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Biomedical subjects

R A Mueller

Publications and source records attributed to R A Mueller.

195 records · Page 11Linked to original sources
PubMedDate not supplied

Changes in cerebrospinal fluid homovanillic acid in children with Ondine's curse.

The cerebrospinal fluid (CSF) concentrations of three acid monoamine metabolites, two purines, and a group of amino acids were determined in two children with chronic central alveolar hypoventilation (Ondine's curse). The levels of all assayed neuroactive substances, metabolites, and amino acids, with one exception, were normal compared to an age-matched group of neurologically healthy children. The levels of the dopamine metabolite homovanillic acid in the children with Ondine's curse were approximately 2.4 times higher than expected for age range. The present findings may indicate a link between central nervous system dopamine activity and chronic central alveolar hypoventilation. Among other possible explanations, the changes seen might represent a primary alteration in dopamine activity or may reflect a change in dopamine turnover resulting from the chronic hypoventilation.

Adenosine↗
PubMedDate not supplied

MacCueSee: a quality control program for the Macintosh computer.

MacCueSee was written to perform routine calculations on quality control concentration values from radioimmunoassay. It is written in Microsoft QuickBASIC for the Apple Macintosh computer. The program calculates within and between assay standard deviation (S.D.) and coefficient of variation from a spreadsheet file containing concentration values of controls analyzed. It also calculates the average concentration +/- 1 S.D. and contraction +/- 2 S.D. to establish between assay ranges. Its flexibility permits varying replicates between assays and automatic exclusion of missed assays. Within assay variability calculations are made for single, duplicate, and triplicate tubes. Results are displayed and can optionally be printed. In addition to radioimmunoassay, MacCueSee can be applied to a number of analytical methods in which quality control is monitored. An example of program use is included.

Microcomputers↗
PubMedDate not supplied

Bombesin increases dopamine function in rat brain areas.

Bombesin is a tetradecapeptide heterogenously distributed in the mammalian brain. Bombesin (45 micrograms) given intracisternally (IC) to unanesthetized rats increased the accumulation of dihydroxyphenylalanine (DOPA) in striatum, olfactory tubercles and hypothalamus after DOPA-decarboxylase inhibition, thus indicating an increased dopamine synthesis. A dose-dependent increase in dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), the principal dopamine metabolites, was seen in several brain areas 1 hr after IC injection of bombesin (0-60 micrograms). In striatum and olfactory tubercles HVA increased more than DOPAC with a maximal increase after 30-45 micrograms. In a time-course experiment a biphasic change of dopamine metabolites was observed in the olfactory tubercles with an actual decrease in metabolite levels 4 hr after 60 micrograms IC bombesin injection. Co-administration of bombesin and naloxone (8 mg/kg IP) or ethanol (2.25 g/kg IP) did not affect the increase in dopamine metabolites seen after bombesin alone. The action of IC administered bombesin on dopamine function was most pronounced in hypothalamus indicating a neuroendocrine regulatory of the peptide.

Animals↗
PubMedDate not supplied

Effect of ethanol on cyclic nucleotides in vivo: consequences of controlling motor and respiratory changes.

Many psychotropic drugs alter cerebellar cyclic guanosine-3',5'-monophosphate (cGMP) content. Whereas apomorphine increased levels, central depressants such as ethanol, chlordiazepoxide or barbiturates, reduce the content of cerebellar cGMP without altering levels of cyclic adenosine-3',5'-monophosphate (cAMP). Additional data indicate that tolerance develops to this reduction of cerebellar cGMP by ethanol. In paralyzed animals, the increase in cerebellar cGMP content induced by apomorphine and the decrease caused by ethanol were dramatically attenuated. Since relatively high doses of ethanol were needed to decrease blood CO2 tension in spontaneously moving rats, changes in respiratory function appear to be of only minor importance in the ethanol-induced decrease in cerebellar cGMP. It is concluded that ethanol-induced changes in content of cerebellar cGMP in vivo may be secondary to alterations in motor and, to a lesser extent, in respiratory function.

