"Mood rings": a new method of objective clinical assessment of peripheral nerve injuries

The clinical assessment of patients with peripheral nerve injury is primarily dependent on subjective clinical examination. We aimed to assess whether a thermotropic liquid crystal ring (TLC-ring) could provide the basis for an objective assessment of peripheral nerve injury by detecting temperature changes in the digits innervated by the damaged nerve. A group of patients with known median, ulnar or both digital nerve injuries were compared against a control group. TLC-rings, marketed to the general public as "mood rings", were applied to the affected and unaffected digits and the colour change recorded. Areas with nerve damage showed a statistically significant difference in colour response to those without damage. This study establishes the ability of TLCs to detect cutaneous temperature changes associated with peripheral nerve injuries. Further studies and improvements are needed to refine TLC as an acute assessment tool for peripheral nerve injuries.

Thermometric diagnosis of peripheral nerve injuries. Assessment of the diagnostic accuracy of a new practical technique

The diagnosis of nerve injury using thermotropic liquid crystal temperature strips was compared blindly and prospectively against operative findings in 36 patients requiring surgical exploration for unilateral upper limb lacerations with suspected nerve injury. Thermotropic liquid crystal strips were applied to affected and non-affected segments in both hands in all subjects. A pilot study showed that a simple unilateral laceration without nerve injury results in a cutaneous temperature difference between limbs, but not within each limb. Thus, for detection of a nerve injury, comparison was made against the unaffected nerve distribution in the same hand. Receiver operating characteristic curve analysis showed that an absolute temperature difference > or = 1.0 degrees C was diagnostic of a nerve injury (area under the curve = 0.985, sensitivity = 100%, specificity = 93.8%). Thermotropic liquid crystal strip assessment is a new, reliable and objective method for the diagnosis of traumatic peripheral nerve injuries. If implemented in the acute setting, it could improve the reliability of clinical assessment and reduce the number of negative surgical explorations.

Reduction of the posterior pelvic ring by non-invasive stabilisation: a report of two cases

We demonstrate radiological evidence that an external pelvic splint is effective at reducing open book pelvic fractures. Its use in the pre-hospital and emergency department settings should be encouraged in the initial management and resuscitation of patients with pelvic fractures.

The fission yeast Taz1 protein protects chromosomes from Ku-dependent end-to-end fusions

A paramount role of telomeres is to prevent chromosome fusions. The fission yeast Taz1 protein regulates diverse telomere functions but is not essential for growth under stress-free conditions. Strikingly, however, taz1(-) cells exhibit lethal telomere fusions when subjected to nitrogen starvation, a treatment that induces an uncommitted G1 state. These fusions are formed by Ku-dependent nonhomologous end joining. Fusions also occur during normal growth in taz1(-) cells that lack rad22(+), a gene involved in homologous recombination. Our data suggest a model whereby taz1(-) telomeres are exposed to the prevailing mode of DNA repair, which is dictated by the cell cycle. Thus, Taz1 caps chromosome ends and provides the telomerespecific interaction that prevents Ku from treating telomeres as double-strand breaks.

Peptide and peptide mimetic inhibitors of antigen presentation by HLA-DR class II MHC molecules. Design, structure-activity relationships, and X-ray crystal structures

Molecular features of ligand binding to MHC class II HLA-DR molecules have been elucidated through a combination of peptide structure-activity studies and structure-based drug design, resulting in analogues with nanomolar affinity in binding assays. Stabilization of lead compounds against cathepsin B cleavage by N-methylation of noncritical backbone NH groups or by dipeptide mimetic substitutions has generated analogues that compete effectively against protein antigens in cellular assays, resulting in inhibition of T-cell proliferation. Crystal structures of four ternary complexes of different peptide mimetics with the rheumatoid arthritis-linked MHC DRB10401 and the bacterial superantigen SEB have been obtained. Peptide-sugar hybrids have also been identified using a structure-based design approach in which the sugar residue replaces a dipeptide. These studies illustrate the complementary roles played by phage display library methods, peptide analogue SAR, peptide mimetics substitutions, and structure-based drug design in the discovery of inhibitors of antigen presentation by MHC class II HLA-DR molecules.

