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Biomedical subjects

D Sanders

Publications and source records attributed to D Sanders.

At least 19 recordsLinked to original sources
PubMed2006

Abscisic acid stimulates the expression of two isoforms of plasma membrane Ca2+-ATPase in Arabidopsis thaliana seedlings.

AT-ACA8 and AT-ACA9 are two plasma membrane (PM) Ca (2+)-ATPases of ARABIDOPSIS THALIANA. In this article the expression of AT-ACA8, AT-ACA9, and of AT-ACA10, a third isoform of Ca (2+)-ATPase closely related to PM Ca (2+)-ATPases, was analysed and the effect of the hormone abscisic acid (ABA) on the expression level of PM Ca (2+)-ATPase specific transcripts was investigated. In adult plants of A. THALIANA, AT-ACA8 and AT-ACA10 are expressed in all organs considered whereas AT-ACA9 is expressed only in flowers. All isoforms of PM Ca (2+)-ATPases can be detected in young seedlings but the amount of AT-ACA9 mRNA is much lower than those of AT-ACA8 and AT-ACA10. ABA markedly and rapidly stimulates the expression of both AT-ACA8 and AT-ACA9 genes in young seedlings but not that of AT-ACA10. ABA also increases the level of AT-ACA8 protein at the PM, suggesting a role for PM Ca (2+)-ATPases in ABA signalling.

Abscisic Acid↗
PubMed2006

Training nurses to save lives of malnourished children.

A qualitative study with a pre- and post-intervention component was undertaken among 66 professional nurses at 11 hospitals in the Eastern Cape to assess their perceptions and attitudes towards severely malnourished children and their mothers/caregivers. Nurses' attitudes were compared before and after attending a 5-day training course to improve the management of malnutrition along with implementing World Health Organization (WHO) guidelines. Severe malnutrition is a major cause of death among paediatric patients in many hospitals in South Africa. A qualitative study with a pre- and post-intervention component was undertaken among 66 professional nurses at 11 hospitals in the Eastern Cape to assess their perceptions and attitudes towards severely malnourished children and their mothers/caregivers. Nurses' attitudes were compared before and after attending a 5-day training course to improve the management of severe malnutrition through implementing the World Health Organisation (WHO) guidelines. Focus group discussions were conducted in isiXhosa following a semi-structured discussion guide. Three themes emerged from these discussions, i.e. nurses placed blame on the mothers for not giving adequate care at home; nurses valued malnourished children less than those with other conditions; and nurses felt resentment towards caregivers. Underlying reasons for the negative attitudes towards severely malnourished children and their caregivers were misunderstandings of the causes of malnutrition, misinterpretation of clinical signs, especially poor appetite, and high mortality during treatment. However, the training course and successful application of the treatment guidelines altered these perceptions and helped nurses to have a better understanding of the causes of the presenting clinical signs. These nurses have begun advocating for raised awareness of the physiological differences that occur in malnutrition and the need to include the WHO Ten Steps of treatment in the nursing curricula and inservice training. A cadre of volunteer nurse-trainers has been formed in Eastern Cape. Experience in this province has shown that in-service training changes attitudes to malnutrition and treatment practices, as well as saving lives.

Anger↗
PubMed2005

Effect of an IMCI intervention on quality of care across four districts in Cape Town, South Africa.

AIMS: To measure the change in quality of care provided to sick children as a result of the routine implementation of the IMCI intervention. METHODS: Structured observations of consultations with sick children, exit interviews with caregivers, and facility reviews were conducted both before and after IMCI intervention in four health districts in Cape Town. Interventions were case management training, orientation courses for supervisors and medical officers, and some reorganisation of management systems. RESULTS: Twenty one nurses in 21 clinics were observed before and after the IMCI intervention; 90 and 70 child observations were conducted before and after IMCI intervention respectively. There was a marked improvement in assessment of danger signs in sick children (7% before versus 72% after), assessment of co-morbidity (integrated score 5.2 versus 8.2), rational prescribing (62% versus 84%), and starting treatment in the clinic (40% versus 70%). However there was no change in the treatment of anaemia or the prescribing of vitamin A or counselling of caregivers. There was no change in the knowledge of caregivers regarding medication or when to return to the health facility. Facilities were well stocked and supervision regular both before and after IMCI. CONCLUSION: This study has shown that under normal operating conditions and in a context of good facility infrastructure and management support, IMCI is associated with improvements in some important aspects of care.

Ambulatory Care↗
PubMed2003

Pregnancy outcomes in foreign-born and US-born women.

