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Biomedical subjects

A J Davis

Publications and source records attributed to A J Davis.

At least 55 records · Page 3Linked to original sources
PubMed1999

Gonadotropin regulation of inhibin alpha-subunit mRNA and immunoreactive protein in cultured chicken granulosa cells.

Gonadotropin regulation of the inhibin alpha-subunit was investigated in chicken granulosa cell cultures. Granulosa layers were isolated from the F(1) and F(3) + F(4) follicles from three to four hens, pooled according to size, dispersed, and cultured (n = 3 replications for each experiment). In Experiments 1 and 2 either ovine LH or FSH was added to the cultures at doses of 0, 5, and 25 ng/ml. The cultures were terminated at 4, 24, and 48 h after plating. For both follicle sizes the expression of mRNA for the inhibin alpha-subunit was less (P < 0.05) at 24 and 48 h in untreated cells than in those treated with both doses of LH. Expression of the mRNA for the inhibin alpha-subunit was significantly increased only by the 25 ng/ml dose of FSH and only in the F(1) follicle at 24 and 48 h compared to the untreated cells. After 48 h of culture, immunoreactive alpha-subunit protein accumulation was greater for both follicle types in the media of cells treated with the highest dose of LH and FSH than in the media from untreated cells. In Experiment 3, doses of 0, 5, 25, or 50 ng/ml of either LH or FSH were added to F(1) and F(3) + F(4) granulosa cells. All cultures were terminated at 48 h. LH and FSH increased the expression of the mRNA and immunoreactive protein for the inhibin alpha-subunit equally in a time-dependent manner. These experiments indicate that gonadotropins enhance the expression of both the mRNA and the protein for the inhibin alpha-subunit in chicken granulosa cells.

Animals↗
PubMed1999

Investigating the role played by protein-lipid and protein-protein interactions in the membrane association of the p120GAP CaLB domain.

The GTPase activating protein, p120GAP, contains an amino acid sequence motif called the Ca2+-dependent lipid binding domain (CaLB) which mediates a protein-protein interaction between p120GAP and annexin VI and also binds to negatively charged phospholipids. Because membrane association of p120GAP is important for the regulation of p21 Ras activity, we have studied the roles played by Ca2+, phospholipids and annexin VI in the membrane association of p120GAP. Here we demonstrate that a truncated CaLB domain GST fusion protein (GSTGAP618-632), lacking the ability to bind to phospholipids, is able to bind to rat fibroblast membranes in a Ca2+- and concentration-dependent manner. In addition, this fusion protein also binds to annexin VI in an amino acid sequence specific but Ca2+ independent manner. Also, when bound to annexin VI in the presence of Ca2+, this fusion protein has the ability to co-bind to phosphatidylserine vesicles. Thus, annexin VI may simultaneously mediate an interaction with p120GAP and also an interaction with membrane phospholipids. This may in part explain the mechanism by which p120GAP associates with membranes in response to Ca2+ elevation and suggests the potential importance of annexin VI in the regulation of p21 Ras and the role CaLB domains may play in the specific recognition of cellular membranes.

Amino Acid Sequence↗
PubMed1999

Angiotensin II concentrations and gut mucosal perfusion in infants undergoing cardiopulmonary bypass.

