High-performance liquid chromatographic method for determination of vanillin and vanillic acid in human plasma, red blood cells and urine

A simple high-performance liquid chromatographic method was developed for the determination of vanillin and its vanillic acid metabolite in human plasma, red blood cells and urine. The mobile phase consisted of aqueous acetic acid (1%, v/v)-acetonitrile (85:15, v/v), pH 2.9 and was used with an octadecylsilane analytical column and ultraviolet absorbance detection. The plasma method demonstrated linearity from 2 to 100 microg/ml and the urine method was linear from 2 to 40 microg/ml. The method had a detection limit of 1 microg/ml for vanillin and vanillic acid using 5 microl of prepared plasma, red blood cells or urine. The method was utilized in a study evaluating the pharmacokinetic and pharmacodynamic effects of vanillin in patients undergoing treatment for sickle cell anemia.

Swainsonine protects both murine and human haematopoietic systems from chemotherapeutic toxicity

The haematopoietic system is sensitive to cytotoxic damage and is often the site of dose-limiting toxicity. We previously reported that swainsonine, an inhibitor of protein glycosylation, reduced the bone marrow toxicity resulting from a single dose of anticancer drugs in otherwise healthy mice. However, more important questions are (1) can swainsonine protect tumour-bearing mice without interfering with the anti-tumour effects of the drugs, and (2) can swainsonine stimulate haematopoietic activity of human, as well as murine, bone marrow. We demonstrate here that swainsonine protects C57BL/6 mice bearing melanoma-derived tumours from cyclophosphamide-induced toxicity without interfering with the drug's ability to inhibit tumour growth. Similar results were obtained in vivo with 3'-azido-3'-deoxythymidine (AZT), a myelosuppressive agent often used in therapy for acquired immune deficiency syndrome. Swainsonine increased both total bone marrow cellularity and the number of circulating white blood cells in mice treated with doses of AZT that typically lead to severe myelosuppression. Swainsonine also increased the number of erythroid and myeloid colony forming cells (CFCs) in short-term cultures of murine bone marrow, restoring the number of progenitor cells to the control level in the presence of AZT doses that reduced CFCs by 80%. With respect to the sensitivity of human haematopoietic cells to swainsonine, we show that swainsonine protected human myeloid progenitor cells from AZT toxicity in vitro. These results suggest that swainsonine may be useful as an adjuvant in several types of human chemotherapy.

Synchronous polyandry and multiple paternity in the frog Crinia georgiana (Anura: Myobatrachidae)

Multiple paternity has rarely been reported in anuran amphibians, with only three previous documented examples. For the Australian frog Crinia georgiana, we observed synchronous polyandry in an average of 44% of matings observed at four field sites. This suggests matings involving more than one male are common in this species. One to eight males were observed in amplectant groups with second males amplexed ventrally. Genetic analyses, using allozyme electrophoresis, of offspring from two matings indicated that at least two of three possible males fathered offspring. Third males were unlikely to have shared paternity, explained by their inappropriate position during amplexus. Multiple paternity may be more common in frogs than has been reported. Copyright 1999 The Association for the Study of Animal Behaviour.

Shift work and its impact upon nurse performance: current knowledge and research issues

Previous research investigating shift work and its impact upon the quality of registered nurse performance and outcomes (including biological, psychosocial and organizational) is reviewed. The present study, which involved non-participant observation of staff nurses (n = 34) within their first year of practice (Part 1 or Part 12 of the United Kingdom Professional Register), is described. The findings demonstrated support for earlier research which suggested that 12 1/2 hour shifts are associated with less effective performance. This study, together with previous research, highlights important indicators for the design and management of future empirical work which is required to investigate the influence of shift work upon process as well as outcomes for nurses, service users and the employing organization. This is particularly pertinent in the light of recent changes in work patterns. The well-being and effectiveness of the nursing workforce requires enhancement, and the effective management of shift-work is a key strategy in achieving this.

