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Biomedical subjects

S A Murray

Publications and source records attributed to S A Murray.

At least 55 records · Page 3Linked to original sources
PubMed1990

Distribution of cytochromes P-450, cytochrome b5, and NADPH-cytochrome P-450 reductase in an entire human liver.

In rat liver there appear to be significant differences between lobes in the concentration of individual cytochrome P-450 isozymes (Sumner and Lodola, Biochem Pharmacol 36: 391-393, 1987). Because studies in patients often rely on small pieces of liver obtained from diverse anatomical locations, it seemed important to determine if the cytochromes P-450 were also heterogeneously distributed in human liver. Accordingly, tissue was obtained from ten different locations in a single human liver including those most commonly biopsied by percutaneous needles, and by surgeons during laparotomy. The differences observed between locations in the microsomal concentrations of carbon monoxide-binding protein (total cytochrome P-450), cytochrome b5, and NADPH-cytochrome P-450 reductase appeared to be small and were not statistically significant. Likewise, no significant differences were observed between locations in the specific content of HLp, HLp3, HLj, HLx or P450MP. However, the specific concentrations of HLd varied almost 2-fold between the microsomes and this was statistically significant in some cases (P less than 0.05). Our results suggest that, in human livers, regional differences in the content of cytochromes P-450 are generally small but may be significant for some isozymes. With the exception of HLd, tissue obtained by percutaneous or surgical liver biopsies is probably representative of the entire organ with regard to the enzymes assayed.

Adult↗
PubMed1990

Differential regulation of liver P-450III cytochromes in choline-deficient rats: implications for the erythromycin breath test as a parameter of liver function.

Progressive liver fibrosis in rats develops when they are fed a diet deficient in choline. This diet also results in a pronounced and selective decrease in the liver microsomal content of a phase I drug-metabolizing enzyme belonging to the cytochrome P-450III gene family. Because P-450III cytochromes characteristically catalyze the N-demethylation of erythromycin, we believed that the production of breath CO2 from erythromycin would be dramatically reduced in choline-deficient rats. However, when 12 choline-deficient rats were compared with 9 control rats, the reduction in CO2 production from erythromycin (mean decrease 71%) was essentially identical to that from aminopyrine (mean decrease 69%), a substrate believed to be metabolized normally by the hepatocyte in fibrotic liver disease. Furthermore, we found that the relative erythromycin and aminopyrine demethylase activities were comparable when measured in vitro in liver microsomes prepared from the choline-deficient rats. To determine the molecular basis for the erythromycin demethylase activity in the choline-deficient rats, the liver microsomes were subjected to immunoblot analysis using a variety of polyclonal and monoclonal antibodies capable of distinguishing individual P-450III-related proteins. Our studies confirm that a major erythromycin demethylase belonging to the P-450III family, termed P-450p, was greatly reduced in the choline-deficient rat liver. However, the specific concentration of a second P-450p-related protein was essentially normal and that of a third P-450p-related protein was actually increased in the choline-deficient rat liver.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminopyrine↗
PubMed1990

Assessment of broadband ultrasound attenuation in the os calcis in vitro.

1. We have examined the relationship between the attenuation of broadband ultrasound in the os calcis in vitro and its bone mineral density measured by quantitative computed tomography and by physical density. 2. Broadband ultrasound attenuation was found to correlate closely with physical density (r = 0.85, P less than 0.0001), but the correlation was less than that observed between quantitative computed tomography and physical density (r = 0.92, P less than 0.0001). Measurements of broadband ultrasound attenuation and quantitative computed tomography were significantly correlated (r = 0.80, P less than 0.0001). 3. Partial correlation analysis showed a significant relationship between broadband ultrasound attenuation and bone density, but when the effect of physical density was taken into account no significant correlation was found between broadband ultrasound attenuation and quantitative computed tomography (r = 0.08, not significant). 4. Broadband ultrasound attenuation in three prospective amputees showed a high degree of concordance between measurements in vivo and in vitro, with no interference by surrounding soft tissues. 5. The correlation between physical density and broadband ultrasound attenuation was independent of quantitative computed tomography, suggesting that the technique measures aspects of density which differ from its mineral density. Broadband ultrasound attenuation holds promise as a reproducible, rapid, radiation-free assessment of skeletal status.

Aged↗
PubMed1990

Broadband ultrasound attenuation in the os calcis: relationship to bone mineral at other skeletal sites.

