PubMed Health⌕ Search

Biomedical subjects

B Russell

Publications and source records attributed to B Russell.

At least 19 recordsLinked to original sources
PubMed1992

Mechanisms for intracellular distribution of mRNA: in situ hybridization studies in muscle.

The intracellular distribution of mRNA in striated muscle fibers is highly ordered, as is the structural organization of the fibers' contractile apparatus. Results from in situ hybridization of muscle mRNA are reviewed in an attempt to discern the mechanisms involved in mRNA distribution and to determine its relationship to developmental, growth, and repair processes in muscle. Nonradioactively labeled complementary RNA probes allow anatomic localization of mRNA at the light and electron microscopic level. Myosin mRNA in striated muscle is concentrated around transcriptionally active nuclei, myosin mRNA is excluded by the myofibrillar mass, myosin mRNA distribution correlates with that of cytoskeletal elements, and myosin mRNA is concentrated in regions of rapid growth and repair. The even distribution of myosin mRNA along the length of myofibrils gives no indication of specific association with either the thick or thin filaments. Of the possible mechanisms directing mRNA distribution, results from in situ hybridization and other analyses support a restricted diffusion model. Diffusion of mRNA (and polysomes) is severely limited by the myofibrillar lattice. It is possible that myosin mRNA is also associated with a cytoskeletal element, which may direct the mRNA to specific intracellular locations and affect translational activity.

Animals↗
PubMed1992

Remodeling of myofibrils: subcellular distribution of myosin heavy chain mRNA and protein.

Myofibril remodeling occurs during the normal life, in growth and development, and in the special case when isoform switching occurs. In this review we concentrate on the ultrastructural aspects of how myosin is incorporated into the A-band. Anatomic methods of study are emphasized that include isotope and immunochemical labeling as well as in situ hybridization. We conclude that the mechanism of remodeling is one of continual orderly exchange between a monomeric myosin pool and the thick filament. Myosin mRNA distribution is intermyofibrillar and nonsarcomeric, which suggests that newly translated myosin is released before diffusion and insertion in the A-band of the myofibrillar lattice.

Animals↗
PubMed1992

Growth hormone-binding proteins of human serum: developmental patterns in normal man.

The binding of GH by a low affinity binding protein (LA-BP) was measured from birth into adulthood and compared with binding of a high affinity binding protein (HA-BP) in human serum. Pooled serum samples for each year of age from birth to 16.5 yr were formed from 2500 separate samples and assayed for both binding proteins using a Sephadex chromatographic method. Individual samples in this age range and those from adults were assayed in a similar manner. Binding of [125I]GH was minimal by both binding proteins in cord blood (binding by LA-BP, 2.77 +/- 0.32%; binding by HA-BP, 2.58 +/- 0.35% mean +/- SEM). A 4-fold increase to maximal binding for LA-BP occurred by the age of 5 yr and remained relatively constant through adolescence, except for a transient decrease at puberty. From 16.5-20 yr of age, binding by LA-BP decreased to a level no greater than that seen at birth. Binding by the HA-BP, which increased 6- to 8-fold reached maximal binding between 23-25 yr of age. Binding by HA-BP did not decrease in adults between the ages of 20-30 yr. Whereas pregnancy increased LA-BP activity, GH binding by HA-BP was unaltered.

Adolescent↗
PubMed1992

Repair of injured skeletal muscle: a molecular approach.

We review cellular and molecular processes involved in injury and repair of skeletal muscle with regard to the amount and location of damage produced. Discussion is based on advances made by use of newer techniques, including immunochemistry, in situ hybridization, molecular biology, ultrastructural analysis, and cell culture. Damage and repair processes after eccentric work, stretch, overload, chronic stimulation, cold injury, and other models are discussed for cellular and molecular components. Hypertrophy or hyperplasia can occur under certain conditions. After injury, satellite cells are activated by growth factors. These cells can also be activated during fiber-type transformation, probably to provide necessary DNA content rather than to supply cells of a new lineage. Emphasis is given to myosin mRNA studied by in situ hybridization to localize subcellular distribution. Increases in mRNA concentration are found near nuclei in damaged regions and at the subcellular sites being repaired in the middle of skeletal muscle fibers or near the myotendon junction. The activation of genes for muscle regulatory factors during development is compared with their activation in regeneration and response to injury.

Animals↗
PubMed1991

The growth hormone-insulin-like growth factor I axis: studies in man during growth.

Several major differences are noted between males and females in their patterns of growth at puberty. Accelerated pubertal growth in both males and females depends upon the integrity of the GH-receptor system. In males, acceleration of growth results primarily from enhanced sensitivity of the GH-receptor-IGF I system to GH brought about by testosterone. Whether testosterone itself is responsible for this observation is still unclear. Perhaps the initial GH, IGF I peak present in males and absent in females occurs at the time when sleep-related rises of gonadotropins and testosterone begin just prior to puberty. Though the pygmy data certainly supports a relationship between testosterone and the GH-receptor-IGF I axis, the undisputed tall stature of eunuchs remains a puzzle. It is possible that the maturing male gonad secretes another growth factor and/or growth inhibitor in conjunction with testosterone and that it is this unidentified factor which modulates growth. At any rate, acceleration of growth in males results from sensitization or the GH-receptor-IGF I system while growth acceleration in females results almost solely from increased secretion of GH and not sensitization of the system.

Adolescent↗
PubMed1991

Hormone and receptor studies: relationship to linear growth in childhood and puberty.