Adenovirus-mediated gene transfer of cGMP-dependent protein kinase increases the sensitivity of cultured vascular smooth muscle cells to the antiproliferative and pro-apoptotic effects of nitric oxide/cGMP

Studies in vitro have underestimated the importance of cGMP-dependent protein kinase (PKG) in the modulation of vascular smooth muscle cell (SMC) proliferation and apoptosis in vivo. This is attributable, in part, to a rapid decline in PKG levels as vascular SMC are passaged in culture. We used a recombinant adenovirus encoding PKG (Ad.PKG) to augment kinase activity in cultured rat pulmonary artery SMC (RPaSMC). Incubation of Ad. PKG-infected RPaSMC (multiplicity of infection = 200) with 8-Br-cGMP decreased serum-stimulated DNA synthesis by 85% and cell proliferation at day 5 by 74%. The effect of 8-Br-cGMP on DNA synthesis in Ad.PKG-infected RPaSMC was blocked by KT5823 (PKG inhibitor), but not by KT5720 (cAMP-dependent protein kinase inhibitor). A nitric oxide (NO) donor compound, S-nitrosoglutathione, at concentrations as low as 100 nM, inhibited DNA synthesis in Ad. PKG-infected RPaSMC, but not in uninfected cells or in cells infected with a control adenovirus. In addition, 8-Br-cGMP and S-nitrosoglutathione induced apoptosis in serum-deprived RPaSMC infected with Ad.PKG, but not in uninfected cells or in cells infected with a control adenovirus. These results demonstrate that modulation of PKG levels in vascular SMC can alter the sensitivity of these cells to NO and cGMP. Moreover, these observations suggest an important role for PKG in the regulation of vascular SMC proliferation and apoptosis by NO and cGMP.

The role of protein glycosylation inhibitors in the prevention of metastasis and therapy of cancer

Oligosaccharide moieties of cell-surface glycoproteins are thought to be involved in recognition events during cancer metastasis and invasion. Swainsonine, an inhibitor of the Golgi alpha-mannosidase II, has been shown to block pulmonary colonization by tumor cells and stimulate components of the immune system. Swainsonine also abrogates much of the toxicity of chemotherapeutic agents and stimulates bone marrow hematopoietic progenitor cells, suggesting additional therapeutic applications. We are currently characterizing the ability of swainsonine to modify cell growth in human and murine bone marrow progenitor cells. Furthermore, we are examining crucial steps in metastasis that depend upon cell surface molecules that play a role in cell-matrix interactions. Our work shows that tumor cell adhesion to collagen IV in vitro is rapidly stimulated by cis-polyunsaturated fatty acids and is dependent on protein kinase C activity. We are investigating the hypothesis that integrins are critical components of this adhesion and are examining potential signal transduction pathways that lead to the modulation of cell adhesion.

Cell type and pathway dependence of synaptic AMPA receptor number and variability in the hippocampus

It has been suggested that some glutamatergic synapses lack functional AMPA receptors. We used quantitative immunogold localization to determine the number and variability of synaptic AMPA receptors in the rat hippocampus. Three classes of synapses show distinct patterns of AMPA receptor content. Mossy fiber synapses on CA3 pyramidal spines and synapses on GABAergic interneurons are all immunopositive, have less variability, and contain 4 times as many AMPA receptors as synapses made by Schaffer collaterals on CA1 pyramidal spines and by commissural/ associational (C/A) terminals on CA3 pyramidal spines. Up to 17% of synapses in the latter two connections are immunonegative. After calibrating the immunosignal (1 gold = 2.3 functional receptors) at mossy synapses of a 17-day-old rat, we estimate that the AMPA receptor content of C/A synapses on CA3 pyramidal spines ranges from <3 to 140. A similar range is found in adult Schaffer collateral and C/A synapses.

An exploratory study of similarities and differences between senior students from different pre-registration nurse education courses

A triangulation design using two simulations, non-participant observation and a semi-structured interview to explore senior student nurse performance in South East England is described. A comparison of student nurse performance (registered general nurse [RGN] programme n = 34; registered nurse Project 2000 diploma programme n = 34; integrated degree programme n = 31) indicated many similarities but also some important differences in outcomes which included: a more systematic approach to information-seeking, better care-planning skills and higher quality nurse performance among integrated degree programme participants; use of a model and the immediate role of the nurse to guide information-seeking and better care-planning skills and weaknesses in clinical nurse performance among RGN programme participants; and weaknesses in the information-seeking, care-planning and clinical nurse performance among Project 2000 diploma participants. There were no significant differences between the clinical performance scores of the RGN and diploma programme participants. The interview data suggested that the integrated degree programme participants had a client focus in contrast to the professional focus of RGN and Project 2000 diploma participants. The findings, however, must be viewed within the context of an exploratory study of limited sample size. The research was funded by the English National Board for Nursing, Midwifery and Health Visiting.

