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Biomedical subjects

M Bond

Publications and source records attributed to M Bond.

At least 127 records · Page 7Linked to original sources
PubMed1982

Dense bodies and actin polarity in vertebrate smooth muscle.

The arrangement of cytoplasmic dense bodies in vertebrate smooth muscle and their relationship to the thin filaments was studied in cells from rabbit vas deferens and portal vein which were made hyperpermeable (skinned) with saponin and incubated with myosin subfragment 1 (S-1). The dense bodies were obliquely oriented, elongated structures sometimes appearing as chains up to 1.5 microns in length; they were often continuous across the cell for 200 to 300 nm and were interconnected by an oblique network of 10-nm filaments. The arrowheads, formed by S-1 decoration of actins, which inserted into both the sides and ends of dense bodies, always pointed away from the dense body, similar to the polarity of the thin filaments at the Z-bands of skeletal muscle. These results show that the cytoplasmic dense bodies function as anchoring sites for the thin filaments and indicate that the thin filaments, thick filaments, and dense bodies constitute a contractile unit.

Actins↗
PubMed1982

Gonococcal opacity variants: susceptibility to antimicrobial agents.

We tested the susceptibility of 34 pairs of isogenic opaque and transparent colony variants of gonococci to nine antimicrobial agents. Only 20% of the opaque and transparent minimal inhibitory concentrations were discordant, and the mean minimal inhibitory concentrations were not significantly different. Selection of opacity variants is, therefore, not necessary for routine susceptibility testing.

Anti-Bacterial Agents↗
PubMed1980

Two mRNAs with different 3' ends encode membrane-bound and secreted forms of immunoglobulin mu chain.

During differentiation, B lymphocytes undergo a shift from expression of membrane-bound IgM to IgM secretion. The mu chains of membrane and secreted IgM, mum and mus, respectively, differ in the amino acid sequence of their carboxy terminal regions. In this paper, we demonstrate that mum and mus heavy chains are encoded by separate mRNAs of 2.7 and 2.4 kb, respectively. Restriction mapping and sequence analysis of mu cDNA clones from a myeloma tumor that produces both types of mu chain indicate that the mum and mus mRNAs are identical throughout the coding region up to the 3' end of the fourth constant region (Cmu 4) domain, but differ in their C terminal coding and 3' untranslated segments. From the nucleotide sequence of the mum cDNA clone, we predict the amino acid sequence of the 41-residue mum C terminal segment or "M" (membrane) segment. This sequence has characteristics consistent with its being a transmembrane peptide. Thus the mus chain has a 20-residue hydrophilic C terminal segment after the Cmu 4 domain, and the mum chain has a 41-residue C terminal segment containing a hydrophobic sequence. We propose that comparable C terminal segments also will be found in other membrane-bound immunoglobulin heavy chains.

Animals↗
PubMed1978

Detection of 31P nuclear magnetic resonance signals in brain by in vivo and freeze-trapped assays.

The (31)P NMR spectrum of energy-related metabolites under strictly aerobic conditions in rapidly respiring tissues under physiological conditions has been approached by the study of the (31)P NMR signals in vivo and in freeze-trapped organs. Freezing the head of the anesthetized animal by liquid N(2), excision of the brain tissue (white and gray matter) at -196 degrees , and transfer to the NMR tube occurs without alteration of the metabolite concentrations. The sample is warmed to the region -15 degrees to -10 degrees , at which temperatures there is sufficient mobility for recording (31)P NMR at concentrations characteristic of brain tissues ( approximately 5 mM) with an adequate signal to noise ratio in 10 min but insufficient mobility for significant enzymatic activity. A approximately 0.4-sec acquisition time is adequate for nuclear relaxation and a 10-min scan gives an adequate signal to noise ratio. Metabolism of creatine phosphate, P(i), and sugar phosphates occurs by 1 hr at -10 degrees and 2 hr at -12 degrees . Extrapolation of the approximately zero order kinetics of disappearance of creatine phosphate and appearance of P(i) suggests that <10% of these two metabolites has been altered in the time of the first measurement.A comparison of the freeze-trapped state and the in vivo metabolite pattern is afforded in preliminary experiments on the head of the living mouse (brain and skeletal tissue) in aerobic and anaerobic states. Longer relaxation times and mild hypoxia due to the restricted diameter of the NMR tube gives significantly lower creatine phosphate/ATP values for this condition. Both direct in vivo and freeze-trapped assays of energy-related metabolites afford excellent approaches to the detection of anoxia and to the evaluation of metabolic control in hypoxic conditions.

