Search PubMed⌕ Search

Biomedical subjects

M R Miller

Publications and source records attributed to M R Miller.

At least 127 records · Page 7Linked to original sources
PubMed1987

Heterotopic synaptic bodies in the auditory hair cells of adult lizards.

The auditory hair cells of adults of eight species of lizards (three gekkonids: Coleonyx variegatus, Gekko gecko, and Cosymbotus platyurus; two teiids: Ameiva ameiva and Cnemidophorus tigris; one anguid: Celestus costatus; one lacertid: Podarcis (Lacerta) sicula; and one iguanid: Crotaphytus wislizeni) were studied by transmission electron microscopy. Heterotopic synaptic bodies were found in some of the auditory hair cells of all of the above species, occurring frequently in the gekkonids but infrequently in other species. The groups of heterotopic synaptic bodies occurred mainly in the infranuclear cytoplasm between the hair cell nucleus and the hair cell plasma membrane. The groups of synaptic bodies that were close to the hair cell nucleus were usually associated with specialized arrays of rough and smooth endoplasmic reticulum. The numbers of heterotopic synaptic bodies were greatest in the gekkonid species and were especially large in Coleonyx variegatus, where an average of 36.8 synaptic bodies occur in one group. The functional significance of the presence of heterotopic synaptic bodies in the auditory hair cells of adults animals is not known.

Age Factors↗
PubMed1987

Importance of airflow obstruction after thoracoplasty.

Thirty six patients previously treated for pulmonary tuberculosis by thoracoplasty were studied to determine the prevalence and effect of airflow obstruction. The mean (SD) FEV1 was 1.3 (0.65) 1 and the mean forced expiratory ratio (FER) 64% (12%). FEV1 was less than predicted in every patient whereas FER was less than predicted in 30, being below the lower 98th percentile in 15 (42%). In the 18 patients who complained of breathlessness the means of the standardised residuals (SR) for FEV1, peak expiratory flow (PEF), and FER were significantly lower and that for residual volume/total lung capacity (RV/TLC) significantly higher than those for the 18 patients who were not breathless (all p less than 0.0001). There was no difference in the smoking history of the two groups. Only three of the 23 patients in whom reversibility of airflow obstruction was assessed showed a greater than 25% increase in PEF. None showed an increase in FEV1 of greater than 15%. The 18 who were breathless had significantly lower values of arterial oxygen tension (PaO2) and higher values of arterial carbon dioxide tension (PaCO2) (p less than 0.0001). Thirteen of these patients were in chronic respiratory failure (PaO2 less than 8.0 kPa or PaCO2 greater than 5.9 kPa, or both) compared with only one of the 18 who were not breathless. The indices correlating best with PaO2 and PaCO2 were SR FEV1 and SR PEF respectively. SR FEV1 accounted for 34% of the variance in PaO2 and SR PEF for 29% of the variance in PaCO2. Airflow obstruction has been found to be common in patients with a thoracoplasty and to be associated with hypoxia and hypercapnia.

Aged↗
PubMed1986

A microinjected monoclonal antibody against human DNA polymerase-alpha inhibits DNA replication in human, hamster, and mouse cell lines.

We have examined the effect that microinjection of a monoclonal antibody directed against human DNA polymerase-alpha (SJK-287) has on DNA synthesis in exponentially growing human, mouse, and hamster cell lines. We show that the SJK-287 antibody, when microinjected directly into the nuclei of cells is capable of inhibiting DNA synthesis in all three cell lines tested. Moreover, the effectiveness with which this antibody can inhibit ongoing DNA synthesis by the microinjection assay is closely correlated with the ability of the antibody to neutralize DNA polymerase-alpha activity fractionated from each cell line in vitro. Two other monoclonal antibodies of the same class, one directed against the cellular p53 protein (PAb122), and one directed against the c-myc protein (PM-8) were also tested for their ability to inhibit ongoing DNA synthesis by direct microinjection and in lysolecithin permeabilized cells. Both monoclonal antibodies failed to inhibit ongoing DNA synthesis in exponentially growing cells by these assays.

Animals↗
PubMed1986

Interaction of monoclonal antibodies directed against bromodeoxyuridine with pyrimidine bases, nucleosides, and DNA.