Differential plasma membrane distribution of metabotropic glutamate receptors mGluR1 alpha, mGluR2 and mGluR5, relative to neurotransmitter release sites

Two group I metabotropic glutamate receptor subtypes, mGluR1 and mGluR5, have been reported to occur in highest concentration in an annulus surrounding the edge of the postsynaptic membrane specialisation. In order to determine whether such a distribution is uniform amongst postsynaptic mGluRs, their distribution was compared quantitatively by a pre-embedding silver-intensified immunogold technique at electron microscopic level in hippocampal pyramidal cells (mGluR5), cerebellar Purkinje cells (mGluR1 alpha) and Golgi cells (mGluR2). The results show that mGluR1 alpha, mGluR5 and mGluR2 each have a distinct distribution in relation to the glutamatergic synaptic junctions. On dendritic spines, mGluR1 alpha and mGluR5 showed the highest receptor density in a perisynaptic annulus (defined as within 60 nm of the edge of the synapse) followed by a decreasing extrasynaptic (60-900 nm) receptor level, but the gradient of decrease and the proportion of the perisynaptic pool (mGluR1 alpha, approximately 50%; vs mGluR5, approximately 25%) were different for the two receptors. The distributions of mGluR1 alpha and mGluR5 also differed significantly from simulated random distributions. In contrast, mGluR2 was not closely associated with glutamatergic synapses in the dendritic plasma membrane of cerebellar Golgi cells and its distribution relative to synapses is not different from simulated random distribution in the membrane. The somatic membrane, the axon and the synaptic boutons of the GABAergic Golgi cells also contained immunoreactive mGluR2 that is not associated with synaptic specialisations. In the hippocampal CA1 area the distribution of immunoparticles for mGluR5 on individual spines was established using serial sections. The results indicate that dendritic spines of pyramidal cells are heterogeneous with respect to the ratio of perisynaptic to extrasynaptic mGluR5 pools and about half of the immunopositive spines lack the perisynaptic pool. The quantitative comparison of receptor distributions demonstrates that mGluR1 alpha and mGluR5, but not mGluR2, are highly compartmentalised in different plasma membrane domains. The unique distribution of each mGluR subtype may reflect requirements for different transduction and effector mechanisms between cell types and different domains of the same cell, and suggests that the precise placement of receptors is a crucial factor contributing to neuronal communication.

Measuring clinical nurse performance: development of the King's Nurse Performance Scale

The development of the King's Nurse Performance Scale to measure clinical nurse performance is described. Instrument construction was informed by the Slater Nursing Competencies Rating Scale [Wandelt, M. A. and Stewart, D. S. (1975) Slater Nursing Competencies Rating Scale. Appleton-Century Crofts, New York] together with key literature and the use of expert opinion. The instrument was utilised to observe the clinical performance of senior student nurses (n = 99) and data which were at the ordinal level were statistically analysed using a variety of non-parametric tests. Key findings of students' observed nursing practice are presented in a separate paper (While et al., unpublished document). Internal consistency testing of the King's Nurse Performance Scale using Cronbach's alpha coefficient revealed a promising alpha for the total instrument (r = 0.93). The subsection alphas indicated that further refinement may enhance the strength of the instrument as a tool for the measurement of performance in different domains of practice. The possible use of the Scale in the professional development of newly qualified nurses is suggested.

