A Double-Pulsar System: A Rare Laboratory for Relativistic Gravity and Plasma Physics

The clocklike properties of pulsars moving in the gravitational fields of their unseen neutron-star companions have allowed unique tests of general relativity and provided evidence for gravitational radiation. We report here the detection of the 2.8-second pulsar J0737-3039B as the companion to the 23-millisecond pulsar J0737-3039A in a highly relativistic double neutron star system, allowing unprecedented tests of fundamental gravitational physics. We observed a short eclipse of J0737-3039A by J0737-3039B and orbital modulation of the flux density and the pulse shape of J0737-3039B, probably because of the influence of J0737-3039A's energy flux on its magnetosphere. These effects will allow us to probe magneto-ionic properties of a pulsar magnetosphere.

Dynamic force responses of skeletal muscle during stretch-shortening cycles

Muscle damage due to stretch-shortening cycles (i.e., cyclic eccentric/concentric muscle actions) is one of the major concerns in sports and occupational related activities. Mechanical responses of whole muscle have been associated with damage in neural motor units, in connective tissues, and the force generation mechanism. The objective of this study was to introduce a new method to quantify the real-time changes in skeletal muscle forces of rats during injurious stretch-shortening cycles. Male Sprague Dawley rats ( n=24) were selected for use in this study. The dorsi flexor muscle group was exposed to either 150 stretch-shortening cycles ( n=12) or 15 isometric contractions ( n=12) in vivo using a dynamometer and electrical stimulation. Muscle damage after exposure to stretch-shortening cycles was verified by the non-recoverable force deficit at 48 h and the presence of myofiber necrosis. Variations of the dynamic forces during stretch-shortening cycles were analyzed by decomposing the dynamic force signature into peak force ( F(peak)), minimum force ( F(min)), average force ( F(mean)), and cyclic force ( F(a)). After the 15th set of stretch-shortening cycles, the decrease in the stretch-shortening parameters, F(peak), F(min), F(mean), and F(a), was 50% ( P<0.0001), 26% ( P=0.0055), 68% ( P<0.0001), and 50% ( P<0.0001), respectively. Our results showed that both isometric contractions and stretch-shortening cycles induce a reduction in the isometric force. However, the force reduction induced by isometric contractions fully recovered after a break of 48 h while that induced by stretch-shortening cycles did not. Histopathologic assessment of the tibialis anterior exposed to stretch-shortening cycles showed significant myofiber degeneration and necrosis with associated inflammation, while muscles exposed to isometric contractions showed no myofiber degeneration and necrosis, and limited inflammation. Our results suggest that muscle damage can be identified by the non-recoverable isometric force decrement and also by the variations in the dynamic force signature during stretch-shortening cycles.

Origin and colonization history of the white-clawed crayfish, Austropotamobius pallipes, in Ireland

The presence of the white-clawed crayfish Austropotamobius pallipes complex in Ireland is suspected to be a result of human translocations. Two hypotheses have been formulated about the origin of the crayfish: from British populations or from western French populations. In order to resolve this question, nine Irish crayfish populations (a total of 124 individuals) were sampled along a south-north cline and investigated by combining two molecular markers: mtDNA and RAPDs. The mtDNA marker, analysed by RFLP on the entire molecule, showed an absence of polymorphism within and among Irish populations. The RFLP haplotype found in Irish populations was only recorded in western French populations and was different from those found in English populations. This result may be explained by a human introduction of crayfish to Ireland from western French populations. RAPD analysis showed a clinal reduction of genetic variability within Irish populations from south to north, associated with an increase in their genetic differentiation. A stepwise model of translocation from the south to the north of Ireland is proposed and discussed.

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Your correspondent receiving £21.22 per hour for bank holiday/night duty (Letters, October) should spare a thought for health care assistants. Because they are not nurses, some of them without even a national vocational qualification (NVQ), they receive the national minimum wage and no enhancements for unsocial hours, night duty or bank holidays. Yet these are the people home managers and matrons rely on for the daily care and comfort of residents, and the good name and reputation of the nursing home.