Telomere transitions in yeast: the end of the chromosome as we know it

Telomere functions vary as the cell cycle progresses. Recent results highlight fluctuating associations between telomeres and DNA polymerases, DNA-damage repair proteins, and centrosome components. These associations reflect diverse roles of telomeres in chromosome maintenance and in the orchestration of chromosome movements during meiosis.

A peroxisome proliferator-activated receptor gamma ligand inhibits adipocyte differentiation

The peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors that regulate glucose and lipid homeostasis. The PPARgamma subtype plays a central role in the regulation of adipogenesis and is the molecular target for the 2, 4-thiazolidinedione class of antidiabetic drugs. Structural studies have revealed that agonist ligands activate the PPARs through direct interactions with the C-terminal region of the ligand-binding domain, which includes the activation function 2 helix. GW0072 was identified as a high-affinity PPARgamma ligand that was a weak partial agonist of PPARgamma transactivation. X-ray crystallography revealed that GW0072 occupied the ligand-binding pocket by using different epitopes than the known PPAR agonists and did not interact with the activation function 2 helix. In cell culture, GW0072 was a potent antagonist of adipocyte differentiation. These results establish an approach to the design of PPAR ligands with modified biological activities.

N-(2-Benzoylphenyl)-L-tyrosine PPARgamma agonists. 3. Structure-activity relationship and optimization of the N-aryl substituent

3-¿4-[2-(Benzoxazol-2-ylmethylamino)ethoxy]phenyl¿-(2S)-((2- benzoylph enyl)amino)propionic acid (1) and (2S)-((2-benzoylphenyl)amino)-3-¿4-[2-(5-methyl-2-phenyloxazol-4-y l)e thoxy]phenyl¿propionic acid (2) are peroxisome proliferator-activated receptor gamma (PPARgamma) agonists and have antidiabetic activity in rodent models of type 2 diabetes. As part of an effort to develop the SAR of the N-2-benzoylphenyl moiety of 1 and 2, a series of novel carboxylic acid analogues, 23-66, modified only in the N-2-benzoylphenyl moiety were synthesized from L-tyrosine and evaluated as PPARgamma agonists. In general, only modest changes in the N-2-benzoylphenyl moiety of 1 and 2 are tolerated. More specifically, the best changes involve bioisosteric replacement of one of the two phenyl rings of this moiety. Addition of substituents to this moiety generally produced compounds that are less active in the cell-based functional assays of PPARgamma activity although binding affinity to PPARgamma may be maintained. A particularly promising set of analogues is the anthranilic acid esters 63-66 in which the phenyl ring in the 2-benzoyl group of 1 and 2 has been replaced by an alkoxy group. In particular, (S)-2-(1-carboxy-2-¿4-[2-(5-methyl-2-phenyloxazol-4-yl)ethoxy]phen yl¿ ethylamino)benzoic acid methyl ester (63) has a pKi of 8.43 in the binding assay using human PPARgamma ligand binding domain and a pEC50 of 9.21 in the in vitro murine lipogenesis functional assay of PPARgamma activity. Finally, 63 was found to normalize glycemia when dosed at 3 mg/kg bid po in the Zucker diabetic fatty rat model of type 2 diabetes.

Two modes of survival of fission yeast without telomerase

Deletion of the telomerase catalytic subunit gene trt1+ in Schizosaccharomyces pombe results in death for the majority of cells, but a subpopulation survives. Here it is shown that most survivors have circularized all of their chromosomes, whereas a smaller number maintain their telomeres presumably through recombination. When the telomeric DNA-binding gene taz1+ is also deleted, trt1- taz1- survivors use the recombinational mode more frequently. Moreover, the massive elongation of telomeres in taz1- cells is absent in the double mutant. Thus, Taz1p appears to regulate telomeric recombination as well as telomerase activity in fission yeast.

Design and synthesis of small molecule interleukin-1 receptor antagonists based on a benzene template

The interleukin-1 proteins (IL-1 alpha and IL-1 beta) are key mediators of inflammatory and immunological responses, and several in vitro and in vivo studies with protein-based antagonists have demonstrated the potential usefulness of IL-1 receptor antagonists to treat various inflammation related diseases. Based on the X-ray crystal structures of IL-1 ligands and site-directed mutagenesis data, a noncontiguous binding epitope encompassing Arg4, Phe46, Ile56, Lys93, Lys103, and Glu105 for IL-1 beta was proposed. In this paper we describe the synthesis and binding assay results of small molecule IL-1 receptor antagonists designed on the basis of the three-dimensional structure of the binding epitope. Among these, the compound 45 was found to inhibit IL-alpha binding to the Type I receptor with an IC50 value of 3 microM. A hypothesis generated using BioCad CATALYST program is also presented to rationalize these observations.

