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A J Davis

Publications and source records attributed to A J Davis.

At least 37 records · Page 2Linked to original sources
PubMed2001

The right-to-die and the duty-to-die: perceptions of nurses in the West and in Japan.

The right-to-die means that the terminally ill person has the right to refuse further treatment. The duty-to-die means that terminally ill persons feel that they have no choice and must refuse treatment because of social factors such as family burden or financial cost to society. This article describes the perceptions of a sample of 72 Japanese nurses and 71 counterparts from the West. The right-to-die received support from all of the western and from a majority of the Japanese sample. However, the duty-to-die received weaker support from the West and rather strong disagreement from Japan. Themes emerged in the two groups from a content analysis of their reactions to the major concepts of right-to-die and duty-to-die, and these included autonomy, values surrounding life, justice, family as a possible coercive agent and family as a partner in decision making. Differences and similarities across the cultures in the meaning of these themes were explored.

Adult↗
PubMed2001

Dietary protein concentration regulates the mRNA expression of chicken hepatic malic enzyme.

Chicken hepatic malic enzyme activity varies with dietary protein content. The mechanisms responsible for this alteration in activity are unclear. In a series of four experiments, broiler chicks were allowed free access for 1.5, 3, 6 or 24 h to a low (13 g/100 g diet), basal (22 g/100 g diet) or high (40 g/100 g diet) protein diet. The diets were isocaloric and had equal concentrations of dietary fat. Hepatic malic enzyme mRNA expression and enzyme activity as well as total liver lipid concentration were examined for each experimental duration. There were no differences in the expression of the mRNA for malic enzyme at 1.5 h, but at 3, 6 and 24 h, malic enzyme mRNA expression was significantly (P < 0.05) reduced in chicks fed the high protein diet and significantly enhanced in chicks fed the low protein diet compared with chicks fed the basal diet. Hepatic malic enzyme activities and total lipid concentration were not different among the chicks fed the different diets at 1.5 and 3 h. At 6 and 24 h, malic enzyme activity and total liver lipid concentration were both significantly greater in birds fed the low protein diet compared with levels in the birds fed the other two diets. In birds fed the high protein diet, malic enzyme activity and total liver lipid concentration were significantly reduced at 24 h compared with birds fed the basal diet. In a final experiment, the observed differences in malic enzyme mRNA expression at 6 h were confirmed when chicks were given access to isocaloric diets with the same protein levels as the initial 4 experiments, but with the dietary concentration of carbohydrate held constant. The results suggest that previously observed alterations in the activity of malic enzyme, which were correlated with dietary protein intake, are due to rapid changes in the mRNA expression of this enzyme.

Animals↗
PubMed2001

Follicle-stimulating hormone regulation of inhibin alpha- and beta(B)-subunit and follistatin messenger ribonucleic acid in cultured avian granulosa cells.

FSH regulation of inhibin alpha-, beta(B)-subunit and follistatin mRNA was investigated in cultured chicken granulosa cells, which were isolated and pooled according to size from the F(4) + F(5) follicles, small yellow follicles (SYF), and large white follicles (LWF). In experiment 1 (four replicate experiments), granulosa cells were cultured, and the effect of FSH (50 ng/ml) on the growth of cells from the different follicles was examined at 24 and 48 h of culture. Cell viability was >95% for all of the granulosa cell cultures at 24 and 48 h. At 24 h, the number of granulosa cells in both the FSH-treated and the untreated cultures for all follicle types was numerically greater than the number of cells originally plated. At 48 h, FSH-treated cultures for all follicle types had twice (P: < 0. 05) the number of cells as the untreated cultures. In experiment 2 (three replicate experiments), FSH increased expression of the mRNA for inhibin alpha-subunit in LWF granulosa cells at 4 and 24 h to detectable levels and increased inhibin alpha-subunit protein accumulation to detectable levels by 24 h in granulosa cells from the LWF. FSH also increased (P: < 0.05) mRNA levels for the inhibin alpha-subunit at 4 and 24 h in SYF granulosa cells and at 24 h in F(4) + F(5) granulosa cells. The effects of FSH on follistatin and ss(B)-subunit were variable with respect to follicle development and culture duration. These results suggest that FSH plays an important role in stimulating the production of mRNA and protein for the inhibin alpha-subunit in small prehierarchical follicles.

Animals↗
PubMed2001

Activin A and gonadotropin regulation of follicle-stimulating hormone and luteinizing hormone receptor messenger RNA in avian granulosa cells.