Although antibodies directed against bromodeoxyuridine (BrdU) are being used in both clinical and basic research laboratories as tools to study and monitor DNA synthesis, little is known about the epitopes with which they react. Four monoclonal antibodies directed against BrdU were produced and were characterized to learn more about the epitopes on BrdU which are important for antibody recognition, to identify compounds other than BrdU which react with the antibodies and which might interfere with immunologic assays for BrdU, and to characterize the reaction of these antibodies with BrdU-containing DNA. By radioimmunoassays, the antibodies generally reacted well with 5-iododeoxyuridine, 5-fluorodeoxyuridine, and 5-nitrouracil. However, none of the antibodies reacted well with uridine--indicating that a substituent on uridine C5 was essential for antibody reactivity--or with 5-bromo- or iodo-cytosine, indicating that the region around pyrimidine C4 is important for antibody recognition. Although the antibodies reacted with 5-halogen-substituted uracil bases, the antibodies reacted much better with the corresponding halogenated nucleosides, indicating that the sugar moiety was important for recognition. The presence of a triphosphate group on C'5 of BrdU (i.e., BrdUTP) did not detectably alter antibody recognition. Three of the antibodies reacted only with purified DNA containing BrdU, whereas one antibody, which exhibited a weak interaction with thymidine, also reacted with BrdU-free DNA. S1 nuclease treatment of purified DNA suggested that all four monoclonal antibodies reacted exclusively with single-stranded regions of BrdU-containing DNA. Comparison of detecting DNA synthesis by [3H]TdR incorporation followed by autoradiography with that by BrdU incorporation followed by indirect immunofluorescence indicated that the latter technique was both an accurate and a sensitive measure of DNA synthesis.

Animals↗
PubMed1986

Verapamil and breast-feeding.

Concentrations of verapamil and norverapamil were measured in the plasma and breast milk of a woman receiving 120 mg verapamil three times daily. Whilst the concentrations of verapamil in breast milk averaged about 64% of those in maternal plasma no drug could be detected in the plasma of the infant. It is concluded that maternal therapy with verapamil does not pose a hazard to the suckling infant.

Adult↗
PubMed1986

Linearity and temperature control of the Fleisch pneumotachograph.

We have investigated the optimal thermal conditions of a Fleisch no. 4 pneumotachograph (PT) necessary for recording maximal forced expiratory maneuvers (MFEM). Our PT assembly was tested with a computer-driven pump and found to be linear up to 14 l/s. Thermocouples (TC) were placed in a peripheral, mid, and a central capillary of the PT. Stable temperature control and consistent PT calibration were best obtained by proportional thermostatic control via the peripheral TC. When the PT was heated to 35 degrees C or above, expirations from either the pump (air at 33 degrees C saturated) or a subject cooled the PT, thus affecting its response. With the PT heated to 30 degrees C, repeated blows caused little change in PT temperature, with no evidence of condensation, thus indicating optimal thermal conditions for recording MFEM.

Biomedical Engineering↗
PubMed1986

Identification of a rat liver cAMP-dependent protein kinase, type II, which binds DNA.

A novel protein kinase which specifically binds single strand DNA was identified in rat liver by chromatography on double strand- and single strand- DNA cellulose. This protein kinase activity was stimulated by cAMP and was inhibited by the heat stable inhibitor, suggesting it was a cAMP-dependent protein kinase. Isoelectric focusing studies confirmed that the single strand DNA-binding protein kinase was indeed a cAMP-dependent protein kinase and had the same pI as cAMP-dependent protein kinase, Type II. The DNA binding capacity of this kinase was primarily localized in the regulatory subunit. These results support the recent hypothesis that in addition to regulating enzymatic activity by phosphorylating proteins, cAMP-dependent protein kinase, Type II, may regulate mammalian gene expression through a mechanism similar to that in prokaryotes.

Animals↗
PubMed1985

Inhibition of DNA replication and DNA polymerase alpha activity by monoclonal anti-(DNA polymerase alpha) immunoglobulin G and F(ab) fragments.

