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Biomedical subjects

D Park

Publications and source records attributed to D Park.

At least 127 records · Page 7Linked to original sources
PubMed1989

Adrenocorticotropin(1-10) and -(11-24) promote adrenal steroidogenesis by different mechanisms.

ACTH1-10 and ACTH11-24 each elicit cortisol secretion submaximally in freshly dispersed or cultured beef adrenal cortical cells. The combination of ACTH1-10 and ACTH11-24 promotes cortisol release to the maximal level elicited by ACTH1-24. Maximal cortisol release by ACTH11-24, but not by ACTH1-24 or ACTH1-10, was enhanced by forskolin. The calcium channel blockers nifedipine and verapamil inhibited cortisol release by ACTH1-10, ACTH1-24 or ACTH11-24, suggesting calcium influx to be essential for steroid secretion regardless of the secretagogue. Vanadium, in a dose-dependent manner, inhibited cortisol secretion elicited by ACTH1-24 and ACTH1-10 but not that caused by ACTH11-24. These results suggest that there are at least two receptors mediating ACTH1-24-dependent steroid secretion. One class of receptor recognizes ACTH1-10 but not ACTH11-24 and is linked to the cAMP messenger pathway.

Adrenal Glands↗
PubMed1988

Day hospital as an alternative to inpatient care for cancer patients: a random assignment trial.

A stratified, random-assignment trial of 442 cancer patients was conducted to evaluate medical, psychosocial, and financial outcomes of day hospital treatment as an alternative to inpatient care for certain cancer patients. Eligible patients required: a 4- to 8-hour treatment plan, including chemotherapy and other long-term intravenous (i.v.) treatment; a stable cardiovascular status; mental competence; no skilled overnight nursing; and a helper to assist with home care. Patients were ineligible if standard outpatient treatment was possible. No statistically significant (p less than 0.05) differences were found between the Adult Day Hospital (ADH) and Inpatient care in medical or psychosocial outcomes over the 60-day study period. The major difference was in medical costs--approximately one-third lower for ADH patients (p less than 0.001) than for the Inpatient group. The study demonstrates that day hospital care of medical oncology patients is clinically equivalent to Inpatient care, causes no negative psychosocial effects, and costs less than Inpatient care. Findings support the trend toward dehospitalization of medical treatment.

Adult↗
PubMed1988

Monoclonal antibodies and conventional antisera to the GABAA receptor/benzodiazepine receptor/Cl- channel complex.

Monoclonal antibodies (mAbs) and conventional antisera were raised to the affinity-purified GABAA receptor/benzodiazepine receptor/Cl- channel complex. The antibodies immunoprecipitated the affinity-purified complex in Triton X-100 and also reacted with the complex in a solid-phase radioimmunoassay. Immunoblots indicated that the mAb 62-3G1 reacted with the 57,000 Mr peptide subunit of the affinity-purified complex, while the antisera mainly reacted with the 51,000 Mr peptide subunit. The mAbs and the antisera also immunoprecipitated the GABAA receptor/benzodiazepine receptor/Cl- channel complex after being solubilized from cerebral cortex membranes by the zwitterionic detergent CHAPS. The immunoprecipitated complex bound 3H-muscimol, 3H-flunitrazepam (FNZ) and 35S-t-butylbicyclophosphorothionate (TBPS). The 3H-FNZ binding was stimulated by GABA, indicating that the functional interactions among the immunoprecipitated components of the complex were preserved. The mAb 62-3G1 also recognized the 57,000 Mr peptide in immunoblots with crude brain membranes. Immunocytochemistry experiments showed that the binding of both the mAb 62-3G1 and 3H-muscimol colocalized throughout the brain. The results suggest that (1) the 57,000 Mr peptide is the muscimol (GABAA receptor agonist) binding peptide of the complex, and (2) in the cerebral cortex, most of the GABAA receptors (GABARs), benzodiazepine receptors (BDZRs), and Cl- channels are physically coupled to one another.

Animals↗
PubMed1987

Endogenous benzodiazepine-like molecules in the human, rat and bovine brains studied with a monoclonal antibody to benzodiazepines.

The anti-benzodiazepine monoclonal antibody 21-7F9 has been used for the identification and study of endogenous benzodiazepine-like molecules in the human, rat and bovine brains. A sandwich radioimmunoassay has been designed for the quantification of the membrane-bound endogenous benzodiazepine-like molecules. The localization of these molecules is not restricted to the brain tissue. They are also present in kidney, liver and spleen as well as in the neuroblastoma X glioma NG108-15 hybrid cell line. Immunoblots show benzodiazepine-like immunoreactivity in the membrane proteins of all of these tissues. The membrane-bound benzodiazepine-like molecules are resistant to limited proteolysis of the membranes. Moreover, this treatment increases the binding of the monoclonal antibody 21-7F9 to the membranes, probably by exposing sites that normally are not accessible to the antibody. Immunocytochemistry experiments show that benzodiazepine-like molecules are also present in samples of human cerebella that have been stored in paraffin since 1940, 15 years before the first chemical synthesis of benzodiazepines. The results indicate that the cerebellar benzodiazepine-like molecules recognized by the antibody are the product of biological (not chemical) synthesis. Benzodiazepine-like immunoreactivity has also been detected in NG108-15 cells that have been cultured for 3 months in serum-free medium. These results suggest that the cells could biosynthesize benzodiazepine-like molecules.

