3D focusing of nanoparticles in microfluidic channels

Dynamic focusing of particles can be used to centre particles in a fluid stream, ensuring the passage of the particles through a specified detection volume. This paper describes a method for focusing nanoparticles using dielectrophoresis. The method differs from other focusing methods in that it manipulates the particles and not the fluid. Experimental focusing is demonstrated for a range of different particle types, and discussed in terms of the operational limits of the device. Dynamic numerical simulations of the particle motion in the device are presented and compared with the experimental results. The potential of the device for nanoparticle control and manipulation in microfluidic chips is discussed.

Dietary vitamin B12 deficiency in an adolescent white boy

Dietary deficiency of cobalamin resulting in tissue deficiency in white individuals is unusual. However, several patients with dietary deficiency who were neither vegan nor Hindu have been described. This report describes the case of a 14 year old boy who was a white non-Hindu with a very low intake of cobalamin, which was not apparent until a detailed dietary assessment was performed. The patient responded rapidly to a combination of oral and parenteral B12. This case illustrates the fact that severe dietary vitamin B12 deficiency can occur in non-Hindu white individuals. Inadequate dietary content of B12 may not be apparent until a detailed dietary assessment is performed. This patient is likely to have had subclinical vitamin B12 deficiency for several years. Increased vitamin B12 requirements associated with the adolescent growth spurt may have provoked overt tissue deficiency.

Outcomes of patients with chronic renal insufficiency in the bypass angioplasty revascularization investigation

BACKGROUND

Although severe chronic kidney disease (CKD) is an independent predictor of mortality among patients with coronary artery disease, the impact of mild CKD on morbidity and mortality has not been fully defined.

METHODS AND RESULTS

Morbidity and mortality for the 3608 patients with multivessel coronary artery disease enrolled in the Bypass Angioplasty Revascularization Investigation randomized trial and registry were compared on the basis of the presence and absence of CKD, defined as a preprocedure serum creatinine level of >1.5 mg/dL. Seventy-six patients had CKD. Patients with renal insufficiency were older and more likely to have a history of diabetes, hypertension, and other comorbidities. Among patients undergoing PTCA, patients with CKD had a greater frequency of in-hospital death and cardiogenic shock (P<0.05 and 0.01, respectively). There was a trend toward a larger proportion of patients with CKD experiencing angina at 5 years (P=0.079). Patients with CKD had more cardiac admissions (P=0.003 and <0.0001 for patients undergoing PTCA and CABG, respectively) and a shorter time to subsequent CABG after initial revascularization than patients without CKD (P=0.01). CKD was associated with a higher risk of death at 7 years, both of all causes (relative risk 2.2, P<0.001) and of cardiac causes (relative risk 2.8, P<0.001).

CONCLUSIONS

CKD is associated with an increased risk of recurrent hospitalization, subsequent CABG, and mortality. This increased risk of death is independent of and additive to the risk associated with diabetes.

Design of a multiblock phantom for radiotherapy dosimetry applications

This note describes the design of a multiblock semi-anatomic phantom, which lends itself to a variety of radiotherapy dosimetry applications, in particular, the audit of external beam treatment planning and delivery. The basic building blocks of the phantom were formed from a variety of tissue substitute materials and could be assembled in many ways to model different cross-sections through the body.

Prevalence of depression and depression recognition in nursing homes

BACKGROUND

The aim of this study was to estimate the prevalence of depression among nursing home residents, and the extent of depression recognition among nursing home staff. Random samples totaling 319 nursing home residents, drawn from a simple random sample of six downstate New York nursing homes were evaluated psychiatrically for depression. Samples of nurse aides, nurses and social workers also assessed the same residents for the presence of depressive symptomatology.

METHOD

Psychiatrists assessed residents using the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R) criteria. Depression measures used were the Cornell Scale for Depression in Dementia, the Feeling Tone Questionnaire, the Hamilton Depression Rating and the Structured Clinical Interview for DSM-III-R Personality Disorders Scale. Nursing and social services staff assessed residents using Depression Recognition Measures.