The effect of monoclonal anti-(DNA polymerase alpha) immunoglobulin G (IgG) and F(ab) fragments on DNA replication in lysolecithin-permeabilized human cells and on DNA polymerase alpha activity was determined. DNA polymerase alpha activity in vitro was inhibited equally by the same concentrations of monoclonal IgGs and F(ab) fragments. However, the IgGs and F(ab) fragments were not equally potent in inhibiting DNA replication in permeable cells. In general, the F(ab) fragments were approximately equal to 10-fold more potent than IgGs in inhibiting DNA replication, suggesting the F(ab) fragments cross the nuclear membrane more readily than IgGs. Immunocytochemical studies demonstrated that at least a fraction of anti-(DNA polymerase alpha) IgGs entered the nucleus of permeable cells. For most antibodies tested, the IgG or F(ab) concentration needed to inhibit replication was several orders of magnitude higher than that needed to neutralize polymerase alpha activity extracted from the same number of cells. Anti-(DNA polymerase alpha) F(ab) fragments were shown to inhibit the discontinuous synthesis of Okazaki DNA, as well as the maturation of Okazaki DNA to larger DNA, thereby implicating DNA polymerase alpha in both of these processes.

Animals↗
PubMed1985

Quantitative studies of auditory hair cells and nerves in lizards.

Because the lizard cochlear duct is anatomically accessible as well as relatively simple in structure it is an excellent model in which to study auditory hair cells, nerve fibers, and innervational patterns. The objectives of this study were to determine the intra- and interspecific variations of auditory hair cell and nerve fiber numbers, nerve fiber/hair cell ratios, and nerve fiber sizes in a varied of lizard species and to relate these to auditory function and phylogeny. Hair cell numbers were determined by SEM and serial frontal sections of the papilla basilaris and nerve fiber numbers and diameters by use of a Zeiss TGZ3 particle counter. The coefficient of variation of hair cell numbers varied from 3.2 to 16.6 (171 specimens, 15 species) and of nerve fiber numbers from 1.2 to 14.4 (381 specimens, 35 species). There was no correlation between hair cell or nerve fiber number and age or sex. The nerve fiber number/hair cell number ratio was 3.5-11.1/1 in small papillae basilares of the iguanid-agamid-anguid type, 2.4-3.2/1 in the teiid type, and 0.6-1.5/1 in the larger specialized papillae of the scincid and gekkonid types. Nerve fibers varied in diameter from 0.8 to 6.0 microns (largest percentage were 2-4 microns) and were unimodally distributed. Larger nerve fibers usually supplied the unidirectionally oriented hair cells of the papilla basilaris. Variations in hair cell and nerve fiber numbers in other vertebrate classes and the functional and phylogenetic aspects of lizard papilla basilaris structure and innervation are discussed.

Animals↗
PubMed1985

Monoclonal antibodies against human DNA polymerase-alpha inhibit DNA replication in permeabilized human cells.

Monoclonal neutralizing antibodies against DNA polymerase-alpha substantially inhibit nuclear DNA replication in lysolecithin-permeabilized cultured human fibroblasts. The degree of inhibition of DNA synthesis is proportional to antibody concentration, and the effect is specific in that RNA synthesis measured under the same experimental conditions is unperturbed. Autoradiographic data demonstrate that the magnitude of the inhibition measured in the mass culture reflects the uniform response of all the constituent cells in the target population. These observations confirm the participation of DNA polymerase-alpha in replicative DNA synthesis and identify a versatile, novel approach to the dissection of mammalian processes of DNA replication and repair.

Antibodies, Monoclonal↗
PubMed1985

Patterns of spirogram abnormality in individual smokers.

Dynamic ventilatory function was measured in 147 male and 212 female smokers with a mean age of 39.3 and 42.5 yr, respectively. The results were compared with values predicted from the results of control subjects who had never smoked, and deviation from predicted was expressed as a standardized residual (SR). Although the flow indices FMF, FEF50, and FEF75 showed a substantial group change in SR for smokers, the distribution of SR indicated changes in the majority of smokers but did not favor the identification of individual subjects as being abnormal. By contrast, the distribution of SR for FEV1/FVC%, FEV3/FVC%, and the time domain indices alpha(1) 75%, MR90%, and mu favored the identification of subjects with marked abnormalities. These volume-standardized indices allowed the identification of 2 patterns of spirometric abnormality prevalent among smokers. Pattern 1 showed changes predominantly in the first 75% of FVC and Pattern 2 showed changes generally confined to the tail of the spirogram; 15% of the female and 14% of the male smokers had Pattern 1 abnormalities, with only 4% of both the female and male smokers showing Pattern 2. These results appear more consistent with the "Dutch hypothesis" and not the "small airways hypothesis" concerning the development of chronic air-flow limitation in smokers.

