Problem-based learning the distance learning way: a bridge too far?

Since problem-based learning is classically associated with campus based, small group learning conducted over protracted periods of time, it should not, in theory, be well suited to the distance learning mode of study. Just how do you write distance learning materials which adequately accommodate the problem-based learning process, and which acknowledge the variety of problems that could be identified for study? This paper critically examines one distance learning initiative designed to test whether problem-based learning may be delivered to student benefit at post-registration, undergraduate nurse programme level.

A Streptomyces coelicolor antibiotic regulatory gene, absB, encodes an RNase III homolog

Streptomyces coelicolor produces four genetically and structurally distinct antibiotics in a growth-phase-dependent manner. S. coelicolor mutants globally deficient in antibiotic production (Abs(-) phenotype) have previously been isolated, and some of these were found to define the absB locus. In this study, we isolated absB-complementing DNA and show that it encodes the S. coelicolor homolog of RNase III (rnc). Several lines of evidence indicate that the absB mutant global defect in antibiotic synthesis is due to a deficiency in RNase III. In marker exchange experiments, the S. coelicolor rnc gene rescued absB mutants, restoring antibiotic production. Sequencing the DNA of absB mutants confirmed that the absB mutations lay in the rnc open reading frame. Constructed disruptions of rnc in both S. coelicolor 1501 and Streptomyces lividans 1326 caused an Abs(-) phenotype. An absB mutation caused accumulation of 30S rRNA precursors, as had previously been reported for E. coli rnc mutants. The absB gene is widely conserved in streptomycetes. We speculate on why an RNase III deficiency could globally affect the synthesis of antibiotics.

Induction of the mesendoderm in the zebrafish germ ring by yolk cell-derived TGF-beta family signals and discrimination of mesoderm and endoderm by FGF

The endoderm forms the gut and associated organs, and develops from a layer of cells which emerges during gastrula stages in the vertebrate embryo. In comparison to mesoderm and ectoderm, little is known about the signals which induce the endoderm. The origin of the endoderm is intimately linked with that of mesoderm, both by their position in the embryo, and by the molecules that can induce them. We characterised a gene, zebrafish gata5, which is expressed in the endoderm from blastula stages and show that its transcription is induced by signals originating from the yolk cell. These signals also induce the mesoderm-expressed transcription factor no tail (ntl), whose initial expression coincides with gata5 in the cells closest to the blastoderm margin, then spreads to encompass the germ ring. We have characterised the induction of these genes and show that ectopic expression of activin induces gata5 and ntl in a pattern which mimics the endogenous expression, while expression of a dominant negative activin receptor abolishes ntl and gata5 expression. Injection of RNA encoding a constitutively active activin receptor leads to ectopic expression of gata5 and ntl. gata5 is activated cell-autonomously, whereas ntl is induced in cells distant from those which have received the RNA, showing that although expression of both genes is induced by a TGF-beta signal, expression of ntl then spreads by a relay mechanism. Expression of a fibroblast growth factor (eFGF) or a dominant negatively acting FGF receptor shows that ntl but not gata5 is regulated by FGF signalling, implying that this may be the relay signal leading to the spread of ntl expression. In embryos lacking both squint and cyclops, members of the nodal group of TGF-beta related molecules, gata5 expression in the blastoderm is abolished, making these factors primary candidates for the endogenous TGF-beta signal inducing gata5.

Novel non-isotopic detection of MutY enzyme-recognized mismatches in DNA via ultrasensitive detection of aldehydes