RESULTS

Based on psychiatric evaluation, the prevalence estimate for probable and/or definite major depressive disorder among testable subjects was 14.4% (95% CI of 10.6%-19.3%); 15.4% were not able to be assessed due to their refusal, impairment of consciousness, or severe physical illness. The estimate for minor depression was 16.8% (95% CI of 12.6%-21.9%). The prevalence of significant depressive symptomatology (including the category of possible depression) was 44.2% (95% CI of 38.2%-50.3%). The corresponding estimates of any depression were 19.7% for social workers, 29% for nurses and 32.1% for nurse aides.

CONCLUSIONS

The prevalence of depressive disorders among nursing home residents is high; depression recognition is relatively low, with only 37%-45% of cases diagnosed by psychiatrists recognized as depressed by staff. A structured Depression Recognition Scale increased the rates of recognition (sensitivity of staff ratings) to 47%-55%, demonstrating the utility of the scale in increasing awareness of symptomatology.

The dielectrophoretic levitation and separation of latex beads in microchips

A linear travelling wave dielectrophoretic (twDEP) microchip was fabricated and used to investigate both the levitation and the twDEP motion of latex beads as a function of applied potential and frequency, suspending medium conductivity, bead size, and surface characteristics. The surface conductance of the latex beads was characterised by measurement of the dielectrophoretic (DEP) crossover frequency. Collection of sample prior to initiation of twDEP was achieved using positive DEP forces generated by an integrated pair of parallel electrodes positioned in front of the twDEP array within the microfluidic channel. The principle of linear twDEP separation is shown using latex beads and rabbit heart cells.

Forensic Psychiatric Nursing: Discursive Practices and the Emergence of a Specialty

1. While some authors argue that specialization is a threat to holistic nursing practice, others suggest that specialization is not only desirable and inevitable but should follow a rigorous process, including specific educational curriculum and examination procedures. 2. Two opposing views regarding forensic nursing are found in contemporary nursing literature. Some authors resist the discourse of specialization in nursing, while the discursive practices of others (e.g., leaders in forensic psychiatric nursing) could reflect a desire for power. 3. Using a poststructuralist approach, the controversy that has accompanied the development of forensic nursing through discursive practices is analyzed.

Is the molecular composition of K(ATP) channels more complex than originally thought?

ATP-sensitive K+ (K(ATP)) channels are abundantly expressed in the heart and may be involved in the pathogenesis of myocardial ischemia. These channels are heteromultimeric, consisting of four pore-forming subunits (Kir6.1, Kir6.2) and four sulfonylurea receptor (SUR) subunits in an octameric assembly. Conventionally, the molecular composition of K(ATP) channels in cardiomyocytes and pancreatic beta -cells is thought to include the Kir6.2 subunit and either the SUR2A or SUR1 subunits, respectively. However, Kir6.1 mRNA is abundantly expressed in the heart, suggesting that Kir6.1 and Kir6.2 subunits may co-assemble to form functional heteromeric channel complexes. Here we provide two independent lines of evidence that heteromultimerization between Kir6.1 and Kir6.2 subunits is possible in the presence of SUR2A. We generated dominant negative Kir6 subunits by mutating the GFG residues in the channel pore to a series of alanine residues. The Kir6.1-AAA pore mutant subunit suppressed both wt-Kir6.1/SUR2A and wt-Kir6.2/SUR2A currents in transfected HEK293 cells. Similarly, the dominant negative action of Kir6.2-AAA does not discriminate between either of the wild-type subunits, suggesting an interaction between Kir6.1 and Kir6.2 subunits within the same channel complex. Biochemical data support this concept: immunoprecipitation with Kir6.1 antibodies also co-precipitates Kir6.2 subunits and conversely, immunoprecipitation with Kir6.2 antibodies co-precipitates Kir6.1 subunits. Collectively, our data provide direct electrophysiological and biochemical evidence for heteromultimeric assembly between Kir6.1 and Kir6.2. This paradigm has profound implications for understanding the properties of native K(ATP)channels in the heart and other tissues.