OBJECTIVES: To determine whether hypothermic cardiopulmonary bypass (CPB) per se causes an increase in angiotensin II (A-II) concentration in infants and to investigate the relationship between A-II concentration and gut mucosal perfusion. DESIGN: Prospective, open, nonrandomized, observational study. SETTING: Children's teaching hospital. PARTICIPANTS: Thirty acyanotic infants requiring CPB. INTERVENTIONS: A-II concentrations were measured on six occasions before, during, and after CPB. An orogastric tonometer allowed intermittent calculations of gastric intramucosal pH (pHi). Gastric mucosal blood flow (flux) was monitored using a laser Doppler flowmeter. Ten infants acted as controls (group 1); 10 infants received captopril, 0.9 mg/kg orally, 45 minutes before induction of anesthesia (group 2), and 10 infants received enalaprilat, 0.06 mg/kg intravenously, just before CPB (group 3). MEASUREMENTS AND MAIN RESULTS: A-II concentrations were abnormally high in 28 of 30 patients before CPB (median, 450 pg/mL (range, 83 to 5,787 pg/mL). A-II concentrations in groups 1 and 2 decreased during CPB, but values remained at twice normal levels throughout surgery (median, 171 to 198 pg/mL post-CPB). A-II concentrations remained normal (range, 52 to 120 pg/mL) during and after CPB in patients receiving enalaprilat (group 3). The authors found no significant correlation between A-II concentration and pHi or flux before, during, or after surgery. CONCLUSIONS: Acyanotic infants requiring cardiac surgery may have high perioperative concentrations of A-II. Hypothermic CPB is associated with a decrease in A-II concentration. Reductions in gut mucosal perfusion seen in some infants during hypothermic CPB are not related to increases in A-II concentrations.

Angiotensin II↗
PubMed1999

Nursing students' response to a case study in ethics.

This paper describes the responses of undergraduate nursing students to an ethical clinical case study. Students in a baccalaureate program were given a case study before a lecture on ethical principles and the same case study after this lecture. These responses raise questions about the content of nursing ethics classes in Japan. The place of individual patient rights and the role of the family in a situation of non-disclosure about diagnosis and prognosis were major issues for the students. The responses reveal the problem of the 'nurse-in-the-middle' between the patient and others whose values differ. Students' post-lecture responses emphasized communication among the people involved.

Adult↗
PubMed1999

Japanese nurses' perceptions about disclosure of information at the patients' end of life.

Information disclosure at the end of life is one of the most debated ethical issues in Japan. This paper, using data from a larger questionnaire survey in which 147 Japanese nurses participated, describes nurses' perceptions about this issue. The nurses perceived that non-disclosure of impending death information to patients was the norm in Japan due to its traditional values. This non-disclosure of information has various impacts on clinical nurses. Tension was evident between the Japanese traditional concepts supported by some nurses and the shift toward Western cultural and ethical values supported by other nurses. The nurses confronted uninformed patients who became suspicious, isolated, angry, or died unprepared for their life's ending. The nurses were placed in the middle between the patient and the family, as nurses became keepers of family secrets, or between nurses' ethical obligations to the patient and those of the institution. The nurses had the belief that at the patient's end of life, it is important to change health professionals' attitude from curing to caring.

Adult↗
PubMed1999

Developmental pattern of phenylalanine hydroxylase activity in the chicken.

Experiments were conducted to determine the conditions for assay of hepatic phenylalanine hydroxylase (PAH) activity in the chicken and to determine the developmental pattern of PAH activity in liver 25,000 x g supernatant. PAH activity was detected in liver supernatant and (postnuclear) 25,000 x g particulate fraction. Optimum assay conditions differed for the two cell fractions, the most notable difference being a broad pH optimum of 7.7 to 9.2 for the supernatant and 4.7 and 5.6 for the particulate fraction. The PAH activity in the supernatant increased to a maximum as L-phenylalanine concentration in the assay medium increased from 0.02 to 0.5 mM and 1.0 mM. Activity increased in the particulate fraction as the Phe concentration increased to 0.5 mM. Substrate inhibition of PAH activity occurred at Phe concentrations of 3 to 5 mM in the supernatant but not in the particulate fraction. Concentrations of the cofactor, 6(R)-5,6,7,8-tetrahydrobiopterin, ranging from 0.09 to 0.75 mM, resulted in maximal PAH activity. The developmental pattern of PAH in supernatant was determined using a modified assay in which substrate and cofactor concentrations and pH were optimum. The PAH activity in liver supernatant was present at a low level in 11 d chick embryos and increased several fold between Days 15 and 17 to a maximum at Days 17 to 21. Activity declined at hatching to levels that were present in 11 to 15 d embryos and remained at this level in male chicks through 4 wk of age. Mature males had higher PAH activity than mature laying females.