A highly sensitive method to detect traces of aldehyde-containing apurinic/apyrimidinic (AP) sites in nucleic acids has been developed. Based on this method, a novel approach to detect DNA base mismatches recognized by the mismatch repair glycosylase MutY is demonstrated. Open chain aldehydes generated in nucleic acids due to spontaneous depurination, DNA damage or base excision of mismatched adenine by MutY are covalently trapped by a new linker molecule [fluorescent aldehyde-reactive probe (FARP), a fluorescein-conjugated hydroxylamine derivative]. DNA containing AP sites is FARP-trapped, biotinylated and immobilized onto neutravidin-coated microplates. The number of FARP-trapped aldehydes is then determined via chemiluminescence using a cooled ICCD camera. AP sites induced in plasmid or genomic calf thymus DNA via mild depurination or by simple incubation at physiological conditions (pH 7, 37 degreesC) presented a linear increase in chemiluminescence signal with time. The procedure developed, from a starting DNA material of approximately 100 ng, allows detection of attomole level (10(-18) mol) AP sites, or 1 AP site/2 x 10(7) bases, and extends by 1-2 orders of magnitude the current limit in AP site detection. In order to detect MutY-recognized mismatches, nucleic acids are first treated with 5 mM hydroxylamine to remove traces of spontaneous aldehydes. Following MutY treatment and FARP-labeling, oligonucleotides engineered to have a centrally located A/G mismatch demonstrate a strong chemiluminescence signal. Similarly, single-stranded M13 DNA that forms mismatches via self-complementation (average of 3 mismatches over 7429 bases) and treated with MutY yields a signal approximately 100-fold above background. No signal was detected when DNA without mismatches was used. The current development allows sensitive, non-isotopic, high throughput screening of diverse nucleic acids for AP sites and mismatches in a microplate-based format.

Explorations in body image care: Peplau and practice knowledge

Practitioners in mental health care have long utilized the work of Hildegard Peplau, both for nursing discourse and for practice. At a time when the role of theory in practice is once more being debated, and when theories are being applied in new contexts, this paper examines the contribution that Peplau's work may have to offer altered body image nursing care. A case study is used to highlight concepts in practice, the paper examining the ways in which Peplau's Theory of Interpersonal Relations complement the other elements of practice knowledge that the nurse uses to assist patients and lay carers alike.

Making midwifery decisions

In order to share practice decision making with women, midwives need to understand their own tacit knowledge and some of the heuristic processes used to arrive at clinical decisions. Arguing that midwifery decision making is intuitive and artful is insufficient defence when accounting for professional practice. Explicit reasoning, individual and shared, should be well to the fore. Contrary to received wisdom, expert practitioners can share their midwifery reasoning with junior colleagues. Role modelling decision making process involves the senior midwife in understanding her own tacit knowledge and coming to terms with practice discussion as a pursuit of understanding, rather than a blame culture activity.

A review of carbon disulfide exposure data and the association between carbon disulfide exposure and ischemic heart disease mortality

Recent regulatory efforts have devoted attention to carbon disulfide (CS2) exposure and its potential effects on the cardiovascular system. To investigate the association between CS2 exposure and ischemic heart disease (IHD) mortality, the analysis presented here had the following objectives: (i) to review historical CS2 exposure data in the viscose rayon industry and identify trends and (ii) to use these historical data to suggest a standard mortality ratio (SMR)-exposure relationship and a threshold level for occupational exposure to CS2, CS2 exposure data were extracted from published studies and used with the SMR versus exposure score relationship developed by Sweetnam et al. (Br. J. Ind. Med. 44, 220-227, 1987) to relate SMRs directly to exposure. Upper and lower bound exposure profiles were derived and used to identify exposure thresholds. For an IHD SMR equal to 100, the upper and lower bound exposures were 60 and 20 ppm, respectively. The analysis indicates that the risk of IHD mortality and its relationship to CS2 exposure is meaningful only for workers exposed to high level for many years. These high levels, which existed many years ago, are no longer found in the workplace. The results of this analysis suggest a safe regulatory exposure level for CS2 between 15 and 20 ppm.

The febrile stress of routine vaccination does not increase central apnoea in normal infants

We tested the hypothesis that the febrile stress of routine vaccination would increase central apnoea in normal infants. Twenty-one normal infants had continuous overnight breathing and temperature recorded at home, before and after 58 routine vaccination episodes. Central apnoea, of at least 5 sec duration, was detected by computer algorithm and confirmed by human inspection. The longest recorded apnoea was 16 sec (n = 1) during 3629 h of sleep. Overnight rectal temperature increased after vaccination (median 0.52 degrees C, 95% CI 0.40, 0.65). Apnoea density reduced on 46/53 vaccination nights (median -29%, 95% CI -20, -37) followed by an increase on subsequent nights (median +10%, 95% CI +1%,+21%). Overall, apnoea density was similar during the 3 nights preceding and 4 nights following vaccination (median +1%, 95% CI +9,-6). The febrile stress of routine vaccination did not increase central apnoea in normal infants.