Towards a fibrous composite with dynamically controlled stiffness: lessons from echinoderms

Sea urchins and sea cucumbers, like other echinoderms, control the tensile properties of their connective tissues by regulating stress transfer between collagen fibrils. The collagen fibrils are spindle-shaped and up to 1 mm long with a constant aspect ratio of approx. 2000. They are organized into a tissue by an elastomeric network of fibrillin microfibrils. Interactions between the fibrils are regulated by soluble macromolecules that are secreted by local, neurally controlled, effector cells. We are characterizing the non-linear viscoelastic properties of sea cucumber dermis under different conditions, as well as the structures, molecules and molecular interactions that determine its properties. In addition, we are developing reagents that will bind covalently to fibril surfaces and reversibly form cross-links with other reagents, resulting in a chemically controlled stress-transfer capacity. The information being developed will lead to the design and construction of a synthetic analogue composed of fibres in an elastomeric matrix that contains photo- or electro-sensitive reagents that reversibly form interfibrillar cross-links.

From iron gaze to nursing care: mental health nursing in the era of panopticism

The purpose of this paper is to question the utilization of mechanical devices (cameras and microphones) to ensure the surveillance of hospitalized patients on psychiatric wards. The works of French philosopher, Michel Foucault, and those of nursing theorist, Jean Watson, are used to support this analysis. A growing number of Canadian psychiatric health care institutions are using mechanical devices for surveillance. The security of staff and patients as well as therapeutic purposes are stated as rationale for these practices. However, a Foucauldian perspective leads us to think otherwise. The metaphor of the panopticon is then used to uncover another reality: a disciplinary one. Within the scope of this paper, the question of surveillance, disciplinary power, caring philosophy, and mental health nursing will be examined.

Titin and the sarcomere symmetry paradox

Titin is thought to play a major role in myofibril assembly, elasticity and stability. A single molecule spans half the sarcomere and makes interactions with both a thick filament and the Z-line. In the unit cell structure of each half sarcomere there is one thick filament with 3-fold symmetry and two thin filaments with approximately 2-fold symmetry. The minimum number of titin molecules that could satisfy both these symmetries is 12. We determined the actual number of titin molecules in a unit cell from scanning transmission electron microscopy mass measurements of end-filaments. One of these emerges from each tip of the thick filament and is thought to be the in-register aggregate of the titin molecules associated with the filament. The mass per unit length of the end-filament (17.1 kDa/nm) is consistent with six titin molecules not 12. Thus the number of titin molecules present is insufficient to satisfy both symmetries. We suggest a novel solution to this paradox in which four of the six titin molecules interact with the two thin filaments in the unit cell, while the remaining two interact with the two thin filaments that enter the unit cell from the adjacent sarcomere. This arrangement would augment mechanical stability in the sarcomere.

Purification, crystallization and quaternary structure analysis of a glycerol dehydrogenase S305C mutant from Bacillus stearothermophilus

Bacillus stearothermophilus glycerol dehydrogenase (GlyDH) is a 39.5 kDa molecular weight metalloenzyme which catalyzes the oxidation of glycerol to dihydroxyacetone with the concomitant reduction of NAD(+) to NADH. Despite its classification as a member of the 'iron-containing' polyol dehydrogenase family, studies on recombinant B. stearothermophilus GlyDH have shown this enzyme to be Zn(2+)-dependent. Crystals of a S305C GlyDH mutant were obtained by the hanging-drop vapour-diffusion method, using ammonium sulfate and PEG 400 as precipitating agents, in the presence and absence of NAD(+). The crystals belong to space group I422, with approximate unit-cell parameters a = b = 105, c = 149 A and one subunit in the asymmetric unit, corresponding to a packing density of 2.6 A(3) Da(-1). The crystals diffract X-rays to at least 1.8 A resolution on a synchrotron-radiation source. Determination of the structure will provide insights into the key determinations of catalytic activity of this class of enzymes, for which no structures are currently available.