Activin A regulation of the expression of mRNA for the LH receptor, FSH receptor, and the inhibin alpha subunit as well as the effect of activin A on the secretion of progesterone were investigated in chicken granulosa cell cultures. Granulosa layers were isolated from the F(1) and F(3) + F(4) follicles from five hens, pooled according to size, dispersed, and cultured for 48 h. In experiment 1 (n = 3 replications), granulosa cells were cultured with or without highly purified ovine (o) FSH at 50 ng/ml and in the presence of 0, 10, or 50 ng/ml of recombinant chicken activin A. Experiment 2 (n = 4 replications) followed the same protocol as experiment 1, except that oFSH was replaced with oLH. Results from these experiments showed that addition of activin A to the granulosa cell cultures had no effect on the expression of mRNA for the inhibin alpha subunit or the FSH receptor, but it did affect the expression of mRNA for the LH receptor. Treatment of F(3) + F(4) granulosa cells with LH stimulated the expression of mRNA for the LH receptor; however, when LH was combined with either dose of activin A, this induction was prevented. The highest dose of activin A with or without LH resulted in decreased expression of the LH receptor compared to the untreated controls in the F(3) + F(4) cell cultures. Progesterone secretion by the granulosa cells from both follicle sizes was not altered by activin A. In experiment 3 (n = 3 replications), the effect of activin A on the growth of granulosa cells was examined with the following treatments: 0, 10, or 50 ng/ml of activin A; 50 ng/ml of either oLH or oFSH; and oLH or oFSH combined with 10 ng/ml of activin A. The highest dose of activin reduced the rate of granulosa cell proliferation in both follicle types. Growth of F(1) and F(3) + F(4) granulosa cells was stimulated by the addition of either gonadotropin, and the presence of 10 ng/ml of activin A with either gonadotropin did not alter this proliferation, except for the LH-treated F(3) + F(4) granulosa cells, in which the increase in proliferation was prevented. The results suggest that activin A could act as a local factor that regulates follicular maturation by preventing excessive or untimely LH receptor expression.

Activins↗
PubMed2000

Two intermembrane space TIM complexes interact with different domains of Tim23p during its import into mitochondria.

Tim23p (translocase of the inner membrane) is an essential import component located in the mitochondrial inner membrane. To determine how the Tim23 protein itself is transported into mitochondria, we used chemical cross-linking to identify proteins adjacent to Tim23p during its biogenesis. In the absence of an inner membrane potential, Tim23p is translocated across the mitochondrial outer membrane, but not inserted into the inner membrane. At this intermediate stage, we find that Tim23p forms cross-linked products with two distinct protein complexes of the intermembrane space, Tim8p-Tim13p and Tim9p-Tim10p. Tim9p and Tim10p cross-link to the COOH-terminal domain of the Tim23 protein, which carries all of the targeting signals for Tim23p. Therefore, our results suggest that the Tim9p-Tim10p complex plays a key role in Tim23p import. In contrast, Tim8p and Tim13p cross-link to the hydrophilic NH(2)-terminal segment of Tim23p, which does not carry essential import information and, thus, the role of Tim8p-Tim13p is unclear. Tim23p contains two matrix-facing, positively charged loops that are essential for its insertion into the inner membrane. The positive charges are not required for interaction with the Tim9p-Tim10p complex, but are essential for cross-linking of Tim23p to components of the inner membrane insertion machinery, including Tim54p, Tim22p, and Tim12p.

Amino Acids↗
PubMed2000

Identification of a novel protein complex containing annexin VI, Fyn, Pyk2, and the p120(GAP) C2 domain.

p120(GAP) (RasGAP) has been proposed to function as both an inhibitor and effector of Ras. Previously we have shown that RasGAP contains a C2 domain which mediates both Ca(2+)-dependent membrane association and protein-protein interactions. Specifically, three proteins have been isolated in a complex with the C2 domain of RasGAP; these are the Ca(2+)-dependent lipid binding protein annexin VI (p70) and two previously unidentified proteins, p55 and p120. Here we provide evidence that p55 is the Src family kinase Fyn and p120 is the focal adhesion kinase family member Pyk2. In addition, in vitro binding assays indicate that Fyn, but not Pyk2 binds directly to annexin VI. Finally, co-immunoprecipitation studies in Rat-1 fibroblasts confirm that Fyn, Pyk2, annexin VI and RasGAP can form a protein complex in mammalian cells.