Acute renal failure due to lymphomatous infiltration of the kidneys

Acute renal failure (ARF) is an unusual manifestation of lymphomatous infiltration of the kidneys. In this article, a patient whose initial presentation of lymphoma was the sudden onset of painless hematuria and ARF is described. The absence of other causes of ARF, together with massively enlarged unobstructed kidneys on renal ultrasonography, strongly suggested an infiltrative process. Renal biopsy established the diagnosis of non-Hodgkin's lymphoma. Pulse steroid therapy was associated with rapid improvement of renal function and kidney size, but a moderate degree of tumor lysis syndrome ensued. Further recovery followed with chemotherapy. Whereas widespread infiltration of the kidneys is present in almost one third of patients with lymphoma at autopsy, this rarely causes clinical symptoms. Nevertheless, because it often responds to therapy, lymphomatous infiltration should be suspected in any patient presenting with unexplained ARF and enlarged kidneys, especially in the setting of widespread lymphoma.

Defining quality student feedback in distance learning

The quality of student feedback is of critical importance in distance learning. Students studying such courses may be geographically far removed from tutors, and limited contact opportunities necessitate a sharp and accurate focus upon aspects of study which link theory, research, clinical practice and written assessment closely together. An understanding of quality feedback begins with an appreciation of the role of distance learning course tutors and the education models which can usefully guide them. Quality also relies upon a close evaluation of support to students as courses are planned, launched and then monitored through course boards or their equivalent.

Induction of cytosolic phospholipase A2 by oncogenic Ras in human non-small cell lung cancer

Mutations in Ras family members that confer oncogenic potential are frequently observed in specific human cancers. We report that human non-small cell lung cancer (NSCLC) lines that harbor oncogenic mutations in Ki-Ras (H460, A549, H2122) synthesized high levels of prostaglandin E2 (PGE2) compared with NSCLC lacking Ras mutations or non-transformed lung epithelial cells (BEAS-2B). This increased PGE2 production was mediated by constitutively high expression of 85-kDa cytosolic phospholipase A2 (cPLA2) and cyclooxygenase 2 (COX-2). The increased expression of cPLA2 protein was mediated through elevated mRNA levels and activation of the cPLA2 promoter. Induction of cPLA2 promoter activity was blocked by expression of dominant-negative forms of Ras. Inhibition of Ras by the farnesyltransferase inhibitor BZA-5B inhibited prostaglandin synthesis in H2122 cells by decreasing expression of both cPLA2 and COX-2. Finally, inhibitors of eicosanoid synthesis blocked anchorage-independent growth of NSCLC lines exhibiting Ki-Ras mutations. These results identify cPLA2 as a novel Ras-inducible regulator of eicosanoid synthesis that participates in cellular transformation.

Comparative genomic hybridization reveals previously undescribed amplifications and deletions in the chronic myeloid leukemia-derived K-562 cell line

We used comparative genomic hybridization (CGH) to identify a number of previously undescribed chromosomal imbalances in K-562, a spontaneously transformed cell line originally derived from leukemic cells of a chronic myeloid leukemia (CML) patient in blast crisis. Noteworthy were a discrete amplification in band 13q31, increased copy number of chromosome arms 1q, 5p, 6p, and 16q, and loss of material from 8p, 9p, 10q, and 17p. Amplification within bands 9q34 and 22q11.2 was consistent with previous descriptions of increased copy number of the CML-specific 5'BCR-3'ABL fusion gene in K-562. However, amplification of a large distal segment, 9q31-->9q34, mostly proximal to the ABL locus, was unexpected and is unlikely to be related to BCR-ABL recombination. Previous karyotype studies are reviewed in detail and compared with the CGH findings.

