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Biomedical subjects

D J Miller

Publications and source records attributed to D J Miller.

At least 199 records · Page 11Linked to original sources
PubMed1986

Effect of osmolality and glycosaminoglycans on motility, capacitation, acrosome reaction, and in vitro fertilizability of bovine ejaculated sperm.

Bovine ejaculated semen was placed in a modified Tyrode's medium with albumin, lactate, and pyruvate. The sperm were washed three times and subjected to nine treatment in a 3 X 3 factorial arrangement. Treatments consisted of osmolality (exposure to 380 mOsmol/kg medium for 5 min, exposure to 340 or 295 mOsmol/kg medium for the entire incubation period), and the presence or absence of glycosaminoglycans (100 micrograms/ml chondroitin sulfate A or 10 micrograms/ml heparin). Sperm were examined at 4.5 h, 8 to 9 h, and 24 to 25 h of incubation (37 degrees C, 5% CO2, and 95% air). Heparin caused head-to-head agglutination of sperm, raised the percent sperm without seminal antigens over the acrosome (capacitated) by 20% at 4.5 h, and doubled the percent of acrosome-reacted sperm. However, this stimulation did not improve in vitro fertilizability. Chondroitin sulfate A tended to maintain motility, but did not affect capacitation or the acrosome reaction, possibly due to glucose inhibition. Both high osmolality treatments tended to reduce motility, especially after 24 h of incubation when the 340 osmolality treatment reduced motility by 14% over the 295 treatment. No consistent effect on capacitation was observed. The 340 and 380 osmolality treatments induced 8.6 and 6.1% more acrosome reactions by 24 h than the 295 treatment. The 340 mOsmol/kg treatment yielded insignificantly higher in vitro fertilization rates, as evidenced by development of zygotes to the two-cell stage. Lack of statistical significance was due to high variation with in vitro fertilization rates.

Acrosome↗
PubMed1986

N-terminal amino acid sequence of cytochrome c-552 from Nitrosomonas europaea.

Nitrosomonas europaea is an ammonia-oxidizing bacterium which contains multiple c-type cytochromes. Few of these components have been assigned physiological roles, but on the basis of molecular weight and redox potential cytochrome c-552 has been considered to be an analogue of the mitochondrial cytochrome-c family of proteins. We present the N-terminal amino acid sequence (47 residues) of cytochrome c-552 and show that this protein is most closely related to the group of small cytochrome-c components from pseudomonads (cytochromes c-551) and is probably evolutionarily distant from the analagous protein (cytochrome c-550) from the nitrite-oxidizing bacterium Nitrobacter agilis.

Amino Acid Sequence↗
PubMed1986

Retention interval and intertrial interval in a serial learning or delayed discrimination task.

In each of four experiments, rats were provided with the same three-event decreasing series (18-1-0) of 0.045-g food pellets in a runway. Tracking, running fast to 18 pellets and running slow to 1 and 0 pellets, was investigated as a function of the temporal interval elapsing between the events of the series (the retention interval), shifts in retention interval, and number of trials each day (or the intertrial interval), a trial being defined as presentation of each of the three events of the series. Neither retention interval, which varied from 15 s to 30 min in various investigations, nor shifts in retention interval affected tracking when only one trial was given each day. But when more than one daily trial was given, tracking was acquired more slowly and was disrupted by a shift in retention interval from 15 s to 5 min. Tracking was also disrupted by a shift from one to two trials each day. These results indicate that when given one 18-1-0 trial each day, the rat partitions events on a first-event/subsequent-event basis; that little forgetting occurs even at long retention intervals; that somewhat different memories signal events when one or more than one 18-1-0 trial occurs each day; and that retention interval deficits can arise owing to the same or similar memories' signaling different events. The results described limit the generality of three hypotheses suggested in two recent investigations: that as retention interval increases, rats find it increasingly difficult to remember and utilize serial position cues; that tracking in serial tasks is not influenced by number of trials each day; and that there are specific stimuli associated with each retention interval which, when changed, necessarily disrupt performance.

Animals↗
PubMed1985

Potentiometric measurements of stoichiometric and apparent affinity constants of EGTA for protons and divalent ions including calcium.

The stoichiometric affinity constants of H+, Ca2+, Mg2+ and Sr+ for the ligand EGTA were determined using a modified version of the pH metric method developed by Moisescu and Pusch (Moisescu, D.G. and Pusch, H. (1975) Pfluegers Arch. 355, 243). The values obtained were slightly higher than those previously published. In addition, the shift in the H+ and Ca2+ stoichiometric constants with ionic strength was found to fit an empirical relationship if the total ionic content of the titration solutions was measured in terms of ionic equivalents, Ie (Johansson, L. (1975) Acta Chem. Scand. A29, 365-373), rather than the formal ionic strength, If. Finally, the apparent affinity of EGTA for Ca2+ ions was measured using an abbreviated form of the titration technique. The measured apparent affinity constant agreed with published results only if calculated with respect to pH (measured) of 7.0, rather than pH (concentration).