Animals↗
PubMed2000

Estradiol regulation of follistatin and inhibin alpha- and beta(B)-subunit mRNA in avian granulosa cells.

Estradiol modulation of granulosa cell growth and regulation of follistatin and inhibin alpha- and beta(B)-subunit mRNA were investigated in cultured chicken granulosa cells. Granulosa cells were isolated and pooled according to size from the F(4) + F(5), small yellow (SYF), and large white (LWF) follicles. Isolated and dispersed granulosa cells were then cultured in the absence or presence of 1 x 10(-5) M 17 beta-estradiol. In Experiment 1 (n = 4 replications) the effect of estradiol on the growth of granulosa cells from the different-sized follicles was examined at 24 and 48 h of culture. Untreated and treated granulosa cells from all three follicle sizes proliferated during culture, and cell viability for all cultures was over 95% throughout the experiment. After 48 h the untreated cultures for all follicle types had 1.6 to 2.2 times (P < 0.05) more cells than the estradiol-treated cultures. In Experiment 2 (n = 3 replications), the cultures were terminated at 4 and 24 h after plating. Follistatin mRNA levels were higher in estradiol-treated cells at 24 h in F(4) + F(5) follicles, at 4 and 24 h in the SYF, and at 4 h in the LWF. beta(B)-subunit mRNA levels were also increased by estradiol at 4 h in F(4) + F(5) cells and at 4 and 24 h in the LWF. Steady state mRNA levels for the alpha-subunit were higher (P < 0.05) in estradiol-treated cultures at 4 and 24 h in F(4) + F(5) follicles and at 24 h in the SYF. Immunoreactive alpha-subunit protein, however, was not increased by estradiol treatment. Thus, whereas estradiol inhibited granulosa cell growth, it exerted a generally stimulatory effect on the expression of FS and the inhibin alpha- and beta(B)-subunit mRNA.

Animals↗
PubMed2000

Dominant transmission of imperforate hymen.

OBJECTIVE: Imperforate hymen is an uncommon anomaly of the reproductive tract, occurring in approximately 0.1% of newborn females. The familial occurrence of imperforate hymen in a child, her mother, and her mother's monozygotic twin is reported. DESIGN: Case report. SETTING: Academic medical center. PATIENT(S): Three affected family members. MAIN OUTCOME MEASURE(S): Karyotype and pedigree analysis. RESULT(S): The proband, presenting with peritonitis, was evaluated at age 12 for imperforate hymen because this condition was diagnosed in her mother at age 14. At age 14, the mother's monozygotic twin was asymptomatic except for primary amenorrhea and was also demonstrated to have imperforate hymen. No other reproductive system abnormalities were known to be present in the remaining family members. Chromosomal structural analysis confirmed that the mother of the proband had no chromosomal abnormalities. CONCLUSION(S): The occurrence of imperforate hymen in two consecutive generations of a family is consistent with a dominant mode of transmission, either sex-linked or autosomal. Previously reported examples of siblings with imperforate hymen suggested a recessive mode of inheritance. Taken together, these cases suggest that imperforate hymen can be caused by mutations in several genes. This case highlights the importance of evaluating all family members of affected patients. Familial examples of other developmental anomalies of the female reproductive tract also suggest a multifactorial genetic etiology.

Adult↗
PubMed2000

Advances in contraception.

Many safe and effective contraceptive methods are currently available, and a stream of new products is being introduced to the market. This article presents the histories, descriptions, and future trends for oral contraceptive pills, hormonal implants and injections, and intrauterine devices. Other methods discussed include barrier methods, spermicides, and emergency contraception, and permanent sterilization.

Adolescent↗
PubMed2000

Repopulation of tumour cells between cycles of chemotherapy: a neglected factor.

Repopulation of clonogenic tumour cells during fractionated radiation treatment is recognised as an important factor affecting local control. Given the longer intervals between cycles and longer total duration of treatment, the impact of repopulation is likely to be greater following chemotherapy. Limited data from experimental models suggest that, after chemotherapy, there is a 'lag period', followed by variable but rapid rates of repopulation of tumour cells, possibly accelerating between cycles. Modelling of these properties indicates that after the initial response, accelerated repopulation between cycles can lead to tumour regrowth without any change in the drug sensitivity of the tumour cells. The importance of repopulation may be comparable with that of intrinsic or acquired cellular resistance in determining the effective resistance of tumours to chemotherapy. Biological agents with rapid onset and short duration of action, which can selectively inhibit tumour-cell repopulation, administered between cycles of chemotherapy, might improve the therapeutic index.