1. We have examined the relationship between broadband ultrasound attenuation in the os calcis and measurements of bone mineral in the distal forearm and lumbar spine of normal and postmenopausal osteoporotic women. 2. Values of broadband ultrasound attenuation in postmenopausal women with vertebral osteoporotic fractures were significantly lower (35%) than in normal pre- and peri-menopausal women (55.4 +/- 3.8 and 79.6 +/- 0.8 dB/MHz, respectively). 3. Broadband ultrasound attenuation correlated significantly with bone mineral content measured in the distal forearm by single-photon absorptiometry (r = 0.77, P less than 0.0001) and with bone mineral content (r = 0.66, P less than 0.0001) and bone mineral density (r = 0.72, P less than 0.0001) measured in the lumbar spine by dual-photon absorptiometry. 4. Although significant, these correlations are not sufficiently close to be predictive. However, the accuracy of broadband ultrasound attenuation in discriminating between normal subjects and patients with vertebral fracture compared very favourably with direct measurements in the spine by dual-photon absorptiometry. 5. Broadband ultrasound attenuation, but not the other measurements, correlated significantly with age in the osteoporotic patients (r = 0.50, P less than 0.05). 6. These findings may reflect the partial dependence of broadband ultrasound attenuation on the intrinsic trabecular architecture of cancellous bone, the disruption of which contributes to an increase in fracture risk.

Absorptiometry, Photon↗
PubMed1990

Family planning in rural Africa: can it work?

High fertility is the major demographic problem presently affecting rural Kenya. Chogoria Hospital has attempted to provide a community based family planning service to address this issue. This paper describes the intervention used and analyses the current contraceptive practice in the area. It is concluded that community based distribution of family planning commodities may be associated with a marked decrease in fertility rate and family size within a relatively short period. Family planning initiatives in Africa may be remarkably cost-effective interventions in the development of a nation and be associated with well spaced and healthy children.

Adolescent↗
PubMed1989

Erythromycin breath test as an assay of glucocorticoid-inducible liver cytochromes P-450. Studies in rats and patients.

The major P-450IIIA gene family member present in human liver is HLp which, like its rat liver orthologue P-450p, is inducible by glucocorticoids and catalyzes erythromycin N-demethylation. To develop a practical method to estimate the amounts of HLp in patients [14C]N-methyl erythromycin was injected into rats that had been pretreated with dexamethasone or with inducers of other forms of cytochrome P-450. The rate of demethylation of this substrate, measured simply as 14CO2 in the breath, correlated well with the concentrations of immunoreactive P-450p protein (r = 0.70), holocytochrome P-450p (r = 0.70), or with erythromycin N-demethylase activity (r = 0.90) determined in the liver microsomes prepared from each rat. Next, [14C]N-methyl erythromycin was administered to 30 patients and there was a sixfold interindividual variation in breath 14CO2 production seemingly unrelated to medications, smoking status or age. However, the average breath test values were twofold greater in female as compared to male patients (P less than 0.01). Breath 14CO2 production rose in patients retested after treatment with the P-450IIIA inducers dexamethasone (P less than 0.05) or rifampicin (P less than 0.05) and was decreased after treatment with the HLp inhibitor triacetyloleandomycin (P less than 0.05). We conclude that the erythromycin breath test provides a convenient assay of P-450IIIA cytochromes in rats and in some patients.

Adult↗
PubMed1988

Dibutyryl cyclic AMP modulation of gap junctions in SW-13 human adrenal cortical tumor cells.

Cultured human adrenal cortical adenocarcinoma cells (SW-13) form a confluent monolayer of epithelial-like cells when seeded into culture flasks. Following a 24-48 hr non-mitotic period, cells begin to divide and become confluent within a week after seeding at 5 X 10(4) cells/cm2. The SW-13 cells were exposed to dibutyryl cyclic AMP (DbcAMP), cyclic AMP (cAMP), sodium butyrate, and adrenocorticotropin (ACTH). The rate of SW-13 cell proliferation was measured with a DNA microfluorometric assay, as well as by procedures measuring the incorporation of 3H-thymidine. In addition, following administration of ACTH and DbcAMP, the fractional area of membrane covered by gap junctions was quantitated with freeze-fracture electron microscopic techniques. Dibutyryl cyclic AMP at a concentration of 1 X 10(-3) M decreased the growth rate of the cell population. There was a corresponding increase in the fractional area of gap junctions found on the cell membrane in 96-hr DbcAMP-treated cultures. ACTH (40 mU/ml) exposure failed to produce an increase in the fractional area of gap junctions or to alter the rate of cell proliferation. From these data it can be suggested that elevations in cAMP levels within the cell can be related to both the proliferation of gap junctions and the decrease in cell proliferation in the SW-13 tumor cell.