OBJECTIVES: To compare pregnancy outcomes between foreign-born women and women born in the United States (US-born). METHODS: A retrospective cohort study (1991-2001) of all deliveries at Grady Memorial Hospital in Atlanta, Georgia. RESULTS: Among 49,904 deliveries, 27% were to foreign-born mothers representing 164 countries grouped into eight geographic regions. Compared with US-born women, foreign-born women had a higher mean birthweight (3315 vs. 3083 g), and a lower risk of preterm delivery (RR 0.46, 95% CI 0.43-0.49), perinatal mortality (RR 0.40, 95% CI 0.36-0.45), hypertension (RR 0.31, 95% CI 0.23-0.41), and HIV infection (RR 0.13, 95% CI 0.10-0.18). However, foreign-born women had an increased risk of diabetes (RR 1.63, 95% CI 1.48-1.79), perineal laceration (RR 1.71; 95% CI 1.66-1.76), and postpartum hemorrhage (RR 1.10; 95% CI 1.05-1.15). CONCLUSIONS: Foreign-born women have better health behaviors, pregnancy outcomes, and a lower risk of infectious diseases than US-born women, but they have a higher risk of certain medical conditions and obstetric complications.

Adolescent↗
PubMed2002

The output of two sevoflurane vaporizers in the presence of helium.

BACKGROUND: Modern vaporizers are designed to deliver accurate and stable concentrations of volatile anaesthetic agents. Carrier gas composition may adversely affect the output from vaporizers. No previous study has tested helium in combination with sevoflurane vaporizers, a clinically useful combination especially in anaesthesia for upper airway obstruction. METHODS: This study evaluated the effect of increasing helium concentrations, carrier gas flow rates and varying the vaporizer dial setting on the output from Blease Datum and Drager Vapor 19.3 sevoflurane vaporizers. RESULTS: The presence of helium in the carrier gas had negligible effects on the output from both of the sevoflurane vaporizers tested. Carrier gas flow rates had the greatest effect on output but changes were within +/- 10% of baseline. CONCLUSION: Helium/oxygen mixtures can be used with these vaporizers without adversely affecting their performance.

Anesthesia, Inhalation↗
PubMed2001

Effect of thymectomy on human peripheral blood T cell pools in myasthenia gravis.

The human thymus is required for establishment of the T cell pool in fetal life, but postnatal thymectomy does not lead to immunodeficiency in humans. Because thymectomy in humans is performed for treatment of myasthenia gravis (MG), we have studied patients with MG for effects of thymectomy on peripheral blood (PB) naive (CD45RA(+), CD62L(+)) and memory (CD45RO(+)) T cells. We have also determined the effect of thymectomy on levels of PB cells containing signal joint TCR delta excision circles (TRECs), a molecular marker of thymus emigrants that have divided few times after leaving the thymus. In 17 nonthymectomized and 26 thymectomized MG patients studied at varying times after thymectomy (1 day to 41 years), we found no significant mean difference in PB T cell TREC levels between ages 40 and 80 years. However, both thymectomized and nonthymectomized MG patients had lower PB T cell TREC levels than did age-matched normal subjects (p < 0.0001 for both). These data demonstrated that MG itself or treatment for MG decreased thymopoiesis independent of thymectomy. Next, to control for disease activity and treatment, we prospectively studied 10 MG patients before and from 27 to 517 days after thymectomy. We found that thymectomy decreased CD4 or CD8 T cell TREC concentrations most when thymopoiesis was active before thymectomy (six of six patients), but had little effect in patients when thymopoiesis was minimal (four of four patients). In contrast, there was no significant effect of thymectomy on absolute numbers of naive PB T cells. Thus, in MG, removal of a thymus with active thymopoiesis resulted in a significant fall in PB TREC(+) T cells postthymectomy.

Adolescent↗
PubMed2001

KP4 fungal toxin inhibits growth in Ustilago maydis by blocking calcium uptake.

KP4 is a virally encoded fungal toxin secreted by the P4 killer strain of Ustilago maydis. From our previous structural studies, it seemed unlikely that KP4 acts by forming channels in the target cell membrane. Instead, KP4 was proposed to act by blocking fungal calcium channels, as KP4 was shown to inhibit voltage-gated calcium channels in rat neuronal cells, and its effects on fungal cells were abrogated by exogenously added calcium. Here, we extend these studies and demonstrate that KP4 acts in a reversible manner on the cell membrane and does not kill the cells, but rather inhibits cell division. This action is mimicked by EGTA and is abrogated specifically by low concentrations of calcium or non-specifically by high ionic strength buffers. We also demonstrate that KP4 affects (45)Ca uptake in U. maydis. Finally, we show that cAMP and a cAMP analogue, N 6,2'-O-dibutyryladenosine 3':5'-cyclic monophosphate, both abrogate KP4 effects. These results suggest that KP4 may inhibit cell growth and division by blocking calcium-regulated signal transduction pathways.