Preliminary data suggested different patterns of hormonal control of linear growth in males and females. To better define these patterns, serum samples were collected from 75-125 boys and a similar number from girls for each year of age between 3-16 yr (n = 2416). Fewer samples were collected from 2-yr-olds, newborns, and adults (n = 151). Samples for each age were aliquoted, combined, and assayed for GH, GH-binding protein (GHBP), insulin-like growth factor-I, and testosterone. GHBP, expressed as a percentage of the [125I]GH bound, increased yearly in males and females, with no relationship to the secretion of sex hormones. The increase in binding of [125I]GH and, by inference, GH receptors occurred at a greater rate between the ages of 2-10 yr than between 10-16 yr (in terms of absolute binding, 1.2 +/- 0.11% vs. 0.38 +/- 0.04% yearly; P less than 0.001). In each age group, however, the increase in GHBP exhibited a strong positive correlation with linear height (r = 0.96-0.98 in males; r = 0.92-0.99 in females). Before puberty, GH and insulin-like growth factor-I concentrations were consistently greater in females. Between 10-16 yr of age, height velocity (centimeters of growth per yr) correlated strongly with GH in girls (r = 0.86), but did not correlate with GH in boys of a similar age (r = -0.13). The major pubertal growth spurt in males strongly correlated with a rise in serum testosterone concentration beginning at age 11 yr (r = 0.92). Small peaks of GH secretion before and after the major period of accelerated growth in males possibly prolonged the major growth phase, but did not initiate it.

Adolescent↗
PubMed1991

Infection control.

"Universal precautions" and "strict infection control procedures" have become health-care facility as well as household terms. However, not much time has been given to explaining the specifics of exactly what they are or how and when they should be applied. The purpose, therefore, of this article is to review these specifics for practicing physicians, regardless of their specialty.

Acquired Immunodeficiency Syndrome↗
PubMed1990

The Yemenite deaf-blind hypopigmentation syndrome. A new oculo-dermato-auditory syndrome.

We have seen a Yemenite sister and brother with cutaneous hypomelanotic and pigmented spots and patches, microcornea, coloboma, severe hearing loss and normal karyotypes. Histopathological examinations of the skin showed absent melanocytes in the depigmented areas; in the normal and hyperpigmented skin there was abundant melanotic pigment. Similar patients have not been described previously, but there are corresponding mutations in mice and rats.

Abnormalities, Multiple↗
PubMed1990

Effect of dietary alpha-linolenic acid on equine monocyte procoagulant activity and eicosanoid synthesis.

To investigate the effects of an omega-3 fatty acid-enriched ration on the in vitro response of equine monocytes to endotoxin, an 8-week feeding trial was conducted in which linseed oil served as the source of the omega-3 fatty acid, alpha-linolenic acid. One group of horses was fed a control pelleted ration and the other group was fed an 8% linseed oil-enriched pelleted ration. After 8 weeks of feeding, monocytes were isolated and incubated in the presence of Escherichia coli O55:B5 endotoxin for 6 hr. After 8 weeks on the rations, the mean procoagulant activity and thromboxane B2 production by endotoxin-stimulated monocytes from horses consuming the linseed oil ration decreased by 51% and 71%, respectively, compared with cells from horses consuming the control ration. There was no difference in monocyte synthesis of 12-hydroxyeicosatetraenoic acid or leukotriene B4 between groups. Fatty acid analysis of membrane phospholipids revealed a decrease in the omega-6:omega-3 ratio in monocytes from horses consuming the linseed oil ration. These data suggest that dietary supplementation with alpha-linolenic acid may modify the response to endotoxin by reducing the synthesis of potentially harmful cellular mediators.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1989

"Blood' exposures.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1989

An evolutionary link for developing mammalian lungs.

Lungs of the human infant and those of other mammals are filled with fluid immediately prior to birth. Studies of the ionic composition of this fluid indicate that active ionic transport processes occur in the epithelial cells of the potential airspaces. The purpose of this study was to see if these active ion pumps were present in developing species other than mammals thus providing a possible evolutionary link to mammals. A series of samples of lung liquid, amniotic fluid, and plasma were taken from embryonic marine turtles gathered from clutches incubating in the beach at Mon Repos, Queensland, Australia during the summer of 1986-87. The concentrations of sodium, potassium and chloride ions and protein measured in these liquids indicated that active pumping processes similar to that seen in the mammalian lung were present in the developing lungs of these marine reptiles and further, circumstantial evidence was gathered to suggest that this liquid was partially reabsorbed prior to hatching. The results support the notion that processes responsible for the normal development of the human lung and lungs of other mammals are also present in the hollow lungs of marine turtles. Thus there is an evolutionary counterpart controlling lung development in more ancient species. It may be possible to generalize this observation to the development of hollow lungs of other species.

Animals↗
PubMed1989

Pharmacotherapeutic treatment of panic disorder in patients presenting with chest pain.

While psychiatric populations with panic disorder have been shown to be responsive to several classes of psychoactive medications, there is little evidence that medical patients with panic disorder respond to similar interventions. In this non-blind, eight-week trial of alprazolam in patients presenting with chest pain and found to have panic disorder, 15 of 20 met the single criterion for improvement: a 50 percent or greater reduction in panic frequency. Several other measures were also significantly positive for those who completed the study. Furthermore, these patients reported a marginally significant drop in episodes of chest pain or discomfort. A double-blind, placebo-controlled trial is now required to test the validity of these findings.

Adult↗