Cadmium↗
PubMed1985

Ultrastructural and X-ray microanalytical studies of EGTA- and detergent-treated heart muscle.

The efficacy of the 'EGTA-treatment' for producing a model of selectively 'skinned' cardiac muscle has been questioned. This paper deals with ultrastructural evidence designed to test whether small ions can gain access to the myofibrillar space of the heart after 'EGTA-treatment'. Lanthanum has been employed because of its widespread use as an 'extracellular' marker and because its presence can be unequivocally demonstrated by X-ray microanalysis. The results of both standard transmission electron microscopy and X-ray microanalysis reveal that, despite some deterioration of the ultrastructure after 'EGTA-treatment' at 2 degrees C for 24 h, lanthanum is still apparently excluded from the intracellular spaces. Parallel runs with detergent treatments, such as Triton X-100 and the alkaloid saponin, demonstrate that La3+ is deposited on the contractile proteins in readily detectable amounts in these circumstances. Even in areas of the sections devoid of visible electron-opaque deposits, recognizable by eye in standard transmission images, X-ray microanalysis frequently revealed the presence of La3+. It is concluded that the sarcolemma persists as a selective permeability barrier to small ions such as La3+ and LaEGTA after 'EGTA-treatment'. These findings are complementary to the mechanical behaviour of chemically treated cardiac muscle.

Animals↗
PubMed1985

The contractile behaviour of EGTA- and detergent-treated heart muscle.

Tension responses of rat ventricular trabeculae subjected to successive 'treatment' with EGTA and Triton X-100 are described in order to investigate the effects of chemical 'skinning' techniques. In some preparations the alkaloid saponin was also used before Triton. Ultrastructural evidence is cited that the 'EGTA-treatment' fails to render cells 'hyperpermeable', i.e. freely permeable to small ions, whereas both saponin and Triton do so. In this paper we show that contractile responses like those described previously for the 'EGTA-treated' tissue can be obtained. However, more detailed examination shows that such behaviour is quantitatively distinct from that of conventionally skinned fibres in a way that is incompatible with the notion of 'hyperpermeability'. The Ca-sensitivity after treatment with either EGTA, saponin or Triton is identical in our hands. However, this is not explained by free access of Ca (and EGTA) to the intracellular space in the EGTA-treated preparation: contractures develop with very different time courses, being fastest after Triton and only marginally slower when first exposed to saponin but a factor of five times slower after 'EGTA-treatment' alone. This applies to contractures evoked direct from Ca2+ concentration congruent to 10(-9) M to the test Ca2+ concentration at constant total buffer concentration. 'EGTA-treated' fibres develop tension when ATP or creatine phosphate (CrP) are removed from the bath. However, responses to ADP and to CrP changes persist with millimolar levels of ATP present, quite unlike the Triton-skinned muscle. Exposure to each of a variety of solutions for 24 h produce preparations showing similar behaviour: whatever the explanation for the EGTA-'skinning' phenomenon it is not dependent upon low bathing Ca2+ concentration. On the basis of the functional characteristics described here, and the structural results cited, we conclude that the cell membrane continues to function as a selective permeability barrier after 'EGTA-treatment': this treatment does not produce a model of a selectively 'skinned' cardiac cell.

Animals↗
PubMed1985

Comparison of electromyographic activity in the lumbar paraspinal muscles of subjects with and without chronic low back pain.

My purpose, in this study, was to test the reflex-spasm model of chronic pain by comparing the levels of muscle activity in the lumbar paraspinal muscles of subjects with and without chronic low back pain (CLBP). Each group, the CLBP group and the nonpain (NP) group, comprised 11 subjects who were matched by age and sex. I used surface electrodes to record integrated electromyographic (IEMG) activity from each side of the low back. All subjects performed three experimental tasks and a reference (normalizing) task. The three experimental tasks were quiet sitting, standing, and sitting during a repetitive unilateral upper extremity task (active sitting). The CLBP and NP groups showed no significant difference for any of the three experimental tasks. For both groups, the active sitting IEMG levels were significantly higher than the quiet sitting and standing IEMG levels. The quiet sitting and standing IEMG levels were not significantly different from each other. The findings of similar levels of IEMG activity in both the CLBP and NP groups while they performed these tasks suggested that the reflex-spasm cycle was not present and, therefore, was not a cause of pain in the subjects with CLBP.

Adult↗
PubMed1984

3,3',5,5'-tetramethylbenzidine/H2O2 staining is not specific for heme proteins separated by gel electrophoresis.

Staining of sodium dodecyl sulfate or lithium dodecyl sulfate gels with 3,3',5,5'-tetramethylbenzidine (TMBZ)/H2O2 after electrophoresis has frequently been used as a specific method of detecting heme proteins. That TMBZ is an electron donor for O2 reduction by the nonheme-soluble cytochrome oxidase/nitrite reductase from Nitrosomonas europaea is now shown; this protein is detected by the TMBZ/H2O2 method. A method for the determination of TMBZ oxidase activity is given; hence, the detection of artifactual staining due to proteins of this type is possible.