Animals↗
PubMed1985

Monoclonal antibodies to benzodiazepines.

Four hybridoma lines secreting monoclonal antibodies to benzodiazepines were produced after BALB/c mice were immunized with a benzodiazepine-bovine serum albumin conjugate. The monoclonal antibodies were purified from ascites fluids, and their binding affinities for benzodiazepines and other benzodiazepine receptor ligands were determined. These antibodies have very high binding affinities for diazepam, flunitrazepam, Ro5-4864, Ro5-3453, Ro11-6896, and Ro5-3438 (the KD values are in the 10(-9) M range). However, these antibodies have low affinities for the benzodiazepine receptor inverse agonists (beta-carbolines) and antagonists (Ro15-1788 and CGS-8216).

Animals↗
PubMed1983

Home, safe home.

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Accident Prevention↗
PubMed1977

Transmitter histochemistry of the rat olfactory bulb. I. Immunohistochemical localization of monoamine synthesizing enzymes. Support for intrabulbar, periglomerular dopamine neurons.

The rat olfactory bulb was studied at the light and electron microscopic level with the indirect immunofluorescence technique and the unlabelled antibody enzyme method (PAP-technique), respectively. Antibodies to all 4 enzymes in the catecholamine synthesis were used. In the principal bulb the first two enzymes, tyrosine hydroxylase (TH) and DOPA decarboxylase (DDC), but not dopamine-beta-hydroxylase (DBH), were present in a proportion of periglomerular cell bodies and dendrites indicating that these neurons synthesize dopamine (DA). This amine may therefore be released as a transmitter substance at some of the intraglomerular dendrodendritic synapses which periglomerular cells form with the mitral cells. There is evidence to suggest that some periglomerular cells use GABA as their transmitter. Thus, a morphologically and physiologically homogenous population of neurons can be subdivided on the basis of transmitter histochemical criteria. There was an impression of more DDC-positive than TH-positive fibers in the glomeruli. Such presumably DDC-positive, but TH-negative processes may represent 5-hydroxytryptamine (5-HT) nerve terminals. DBH-positive fibers were seen in the granular, external plexiform, and very rarely, in the glomerular layers, probably representing noradrenaline (NA) nerve terminals ascending from the lower brain stem. Weakly fluorescent DDC-positive fibers may represent nerve terminals of ascending 5-HT neurons. No phenylethanolamine-N-methyltransferase (PNMT)-positive neurons were observed.

Animals↗
PubMed1977

Dysphagia.

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Deglutition Disorders↗
PubMed1977

Dysphagia.

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Deglutition Disorders↗
PubMed1977

Immunohistochemical studies on the localization and distribution of monoamine neuron systems in the rat brain II. Tyrosine hydroxylase in the telencephalon.

Extensive plexuses of TH-positive nerve terminals were found in many parts of the telencephalon, mainly confined to the subcortical and limbic cortical structures. Of special interest were the distinct networks of varying densities in the amygdaloid cortex, the entorhinal cortex, the prepiriform cortex, the anterior cingulate cortex and the (pre-)frontal cortex. Their distribution is identical with the patterns observed in recent studies on cortical dopamine nerve terminals using certain modifications of the Falck-Hillarp technique. The extremely dense TH innervations patterns of the caudate nucleus, nucleus accumbens, tuberculum olfactorium and the less dense basket-like innervation of the lateral septal nuclei could also be demonstrated. TH-positive cell bodies in a periglomerular position could be observed in the olfactory bulb. A few TH-positive cell bodies were observed in the area around the anterior commissure and in the cingulate cortex. In one area, the hippocampal formation, TH-positive dotlike structures were located in the position of the mossy fibres. In all probability they do not belong to monoamine neurons but may contain a cross-reacting protein. In general, the distribution and density of TH-positive terminals agrees well with extensive regional, biochemical studies on TH activity performed by other groups. Minor discrepancies are discussed. As stated in a parallel study on the distribution of TH in the mes- and diencephalon these findings indicate that TH activity is closely related to the amount of enzyme protein. The TH enzyme levels seem to be much higher in the DA than in the NA nerve terminals of the forebrain which would explain the preferential demonstration of DA terminals in the forebrain using TH antiserum and the high and low TH enzyme activity in DA and NA rich regions, respectively.

Animals↗