Fission yeast Taz1 protein is required for meiotic telomere clustering and recombination

The alignment of homologous chromosomes during meiosis is essential for their recombination and segregation. Telomeres form and protect the ends of eukaryotic linear chromosomes, and are composed of tandem repeats of a simple DNA sequence and the proteins that bind to these repeats. A role for telomeres in meiosis was suspected from observations of telomere clustering in meiotic cells, and has now been supported experimentally by the dramatic rearrangement of telomere locations during premeiotic stages in fission yeast. Here we show that the fission yeast telomere protein, Taz1, is required for stable association between telomeres and spindle pole bodies during meiotic prophase. In the absence of Taz1, telomere clustering at the spindle pole bodies is disrupted, meiotic recombination is reduced, and both spore viability and the ability of zygotes to re-enter mitosis are impaired to a level that would be expected if chromosome segregation were occurring randomly. Such telomeric association mediated by telomere-specific proteins may also be important for proper chromosome alignment and recombination during meiosis in humans.

Prolonged asystole induced by head up tilt test. Report of four cases and brief review of the prognostic significance and medical management

Head up tilt is an established test for assessing patients with vasovagal syncope. Prolonged asystole during the test has previously been reported in patients suffering from the malignant form of this syndrome. Little is known about the prognostic significance of this response and there is no consensus about the optimum treatment. Four such patients are reported who were treated pharmacologically. During follow up they remained free from major events and their symptoms were well controlled. Conservative management is the initial method of choice and only if this fails should implantation of a dual chamber permanent pacemaker be considered.

Regulation of telomere length and function by a Myb-domain protein in fission yeast

Telomeres, the specialized nucleoprotein structures that comprise the ends of eukaryotic chromosomes, are essential for complete replication, and regulation of their length has been a focus of research on tumorigenesis. In the budding yeast Saccharomyces cerevisiae, the protein Rap1p binds to telomeric DNA and functions in the regulation of telomere length. A human telomere protein, hTRF (human TTAGGG repeat factor) binds the telomere sequence in vitro and localizes to telomeres cytologically, but its functions are not yet known. Here we use a genetic screen to identify a telomere protein in fission yeast, Taz1p (telomere-associated in Schizosaccharomyces pombe), that shares homology to the Myb proto-oncogene DNA-binding domain with hTRF. Disruption or deletion of the taz1+ gene causes a massive increase in telomere length. Taz1p is required for the repression of telomere-adjacent gene expression and for normal meiosis or sporulation. It may be a negative regulator of the telomere-replicating enzyme, telomerase, or may protect against activation of telomerase-independent pathways of telomere elongation.

Bacterial endocarditis involving a subaortic membrane

A subaortic membrane predisposes to bacterial endocarditis usually affecting the aortic valve and left ventricular outflow tract. Endocarditis involving the subaortic membrane itself has been described twice only; once at operation and once at postmortem. The case of a man with vegetations involving a subaortic membrane that were detected preoperatively and the echocardiographic appearances of these findings are reported.

Human isotype antibody responses to an Onchocerca volvulus glutathione S-transferase

Human isotype specific antibody responses to a recombinant pi-class glutathione S-transferase (Ov24) from Onchocerca volvulus were assessed by ELISA, using a large and well-characterized bank sera (n = 238) from an hyper-endemic area of moderate intensity from Sierra Leone. IgG1, IgG4 and IgA responses, but neither IgG2 nor IgE response, to Ov24 were detected in infected subjects. The relationships between Ov24 antibody levels and skin microfilarial density, number of nodules, age, sex, eosinophil counts and clinical sign of reactive and chronic pathology were analysed using Pearson's correlation coefficient. Significant correlations between both IgA and IgG3 antibody levels and age were found (P < 0.01). Although no firm conclusions could be drawn from this study sample regarding the relationships between antibody levels and parasite load or clinical status, a negative correlation (P = 0.06) between Ov24 IgG3 antibody levels and microfilarodermia was found.