Randomised controlled trial of training health visitors to identify and help couples with relationship problems following a birth

BACKGROUND

Stresses imposed by parenthood can provoke or intensify relationship problems between parents. These problems, which are often associated with postnatal depression, can have serious consequences for family well-being but are often not revealed to primary health care personnel.

AIM

To evaluate a means of extending the primary health care team's ability to identify and respond to relationship problems of mothers and their partners in the postnatal period.

DESIGN OF STUDY

Cluster randomised controlled trial.

SETTING

Specially trained health visitors in nine 'intervention' clinics--each matched with a 'control' clinic' in an outer London borough.

METHOD

Health visitors in intervention clinics invited mothers attending for the six-to-eight-week developmental check to complete a screening scale for relationship problems, and offered help (supportive listening, advice, or referral) if needed. When visiting the clinic for the 12-week immunizations, mothers from all clinics were asked to complete a follow-up self-report questionnaire. After the completion of the trial, 25 women who had attended the intervention clinics and had been offered support with a relationship problem were interviewed to elicit their views on the acceptability and value of the intervention. All 25 of the health visitors engaged in the intervention were asked to complete a questionnaire on their experience.

RESULTS

Screening led to striking differences between intervention and control clinics in the percentage of women identified at the six-to-eight-week check as potentially in need of help with a relationship problem (21% versus 5%, P = 0.007) and in the percentage actually offered help (18% versus 3%, P = 0.014). About one-half of the mothers so identified were also identified as having postnatal depression. At the 12-week visit for immunizations, the intervention group was twice as likely (P = 0.006) as the control group to report having discussed relationship problems with the health visitor and 75% more likely (P = 0.046) to report having received help with a problem.

CONCLUSION

The intervention offers a useful way of extending the primary health care team's ability to respond to problems that often have serious consequences for family well-being.

Confirmation that offspring from families with alcohol-dependent individuals have greater hypothalamic-pituitary-adrenal axis activation induced by naloxone compared with offspring without a family history of alcohol dependence

BACKGROUND

This study was designed to confirm our previous findings that nonalcoholic offspring from families with alcohol-dependent individuals have greater hypothalamic-pituitary-adrenal axis activation induced by opioid blockade compared with nonalcoholic subjects without a family history of alcohol dependence.

METHODS

Sixty-four nonalcoholic subjects aged 18 to 25 years were enrolled in the protocol. Twenty-seven subjects were offspring from families with alcohol dependence and were designated as family history-positive subjects (FHP). Thirty-seven subjects were biological offspring of non-alcohol-dependent parents and were designated as family history-negative subjects (FHN). Subjects received naloxone hydrochloride (0, 50, 125, 375, and 500 microg/kg) in double-blind, randomized order; adrenocorticotropin (ACTH) and cortisol were monitored over 120 min.

RESULTS

No hormone differences at baseline or during placebo administration were identified between FHP and FHN subjects. FHP subjects had greater ACTH and cortisol response to opioid receptor blockade induced by naloxone hydrochloride compared with FHN subjects.

CONCLUSIONS

These observations confirm previous findings that differences in ACTH and cortisol dynamics between FHP and FHN subjects can be unmasked by opioid receptor blockade.

A prospective randomized comparison of 270 degrees fusions to 360 degrees fusions (circumferential fusions)

STUDY DESIGN

Prospective randomized comparison of anterior lumbar interbody fusion (ALIF) plus transpedicular instrumentation plus posterolateral fusion (PLF) (360 degrees fusion) to ALIF plus transpedicular instrumentation without PLF (270 degrees fusion).

OBJECTIVES

To compare the clinical outcomes, costs, and utilization of health resources of 360 degrees versus 270 degrees fusions.

BACKGROUND

The 360 degrees fusion is effective, but its costs and utilization of health resources are high. The PLF often resorbs and may not be necessary.

METHODS

Before and after surgery pain was measured by the Numerical Rating Scale (NRS), and function was measured by the Oswestry Low Back Disability Index (OSI). Costs were calculated by billing records. Operating times, blood loss, and hospital stays were measured at the time of hospital discharge.