Antifungal Agents↗
PubMed2001

The role of ion channels in light-dependent stomatal opening.

Stomatal opening represents a major determinant of plant productivity and stress management. Because plants lose water essentially through open stomata, volume control of the pore-forming guard cells represents a key step in the regulation of plant water status. These sensory cells are able to integrate various signals such as light, auxin, abscisic acid, and CO(2). Following signal perception, changes in membrane potential and activity of ion transporters finally lead to the accumulation of potassium salts and turgor pressure formation. This review analyses recent progress in molecular aspects of ion channel regulation and suggests how these developments impact on our understanding of light- and auxin-dependent stomatal action.

Adaptation, Physiological↗
PubMed2001

Mobilization of Ca2+ by cyclic ADP-ribose from the endoplasmic reticulum of cauliflower florets.

The NAD+ metabolite cADP-Rib (cADPR) elevates cytosolic free Ca2+ in plants and thereby plays a central role in signal transduction pathways evoked by the drought and stress hormone abscisic acid. cADPR is known to mobilize Ca2+ from the large vacuole of mature cells. To determine whether additional sites for cADPR-gated Ca2+ release reside in plant cells, microsomes from cauliflower (Brassica oleracea) inflorescences were subfractionated on sucrose density gradients, and the distribution of cADPR-elicited Ca2+ release was monitored. cADPR-gated Ca2+ release was detected in the heavy-density fractions associated with rough endoplasmic reticulum (ER). cADPR-dependent Ca2+ release co-migrated with two ER markers, calnexin and antimycin A-insensitive NADH-cytochrome c reductase activity. To investigate the possibility that contaminating plasma membrane in the ER-rich fractions was responsible for the observed release, plasma membrane vesicles were purified by aqueous two-phase partitioning, everted with Brij-58, and loaded with Ca2+: These vesicles failed to respond to cADPR. Ca2+ release evoked by cADPR at the ER was fully inhibited by ruthenium red and 8-NH2-cADPR, a specific antagonist of cADPR-gated Ca2+ release in animal cells. The presence of a Ca2+ release pathway activated by cADPR at higher plant ER reinforces the notion that, alongside the vacuole, the ER participates in Ca2+ signaling.

Adenosine Diphosphate Ribose↗
PubMed2001

The wheat cDNA LCT1 generates hypersensitivity to sodium in a salt-sensitive yeast strain.

Salinity affects large areas of agricultural land, and all major crop species are intolerant to high levels of sodium ions. The principal route for Na(+) uptake into plant cells remains to be identified. Non-selective ion channels and high-affinity potassium transporters have emerged as potential pathways for Na(+) entry. A third candidate for Na(+) transport into plant cells is a low-affinity cation transporter represented by the wheat protein LCT1, which is known to be permeable for a wide range of cations when expressed in yeast (Saccharomyces cerevisiae). To investigate the role of LCT1 in salt tolerance we have used the yeast strain G19, which is disrupted in the genes encoding Na(+) export pumps and as a result displays salt sensitivity comparable with wheat. After transformation with LCT1, G19 cells became hypersensitive to NaCl. We show that LCT1 expression results in a strong decrease of intracellular K(+)/Na(+) ratio in G19 cells due to the combined effect of enhanced Na(+) accumulation and loss of intracellular K(+). Na(+) uptake through LCT1 was inhibited by K(+) and Ca(2+) at high concentrations and the addition of these ions rescued growth of LCT1-transformed G19 on saline medium. LCT1 was also shown to mediate the uptake of Li(+) and Cs(+). Expression of two mutant LCT1 cDNAs with N-terminal truncations resulted in decreased Ca(2+) uptake and increased Na(+) tolerance compared with expression of the full-length LCT1. Our findings strongly suggest that LCT1 represents a molecular link between Ca(2+) and Na(+) uptake into plant cells.

Adaptation, Physiological↗
PubMed2001

Phylogenetic relationships within cation transporter families of Arabidopsis.

