume (1%) of phagocytes, which often contain degraded sperm. A 53,000-Da esterase in the semen is inhibited by diisopropyl fluorophosphate, but not by soybean trypsin inhibitor (STI). Differential centrifugation experiments now reveal that 70% of the esterase activity (formerly described as a sperm protease precursor; Levine and Walsh, 1980) is associated with the phagocytes, which sediment more rapidly than the sperm. The 53K esterase is also present in spawned ovaries and testes. However, as previously reported, the sperm do contain an STI-inhibitable protease as shown by the digestion of [14C]lysozyme. Intact sperm exhibit STI-inhibitable hydrolytic activity toward N-alpha-[3H]benzoyl-L-arginine ethyl ester [3H]BAEE), but crude homogenates do not until they are extracted at pH 2.5 and fractionated by ion exchange chromatography. Although not obtained in pure form, the protease activity appears to migrate with a molecular weight of 20,000 (gel filtration). The protease and the esterase differ markedly in acid stability. After preincubation at pH 2.5 the protease still hydrolyzes [3H]BAEE, while the esterase is irreversibly inactivated. This last observation may explain an earlier interpretation (A. E. Levine and K. A. Walsh, 1980, J. Biol. Chem. 255, 4814-4820) that the 53K enzyme dissociated at pH 2.5 into two unequal subunits, one of which was the active protease. Since it has been shown that the contaminating phagocytes contribute most of the esterase activity of the semen, the occurrence of even a small number of nonsperm cells cannot be ignored in future investigations of sperm enzymes.

Animals↗
PubMed1984

Effect of equilibration zones on stability, uniformity, and homogeneity profiles of vapors and aerosols in the ADG nose-only inhalation exposure system.

A commercially available, inexpensive, nose-only exposure chamber was modified to include removable equilibration zones, and the effect of these zones on chamber performance was determined. Since limited performance data were available concerning this unit, a more extensive characterization was performed. EPA limit concentrations (greater than or equal to 5 mg/liter) of toluene vapor or corn oil aerosol, and relatively low concentrations of uranine aerosol (less than or equal to 50 micrograms/liter) were produced by standard techniques. The presence or absence of equilibration zones did not affect the stability or uniformity of toluene vapor atmospheres, with the coefficient of variation (CV) not exceeding 3.33% in all experiments. In contrast, the presence of two equilibration zones was found to progressively enhance the uniformity of the inhalable test aerosols in the animal exposure zone (CV less than or equal to 3.16%). Matrix sampling revealed that in both uranine and corn oil experiments, the center matrix point concentration was consistently lower than samples taken in the actual animal breathing zone. Equilibration zones markedly reduced the difference between breathing zone and center point concentrations. These performance data indicated that the modified ADG nose-only exposure system performed exceptionally well with the materials that were studied. Results were comparable to those describing whole-body chamber performance. The ready availability of this inexpensive prototype lends itself to standardization of techniques between laboratories.

Aerosols↗
PubMed1983

Action of insulin on the transport of 3-O-methylglucose in frog sartorius muscles.

The initial rate of entry of 3-O-methyl-D-glucose into isolated frog sartorius muscles was measured at various concentrations of substrate, at 0, 9, 19, or 29 degrees C, after prior incubation at 19 degrees C with a maximally stimulating concentration of insulin. Control muscles were treated similarly, except for the omission of insulin. A saturable transport system provided for most of the entry of 3-O-methylglucose into muscle cells, but a small amount of penetration occurred by a nonsaturable route. The major effect of insulin was to produce a large increase in activity of the suturable system. The Vmax of entry increased, but there was no significant change in the apparent Km. The ratio of insulin-stimulated to basal Vmax was 10 when transport was measured at 29 degrees C but was 22 at 0 degrees C. These findings support the hypothesis that, although a large part of the effect of insulin on sugar transport can be accounted for by an increase in the number of functional transporters in the plasma membrane, there is a separate hormonal effect that permits a relatively greater activity of transporters at lower temperatures, compared with control rates. An additional effect of insulin was to produce a small but definite increase in the entry of sugar by the nonsaturable transport system.

3-O-Methylglucose↗
PubMed1983

Selective loss of a plasma membrane protein associated with contraction of skeletal muscle.

Muscle proteins were labeled by incubating isolated frog sartorius muscles with [3H]- or [14C]phenylalanine. Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis of plasma membrane fractions revealed a major protein band with an apparent molecular weight of approx. 96,000. Radioactivity in this band showed a clearly delineated decrease, relative to other bands, when previously labeled muscles were induced to contract either by electrical stimulation or by increasing the influx of Ca2+ from the incubation medium. It is postulated that a Ca2+-activated neutral protease may account for this decrease in labeled membrane protein.

Animals↗
PubMed1983

Personality, prior drug use, and introspective experience during nitrous oxide intoxication.

This report compares data on some personality characteristics and prior drug experiences of 60 volunteer young men with their subjective psychological responses while inhaling 40% nitrous oxide-oxygen mixtures for 20 min in a naturalistic laboratory setting. A rather specific trait-openness to "internal," reverie-type experiences-was very significantly related to a wide variety of drug responses, while several more general traits-including introversion and neuroticism-and openness to nonreverie mental experiences were unrelated to drug response. Prior illicit drug use was related only to mood on nitrous oxide, and not to other effects. Implications of the findings in the field of drug abuse are discussed.

Adult↗
PubMed1982

Use of tritiated 3-O-methyl-D-glucose for studies of membrane transport. Caveat.

Tritiated 3-O-methyl-D-glucose has many useful attributes as a model substance for studies of the transport of glucose across cell membranes. However, preparations of high specific radioactivity can decompose within a few months, producing radioactive impurities that can cause a several-fold increase in the apparent rate of sugar transport. In our investigation radioactive contaminants entered frog skeletal muscle cells by free diffusion rather than by facilitated transport. Much of the contaminating radioactive material could be removed by evaporating the solvent and redissolving the sugar. Tritiated sugar samples that had a specific activity below 0.1 Ci/mmol remained stable and suitable for transport measurements after several years of storage at -20 degrees C. In order to evaluate the suitability of a given tritiated preparation of sugar for transport measurements, it is recommended that its behavior be compared with that of a stable reference standard of low specific activity.

3-O-Methylglucose↗
PubMed1982

Nonvocal language acquisition in adolescents with severe physical disabilities: Bliss symbol versus iconic stimulus formats.

This study compared training in two language systems for three severely handicapped, nonvocal adolescents: the Bliss symbol system and an iconic picture system. Following baseline, training and review trials were implemented using an alternating treatments design. Daily probes were conducted to assess maintenance, stimulus generalization, and response generalization, and data were collected on spontaneous usage of either language system throughout the school day. Results showed that students required approximately four times as many trials to acquire Bliss symbols as iconic pictures, and that students maintained a higher percentage of iconic pictures. Stimulus generalization occurred in both language systems, while the number of correct responses during responses generalization probes was much greater for the iconic system. Finally, students almost always showed more iconic responses than Bliss responses in daily spontaneous usage. These results suggest that an iconic system might be more readily spontaneous usage. These results suggest than an iconic system might be more readily acquired, maintained, and generalized to daily situations. Implications of these findings for the newly verbal person were discussed.

Adolescent↗