RESULTS

There were 48 patients: 21 women and 27 men. Mean age was 42 years. Follow-up averaged 35 months (range 24-45 months). In both 360 degrees and 270 degrees fusions, there were significant improvements in NRS and OSI, and the percentage of solid ALIF was high. Only 14% of PLF appeared solid bilaterally and 18% appeared solid on one side only. There were no significant differences in changes in NRS, changes in OSI, or percentage solid ALIF between the 360 degrees and 270 degrees fusions. However, the 270 degrees fusion group had significantly less blood loss, shorter operative times, shorter hospital stays, and lower professional fees, and although hospital charges were lower, this difference was not significant.

CONCLUSION

Both the 360 degrees and 270 degrees fusions significantly reduce pain and improve function, and there are no significant clinical differences between them. However, there were shorter operating times, less blood loss, lower costs, and less utilization of health care resources associated with the 270 degrees fusions.

Congenital left ventricular aneurysm: clinical, imaging, pathologic, and surgical findings in seven new cases

BACKGROUND

Congenital left ventricular aneurysm is a poorly understood and potentially lethal entity. Methods and Results In a clinicopathologic study of 7 new cases, the major presenting features in 6 patients were congestive heart failure in 4, ventricular arrhythmias in a 32-week fetus, and multiple congenital anomalies in a fetus with trisomy 13. Accurate diagnosis was achieved in all 3 living patients by echocardiography, angiocardiography, and magnetic resonance imaging. The aneurysm was predominantly apical in 3 and involved most of the left ventricular free wall in 4. Of the 3 living patients, medical management alone sufficed in 2. The third, a newborn boy, underwent a new and successful aneurysm-exclusion left ventriculoplasty. The mitral valve was abnormal in all 4 autopsied cases, the papillary muscles being short, thin, or absent. The aneurysm was thinner and its area was larger than that of the nonaneurysmal left ventricle in all necropsied patients.

CONCLUSIONS

Congenital left ventricular aneurysm appears to be a developmental anomaly, an idiopathic dysplasia of left ventricular endocardium and myocardium. No evidence of a viral etiology was found. Some neonates can be managed medically, but others require urgent surgical intervention. A new surgical operation is presented, a functional left ventricular aneurysmectomy that minimizes intraoperative and postoperative blood loss and that preserves the coronary arteries.

Expression and characterization of recombinant rat alpha 3(IV)NC1 and its use in induction of experimental autoimmune glomerulonephritis

BACKGROUND

The autoantigen in Goodpasture's disease is known to be the non-collagenous domain of the alpha3 chain of type IV collagen, alpha 3(IV)NC1. There is mounting evidence that alpha 3(IV)NC1 is also a target of autoimmunity in experimental autoimmune glomerulonephritis (EAG). Sado et al. [Kidney Int 1998; 53, 664-671] have reported that recombinant human alpha 3(IV)NC1 and alpha4(IV)NC1 are nephritogenic in WKY rats. We have proposed that immunization with homologous antigen is more appropriate for detailed investigation of autoimmunity in EAG.

METHODS

To this end, we have cloned and sequenced rat alpha 3(IV)NC1 and expressed it in COS-7 cells. Recombinant rat alpha 3(IV)NC1, secreted into the COS-7 cell supernatant, was purified on an anti-M2 FLAG affinity column and characterized by western blotting. Recombinant antigen was then used to immunize WKY rats, in order to induce EAG.

RESULTS

The recombinant material was antigenic as judged by binding to sera from patients with Goodpasture's disease and a mAb to alpha 3(IV)NC1. Immunization of WKY rats (n=5), with recombinant rat alpha 3(IV)NC1 in FCA at a dose of 1 mg/kg resulted in circulating anti-GBM antibodies directed towards alpha 3(IV)NC1, linear deposits of IgG on the GBM, albuminuria, deposits of fibrin in the glomeruli, severe focal necrotizing glomerulonephritis with crescent formation, and glomerular influx of CD8+ T cells and macrophages. Western blot analysis demonstrated that sera from these rats bound strongly to recombinant rat alpha 3(IV)NC1, as well as to collagenase-solubilized human and rat GBM. The pattern of binding was indistinguishable from that of sera from patients with Goodpasture's disease.

CONCLUSIONS

This purified recombinant rat alpha 3(IV)NC1, which is both antigenic and nephritogenic, will be of value in analysing autoimmune responses in experimental anti-GBM disease.