Systemic sclerosis associated with right ventricular cardiomyopathy

Systemic sclerosis is an uncommon multisystem disorder of unknown aetiology which predominantly affects the skin. Cardiac involvement, which is far more common than was originally realized, may affect any part of the heart but most frequently affects the left ventricular myocardium. Right ventricular dysfunction is usually associated with pulmonary vascular disease. We report a case of systemic sclerosis associated with right ventricular cardiomyopathy in whom pulmonary artery pressures were normal.

Impaired matching of perfusion and ventilation in heart failure detected by 133xenon

In severe chronic heart failure (CHF) the ventilatory cost of CO2 elimination during exercise (VE/VCO2) is increased, suggesting ventilation/perfusion (V/Q) mismatch. The relationship of exercise VE/VCO2 regression slope m to deadspace ventilation was studied in 15 patients with CHF who underwent cardiopulmonary exercise testing and arterial blood gas monitoring. Regional lung ventilation and perfusion was studied, using 133xenon, at rest and peak exercise in a further group of 10 CHF patients and in five normal subjects. VE/VCO2 slope m correlated well with deadspace ventilation at peak exercise in the 15 patients with CHF. We therefore used exercise VE/VCO2 slope m to categorize CHF patients undergoing 133xenon imaging into groups with increased (slope m > 36) or normal (slope m < 36) exercise deadspace ventilation. In normals, resting V/Q determined by 133xenon showed a gravitational gradient, which improved on exercise as a result of relative increases and of relative reductions in regional perfusion; no significant changes in regional ventilation distribution were detected. In patients with CHF who had normal slope m (n = 5), rest and exercise V/Q were similar to the normal subjects. In CHF patients with increased slope m (n = 5) however, the resting gravitational gradient of V/Q was lost, and there were no significant changes in relative perfusion distribution on exercise. These findings suggest that the increased ventilatory cost of CO2 elimination found in certain patients with CHF is related to inability to coordinate and optimise the relative distribution of lung perfusion with respect to ventilation during exercise.

How do the clinical findings in patients with pericardial effusions influence the success of aspiration?

OBJECTIVE

To identify features associated with success or failure of aspiration of pericardial effusion.

METHOD

A retrospective analysis of 36 drainage procedures in 30 patients with pericardial effusion was performed using patient records and echocardiograms.

RESULTS

Unsuccessful aspiration was associated with pericardial loculation but not with the seniority of the operator or the size and position of the effusion. Pericardiocentesis relieved symptoms of breathlessness in 21 of 26 patients who had a pericardial effusion suspected of causing dyspnoea. These 21 patients had few clinical or echocardiographic signs of classic tamponade.

CONCLUSION

The paucity of abnormal physical or echocardiographic signs of tamponade in breathless patients with pericardial effusion does not exclude symptomatic benefit being derived from pericardiocentesis. Pericardial aspiration is safe in appropriate hands, although aspiration of loculated effusions may not be as successful as aspiration of non-loculated effusions.

Complications of transvenous temporary pacemaker insertion

The indications for temporary pacemaker insertion are more widely documented than the complications. Awareness of the potential complications allows quicker diagnosis and may therefore be lifesaving. This article provides a practical guide to overcoming the complications of pacemaker insertion.

Permanent pacing in patients with tricuspid valve replacements

OBJECTIVE

To assess the incidence and complications of permanent pacing in patients who undergo tricuspid valve replacement.

DESIGN

A retrospective study of records of patients who had a tricuspid valve replacement between 1978 and 1993 at the Middlesex hospital.

RESULTS

45 patients with tricuspid valve replacements were followed up for a total of 104 patient years. Ten patients (22%) required permanent pacing, five with epicardial leads and five with endocardial. Endocardial leads had significantly lower initial implantation thresholds and were associated with fewer complications.

CONCLUSION

Patients undergoing tricuspid valve replacement frequently require permanent pacing. Endocardial or epicardial lead insertion should be considered at the time of tricuspid valve replacement.

Life-threatening, localized angio-oedema associated with streptokinase

We report what we believe to be the first documented case of localized angio-oedema of the upper airway secondary to streptokinase.