Adult↗
PubMed1985

Time domain spirogram indices. Their variability and reference values in nonsmokers.

A cross-sectional population survey of dynamic ventilatory lung function was performed to determine the variability of and reference values for time domain spirogram indices. The reference population comprised 83 men and 143 women who were healthy nonsmokers. The time domain indices were derived from the blow with the largest sum of FVC and FEV1. Prediction equations for FEV1 and mean flow between 25 and 75% FVC were little influenced by methods for selecting the data from the 3 blows recorded. The variability of the first 2 moments of the spirogram increased with age, requiring a log transformation for regression analysis. Prediction equations for conventional and time domain spirometric indices are presented and reference values are proposed based on an estimated percentile derived from the predicted value and the residual standard deviation from regression. Two time domain indices are identified that may prove better suited than conventional indices for identifying abnormalities in the tail of the spirogram.

Adult↗
PubMed1984

Radiological prediction of pulmonary hypertension in chronic obstructive pulmonary disease.

A study was undertaken to determine whether measurements of radiological indices from postero-anterior chest X-rays were useful in predicting pulmonary artery hypertension. Measurements of the transhilar (THD) and pulmonary lobar distances (PLD) as well as the width of the descending branch of the right pulmonary artery (DB) were made from X-rays of 100 patients with chronic obstructive pulmonary disease. For these patients the forced expiratory volume in 1 s was 1.2 +/- 0.6 l (group mean +/- SD), the arterial PO2 was 62.2 +/- 14.5 mmHg and the mean pulmonary artery pressure (PAP) was 26.7 +/- 11.9 mmHg. Considerable differences in the measurement of THD and PLD were found between and within observers whereas the measurement of DB was more reproducible. DB was better correlated (r = 0.59, P less than 0.001) with PAP than were THD and PLD. Using a stepwise multiple regression procedure including other physiological variables, it was found that DB and arterial PO2 were the only significant (P less than 0.05) predictors of PAP, together accounting for 48% of the variation in PAP, with DB being the more important predictor.

Female↗
PubMed1983

Subcellular location of a soluble factor that stimulates DNA replication in permeable animal cells.

The subcellular location of a soluble DNA replication-stimulating factor released from lysolecithin-permeabilized cultured mammalian cells was investigated by cytochalasin B (CB) enucleation. In both Chinese hamster ovary cells and baby hamster kidney (BHK) cells, approx. 70% of the total activity of the replication-stimulating factor was associated with the karyoplast fraction. In neither cell line did the replication-stimulating factor show any significant change in activity or in subcellular location between G1 and S period synchronized cells. The general nature and mechanism of action of this stimulatory factor were characterized in order to show that it was similar to "cytoplasmic" factors reported to stimulate DNA replication in other subcellular systems. The predominantly nuclear location of the replication-stimulating factor supports a physiological role in DNA metabolism in animal cells.

Animals↗
PubMed1983

Identification of mammalian DNA repair factors using a reconstituted subcellular system. Partial characterization and subcellular location of a DNA repair-stimulating protein in hamster cells.

By reconstituting lysolecithin-permeabilized hamster cells with endogenous proteins, a protein(s) which stimulated bleomycin-induced DNA repair synthesis was identified. The repair protein was inactivated by proteinase K and had an apparent molecular weight of 12 000-15 000 D. The following enzymatic activities were not detected in the partially purified DNA repair protein: general endonuclease, apurinic endonuclease, exonuclease, DNA polymerase or DNA polymerase beta-stimulating activity. The subcellular location of the DNA repair-stimulating activity was investigated by cytochalasin B enucleation; approx. 80% of the activity was associated with karyoplasts, suggesting a nuclear location. Neither the activity nor subcellular location of the repair protein fluctuated appreciably during the cell cycle, consistent with a physiological role in DNA repair. Although the function of the DNA repair protein is not yet known, this approach should be useful in identifying and characterizing mammalian DNA repair proteins.

Animals↗