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Biomedical subjects

T Miller

Publications and source records attributed to T Miller.

At least 217 records · Page 12Linked to original sources
PubMed1989

Pulmonary vascular hemodynamics in chronic lung disease patients with and without oxyhemoglobin desaturation during sleep.

Nonapneic, nocturnal oxyhemoglobin desaturation (NOD) during rapid-eye-movement (REM) sleep has been proposed as a predecessor and possible etiologic factor in the development of pulmonary hypertension in patients both with restrictive and obstructive chronic lung disease. The association between abnormal waking cardiopulmonary hemodynamics and NOD has not been established in patients with mild daytime hypoxemia. Gas exchange, pulmonary function, red cell mass, radionuclide gated cardiac ejection fraction, and supine cardiopulmonary hemodynamics were examined in 36 patients with chronic lung disease. All had a daytime PaO2 greater than 60 mm Hg and REM sleep-related NOD for greater than 5 minutes, to 85 percent or lower. These data were compared to those from 13 subjects with similar symptoms and objective measures of pulmonary dysfunction but without evidence of NOD. Patients with NOD showed more end organ evidence of hypoxemia and more abnormal cardiopulmonary hemodynamics than patients with similar degrees of lung disease but without NOD. The relative role of daytime vs nocturnal hypoxemia in inducing hemodynamic differences between groups cannot be determined from this study.

Heart↗
PubMed1989

The rate of fall of arterial oxyhemoglobin saturation in obstructive sleep apnea.

During breath holding, correlations have been demonstrated between the rate of fall of arterial oxyhemoglobin saturation (dSaO2/dt) and the following: thoracic gas volume at apnea onset, resting oxygen consumption, preapneic arterial oxyhemoglobin saturation (SaO2) and obesity. A key factor influencing dSaO2/dt is mixed venous oxyhemoglobin saturation (SvO2) as recently demonstrated in an animal model of obstructive apnea. The purpose of the present study was to see if dSaO2/dt was related to SvO2 during sleep in a group of subjects with severe obstructive sleep apnea (OSA) and varying levels of SvO2. Eight OSA subjects were studied during sleep with indwelling arterial and central venous catheters. Continuous SaO2 was measured by ear oximetry while continuous SvO2 was measured through the fiberoptic bundle of a Shaw Opticath catheter. Thirty percent or more of all obstructive apneas were scored for duration, preapneic SaO2, SvO2 and dSaO2/dt. Least squares regression was used to examine the relationship between dSaO2/dt and other measured variables. The dSaO2/dt showed a consistent negative correlation with preapneic SvO2 and was not related to duration. Mean dSaO2/dt during sleep correlated to some degree with the degree of gas exchange (Qva/Qt) abnormality prior to sleep. It is concluded that in humans, SvO2 plays a substantial role in determining dSaO2/dt. Potentially, the presence of gas exchange abnormalities (eg, found in intrinsic lung disease) causing hypoxemia and low SvO2 may steepen dSaO2/dt, lowering the nadir level of apneic desaturation for the same duration of apnea found in a patient with more normal gas exchange.

Humans↗
PubMed1989

TRH pharmacokinetics and nerve stimulation evoked prostatic fluid secretion during TRH infusion in the dog.

The pharmacokinetics of TRH have been determined in man and the rat as well as other species whose serum contains TRH degrading enzymes, TRH pharmacokinetics have not been determined in the dog. This species is unusual in that its serum contains little or no TRH degrading activity. TRH pharmacokinetics were determined from measurements of plasma TRH concentrations during and following a 1-h infusion of TRH, 20 micrograms.kg-1.min-1, into dogs bearing prostatic urethral cannula. During TRH administration prostatic fluid secretion was evoked by hypogastric nerve stimulation and the content of TRH immunoreactive material in prostatic fluid was determined. Prostatic fluid was also collected after hypogastric nerve stimulation in dogs that did not receive TRH infusion. The TRH plasma profile in TRH-infused dogs exhibited two-compartment characteristics with an initial half-time of 10.4 +/- 5.4 (mean +/- SD) min, a terminal half-time of 69.4 +/- 24 min, and a metabolic clearance rate of 7.64 +/- 4.48 ml.min-1.kg-1. These findings suggest that the half-time of TRH is longer, and its metabolic clearance rate is less, in the dog than in humans or rats. TRH administration was not associated with altered nerve induced prostatic fluid secretion. Prostatic fluid samples contained TRH immunoreactive material regardless of whether they were collected after epithelial cell stimulation with pilocarpine, or after hypogastric nerve stimulation. In contrast to previous results with vasoactive intestinal peptide, TRH does not acutely alter prostatic fluid secretion. As has been reported for prostatic tissue extracts, immunoreactive material is present in prostatic fluid and appears to arise from epithelial cells.