Uptake and translocation of cationic nutrients play essential roles in physiological processes including plant growth, nutrition, signal transduction, and development. Approximately 5% of the Arabidopsis genome appears to encode membrane transport proteins. These proteins are classified in 46 unique families containing approximately 880 members. In addition, several hundred putative transporters have not yet been assigned to families. In this paper, we have analyzed the phylogenetic relationships of over 150 cation transport proteins. This analysis has focused on cation transporter gene families for which initial characterizations have been achieved for individual members, including potassium transporters and channels, sodium transporters, calcium antiporters, cyclic nucleotide-gated channels, cation diffusion facilitator proteins, natural resistance-associated macrophage proteins (NRAMP), and Zn-regulated transporter Fe-regulated transporter-like proteins. Phylogenetic trees of each family define the evolutionary relationships of the members to each other. These families contain numerous members, indicating diverse functions in vivo. Closely related isoforms and separate subfamilies exist within many of these gene families, indicating possible redundancies and specialized functions. To facilitate their further study, the PlantsT database (http://plantst.sdsc.edu) has been created that includes alignments of the analyzed cation transporters and their chromosomal locations.

Antiporters↗
PubMed2001

Prevention of anterior glottic restenosis in a canine model with topical mitomycin-C.

To develop a model for recurrent anterior glottic stenosis and to test the efficacy of topical mitomycin-C in preventing restenosis, we induced anterior glottic stenosis with a CO2 laser in 5 dogs. In 3 dogs, recurrence was established after surgical lysis. Subsequently, the 3 dogs received a single topical 3-minute treatment with a 1% solution of mitomycin-C after a second surgical lysis. In a parallel experiment, the other 2 dogs received a single topical 3-minute treatment with a 1% solution of mitomycin-C after the initial surgical lysis. An anterior glottic web was induced in all 5 dogs with the CO2 laser. The 3 dogs experienced restenosis at the anterior glottis after surgical lysis alone. Mitomycin-C prevented anterior glottic restenosis in 2 of the 3 dogs treated twice and in both of the dogs treated once (p = .02). We conclude that a recurrent stenosis of the anterior glottis may be induced reproducibly in the canine model with the CO2 laser. Application of topical mitomycin-C after lysis of an anterior glottic stenosis produces a statistically significant reduction in the rate of restenosis as compared to surgical lysis alone.

Administration, Topical↗
PubMed2001

Pyridostigmine bromide and the long-term subjective health status of a sample of female reserve component Gulf War veterans: a brief report.

The role of pyridostigmine bromide (PB) pills in explaining the long-term subjective health status of a sample of over 100 female Reserve Component Gulf War veterans was examined through regression analysis. Results fell just short of significance (p < .06) for the prediction of subjective health approximately six years after the war and were clearly not significant for the prediction of subjective health at previous times. Results parallel Golomb's 1999 RAND report, which found suggestive but not conclusive evidence for the possible adverse effects of Gulf War veterans' consumption of pyridostigmine bromide pills. Our data suggest that use of more than 10 pills may have been especially risky with respect to long-term subjective health.

Adult↗
PubMed2001

Petrolatum versus Resurfix ointment in the treatment of pressure ulcers.

This study compares the therapeutic effects of a new topically applied, nonprescription medication that has been introduced for re-epithelialization of ulcers and erosions of the skin, with petrolatum in treating pressure ulcers of shallow depth (Stage I and Stage II). A 6-week, randomized, double-blind study was performed on 19 patients with Stage I or Stage II pressure ulcers. The patients received either the new nonprescription medication or petrolatum, which served as a control. After the course of the study, the study ointment effected resolution in a majority of pressure ulcers (9 out of 10), while only one out of three ulcers treated with petrolatum resolved in the same time period. These preliminary results show that the study ointment is a safe and effective treatment for Stage I and II pressure ulcers.

Aged↗
PubMed2001

Evaluating the clinical management of severely malnourished children--a study of two rural district hospitals.

BACKGROUND: Severe malnutrition is an important cause of preventable mortality in most South African hospitals. Work recently done in two rural Eastern Cape hospitals supports the literature which shows that many deaths occur as a result of outdated clinical practices and that improving these practices reduces case fatality rates. Rapid assessment of clinical management in paediatric wards is necessary to highlight areas for improvement. OBJECTIVE: To assess the management of severely malnourished children in two rural district hospitals and to recommend improvements for their care. METHODS: Based on draft World Health Organisation (WHO) guidelines for inpatient care of children with severe malnutrition, data collection instruments were developed in conjunction with the district nutrition team to assess the quality of care given to malnourished children in two Mount Frere hospitals, Eastern Cape. Data were collected through retrospective review of case records, with detailed studies of selected cases, structured observations of the paediatric wards, and interviews with ward sisters and doctors. RESULTS: The combined case fatality rate for severe malnutrition was 32%. Inadequate feeding, poor management of rehydration and infection, lack of resources, and a lack of knowledge and motivation among staff were identified as areas that need attention. CONCLUSION: The clinical management of severely malnourished children can be rapidly assessed to highlight areas for improvement. Involving staff in the assessment process has led to their active involvement in improving the management of malnourished children in their hospitals.

Child↗