Quantification of the selective retention of palladium octabutoxynaphthalocyanine, a potential photothermal drug, in mouse tissues

Palladium octabutoxynaphthalocyanine (PdNc(OBu)8) is a potential photothermal therapy (PTT) agent, absorbing strongly in the near-infrared region with no ability to induce photodynamic-type sensitisation (unlike many related napthalocyanines). We report here on the application of high pressure liquid chromatography (HPLC) with near-infrared absorption detection for the determination of the tissue accumulation and clearance of PdNc(OBu)8 in a tumour-bearing mouse model (Balb/c mice with EMT6 carcinoma tumour). Due to its insolubility in aqueous-based solvents, the drug was delivered intraperitoneally in a Cremophor-containing vehicle. Good selective accumulation of the drug into the tumour versus muscle or skin is observed, with the best combination of selectivity and tumour concentration occurring at 24-72 h after drug administration. Clearance times are quite long. Comparison with other similar drugs as reported in the literature indicates that the Cremophor-containing vehicle is likely in large part responsible for the observed pharmacokinetic behaviour. This drug shows potential for PTT and will be investigated further for therapy in this animal model.

Image quality assessment in contemporary interventional cardiology laboratories: spatial and low-contrast video resolution

Two measures of fluoroscopic image quality-high-contrast video spatial resolution and low-contrast video resolution-were assessed in 64 interventional cardiology catheterization laboratories. The results of high-contrast spatial resolution testing indicate variable levels of performance with median values of 1.5, 2.0, and 2.5 line pairs/mm at the three levels of magnification. The results of the low-contrast video resolution testing indicate clinically relevant limitations in performance. This was particularly true when testing was performed in a dynamic mode under simulated large patient conditions. Under these conditions, 50% of systems failed to detect a wire of diameter 0.017". In addition, limited system dynamic range was identified in a substantial fraction of laboratories and may contribute to these important variations in performance. Taken together, these findings serve to characterize overall system performance in the current era of interventional cardiology and reaffirm the continued need for image quality assessment programs.

Functional analysis of gapped microbial genomes: amino acid metabolism of Thiobacillus ferrooxidans

A gapped genome sequence of the biomining bacterium Thiobacillus ferrooxidans strain ATCC23270 was assembled from sheared DNA fragments (3.2-times coverage) into 1,912 contigs. A total of 2,712 potential genes (ORFs) were identified in 2.6 Mbp (megabase pairs) of Thiobacillus genomic sequence. Of these genes, 2,159 could be assigned functions by using the WIT-Pro/EMP genome analysis system, most with a high degree of certainty. Nine hundred of the genes have been assigned roles in metabolic pathways, producing an overview of cellular biosynthesis, bioenergetics, and catabolism. Sequence similarities, relative gene positions on the chromosome, and metabolic reconstruction (placement of gene products in metabolic pathways) were all used to aid gene assignments and for development of a functional overview. Amino acid biosynthesis was chosen to demonstrate the analytical capabilities of this approach. Only 10 expected enzymatic activities, of the nearly 150 involved in the biosynthesis of all 20 amino acids, are currently unassigned in the Thiobacillus genome. This result compares favorably with 10 missing genes for amino acid biosynthesis in the complete Escherichia coli genome. Gapped genome analysis can therefore give a decent picture of the central metabolism of a microorganism, equivalent to that of a complete sequence, at significantly lower cost.

The PRESTO (Prevention of restenosis with tranilast and its outcomes) protocol: a double-blind, placebo-controlled trial

BACKGROUND

Tranilast is a unique drug in clinical development for the prevention of restenosis after percutaneous transluminal coronary revascularization (PTCR). Tranilast interferes with proliferation and migration of vascular medial smooth muscle cells induced by platelet-derived growth factor and transforming growth factor beta1. Collagen synthesis in vascular medial smooth muscle cells is inhibited by tranilast, which also inhibits the release or production of cyclooxygenase-2 and restores cytokine-induced nitric oxide production. These mechanisms may contribute to the reduction of angiographic restenosis after coronary intervention previously reported in clinical studies.