Animals↗
PubMed1988

Sequence of a full-length cDNA for rat lung beta-galactoside-binding protein: primary and secondary structure of the lectin.

A full-length cDNA for rat lung beta-galactoside lectin (subunit Mr approximately 14,000, lectin 14K) was cloned and the nucleotide sequence determined. The deduced amino acid sequence agrees with the amino acid composition and direct amino acid sequence analysis of purified rat lung lectin peptides. We found that the amino-terminal alanine is blocked with an acetyl group. Comparison of the amino acid sequence with other proteins shows a high degree of homology only with other vertebrate lectin sequences, supporting the suggestion that these lectins may constitute a unique class of vertebrate proteins. The amino acid composition and sequence of lectin peptides, the sequence of lectin cDNA, and isoelectric focusing of purified lectin indicate that rat lung lectin 14K is composed predominantly of a single protein. In addition, rat uterus lectin 14K was found to be the same protein as that present in lung. We characterized the secondary and tertiary structure of rat lung lectin 14K by circular dichroism, by analytical ultracentrifugation, and by computer analysis of its primary structure. Results of these experiments suggest that lectin 14K is primarily a hydrophilic protein with an asymmetric, elongated structure consisting of approximately equal amounts of alpha helix, beta sheet, beta turn, and random coil. We found that Cys-2 and Cys-130 react most rapidly with iodoacetamide; one or both of these residues may be primarily responsible for the thiol requirement of lectin activity.

Amino Acid Sequence↗
PubMed1988

Structure of a gap junction gene: rat connexin-32.

A genomic clone for the rat liver gap junction protein (connexin-32) was isolated and characterized by restriction enzyme mapping and sequence analysis. While the complete coding sequence is contained within one uninterrupted block, the 5'-untranslated region of the transcript contains a 6.1 kb intron. Both S1 nuclease protection and primer extension assays indicate multiple transcription start sites. Sequences homologous to cAMP response elements are found near the transcription start sites and within the 3'-end of the intron.

Animals↗
PubMed1988

Primary intraocular lymphoma (ocular reticulum cell sarcoma) diagnosis and management.

The authors retrospectively reviewed the diagnosis and management of 20 intraocular lymphoma patients who initially presented with either ocular or central nervous system (CNS) disease. As the ophthalmic community has become more aware of this entity, the interval between symptoms and diagnosis has significantly shortened. Diagnosis can usually be made on cytopathologic examination of vitreous cells. However, in three cases more than one vitreous biopsy was necessary. Results of cytologic examination appeared to be more accurate than those of conventional lymphocyte surface marker studies in the diagnosis of an intraocular lymphoma. Long-term survival occurred in some patients treated with a combination of intrathecal chemotherapy and ocular/CNS irradiation.

Adult↗
PubMed1988

Tumorigenicity of simian virus 40-hepatocyte cell lines: effect of in vitro and in vivo passage on expression of liver-specific genes and oncogenes.

Five simian virus 40 (SV40)-hepatocyte cell lines were examined for tumorigenicity and the effect of in vitro passage on the expression of four liver-specific genes (albumin, transferrin, alpha 1-antitrypsin, and phosphoenolpyruvate carboxykinase), two oncogenes (c-Ha-ras and c-raf), and two genes associated with hepatocarcinogenesis (alpha-fetoprotein and placental-type glutathione-S-transferase). At low passage (12 to 22), all five cell lines expressed the four liver-specific genes at levels similar to those in the liver and were not tumorigenic or were weakly tumorigenic. At high passage (33 to 61), the cell lines formed carcinomas, and four out of five cell lines produced primary tumors that metastasized. At least two cell lines produced well-differentiated hepatocellular carcinomas that expressed liver-specific RNAs. Levels of expression of liver-specific genes changed with time in culture. Some of the changes in liver-specific gene expression in the tumor tissue (such as for the phosphoenolpyruvate carboxykinase gene) paralleled those that occurred with in vitro passage, while other changes (such as for the albumin gene) did not parallel those that occurred with in vitro passage. Correlations between enhanced expression of c-Ha-ras and tumorigenic potential and between the process of SV40 immortalization and induced expression of c-raf and glutathione-S-transferase-P were observed. Induction of alpha-fetoprotein was detected with in vitro and in vivo passage only in the CWSV14 cell line and was paralleled by diminished albumin expression. In conclusion, we developed a model system with five SV40-hepatocyte cell lines, tumors induced by them, and tumor cell lines to examine changes in gene expression that accompany the progression from a normal cell to a hepatocellular carcinoma. Because the SV40-hepatocyte cell lines and tumor cell lines remain highly differentiated and vary in the magnitude of expression of specific genes, they can be used to study the molecular mechanisms regulating gene expression, in particular those regulating specific genes associated with differentiation.

Animals↗