Animals↗
PubMed2000

Bradyzide, a potent non-peptide B(2) bradykinin receptor antagonist with long-lasting oral activity in animal models of inflammatory hyperalgesia.

Bradyzide is from a novel class of rodent-selective non-peptide B(2) bradykinin antagonists (1-(2-Nitrophenyl)thiosemicarbazides). Bradyzide has high affinity for the rodent B(2) receptor, displacing [(3)H]-bradykinin binding in NG108-15 cells and in Cos-7 cells expressing the rat receptor with K(I) values of 0.51+/-0.18 nM (n=3) and 0.89+/-0.27 nM (n=3), respectively. Bradyzide is a competitive antagonist, inhibiting B(2) receptor-induced (45)Ca efflux from NG108-15 cells with a pK(B) of 8.0+/-0.16 (n=5) and a Schild slope of 1.05. In the rat spinal cord and tail preparation, bradyzide inhibits bradykinin-induced ventral root depolarizations (IC(50) value; 1.6+/-0.05 nM (n=3)). Bradyzide is much less potent at the human than at the rodent B(2) receptor, displacing [(3)H]-bradykinin binding in human fibroblasts and in Cos-7 cells expressing the human B(2) receptor with K(I) values of 393+/-90 nM (n=3) and 772+/-144 nM (n=3), respectively. Bradyzide inhibits bradykinin-induced [(3)H]-inositol trisphosphate (IP(3)) formation with IC(50) values of 11.6+/-1.4 nM (n=3) at the rat and 2.4+/-0.3 microM (n=3) at the human receptor. Bradyzide does not interact with a range of other receptors, including human and rat B(1) bradykinin receptors. Bradyzide is orally available and blocks bradykinin-induced hypotension and plasma extravasation. Bradyzide shows long-lasting oral activity in rodent models of inflammatory hyperalgesia, reversing Freund's complete adjuvant (FCA)-induced mechanical hyperalgesia in the rat knee joint (ED(50), 0.84 micromol kg(-1); duration of action >4 h). It is equipotent with morphine and diclofenac, and 1000 times more potent than paracetamol, its maximal effect exceeding that of the non-steroidal anti-inflammatory drugs (NSAIDs). Bradyzide does not exhibit tolerance when administered over 6 days. In summary, bradyzide is a potent, orally active, antagonist of the B(2) bradykinin receptor, with selectivity for the rodent over the human receptor. British Journal of Pharmacology (2000) 129, 77 - 86

Administration, Oral↗
PubMed2000

Temporal response of hepatic threonine dehydrogenase in chickens to the initial consumption of a threonine-imbalanced diet.

Amino acid imbalances contribute to higher requirements of amino acids than would occur if the dietary profile of amino acids perfectly matched the requirements. The mechanisms of imbalances have not been fully elucidated. Because threonine dehydrogenase (TDH) activity in liver mitochondria increases in chicks and rats subjected to threonine imbalance, the current study was carried out to determine whether the change in TDH activity occurs rapidly enough after the consumption of an imbalanced diet to be considered a possible primary metabolic response. In a series of experiments, Leghorn chicks were allowed free access to a semipurified basal diet marginally limited in threonine or the same diet containing a mixture of indispensable amino acids (IAA) lacking threonine to cause a threonine imbalance. In the first experiment, dietary supplements of 5.5 and 11.1% IAA were used to determine a level of supplement that would cause a robust response in the specific activity of TDH. Feed intake, body weight gains and efficiency of feed utilization were lower and specific activities of TDH were higher in chicks fed 11.1% IAA than in those fed 5.5% IAA. In subsequent experiments, hepatic TDH activities and plasma amino acid profiles of the control and experimental groups were determined at 1. 5, 3, 6, 12 and 24 h after the first offering of the diet containing 11.1% IAA. The specific activities of TDH in chicks fed the IAA supplement were 40-150% higher (P < 0.05) and plasma threonine concentrations were 42-53% lower (P < 0.05) than in chicks fed the basal diet at all times except 1.5 h. These results indicate that changes in the capacity for threonine degradation via TDH may occur in the liver within a few hours after the consumption of a threonine-imbalanced diet and suggest the possibility that altered TDH activity may contribute to the increased threonine requirement associated with threonine imbalance.