The global transcriptional regulators, SSN6 and TUP1, play distinct roles in the establishment of a repressive chromatin structure

Repression of a-cell specific gene expression in yeast alpha cells requires MAT alpha 2 and MCM1, as well as two global repressors, SSN6 and TUP1. Previous studies demonstrated that nucleosomes positioned adjacent to the alpha 2/MCM1 operator in alpha cells directly contribute to repression. To investigate the possibility that SSN6 and TUP1 provide a link between MAT alpha 2/MCM1 and neighboring histones, nucleosome locations were examined in ssn6 and tup1 alpha cells. In both cases, nucleosome positions downstream of the operator were disrupted, and the severity of the disruption correlated with the degree of derepression. Nevertheless, the observed changes in chromatin structure were not dependent on transcription. Our data strongly indicate that SSN6 and TUP1 directly organize repressive regions of chromatin.

Electrophoretic evidence that single-stranded regions of one or more nucleotides dramatically increase the flexibility of DNA

The influence of single-stranded nicks and gaps on the flexibility of DNA has been investigated by subjecting to gel electrophoresis sets of molecules containing single-stranded regions of defined position and length. The DNA molecules were produced by ligating together synthetic oligomers that contained either nicks or single-stranded gaps of 1-4 nucleotides; the oligomer repeat lengths were 20, 21, 22, 23, or 26 bp, in order to produce nicks or gaps that were either in- or out-of-phase with the helix repeat of DNA. Nick-containing DNA molecules displayed nearly normal electrophoretic behavior, with maximum reductions in gel mobility (41 degrees C; 12% polyacrylamide gels) of approximately 10% for 230-bp molecules containing 10 nicks. In contrast, molecules containing gaps of 2-4 nucleotides demonstrated dramatic reductions in mobility, approaching one-half of the values of their full-duplex counterparts; molecules containing 1-nucleotide gaps displayed intermediate behavior. The observed (relative) mobilities of molecules containing gaps of more than 1 nucleotide were remarkably insensitive to temperature and to the presence of magnesium ions in the electrophoresis buffer. The central conclusion of the current study is that single-stranded gaps represent points of swivel-like character, whereas nicks retain much of the rigid character of double-helical DNA.

False aneurysm of the pulmonary artery associated with cardiac catheterisation

A false aneurysm of the pulmonary artery developed in a 59 year old woman as a complication of right-sided cardiac catheterisation. This rare, life-threatening condition was successfully treated with coil embolisation of the feeding artery. Cardiologists and intensive care doctors should be aware of the possibility of the formation of false aneurysms of the pulmonary artery after Swan-Ganz and other right heart catheterisation. Appropriate therapy could be life-saving.

Reversibility and benign recurrence of complete heart block in athletes

In two patients, symptoms associated with complete heart block and physical training resolved with deconditioning. In one patient, symptoms recurred after resumption of training but she has remained well for 4 years without a pacemaker. This suggests that complete heart block induced by fitness is benign, even when symptomatic.

Monocyte adhesion to human saphenous vein in vitro

Monocyte adhesion to endothelium is believed to be an initiating event in atherosclerosis both in arteries and in saphenous vein coronary artery bypass grafts. We have developed a method to quantify adhesion of 51Cr-labelled human blood monocytes to saphenous vein. Adhesion to the intimal surface was measured to uniform 6 mm diameter discs, the adventitia of which was embedded in a layer of inert silicone grease. The identity, number and location of bound cells was further defined by scanning electron microscopy. The proportion of monocytes adhering to discs of freshly-isolated vein was 7.1 +/- 1.2% (SE, n = 8), which was equivalent to 500 +/- 80 monocytes/mm2. The percentage of monocytes adhering was independent of the number of monocytes added in the range 5-50 x 10(4). Scanning micrographs showed 80% endothelial coverage with monocytes adhering preferentially but not exclusively to subendothelium. Endothelial removal increased monocyte adhesion by 1.60 +/- 0.15-fold (n = 8, P less than 0.01). Vein surgically prepared for use in coronary bypass surgery, had a 50% reduction in endothelial coverage and a small but non significant (1.14 +/- 0.13-fold, n = 8) increase in monocyte adhesion. Treatment of freshly-isolated vein for 4 h at 37 degrees C with 1 micrograms/ml of E. Coli endotoxin followed by extensive washing did not remove endothelium but increased monocyte adherence by 1.46 +/- 0.18-fold (n = 8, P less than 0.05). The proportion of monocytes adhering to veins which had been cultured for 14 days was similar to freshly isolated veins (6.4 +/- 0.8%, n = 7), but in cultured veins, monocytes adhered preferentially to cells with typical endothelial morphology. Endotoxin treatment of cultured freshly-isolated veins increased monocyte adhesion by 1.77 +/- 0.23-fold (n = 8, P less than 0.05). The data show that both endothelial activation, and exposure of subendothelium promote monocyte adhesion to human saphenous vein.