Impaired vision for binocular tasks after unilateral optic nerve regeneration in the frog Litoria moorei

Behavioural responses to objects in the binocular field were examined in frogs with one regenerate and one intact optic nerve. Data were compared to those for normal controls and for frogs with vision via one intact optic nerve. During prey acquisition, frogs with regenerated optic nerves underestimated the distance to the prey on their first strike; as a consequence, the regenerate series made several attempts to achieve a successful prey capture. By contrast, normal frogs and those using only one eye struck accurately at the prey and usually captured it on the first attempt. However, frogs using only one eye struck from a closer distance than either the regenerate or normal series. Frogs with regenerated optic nerves also made more errors than either of the other series when leaping through a set of closely spaced horizontally aligned rods. Our results show that prey capture and the negotiation of horizontally aligned rods is impaired in animals using one regenerated and one intact optic nerve as compared to both normal frogs and those using only one eye. We suggest that the poor visual performance for frogs with one regenerated and one intact optic nerve for tasks presented in the binocular field is related to the integration of a degraded and a normal image within the visual centres.

Inhaled nitric oxide and persistent pulmonary hypertension of the newborn. The Inhaled Nitric Oxide Study Group

BACKGROUND

Persistent pulmonary hypertension of the newborn causes systemic arterial hypoxemia because of increased pulmonary vascular resistance and right-to-left shunting of deoxygenated blood. Inhaled nitric oxide decreases pulmonary vascular resistance in newborns. We studied whether inhaled nitric oxide decreases severe hypoxemia in infants with persistent pulmonary hypertension.

METHODS

In a prospective, multicenter study, 58 full-term infants with severe hypoxemia and persistent pulmonary hypertension were randomly assigned to breathe either a control gas (nitrogen) or nitric oxide (80 parts per million), mixed with oxygen from a ventilator. If oxygenation increased after 20 minutes and systemic blood pressure did not decrease, the treatment was considered successful and was continued at lower concentrations. Otherwise, it was discontinued and alternative therapies, including extracorporeal membrane oxygenation, were used.

RESULTS

Inhaled nitric oxide successfully doubled systemic oxygenation in 16 of 30 infants (53 percent), whereas conventional therapy without inhaled nitric oxide increased oxygenation in only 2 of 28 infants (7 percent). Long-term therapy with inhaled nitric oxide sustained systemic oxygenation in 75 percent of the infants who had initial improvement. Extracorporeal membrane oxygenation was required in 71 percent of the control group and 40 percent of the nitric oxide group (P=0.02). The number of deaths was similar in the two groups. Inhaled nitric oxide did not cause systemic hypotension or increase methemoglobin levels.

CONCLUSIONS

Inhaled nitric oxide improves systemic oxygenation in infants with persistent pulmonary hypertension and may reduce the need for more invasive treatments.

Imaging of radiocarbon-labelled tracer molecules in neural tissue using accelerator mass spectrometry

Autoradiography is widely and successfully used to image the distribution of radiolabelled tracer molecules in biological samples. The method is, however, limited in resolution and sensitivity, especially for 14C. Here we describe a new method for imaging 14C-labelled tracers in sections of biological tissue. A highly focused beam of gallium ions bombards the tissue, which is eroded (sputtered) into constituent atoms, molecules and secondary ions. The 14C ions are detected in the secondary beam by the most sensitive method available, namely accelerator mass spectrometry. The specimen is scanned pixel by pixel (1 x 2 microm), generating an image in a manner analogous to scanning electron microscopy. The method can thus be regarded as a specialized form of scanning secondary ion mass spectrometry (SIMS), referred to here as SIAMS (ref. 2). We have used SIAMS to localize the neurotransmitter gamma-aminobutyric acid (GABA) in thin sections of cerebral cortex, and show that it can generate 14C images that are much improved on 14C autoradiography. A scan takes 10-20 min and reveals individual axons, neurons and glial cells at high sensitivity. In principle, the resolution could be increased by up to tenfold, and the method could be extended to some other nuclides.

Key influences on the professional socialisation and practice of students undertaking different pre-registration nurse education programmes in the United Kingdom

A principal aim of pre-registration nurse education programmes is the process of effective socialisation of students into the professional role. Key influences on the professional socialisation and practice of students undertaking such programmes were explored using a semi-structured interview approach (N = 99). This work formed part of a major comparative study of outcomes of pre-registration nurse education programmes in the United Kingdom. Analysis revealed differences between the programmes regarding positive influences of the respective courses; therapeutic influences of the practice environment; modelling performance on exemplars of high quality practice; and the identification of teachers within the educational setting and nurses in practice as key persons. This study has confirmed that the positive influence of the education programmes and the practice environment as well as high quality role models from both education and practice establishments are critical to the professional socialisation of student nurses.