Animals↗
PubMed1999

Thermal regulation and mild intraoperative hypothermia.

Homeothermic species such as birds and mammals require an almost constant internal body temperature to preserve normal physiological and metabolic function. When the internal temperature deviates significantly from normal, metabolic function deteriorates and death may result. The efficiency of the thermoregulatory system is highly affected by the administration of medication and by illnesses. Hypothermia may result, especially when these conditions are associated with exposure to a cold environment. Because such conditions exist during anaesthesia and surgery, the understanding of the physiology of the thermoregulatory system and the associated perianaesthetic thermal disturbances is essential to a proper intraoperative management. The purpose of this review is to provide clinicians with a better understanding of these principles, and also to elaborate on the most recent advances in this field, which should help to improve intraoperative anaesthetic temperature management.

Journal Article↗
PubMed1999

Global influence of American nursing: some ethical issues.

This article raises some questions about the global influence of nursing in the USA and describes some problems that may come about because of it. Selected American values that are embedded in nursing and ethics are found in American nursing education, practice and research. These can then be exported to countries with very different cultural definitions and values. One such country is Japan. The discrepancy between national cultural norms and imported ideals of nursing practices can create ethical problems for nurses in these countries.

Cultural Characteristics↗
PubMed1999

Elderly Japanese people living in small towns reflect on end-of-life issues.

This article, reporting on selected data from a larger study, discusses some responses to end-of-life questions that elderly Japanese people who were living in small towns gave in a questionnaire survey. Japan is now the country with the largest number of elderly people in the world and confronts numerous social and economic questions concerning how best to cope with its older population. Although it is a highly urbanized society, Japan also has large semirural areas. The focus here is on the questions in the survey that sought responses to ethical dimensions of end-of-life issues. The findings demonstrate the strength of traditional values that still exist throughout small towns in Japan.

Advance Care Planning↗
PubMed1998

Making mistakes when predicting shifts in species range in response to global warming.

Many attempts to predict the biotic responses to climate change rely on the 'climate envelope' approach, in which the current distribution of a species is mapped in climate-space and then, if the position of that climate-space changes, the distribution of the species is predicted to shift accordingly. The flaw in this approach is that distributions of species also reflect the influence of interactions with other species, so predictions based on climate envelopes may be very misleading if the interactions between species are altered by climate change. An additional problem is that current distributions may be the result of sources and sinks, in which species appear to thrive in places where they really persist only because individuals disperse into them from elsewhere. Here we use microcosm experiments on simple but realistic assemblages to show how misleading the climate envelope approach can be. We show that dispersal and interactions, which are important elements of population dynamics, must be included in predictions of biotic responses to climate change.

Animals↗
PubMed1998

Further evidence that the WT1 gene does not have a role in the development of the derivatives of the müllerian duct.

OBJECTIVE: Several lines of evidence suggest that expression of the WT1 transcription factor gene is necessary for normal development of the renal and male reproductive systems. Female patients with severe reproductive tract developmental defects were examined for WT1 gene mutations. STUDY DESIGN: The WT1 gene was analyzed in 25 patients with congenital absence of the uterus and vagina for mutations. Genomic deoxyribonucleic acid prepared from blood leukocytes was subjected to Southern blot analysis and denaturing gradient gel electrophoresis. RESULTS: Common WT1 gene deoxyribonucleic acid sequence polymorphisms were found in both normal control subjects and patients with congenital absence of the uterus and vagina. No deoxyribonucleic sequence differences or mutations likely to cause congenital absence of the uterus and vagina were detected in the patients. CONCLUSIONS: The absence of WT1 gene mutations in patients with congenital absence of the uterus and vagina supports the hypothesis that WT1 expression is required only for later urogenital development, after the mesonephric and paramesonephric ducts have already formed.

Base Sequence↗
PubMed1998

Antibiotic prophylaxis for ERCP: a comparison of oral ciprofloxacin with intravenous cephazolin in the prophylaxis of high-risk patients.