Analysis of current trends in United States mesothelioma incidence

Mesothelioma incidence often is interpreted as an index of past exposure to airborne asbestos. The mesothelioma rate for US males exhibits an increasing trend throughout the 1970s and early 1980s. The trend has been attributed to occupational exposure in the shipbuilding industry during World War II, in manufacturing, and in building construction. Incidence data (1973-1992) from the Surveillance, Epidemiology, and End Results Program were used to investigate current trends in age-adjusted and age-specific mesothelioma rates. An age and birth-cohort model was used to project both lifetime probabilities of mesothelioma by cohort and the annual number of cases expected over the next 70 years. The current trend in female rates is flat (age-adjusted rate = 0.30 per 100,000). The estimated lifetime risk for females is 2.5 x 10(-4), independent of birth cohort. The projected average annual number of female cases is 500. For males, the age-adjusted mesothelioma rate is increasing solely due to the age group 75 years and over, albeit at a declining growth rate. Lifetime risk for males peaks at 2 x 10(-3) for the 1925-1929 birth cohort, then decreases to 5 x 10(-4) for the 1955-1959 birth cohort. The pattern of rates reflected in the age and birth-cohort model suggests a peak in the annual number of mesothelioma cases for males at 2,300 before the year 2000. The number of male cases then will drop during the next 50-60 years toward 500. These trends mirror the US trend in raw asbestos consumption and a reduction in workplace airborne asbestos levels.

A benchmark concentration for carbon disulfide: analysis of the NIOSH carbon disulfide exposure database

A statistical analysis of the NIOSH (National Institute for Occupational Safety and Health) carbon disulfide (CS2) exposure database was conducted for purposes of establishing a benchmark concentration (BMC) for CS2. The analysis addressed the effects of CS2 exposure on the peripheral nervous system and on ischemic heart disease risk factors. The BMC is based on models relating response to exposure determined from statistical analysis of the continuous exposure data for individuals recorded in the NIOSH database. The results demonstrate that changes in the responses associated with increases in CS2 exposure at levels represented in the NIOSH database are relatively small after adjustment for confounders. The only response variables that had statistically significant relationships with CS2 were the peroneal nerve MCV (motor conduction velocity) and the peroneal nerve amplitude ratio. Based on these results, BMCs of 16.2 and 18.5 ppm were derived for MCV and amplitude ratio, respectively.

Illness careers: the chronic illness experience

The provision of skillful psychosocial care to patients suffering from chronic illnesses starts with an appreciation of what it is like to live with a chronic condition. Definitions of self-esteem may be realigned when patients encounter a prolonged problem, and reliance upon professional help. Getting inside the experience of such illness may be key to understanding patient motivation, noncompliance with therapy and altered patterns of social engagement. Individuals' personal constructs may usefully then be used to explore the extent to which chronic illness sufferers share common problems and needs.

Critical reading

Evidence based practice is funded upon a systematic review of research and related literature. This extends to many reports and papers, spanning several different types of evidence. Critical reading involves asking different sorts of questions of each type of evidence. The process of evaluating such literature may be lengthy, and demand collaborative efforts amongst midwives, who draw upon local expertise in research, or one of the relevant databases. Changes in practice is mandated where midwives can point to sufficient systematically evaluated evidence in support of adjusted ways of delivering midwifery care.

Dementia and personhood: a focus for care?

The philosophy of nursing emphasizes the importance of holistic care delivered to an individual and their significant others through a shared understanding of the person. Dementia, however, strikes at the very nature of personhood, and carers are challenged to re-evaluate how care can be adjusted to help preserve dignity and independence during a very variable span of deteriorating mental function. This paper explores the impact of dementia on patients and carers through the meanings of self and body image which give individuality to each of us. It concludes by highlighting how recognition of this may assist carers to accommodate the necessary changes associated with the illness.

Caring for a man with Alzheimer's disease

A disease progresses at varying pace, posing significant problems for care assessment and planning. Nursing care is supplemental to that offered by relatives, challenging the nurse to liaise effectively. Supporting the lay carers is central within the care plan and continues beyond the death of the patient.