Operationalisation of an observation instrument to explore nurse performance

This paper explores the operationalization of an observation instrument to explore actual situated behaviour in the clinical setting. Challenges encountered during this process and strategies employed to address these difficulties are discussed. This work formed part of a comparative study of outcomes of pre-registration nurse education programmes commissioned by the English National Board for Nursing, Health Visiting and Midwifery.

Analysis of error-correction constraints in an optical disk

The compact disk read-only memory (CD-ROM) is a mature storage medium with complex error control. It comprises four levels of Reed Solomon codes allied to a sequence of sophisticated interleaving strategies and 8:14 modulation coding. New storage media are being developed and introduced that place still further demands on signal processing for error correction. It is therefore appropriate to explore thoroughly the limit of existing strategies to assess future requirements. We describe a simulation of all stages of the CD-ROM coding, modulation, and decoding. The results of decoding the burst error of a prescribed number of modulation bits are discussed in detail. Measures of residual uncorrected error within a sector are displayed by C1, C2, P, and Q error counts and by the status of the final cyclic redundancy check (CRC). Where each data sector is encoded separately, it is shown that error-correction performance against burst errors depends critically on the position of the burst within a sector. The C1 error measures the burst length, whereas C2 errors reflect the burst position. The performance of Reed Solomon product codes is shown by the P and Q statistics. It is shown that synchronization loss is critical near the limits of error correction. An example is given of miscorrection that is identified by the CRC check.

Perisynaptic location of metabotropic glutamate receptors mGluR1 and mGluR5 on dendrites and dendritic spines in the rat hippocampus

Ionotropic and metabotropic (mGluR1a) glutamate receptors were reported to be segregated from each other within the postsynaptic membrane at individual synapses. In order to establish whether this pattern of distribution applies to the hippocampal principal cells and to other postsynaptic metabotropic glutamate receptors, the mGluR1a/b/c and mGluR4 subtypes were localized by immunocytochemistry. Principal cells in all hippocampal fields were reactive for mGluR5, the strata oriens and radiatum of the CA1 area being most strongly immunolabelled. Labelling for mGluR1b/c was strongest on some pyramids in the CA3 area, weaker on granule cells and absent on CA1 pyramids. Subpopulations of non-principal cells showed strong mGluR1 or mGluR5 immunoreactivity. Electron microscopic pre-embedding immunoperoxidase and both pre- and postembedding immunogold methods consistently revealed the extrasynaptic location of both mGluRs in the somatic and dendritic membrane of pyramidal and granule cells. The density of immunolabelling was highest on dendritic spines. At synapses, immunoparticles for both mGluR1 and mGluR5 were found always outside the postsynaptic membrane specializations. Receptors were particularly concentrated in a perisynaptic annulus around type 1 synaptic junctions, including the invaginations at 'perforated' synapses. Measurements of immunolabelling on dendritic spines showed decreasing levels of receptor as a function of distance from the edge of the synaptic specialization. We propose that glutamergic synapses with an irregular edge develop in order to increase the circumference of synaptic junctions leading to an increase in the metabotropic to ionotropic glutamate receptor ratio at glutamate release sites. The perisynaptic position of postsynaptic metabotropic glutamate receptors appears to be a general feature of glutamatergic synaptic organization and may apply to other G-protein-coupled receptors.

Target-cell-specific concentration of a metabotropic glutamate receptor in the presynaptic active zone

The probability of synaptic neurotransmitter release from nerve terminals is regulated by presynaptic receptors responding to transmitters released from the same nerve terminal or from terminals of other neurons. The release of glutamate, the major excitatory neurotransmitter, is suppressed by presynaptic autoreceptors. Here we show that a metabotropic glutamate receptor (mGluR7) in the rat hippocampus is restricted to the presynaptic grid, the site of synaptic vesicle fusion. Pyramidal cell terminals presynaptic to mGluR1alpha-expressing interneurons have at least a ten-fold higher level of presynaptic mGluR7 than terminals making synapses with pyramidal cells and other types of interneuron. Distinct levels of mGluR7 are found at different synapses made by individual pyramidal axons or even single boutons. These results raise the possibility that presynaptic neurons could regulate the probability of transmitter release at individual synapses according to the postsynaptic target.