Adenosine Triphosphate↗
PubMed1975

Assessment of outcome after severe brain damage.

Persisting disability after brain damage usually comprises both mental and physical handicap. The mental component is often the more important in contributing to overall social disability. Lack of an objective scale leads to vague and over-optimistic estimates of outcome, which obscure the ultimate results of early management. A five-point scale is described--death, persistent vegetative state, severe disability, moderate disability, and good recovery. Duration as well as intensity of disability should be included in an index of ill-health; this applies particularly after head injury, because many disabled survivors are young.

Activities of Daily Living↗
PubMedDate not supplied

Calcium content of mitochondria and endoplasmic reticulum in liver frozen rapidly in vivo.

The recognition that the endoplasmic reticulum (ER), rather than the mitochondria, is the main organelle regulating the cytoplasmic Ca2+ concentration in non-muscle cells supports the notion that an alternative physiological role of mitochondrial Ca transport is the modulation of Ca-sensitive mitochondrial enzymes through small (micromolar) fluctuations in the concentration of mitochondrial matrix Ca2+. The latter mechanism could operate only if the mitochondrial Ca concentration were low, as it is in muscle and retinal rods, below the levels saturating the regulated enzymes. In contrast, if the ER serves as an intracellular Ca store, its Ca content would be expected to be high. In view of the major metabolic function of the liver, the question of whether hepatic mitochondrial matrix Ca2+ regulates metabolism is particularly important, but the range of Ca concentrations reported for isolated liver mitochondria is too wide to provide a conclusive answer. Therefore, we have used electron probe X-ray microanalysis (EPMA) to measure the subcellular distribution of Ca in liver snap-frozen in vivo, and report here that the endoplasmic reticulum is a major intracellular store of Ca, while the concentration of Ca in mitochondria is low and compatible with the regulation of mitochondrial enzymes.

Animals↗
PubMedDate not supplied

Generating ideas for research: an Australian research experience.

Recent changes in the educational system and career developments in Australia have provided Australian clinical nurses with an opportunity to conduct research in their practice. In this article, the nursing staff of an Australian gastroenterology unit describe their experience in defining a research project.

Australia↗
PubMedDate not supplied

Widespread bone disease in acute myeloid leukaemia.

We describe a 11-year-old boy with acute myeloid leukaemia who presented with widespread bone disease. Spine X-rays revealed multiple crush fractures and there were multiple hot spots on the bone scan. The bone-mineral density was markedly reduced but there was no hypercalcaemia or hypercalcuria. Bone marrow aspirate revealed 98% blast cells and a balanced translocation between chromosomes 10 and 17 in seven of nine metaphases. Plasma interleukin-6 level before chemotherapy was high at 53 pg/ml. We postulate that the mechanism for bony destruction in this case was similar to that in the adult disease myeloma.

Bone Density↗
PubMedDate not supplied

Development of an instrument to study the sexual relationship of partners during pregnancy.

The development of an objective self-report instrument designed to identify the domain of sexual behaviours during pregnancy is described. The Pregnancy and Sexuality Questionnaire (PSQ) is concerned with sexual interest and arousal and with specific sexual behaviours of partners in a stable heterosexual relationship. Data were obtained two weeks apart from 15 couples presenting to an antenatal class and from two additional females whose partners did not participate. The validity and reliability of the PSQ are considered with particular emphasis on test-retest reliability. The results in general support the reliability of the instrument. The questionable reliability of some items is attributed to the natural sequence of change in sexual behaviours during pregnancy and to the relatively small sample size used. The PSQ appears to be sufficiently robust to be confidently applied both in sexual behaviour research and as an adjunct to clinical practice.

Adult↗
PubMedDate not supplied

Teaching infant resuscitation skills to mothers.

This paper describes the evaluation of a program designed to teach basic infant resuscitation skills to mothers during the period of postnatal hospitalization. Data collected from participants before and immediately after the program, and at six months, follow-up indicated that knowledge of resuscitation techniques had moderately improved, however there was a substantial increase in participants' confidence and an associated reduction in anxiety. An additional aspect of the evaluation was to identify any logistical problems; data obtained from postnatal midwifery staff indicated none were evident. It was concluded that the Infant Resuscitation Education Program should be implemented for all mothers of newborn infants.

Female↗