METHODS

The primary objective of this multicenter study of 11,500 patients is to compare the composite clinical event rate of death, myocardial infarction, or the need for ischemia-driven target vessel revascularization of tranilast (300 and 450 mg twice daily) for 1 or 3 months with that of placebo in patients undergoing PTCR with or without stenting for single or multiple vessels over a 9-month period. The lesions can be de novo or restenotic. All revascularization procedures and the use of glycoprotein IIb/IIIa agents are permitted. The inclusion criteria are meant to allow an "all comer" approach for generalization of results to the broadest possible PTCR population. A subset population (n = 2000) will undergo 9-month follow-up angiography, 1000 of which will also undergo intravascular ultrasound (n = 1000). This study is the first tranilast trial to be conducted in a Western population to confirm the improved angiographic findings reported in Japanese patients and to determine if the clinical sequelae of restenosis are also reduced.

CONCLUSION

This multicenter study is the largest restenosis trial planned to date. It will test whether tranilast, a drug with multiple actions aimed at affecting proliferation and migration of vascular smooth muscle cells, can reduce clinical, angiographic, and intravascular ultrasound assessments of restenosis.

Foucault and nursing: a history of the present

While a commitment to the development of nursing theory has been a significant force in nursing scholarship, particularly in the US, the authors have noted a recent trend among nurses in different countries to develop Foucauldian interpretations of nursing. The objective of this paper is to identify those publications by nurses that employ a Foucauldian perspective and to provide a useful summative review of these works to date, which illustrate the potential contribution of a Foucauldian reading of nursing. The authors have reviewed 27 publications written by nurses which present a Foucauldian analysis. These publications were issued between 1987 and 1998 in English, Portuguese and German. The most frequent concepts treated in the literature reviewed are power/knowledge, surveillance, discourse, discipline, resistance, docile bodies, clinical gaze, and panopticon. The literature reviewed illustrates that Foucault's concepts can have a profound impact on the way we conceive of nursing as a discipline and as a profession. Nursing care becomes a political event, nursing knowledge contributes to the dissemination of regimes of truth, and nurses, rather than being powerless, are perceived as professionals who exercise power over life in society. A Foucauldian reading of nursing enables nurses to move into a broader interdisciplinary and critical scholarship.

Use of latent class analyses for the estimation of prevalence of cognitive impairment, and signs of stroke and Parkinson's disease among African-American elderly of central Harlem: results of the Harlem Aging Project

A probability sample (response rate of 79.4%) of 164 African-American elderly residing in central Harlem was assessed using several standard cognitive screening measures and scales measuring stroke and Parkinson's symptoms, respectively. Both traditional cutting scores and the methods of latent class analysis were used to estimate point prevalence. The latent class prevalence ratio estimates range from 10 to 14%. The confidence intervals for cognitive impairment ranged from 5 to 18% with an average estimate of 12%. The latent class estimate for stroke effects was 11% and for two measures of neurological signs associated with Parkinson's disease 7 and 12%. About 2-3% of the sample were communication disordered, and 5% had significant ambulation disorder. These results indicate that a relatively large proportion of elderly community residents of central Harlem evidenced or reported health problems, any or all of which may constitute a public health challenge.

Catheter-based reperfusion of unprotected left main stenosis during an acute myocardial infarction (the ULTIMA experience). Unprotected Left Main Trunk Intervention Multi-center Assessment

The ULTIMA registry was a prospective, multicenter, international registry of 277 patients who underwent percutaneous coronary interventions of unprotected left main trunk stenosis. The 40 patients who underwent an emergency percutaneous left main intervention for acute myocardial infarction are the focus of this study. We compared the results of primary angioplasty with primary stenting, characterizing both the short-term (in-hospital) and long-term (12-month) outcomes. Of the 40 patients, 23 underwent primary angioplasty, whereas 17 underwent primary stenting. The angiographic success rate was an 88% for the cohort. The in-hospital death or coronary artery bypass grafting rate was 65% for the entire group, 74% for the percutaneous transluminal coronary angioplasty group (PTCA), and 53% for the stent group (p = 0.2). The in-hospital death rate was 55% for the entire cohort, 70% for the PTCA group, and 35% for the stent group (p = 0.1). The 12-month rate of death or bypass surgery was 83% and 58% for the PTCA and stent groups, respectively (p = 0.047). The 12-month survival rate was 35% and 53% for the PTCA and stent groups, respectively (p = 0.18). Bypass surgery was required in 6 patients in the PTCA group and 2 patients in the stent group (p = 0.07). Patients undergoing percutaneous interventions for unprotected left main myocardial stenosis during an acute myocardial infarction are critically ill; an initial percutaneous revascularization approach appears feasible and may be the preferred revascularization strategy. Primary stenting was associated with improved clinical outcomes.