Regulation of the adhesion of a human breast carcinoma cell line to type IV collagen and vitronectin: roles for lipoxygenase and protein kinase C

We have investigated the regulation of adhesion of metastatic human breast carcinoma cells to various protein substrates in the presence or absence of the protein kinase C (PKC) activator, 12-tetradecanoyl phorbol 13-acetate (TPA) or calcium ionophore A23187 (A23187). Both TPA and A23187 dramatically enhanced MDA-MB-435 cell adhesion to type IV collagen (collagen IV), vitronectin, and, to some extent, fibronectin and laminin. Adhesion to BSA and polylysine were not affected. TPA and A23187 induced substantial dose-dependent effects that were apparent after 30- and 60-min incubations, respectively, whereas a phorbol ester, which does not activate PKC, had no effect. A23187, but not TPA, induced a release of arachidonic acid (AA) from MDA-MB-435 cells. Nordihydroguaiaretic acid, a lipoxygenase inhibitor, prevented A23187 and exogenous AA, but not TPA, from stimulating cell adhesion to collagen IV. In contrast, the increase in adhesion to vitronectin induced by A23187 and AA was, at best, only partially inhibited by nordihydroguaiaretic acid treatment. Calphostin C, a PKC inhibitor, blocked the stimulation of adhesion by A23187, exogenous AA, and TPA to both collagen IV and vitronectin. Together, these results suggest that calcium mobilization activates the release of AA and its metabolism through a lipoxygenase pathway leading to a rapid increase of MDA-MB-435 cell adhesion to collagen IV, whereas other mechanisms regulate adhesion to vitronectin. Finally, PKC activation, occurring downstream from calcium mobilization or the AA effects, is a key event involved in the regulation of adhesion to both proteins.

Bryostatin 1 activates splenic lymphocytes and induces sustained depletion of splenocyte protein kinase C activity in vivo after a single intravenous administration

Bryostatin 1 activates and subsequently down-regulates protein kinase C (PKC) in vitro and has potential use as an immunomodulator and as an anti-cancer agent. Despite extensive examination of its activities in vitro and anti-tumor effects in vivo, previous studies have failed to document that bryostatin 1 modulates total cellular PKC activity in tumor or normal tissues when administered in vivo. After a single bolus injection of bryostatin 1 (1.0 microgram) in normal C57BI/6 mice, blood was drawn at various intervals and assayed for bryostatin 1 levels. In addition, spleens from bryostatin-treated mice were harvested 10 min to 10 days after treatment, weighed and analyzed for cell numbers, PKC activity and cell surface phenotypes. Bryostatin 1 levels in plasma rose rapidly, reaching peak levels of 56.5 nM less than 1 min after injection, and then declined to undetectable levels by 1 h. A similar pattern was observed when bryostatin 1 was incubated with leukemia cells in vitro, raising the possibility that the rapid fall in plasma levels results from intracellular uptake and binding. Bryostatin 1 induced marked depletion of total splenocyte PKC activity (as much as 69% relative to control values) at 24-96 h after drug administration, but not at earlier times (i.e. 1 h). A single injection of bryostatin 1 also induced expression of the T cell activation marker CD69, leading to positivity in 53% of cells at 3-24 h versus 11% in control mice, and resulted in marked splenomegaly, associated with increased numbers of nucleated cells at 48-96 h. Together, these studies demonstrate that despite rapid disappearance of the drug from plasma, a single i.v. dose of bryostatin 1 exhibits significant and sustained effects on normal murine spleen cells, including early lymphocyte activation, prolonged depletion of PKC activity, splenocyte proliferation and splenomegaly. These findings may have implications for attempts to understand the in vivo effects of bryostatin 1 in normal host tissues.