BACKGROUND: Cholangitis and septicaemia are serious complications of endoscopic retrograde cholangiopancreatography (ERCP). They occur mainly following therapeutic ERCP in the setting of an obstructed biliary system. The optimum prophylactic antibiotic regimen in such patients is not yet defined but usually depends on intravenous agents. AIM: To compare the efficacy of oral ciprofloxacin with intravenous cephazolin. METHODS: One hundred and fifty patients at high risk from septic complications were randomized prospectively to either oral ciprofloxacin (750 mg b.d.) or intravenous cephazolin (1 g b.d.), commenced at least 90 min prior to the ERCP and continued for 3 days. Bacteriological cultures were taken from bile during the procedure and from blood both immediately and at 24 h post-procedure. RESULTS: There were no significant differences between the two treatment groups in the pre-ERCP clinical or radiological findings or in the types of procedure performed. One patient did not undergo an ERCP and was excluded from the final analysis. Of the 77 patients in the ciprofloxacin group there were no positive blood cultures and one positive culture from a nasobiliary drain. Two out of the 72 cephazolin patients had positive blood cultures immediately post-ERCP; one of these two patients and one other cephazolin patient had positive bile cultures. There were no cases of cholangitis or septicaemia in the ciprofloxacin group and three cases in the cephazolin group. One patient from each treatment group died within the 7-day study. Adverse drug reactions were minimal and none of the different clinical outcomes in the two groups reached statistical significance. CONCLUSION: Oral ciprofloxacin is a cost-effective prophylactic agent for high-risk ERCP.

Administration, Oral↗
PubMed1998

Tim23p contains separate and distinct signals for targeting to mitochondria and insertion into the inner membrane.

The Tim23 protein is an essential inner membrane (IM) component of the yeast mitochondrial protein import pathway. Tim23p does not carry an amino-terminal presequence; therefore, the targeting information resides within the mature protein. Tim23p is anchored in the IM via four transmembrane segments and has two positively charged loops facing the matrix. To identify the import signal for Tim23p, we have constructed several altered versions of the Tim23 protein and examined their function and import in yeast cells, as well as their import into isolated mitochondria. We replaced the positively charged amino acids in one or both loops with alanine residues and found that the positive charges are not required for import into mitochondria, but at least one positively charged loop is required for insertion into the IM. Furthermore, we find that the signal to target Tim23p to mitochondria is carried in at least two of the hydrophobic transmembrane segments. Our results suggest that Tim23p contains separate import signals: hydrophobic segments for targeting Tim23p to mitochondria, and positively charged loops for insertion into the IM. We therefore propose that Tim23p is imported into mitochondria in at least two distinct steps.

Binding Sites↗
PubMed1998

Expression pattern of messenger ribonucleic acid for follistatin and the inhibin/activin subunits during follicular and testicular development in gallus domesticus.

The expression of mRNA for follistatin and the inhibin/activin subunits was investigated in the follicles of laying hens and the testes of immature and mature roosters. Total RNA was isolated from immature and mature testes and from individual granulosa layers of the F1 through F5 follicles, from a pool of the F6-F8 follicles, from the small yellow follicles, and from the combined granulosa and theca layers of the large white follicles. Northern blot analysis was performed, and a follistatin mRNA transcript of approximately 2. 4 kilobases (kb) was detected in immature testes and in the following follicles: F5, the pool of F6-F8, and small yellow and large white follicles. The greatest expression of follistatin occurred in the small yellow follicles, and in this tissue two minor transcripts of approximately 1.7 and 3.7 kb were also detected. The inhibin alpha subunit was expressed in both testes samples and in all of the follicles except the large white follicles. Expression of the alpha subunit was greatest in the F5 follicle, and expression decreased with follicle maturity. As previously reported, the inhibin/activin ssA subunit was found in the greatest abundance in the F1 follicle, with lesser amounts detected in the other hierarchical follicles and immature testes. In contrast to the ssA subunit, the inhibin/activin ssB subunit was not detected in the four largest hierarchical follicles but was expressed in greatest abundance in the pool of F6-F8 and small yellow follicles. This represents the first report, to our knowledge, of the detection of follistatin mRNA in the hen ovary and rooster testes. The restriction of follistatin mRNA expression to the small follicles suggests that follistatin, by regulating activin and/or inhibin availability, may play a critical role in early follicular development.