Analysis of fluorescence energy transfer in duplex and branched DNA molecules

Nonradiative fluorescence energy transfer (FET) is thought to be a highly sensitive measure of distance, occurring through a dipole coupling (Forster) mechanism in which the efficiency of FET depends on the inverse sixth power of the distance between fluorophores. The current work assesses the utility of FET for measuring distances in duplex and branched DNA molecules. The apparent efficiencies of FET between donor (fluorescein) and acceptor (eosin) fluorophores attached to opposite ends of oligonucleotide duplexes of varying length were determined; the results suggest that FET is a useful qualitative indicator of distance in DNA molecules. However, the apparent FET efficiency values cannot be fit to the Forster equation without the specification of highly extended DNA-to-fluorophore tethers and motionally restricted fluorophores, conditions that are unlikely to coexist. Three other lines of evidence further suggest that factors in addition to Forster transfer contribute to apparent FET in DNA: (1) The efficiency of FET appears to depend on the base sequence in some instances. (2) Donor fluorescence changes with the extent of thermally induced DNA melting in a sequence-dependent fashion, indicating dye-DNA interactions. (3) The distances between the ends of various pairwise combinations of arms of a DNA four-way junction do not vary as much as expected from previous work. Thus, the occurrence of any nondipolar effects on energy transfer in oligonucleotide systems must be defined before distances in DNA molecules can be quantified by using FET.

Geometry of a branched DNA structure in solution

An approximate geometry of a stable, four-way DNA junction has been determined in free solution by applying the technique of transient electric birefringence. The current approach consists of (i) construction of a set of six molecules in which two of the four arms of a synthetic junction are elongated by approximately 9-fold (in each of the six possible two-arm combinations), (ii) determination of the ratios of the longest birefringence decay time of each elongated junction to the decay time of a linear control molecule, and (iii) comparison of the experimental ratios with corresponding ratios computed as a function of the junction interarm angle. The result is a set of six angles that define the geometry of the junction. In the presence of magnesium ions, the junction adopts a geometry in which particular pairs of arms approach colinearity. Furthermore, the geometry of the junction is significantly altered in the absence of magnesium, adopting a more uniform structure, although such an effect is not apparent on gels. The application of transient electric birefringence, as described in the current study, should be useful for the characterization of a broad range of tertiary structures in both DNA and RNA.

Simple three-program implantable muscle stimulator with optical control

We describe an implantable stimulator which is capable of producing both continuous and intermittent patterns of indirect muscle stimulation. Switching between modes is achieved remotely via a percutaneous optical link and only standard laboratory techniques are employed in the construction of the device. It has been used to assess the influence of the pattern of stimulation on type transformation of mammalian skeletal muscle.

Gel electrophoretic analysis of the geometry of a DNA four-way junction

Branched DNA molecules (Holliday structures) are believed to be key intermediates in the process of homologous genetic recombination. However, despite the importance of such structures, their transient nature makes it difficult to analyze their physical properties. In an effort to evaluate several models for the geometry of such branched molecules, a stable, synthetic DNA four-way junction has been constructed. The geometry of the synthetic junction has been probed by gel electrophoresis, utilizing the fact that bent DNA molecules demonstrate reduced mobilities on polyacrylamide gels to an extent that varies with the degree of the bend angle. From the synthetic four-way junction, we have produced a set of molecules in which all combinations of two junction arms have been extended by 105 base-pairs. The electrophoretic mobilities of the extended junctions differ in a manner which indicates that the junction is not a completely flexible structure; nor is it tetrahedral or planar-tetragonal. Instead, the four strands that comprise the DNA four-way junction are structurally non-equivalent. The significance of these observations with regard to previous models for four-way junction geometry is discussed.