Identification and cloning of TWIK-originated similarity sequence (TOSS): a novel human 2-pore K+ channel principal subunit

We have identified and cloned a new member of the mammalian tandem pore domain K+ channel subunit family, TWIK-originated similarity sequence, from a human testis cDNA library. The 939 bp open reading frame encodes a 313 amino acid polypeptide with a calculated Mr of 33.7 kDa. Despite the same predicted topology, there is a relatively low sequence homology between TWIK-originated similarity sequence and other members of the mammalian tandem pore domain K+ channel subunit family group. TWIK-originated similarity sequence shares a low (< 30%) identity with the other mammalian tandem pore domain K+ channel subunit family group members and the highest identity (34%) with TWIK-1 at the amino acid level. Similar low levels of sequence homology exist between all members of the mammalian tandem pore domain K+ channel subunit family. Potential glycosylation and consensus PKC sites are present. Northern analysis revealed species and tissue-specific expression patterns. Expression of TWIK-originated similarity sequence is restricted to human pancreas, placenta and heart, while in the mouse, TWIK-originated similarity sequence is expressed in the liver. No functional currents were observed in Xenopus laevis oocytes or HEK293T cells, suggesting that TWIK-originated similarity sequence may be targeted to locations other than the plasma membrane or that TWIK-originated similarity sequence may represent a novel regulatory mammalian tandem pore domain K+ channel subunit family subunit.

Who calls 999 and why? A survey of the emergency workload of the London Ambulance Service

BACKGROUND

In 1996-97 there were 623,000 emergency (999) calls made to the London Ambulance Service (LAS) and this represents a 30% increase over the previous five years. The reasons for this increase, which is also observed nationally, remain unknown. It has been suggested that some callers may be using the 999 service "inappropriately" but no data are available from the ambulance service.

OBJECTIVE

To describe the workload of the emergency ambulance service in London with specific reference to the nature and characteristics of 999 calls, to determine who dials 999 and why, and to establish the number and types of calls that could most appropriately be dealt with by other agencies.

DESIGN

A one week census of all emergency calls responded to by the LAS.

SETTING

Sixty eight LAS stations.

METHODS

Collation of all routine LAS incident forms (LA4) including the classification of the crews' free text description of the incident. This was supplemented by a detailed workload questionnaire for 25% of calls.

RESULTS

There were 10,921 calls responded to from 29 April to 5 May 1996. The census showed that the daily number of calls was highest on Saturday and lowest on Wednesday with about half being made during normal general practitioner (GP) working hours. Half of all calls were for women and one third were for people aged > or = 65. Accidents were the commonest type of incident (24%). The remainder comprised various medical conditions such as respiratory, cardiac, and obstetric problems. In 1.5% of calls there was no illness, injury, or assistance required and 5% were for "general assistance" and mostly concerned people aged > or = 65. The workload survey indicated that two thirds of incidents occurred at home and 70% of callers had not tried to contact a GP before dialing 999. In the professional opinion of the responding crew, 60% of calls required a 999 response, with the remainder thought more appropriately dealt with by other services such as primary care, psychiatric services, and social services.

CONCLUSIONS

This study suggests that while the majority of 999 calls were "appropriate", part of the 999 workload could be dealt with by other services. More research is required to clarify why people contact the 999 service for non-emergency incidents and also to establish the views of GPs and other agencies as to the role and function of the IAS.