Chronic inhalation of nitric oxide inhibits neointimal formation after balloon-induced arterial injury

Systemic and local intravascular NO administration inhibits neointimal formation after vascular injury in animal models. NO appears to attenuate smooth muscle proliferation both directly and indirectly by preventing the release of growth factors. Inhalation of low concentrations of NO dilates pulmonary vascular smooth muscle but does not cause systemic vasodilatation. Recently, NO inhalation was found to inhibit platelet function in vivo. We studied the effects of NO inhalation on neointimal formation after balloon-induced injury of the adult rat carotid artery. Beginning 60 minutes before carotid injury, rats breathed either air with 0 or 80 ppm NO for 14 days. Rats were killed, carotid arteries were fixed and paraffin-embedded, and neointimal formation was measured by analyzing the ratio of intimal to medial areas (I/M ratio) in carotid artery cross sections. Intimal hyperplasia was evident in both groups of animals, but I/M ratios were 43% less in animals breathing 80 ppm NO for 2 weeks than in animals breathing air alone (0.78 +/- 0.12 and 1.37 +/- 0.11 [mean +/- SE], respectively; P < .02). Similarly, 1 week after carotid injury, neointimal formation was less in rats breathing 80 ppm NO than in rats breathing air alone (I/M ratio, 0.39 +/- 0.11 versus 0.76 +/- 0.06; P < .02). Breathing 20 ppm NO for 2 weeks or 80 ppm NO for 1 week followed by air alone for 1 week did not attenuate neointimal formation measured at 14 days. In anesthetized rats breathing 80 ppm NO or air alone for 1 hour, neither systemic blood pressure nor bleeding time differed. These observations demonstrate that inhaling 80 ppm NO inhibits neointimal formation after balloon-induced carotid artery injury in rats. NO inhalation may represent a safe and novel method of preventing restenosis after percutaneous angioplasty.

Surveillance of vaccine-related adverse events in the first year of life: a Manitoba cohort study

This study used data from the population database through which the province of Manitoba, Canada, administers its universal health insurance plan. Enrollment, hospitalization, and immunization files from children born in the 1987-1989 period were linked using the unique identification number assigned to each population member. Analysis of these linked data successfully identified serious potential adverse events in the first year of life and the timing of events around immunization. Not only is population-based active surveillance for immunization-related events feasible, but the techniques described, applied to years of data accumulated through surveillance, offer powerful research tools. Baseline population incidences of adverse events were calculated, temporal relationships between events and immunization assessed, and incidences for events showing true temporal associations determined. Eventual goals are the quantification of vaccine-related risk and the gathering of evidence concerning casual associations. The approach could be used readily by several other Canadian provinces and by health maintenance organizations in the United States.

Reminding and monitoring: new uses of administrative data for preventive care

This article illustrates how administrative data can be used to improve population health in an environment of fiscal constraint. In our universal single-payer health system, health care providers submit standardized data. This allows provinces to create health information utilities that generate population-based data that can be used for research and health care delivery. Although more study is needed to determine the cost-effectiveness of using such data to raise the rates of primary and secondary prevention, it appears that appropriately designed information systems could improve population health with relatively little additional cost.

An Electrophoretic Investigation of Relationships of Diploid and Tetraploid Species of Australian Desert Frogs Neobatrachus (Anura: Myobatrachidae)

Allozyme electrophoresis of 27 loci was used to characterise genetic variation among 29 populations of six diploid species of the myobatrachid frog genus Neobatrachus. All six species are well differentiated genetically with the percentage of fixed differences between species ranging from 11 to 59%. The genetic data are in agreement with the currently accepted species boundaries. The four tetraploid species were examined for 25 of the 27 loci assayed in the diploid species. In contrast to the diploid species, the tetraploid species shared electromorphs with each other at all the loci examined. The tetraploid species were examined for the presence of electromorphs specific to individual diploid species. The majority of these electromorphs were observed in the tetraploid species. For cases in which the range of a tetraploid species contacts that of a diploid species and the diploid population can be characterised by unique electromorphs, then evidence of current gene flow was found in the direction of the tetraploid populations. The data are compatible with single or multiple discrete or hybrid origins of the tetraploids overlain by gene flow among the tetraploids and between the tetraploids and some and perhaps all of the diploids by means of geographically limited but ongoing episodes of introgressive hybridisation.