Adrenal Cortex Neoplasms↗
PubMed1988

Characterization of the morphological, growth, and steroidogenic effect of TPA on mouse Y-1 adrenal cortical tumor cells in culture.

The tumor-promoting agent 12-0-tetradecanoyl-phorbol-13-acetate (TPA) caused a time- and dose-dependent morphological change in Y-1 adrenocortical tumor cells. The morphological alteration was apparent 2 hr following addition of 1 microgram/ml TPA to cell cultures and became more striking with longer treatment times. Smaller doses of TPA took a longer time to produce an effect. Cultures grown in the presence of TPA exhibited more rounding and piling up of cells than similar cultures maintained in medium lacking TPA. These TPA-stimulated morphological changes were reversible, and after 24 hr in TPA-free media, the cultured cells began to flatten. After 96 hr in TPA-free media they resembled the control cultures. The reversibility of the morphological change was also dose dependent: cells treated with 1 microgram/ml TPA took a longer time to resume the typical control morphology than did cultures treated with 0.01 microgram/ml TPA. In addition, TPA treatment resulted in a decrease in cell growth rate, an increase in steroid production, and an increase in the localization of free catalytic units of cAMP-dependent protein kinase in the cytoplasm. The steroidogenic effect of ACTH on the cell population was inhibited in cultures maintained in TPA. The results of this study indicate that TPA induces morphological changes in the Y-1 adrenocortical tumor cell population while increasing steroidogenesis and the activation of cAMP-dependent protein kinase and decreasing cell growth rate.

Adrenal Cortex Neoplasms↗
PubMed1988

Effects of cytochalasin B and colchicine on the morphology of SW-13 human adrenal cortical tumor cells in culture.

Human adrenal cortical tumor cells (SW-13) grow into a typical epithelial cell monolayer when seeded onto culture dishes. The cells of the SW-13 population monolayer appear flattened with few conspicuous surface features. The cells are attached to one another at their lateral borders and are arranged in a cobblestone-like manner. Following Triton X-100 extraction, the distribution of the cytoskeletal elements was observed with scanning electron microscopic techniques to correspond to the shape of the non-extracted cell. Changes in the distribution and morphology of projections on the cell surface as well as changes in cell shape were revealed after treatment of the cultures with compounds which bring about microtubular and microfilament disruption. Following 60 minute treatment of the cell population with cytochalasin B (10 micrograms/ml), 90% of the cells became round while remaining attached to neighboring cells and to the substrate by slender cell processes and filopodia. Some bleeding could be seen on the cell surfaces of cytochalasin B treated cultures and an increase in the number of microvilli was evident. When the cytoskeletal elements were observed with scanning electron microscopic techniques after Triton X-100 extraction, the amount of peripheral cytoskeletal elements was decreased and only slender projections of the microfilaments and microtubules were evident. Colchicine (0.06 micrograms/ml) treatment of the SW-13 adrenal cell population resulted in the appearance of surface blebs within 10 minutes of the initiation of treatment. The changes in surface projections are discussed in relationship to the loss of microtubules and microfilaments from the cytoplasm of the cell.

Adrenal Cortex Neoplasms↗
PubMed1987

Effects of intravenous etidronate disodium on skeletal and calcium metabolism.

The induction of hypercalcemia in malignant disease is almost invariably associated with increased bone resorption. However, tumor-induced changes in bone formation and renal tubular resorption of calcium are also important factors that induce hypercalcemia in some patients. In addition, alterations in calcium fluxes to and from the extracellular fluid secondary to hypercalcemia are important in maintaining or aggravating the hypercalcemic effects of increased bone resorption. These factors significantly affect the responses to treatment of hypercalcemia with inhibitors of bone resorption. This study examined the relative importance of these factors and the effects of intravenous etidronate disodium (etidronate) in neoplastic bone disease with and without hypercalcemia and in Paget's disease of bone. It is concluded that intravenous etidronate is an effective inhibitor of bone resorption, which accounts in large measure for its effects on serum calcium concentrations. These studies of etidronate in hypercalcemia suggest the response is sustained for several weeks.

Aged↗
PubMed1987

Ultrastructural localization of cyclic adenosine 3',5'-monophosphate-dependent protein kinase after adrenocorticotropin stimulation in adrenal cortical tumor cells.