Benzidines↗
PubMed1984

Predicting rehospitalization at a community mental health center: a "double-crossed" validation.

Used a multiple regression equation that contained a variety of demographic and diagnostic measures as predictor variables to predict 5-year recidivism in a group of 100 psychiatric inpatients hospitalized at a community mental health center. This equation then was cross-validated via the prediction of recidivism in a second group of 100 inpatients. A predictive equation derived from an analysis of this second group of patients then was used in a "double-crossed' validation back to the first group. Diagnoses that involved schizophrenia and drug abuse, major psychotropic drug regimens, and a failure to appear for follow-up therapy as an outpatient emerged consistently as predictor variables.

Aftercare↗
PubMed1984

EGTA purity and the buffering of calcium ions in physiological solutions.

Results are presented for the purity of three commercial brands of the Ca chelator EGTA [ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid] as determined with pH-metric and oxalate precipitation methods and other techniques. The effect that the observed degree of hydration (2-4%) has on calculated values for [Ca2+] in Ca-EGTA solutions is described with reference to a theoretical dose-response relationship. In addition to the corrections for purity, the adjustments necessary to allow for ionic strength and the correction of pH readings to yield true [H+] activity or concentration values are described. These several corrections result in both a shift and a shape change for the dose-response curve compared with the curve calculated without these corrective procedures. Some authors have already taken some of these aspects into account, but this has not generally been made clear in the literature heretofore. The points raised may help to account for the wide variation of reported [Ca2+] ranges for Ca-sensitive cellular processes.

Animals↗
PubMed1983

CO-binding c-type cytochromes and a high-potential cytochrome c in Nitrosomonas europaea.

The purification of two soluble CO-binding cytochromes c from Nitrosomonas europaea is described. Cytochrome cCO-550 ran on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis with an apparent Mr of 32 000, whereas for cytochrome cCO-552 the apparent Mr was 16 000. Redox potentials (Em, 7) were determined as +140 and -50mV respectively. Cytochrome cCO-550 was co-purified with a cytochrome c-553, for which an unusually high redox potential of +450mV was measured. These latter components were not resolved by gel-filtration chromatography or electrophoresis under denaturing conditions.

Carbon Monoxide↗
PubMed1982

Characterization of the c-type cytochromes of Nitrosomonas europaea with the aid of fluorescent gels.

When a total soluble extract of Nitrosomonas europaea was denatured with dodecyl sulphate, subjected to dodecyl sulphate/polyacrylamide-gel electrophoresis and illuminated with near-u.v. light, eight bands of protein fluorescence were observed. All but one of these bands were red in colour, a property characteristic of c-type cytochromes. Standard techniques were used to purify soluble c-type cytochromes from this organism, and it was then possible to assign all but two very minor bands to specific c-type cytochromes, namely hydroxylamine oxidase, cytochrome c-554, cytochrome c-552 and a cytochrome c-550 not previously described. The eight band had fluorescence peaking in the green region of the spectrum, probably caused by covalently bound flavin, and co-purified with hydroxylamine oxidase. The following physical properties were determined for these components: isoelectric point, molecular weights according to gel filtration and mobility on dodecyl sulphate/polyacrylamide gels, and alpha-band spectra at room temperature and 77K. Redox potentials were measured as follows: cytochrome c-554, E(m,7) = +20mV; cytochrome c-552, E(m,7) = +230mV; cytochrome c-550, E(m,7) = +140mV. When washed membranes were applied to dodecyl sulphate/polyacrylamide gels in the same way, a number of fluorescent bands were observed that could be matched by soluble proteins. In addition, there was one band that could not be detected in supernatants, migrating with an apparent molecular weight of 24000. This species is probably coincident with a c-type cytochrome having E(m,7) = +170mV found in redox titration of these membranes. In future studies, gel fluorescence should form a useful complement to spectroscopy for analysis of cytochrome composition in active cell-free preparations or semi-purified material.

Cytochrome c Group↗
PubMed1981

Hepatitis B infection in hospital personnel during an eight-year period; policies for screening and pregnancy in high risk areas.

From 1972 through 1979, acute hepatitis, type B, or asymptomatic hepatitis B surface (HBs) antigenemia developed in 34 employees at Yale-New Haven Hospital. The average yearly incidence of the infection was 1.2 cases per 1,000 employees. The incidence was highest in those administering venipunctures followed, respectively, by those in the emergency room, hemodialysis unit, housestaff, laboratory, general nursing, and support service personnel. Three cases were detected during eight years of routine screening of personnel; in 1972, one of these, a pregnant nurse working in the hemodialysis unit, was moved from that unit. Subsequently, seven personnel in the unit have been transferred during pregnancy. However, staphylococcal pneumonia was acquired by one of them on a medical floor, and another nurse, seeking work in oncology, was not hired while pregnant. Both cases resulted in administrative complaints. Currently, we screen personnel in the hemodialysis and venipuncture units quarterly for hepatitis B surface antigen (HBsAg) and antibody (anti-HBs) (participation is optional for those in the emergency room and oncology) and strongly urge seronegative pregnant women to transfer from these areas.

Connecticut↗