Activins↗
PubMed1998

Long term follow-up of CEOP in the treatment of HIV related non-Hodgkin's lymphoma (NHL).

BACKGROUND: The development of non-Hodgkin's lymphoma (NHL) in AIDS conveys a poor prognosis with less than 10% of patients surviving beyond two years. These tumours are generally aggressive and often require systemic chemotherapy to bring about effective palliation. AIMS: To report on the long term follow-up of patients with HIV related NHL treated with CEOP chemotherapy. METHODS: This is a retrospective analysis of a group of 18 patients treated at two institutions between October 1990 and 1992 with modified CEOP chemotherapy. Doses were calculated using cyclophosphamide 750 mg/m2, epirubicin 50 mg/m2, vincristine 2 mg and prednisone 75-100 mg x five days, however initial doses of cyclophosphamide and epirubicin were modified to 50-75% of calculated dose. RESULTS: Seventeen of the 18 patients were male, one female; age range 26-79 (median 36 years); seven with immunoblastic, three Burkitt's, one Ki-1 (anaplastic), six diffuse large cell, and one mixed large and small cell. Eight patients (44%) achieved a complete remission, with seven patients (39%) achieving a partial remission, for an overall response rate of 83% (95% CI = 59-96%). Survival ranged from three-35 months (median nine months). Interestingly, four patients (22%) survived more than two years (median 31 months), three remaining in complete remission at the time of death. Generally therapy was well tolerated and toxicity was manageable. CONCLUSIONS: CEOP is an effective, tolerable and safe regimen and our long term follow-up suggests that there is a small sub-population of patients with HIV and lymphoma who may have a better prognosis and as such would clearly benefit from systemic chemotherapy as a means of prolonging survival and not simply palliation.

Adult↗
PubMed1998

Lung function in premature lambs and rabbits treated with a recombinant SP-C surfactant.

We evaluated the efficacy of a recombinant surfactant protein-C (rSP-C) surfactant in vitro and in vivo, using ventilated preterm lambs and rabbits. The surface tension measured with a Wilhelmy balance of the rSP-C surfactant was lower than the surface tension of natural sheep surfactant (containing SP-B and SP-C). The rSP-C and natural surfactants were equivalently sensitive to inhibition by plasma. Over a 5-h study period, lambs treated with 100 mg/kg rSP-C and natural surfactants at birth had similar PCO2, lung mechanics, and FRC values. Indicators of injury also were not different. In preterm rabbits ventilated with 3 cm H2O positive end-expiratory pressure (PEEP), similar compliance responses were measured for the rSP-C and natural surfactant. Large-aggregate surfactants recovered from alveolar washes of the lambs treated with rSP-C or natural surfactant retained their function when tested in preterm rabbits. In conclusion, the rSP-C surfactant was effective in preterm animals with surfactant deficiency.

Animals↗
PubMed1998

Informed consent in a multicultural cancer patient population: implications for nursing practice.

Obtaining informed consent, an ethical obligation of nurses and other health care providers, occurs routinely when patients make health care decisions. The values underlying informed consent (promotion of patients' well-being and respect for their self-determination) are embedded in the dominant American culture. Nurses who apply the USA's cultural values of informed consent when caring for patients who come from other cultures encounter some ethical dilemmas. This descriptive study, conducted with Latino, Chinese and Anglo-American cancer patients in a large, public, west-coast clinic, describes constraints on the informed consent process in a multicultural setting, including language barriers, the clinical environment, control in decision making, and conflicting desired health outcomes for health care providers and patients, and suggests some implications for nursing practice.

Asian↗