Alcohol Oxidoreductases↗
PubMed2000

Molecular cloning and expression analysis of the complementary deoxyribonucleic acid for chicken inhibin/activin beta(B) subunit.

Inhibins and activins are dimeric peptide hormones that play an integral role in the intraovarian regulation of folliculogenesis. The domestic hen, with its well-defined follicular hierarchy, provides a unique model in which to study the role of these hormones in follicular development. In the present study, the complete coding sequence and deduced amino acid sequence for the chicken inhibin/activin beta(B) subunit has been determined from cDNA clones isolated from a chicken ovarian granulosa cell library. This beta(B)-subunit cDNA predicts a precursor protein of 392 amino acids containing the mature C-terminal 115 amino acid beta(B) subunit. When compared to the beta(B) subunit isolated from a variety of species, the chicken cDNA clone showed high nucleotide identity in the full-length coding region (>70%) and in the mature coding region (>80%). In addition, the deduced amino acid sequence of chicken beta(B) subunit showed greater than 95% identity compared to other species in the mature peptide region. Expression of the beta(B)-subunit mRNA was detected by reverse transcription-polymerase chain reaction in both gonadal and extragonadal tissues. Northern blot analysis detected expression in the gonadal tissues only, specifically in the granulosa tissue from the F3-F5 follicles, small yellow follicles (SYF), large white follicles, and immature and mature rooster testes. A major transcript of approximately 4.1 kilobases (kb) and three minor transcripts of approximately 8.4 kb, 6.5 kb, and 1.7 kb were detected in the SYF granulosa samples. To examine the expression pattern of the beta(B) subunit around the stage of follicle selection, the SYF granulosa was subdivided into two groups: 6-8 mm and 9-12 mm. Quantification of RNA expression (n = 3) showed that expression of the beta(B) subunit was maximal in the 6-8 mm SYF. Activin B, as well as other intraovarian signals, may regulate early follicle selection and/or development in the chicken.

Activins↗
PubMed2000

Cerebral hyperthermia in children after cardiopulmonary bypass.

BACKGROUND: Cerebral hyperthermia after hypothermic cardiopulmonary bypass has been poorly documented for adults and never in children. This study was designed to monitor brain temperature during and up to 6 h after cardiopulmonary bypass in infants and children. METHODS: Fifteen infants and children, between 3 months and 6 yr of age, were studied. A right retrograde jugular bulb catheter was used to measure the jugular venous bulb temperature (JVBT) during the procedure and the first 6 h in the critical care unit. The temperature of the blood from the bypass machine was measured at the aorta through the cannula using an indwelling temperature probe. All data were acquired every minute. RESULTS: The age of the patients ranged from 3 to 71 months (median, 15 months). The mean weight was 11.5 +/- 8.4 kg. The mean JVBT recorded at the end of cardiopulmonary bypass was 36.9 +/- 1.4 degrees C but reached 39.6 +/- 0.8 degrees C after six h (P < 0.01). The kinetics of brain rewarming was determined by the slope of the mean JVBT and corresponded to y +/- 0.006x + 37.21 (r2 = 0.97). The JVBT differed from the tympanic temperature after 200 min (P < 0.01) and the lower esophageal (P < 0.05) and rectal (P < 0.001) temperatures after 300 min. After 6 h, the tympanic, rectal, and lower esophageal temperatures were 37.8 +/- 0.9, 37.7 +/- 0.6, and 38.4 +/- 0.7 degrees C, respectively, whereas the JVBT was 39.6 +/- 0.8 degrees C (P < 0.001). However, the correlation coefficients between the JVBT and the tympanic, rectal, and esophageal temperatures were 0.98, 0. 85, and 0.97, respectively. No complications were recorded with placement of the jugular bulb catheter. CONCLUSIONS: Mean JVBT was significantly increased over the mean core temperature at all times from rewarming by cardiopulmonary bypass onward. Although the lower esophageal, rectal, and tympanic temperatures correlated well with JVBT, all three failed to reflect JVBT during recovery. This observation might help to elucidate factors involved in the functional and structural neurologic injury known to occur in pediatric patients.

Body Temperature↗
PubMed2000

The bioethically constructed ideal dying patient in USA.

Using research data collected from terminally ill cancer patients and their family members in four ethnic groups living in a west coast city of the USA, this paper describes the concept of the ideal dying patient. This concept, constructed by the health professionals giving care to these patients, has implications for nursing ethics in a multi-cultural society as well as in cross cultural ethics research.

California↗