To increase our knowledge of the molecular details of peptide hormone action, a specific immunogold staining procedure for the ultrastructural localization of cAMP-dependent protein kinase regulatory (RI) and catalytic (C) subunits was used in Y-1 adrenal cortical tumor cells. The Y-1 adrenal cell responds to ACTH (40 mU/ml) with a decrease in cell division and an increase in steroid production. Corresponding to the decrease in rate of cell division and the increase in steroid production, there was a 2-fold increase in both nuclear and cytoplasmic localization of the C subunit after 60-min ACTH (40 mU/ml) treatment of the culture. The amount of immunogold staining in the adrenal tumor cells after localization with antiserum of the RI subunit decreased after 60-min ACTH (40 mU/ml) stimulation. A 2-fold decrease in labeling in the cytoplasm and nucleus was observed for the RI subunit. The loss of RI subunit from the soluble fraction of the cytoplasm of the cell or an alteration of this RI subunit is suggested by this investigation. Since there was no increase in the RI subunit in the nuclear compartment, a loss of RI subunit from the cytoplasm into the nucleus seems unlikely. The observed immunogold changes in the C subunit after ACTH treatment correspond to the reported changes observed with light microscopic techniques with a fluorescein-coupled inhibitor as a probe for the localization of free C. The immunogold technique allows for the ultra-structural identification and quantification of nuclear as well as the cytoplasmic sites of cAMP-dependent protein kinase after hormonal stimulation. These results support the proposed role of protein kinase as a mediator of the ACTH response.

Adrenal Cortex Neoplasms↗
PubMed1986

Cyclic AMP-dependent protein kinase-mediated desensitisation of adrenal tumour cells.

Y-1 mouse adrenal cortical tumour cells increase their production of steroids and cAMP while decreasing cell population growth in response to treatment with ACTH. With a fluorescent conjugate of the heat-stable protein kinase inhibitor, the time- and dose-dependent dissociation of cAMP-dependent protein kinase can be demonstrated following ACTH stimulation of Y-1 adrenal tumour cells, and the kinetics of its free catalytic subunits can be followed. After 60 min ACTH (6 X 10(-10) M) stimulation, a 4-fold rise in catalytic subunits was detected in the nucleus while a 2-fold increase was noted in the cytoplasm. When Y-1 cells had been previously treated with ACTH, they no longer secreted steroids to the same level in response to a subsequent exposure to ACTH. In addition to the altered steroidogenic response the cells become resistant to the effect of subsequent ACTH treatment on cell division and cAMP production as measured by protein kinase dissociation. Y-1 adrenal cells, that had been pretreated with ACTH, had an altered activation of protein kinase. Although there was an increase in cytoplasmic dissociation following subsequent ACTH stimulation of the pretreated cell, this increase was negligible when compared to that in the non-pretreated cultures. The nucleus of the ACTH-pretreated cell failed to significantly dissociate protein kinase following subsequent ACTH treatment. The data suggest that the phenomenon of desensitisation may be due to a decrease in dissociation of cAMP-dependent protein kinase, especially in the nucleus.

Adrenal Gland Neoplasms↗
PubMed1985

Intracellular kinetics of free catalytic units dissociated from adenosine 3',5'-monophosphate-dependent protein kinase in adrenocortical tumor cells (Y-1).

To define the role of cAMP in the actions of ACTH, the dissociation of cAMP-dependent protein kinase and the subsequent intracellular location of its free catalytic units were monitored after exposure of Y-1 cells to ACTH, FSH, or cyclic nucleotide analog. To accomplish this, a fluorescinated cytochemical probe was used that complexes specifically with free catalytic units from cAMP-dependent protein kinase. Also, the effects of hormone or nucleotide on secretion of fluorogenic steroids and DNA synthesis were examined. Y-1 cells dissociated protein kinase in a dose-dependent fashion when exposed to ACTH or cAMP analog, but did not respond to FSH, which was one of the control agents used. After 30 min of treatment with 1.5 X 10(-10) M ACTH, free catalytic units were observed only in the cytoplasm of Y-1 cells, whereas a similar time of exposure to 3 X 10(-10) M ACTH led to the appearance of catalytic units in nucleolus as well as in cytoplasm. ACTH (6 X 10(-10) M) caused a rise in cytoplasmic and nucleolar protein kinase dissociation proportionally greater than that seen in cultures exposed to 3 X 10(-10) M ACTH. Upon treatment with 6 X 10(-10) M ACTH, the amount of free catalytic units in cytoplasm and nucleolus was detectably greater than that in controls within 1 min of stimulation and continued to rise with increasing time of exposure to hormone. The nuclear, mostly nucleolar, content of free catalytic unit appeared to peak after 15 min of stimulation, while cytoplasmic enzyme levels continued to rise up to 60 min. Exposure of Y-1 cells to nucleotide analog caused cAMP-dependent protein kinase dissociation with temporal kinetics and a subcellular distribution similar to that seen after ACTH stimulation. We conclude that actions of ACTH are mediated by cAMP-dependent protein kinases. Further, there appear to be two intracellular pools of protein kinase, one nucleolar, the other cytoplasmic, and these may be independently regulated, with the nucleolar enzyme requiring higher concentrations of ACTH for dissociation than those needed for cytoplasm protein kinase. These observations may be relevant to the fact that more ACTH is required to inhibit DNA synthesis than is necessary to enhance steroid production.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1984