Animals↗
PubMedDate not supplied

Action of zolpidem on responses to GABA in relation to mRNAs for GABA(A) receptor alpha subunits within single cells: evidence for multiple functional GABA(A) isoreceptors on individual neurons.

The relationship between zolpidem sensitivity and GABA(A) receptor alpha subunits was studied in individual dissociated neurons from rat brain. Using whole-cell recording, similar EC50 values were demonstrated for the effect of gamma-aminobutyric acid (GABA) on gated-chloride currents from substantia nigra reticulata (SNR) and lateral septal neurons. Subsequently, many neurons from both the SNR or lateral septum were found to exhibit enhanced GABA-gated chloride currents across concentrations of zolpidem ranging from 10 to 300 nM. Some neurons exhibited a greater than 20% increase in responsiveness to GABA at 30 nM of zolpidem without further increase at higher concentrations of zolpidem. Conversely, zolpidem enhancement of GABA from another group of neurons was not observed at 30 nM zolpidem, but between 100 and 300 nM the response to GABA increased greater than 20%. Finally, a third group of neurons reached both of these criteria for zolpidem enhancement of GABA. This latter spectrum of responses to GABA after varying concentrations of zolpidem was consistent with the presence of either two GABA(A) receptors or a single receptor with differing affinities for zolpidem on an individual neuron. Following determination of the sensitivity of neurons from SNR or lateral septum to zolpidem, cytoplasm was extracted from some individual cells to allow identification of cellular mRNAs for the alpha1, alpha2 and alpha3 GABA(A) receptor subunits with RT-PCR. Those neurons that responded to the 30 nM zolpidem concentration invariably expressed the alpha1-GABA(A) receptor subunit. This result is consistent with the GABA(A) alpha1-receptor subunit being an integral part of a functional high-affinity zolpidem type 1-BZD receptor complex on neurons in brain. Those neurons which showed enhancement of GABA from 100 to 300 nM zolpidem contained mRNAs for the alpha2 and/or the alpha3 receptor subunits, a finding consistent with these alpha subunits forming type 2-BZD receptors. Some individual dissociated SNR neurons were sensitive to both low and high concentrations of zolpidem and contained mRNAs for all three alpha-receptor subunits. These latter individual neurons are proposed to have at least two functional GABA(A) receptor subtypes. Thus, the present investigation emphasizes the importance of characterizing the relationship between endogenous GABA(A) receptor function and the presence of specific structural components forming GABA(A) receptor subtypes on neurons.

Animals↗
PubMedDate not supplied

Lessons from a doctoral thesis.

The production of a doctoral thesis is a time-consuming affair that until recently was done in conjunction with professional publishing services. Advances in computer technology have made many sophisticated desktop publishing techniques available to the microcomputer user. We describe the computer method used, the problems encountered, and the solutions improvised in the production of a doctoral thesis by computer. The Apple Macintosh was selected for its ease of use and intrinsic graphics capabilities. A scanner was used to incorporate text from published papers into a word processing program. The body of the text was updated and supplemented with new sections. Scanned graphics from the published papers were less suitable for publication, and the original data were replotted and modified with a graphics-drawing program. Graphics were imported and incorporated in the text. Final hard copy was produced by a laser printer and bound with both conventional and rapid new binding techniques. Microcomputer-based desktop processing methods provide a rapid and cost-effective means of communicating the written word. We anticipate that this evolving technology will have increased use by physicians in both the private and academic sectors.

Academic Dissertations as Topic↗
PubMedDate not supplied

Diaphyseal lengthening for brachymetatarsia.

The authors present a case report of brachymetatarsia. The literature is reviewed, various surgical treatments are discussed, and the preferred surgical procedure that relieved symptoms and achieved cosmetic approval is described.

Adult↗