A simultaneous outbreak of respiratory syncytial virus and parainfluenza virus type 3 in a newborn nursery.

Over a 3-week period, 20 of 34 (59%) infants in a newborn nursery developed nosocomial viral respiratory tract disease. Either respiratory syncytial virus (seven infants) or parainfluenza virus type 3 (five) or both (two) were demonstrated in respiratory secretions from 14 of the 20 symptomatic patients. Symptoms in the 20 infants included rhinitis (15 infants), cough (14), apnea (eight), pulmonary infiltrates (seven), and fever (six). There were no differences in symptoms between children infected with respiratory syncytial virus alone, with parainfluenza virus alone, or with both viruses concurrently. Patients were clustered in the nursery by agent: infants with the same virus tended to share contiguous bed spaces, supporting the concept that parainfluenza virus as well as respiratory syncytial virus can be transmitted from patient to patient. In addition to this risk for contiguous bed spaces, the presence of a nasogastric tube was associated with risk of illness (P less than 0.05). In the presence of a nursery outbreak of respiratory tract disease, more than one virus may circulate concurrently, and an individual patient may be infected simultaneously by more than one virus.

Boston↗
PubMed1984

Hormone-induced intercellular signal transfer dissociates cyclic AMP-dependent protein kinase.

We used co-cultures of porcine ovarian granulosa cells and mouse adrenocortical tumor cells (Y-1) to examine the kinetics of contact-dependent intercellular signal transfer and to assess the molecular mechanisms employed by this process. Exposure to follicle-stimulating hormone (FSH) caused cAMP-dependent protein kinase dissociation in granulosa cells and, with time, in Y-1 cells if, and only if, they contacted a responding granulosa cell. Y-1 cells close to a granulosa cell but not touching it failed to respond similarly. In reciprocal experiments, co-cultures were stimulated with adrenocorticotropic hormone (ACTH). Y-1 cells dissociated protein kinase as did granulosa cells in contact with Y-1 cells; however, granulosa cells that were not in contact with Y-1 cells failed to respond to the hormone. Fluorogenic steroids were secreted by Y-1 cells cultured alone and stimulated with ACTH, but were not secreted by cultures exposed to FSH. Neither hormone caused fluorogenic steroid production by granulosa cells. On the other hand these steroids were secreted in co-cultures stimulated with ACTH and to a lesser degree in co-cultures exposed to FSH. Autoradiography revealed that I125-FSH bound only to granulosa cells, never to Y-1 cells, even if they were in contact with an ovarian cell. The possibility of cell fusion was tested by experiments in which Y-1 cell membranes were labeled with cationized ferritin. These cells were then placed in co-culture with ovarian granulosa cells that had previously been allowed to ingest latex spheres. At regions of gap junctions between Y-1 and granulosa cells ferritin remained attached to the adrenal cell membrane and was never observed to migrate to the granulosa cell membrane. From these data, we conclude that hormone specific stimulation of one cell type leads to protein kinase dissociation in heterotypic partners only if they contact a hormone responsive cell. This signal transfer is bidirectional, exhibits temporal kinetics and occurs in the absence of apparent cell fusion. The only structural feature connecting Y-1 and granulosa cells were gap junctions implying they provided the communication channels; however, alternative mechanisms cannot be excluded. We have not established the identity of the signal being transferred although cAMP is a logical candidate.

8-Bromo Cyclic Adenosine Monophosphate↗