A systematic approach to pacemaker assessment

Despite the increasing use of pacemaker therapy, assessment of pacemaker function and electrocardiogram (ECG) interpretation continue to challenge even experienced critical care nurses. Accurate assessment of pacemaker function is essential in the evaluation of patients, especially patients with symptoms that may be related to pacemaker malfunction such as syncope or palpitations. This article will review pacing concepts and pacing system components. A systematic approach to ECG interpretation will be presented that can be used in a variety of clinical settings.

Molecular characterisation of four cases of intrachromosomal triplication of chromosome 15q11-q14

CONTEXT

Chromosomal abnormalities that involve the proximal region of chromosome 15q occur relatively frequently in the human population. However, interstitial triplications involving one 15 homologue are very rare with three cases reported to date.

OBJECTIVE

To provide a detailed molecular characterisation of four additional patients with interstitial triplications of chromosome 15q11-q14.

DESIGN

Molecular analyses were performed using DNA markers and probes specific for the 15q11-q14 region.

SETTING

Molecular cytogenetics laboratory at the University of Chicago.

SUBJECTS

Four patients with mild to severe mental retardation and features of Prader-Willi syndrome (PWS) or Angelman syndrome (AS) were referred for molecular cytogenetic analysis following identification of a suspected duplication/triplication of chromosome 15q11-q14 by routine cytogenetic analysis.

MAIN OUTCOME MEASURES

Fluorescence in situ hybridisation (FISH) was performed to determine the type of chromosomal abnormality present, the extent of the abnormal region, and the orientation of the extra chromosomal segments. Molecular polymorphism analysis was performed to determine the parental origin of the abnormality. Methylation and northern blot analyses of the SNRPN gene were performed to determine the effect of extra copies of the SNRPN gene on its methylation pattern and expression.

RESULTS

Fluorescence in situ hybridisation (FISH) using probes within and flanking the Prader-Willi/Angelman syndrome critical region indicated that all patients carried an intrachromosomal triplication of proximal 15q11-q14 in one of the two chromosome 15 homologues (trip(15)). In all patients the orientation of the triplicated segments was normal-inverted-normal, suggesting that a common mechanism of rearrangement may have been involved. Microsatellite analysis showed the parental origin of the trip(15) to be maternal in three cases and paternal in one case. The paternal triplication patient had features similar to PWS, one maternal triplication patient had features similar to AS, and the other two maternal triplication patients had non-specific findings including hypotonia and mental retardation. Methylation analysis at exon 1 of the SNRPN locus showed increased dosage of either the paternal or maternal bands in the paternal or maternal triplication patients, respectively, suggesting that the methylation pattern shows a dose dependent increase that correlates with the parental origin of the triplication. In addition, the expression of SNRPN was analysed by northern blotting and expression levels were consistent with dosage and parental origin of the triplication.

CONCLUSIONS

These four additional cases of trip(15) will provide additional information towards understanding the phenotypic effects of this abnormality and aid in understanding the mechanism of formation of other chromosome 15 rearrangements.

Effects of amoxicillin/clavulanate or azithromycin on nasopharyngeal carriage of Streptococcus pneumoniae and Haemophilus influenzae in children with acute otitis media

The effect of antibiotic therapy on nasopharyngeal colonization by Streptococcus pneumoniae and Haemophilus influenzae was evaluated in children diagnosed with acute otitis media. Children were randomly assigned to receive either amoxicillin/clavulanate or azithromycin therapy, and nasopharyngeal swabs were obtained for culture before and after starting therapy. Amoxicillin/clavulanate therapy eradicated or suppressed all strains of S. pneumoniae susceptible to penicillin, 75% of strains with intermediate resistance, and 40% of strains resistant to penicillin. Azithromycin therapy cleared two-thirds of azithromycin-susceptible strains of S. pneumoniae but none of azithromycin-nonsusceptible strains. Selection for antibiotic-resistant strains in individual children was not observed in children who received amoxicillin/clavulanate therapy but was observed in 2 children who received azithromycin therapy. Carriage of H. influenzae was also reduced by antimicrobial therapy but more so by amoxicillin/clavulanate. Antibiotic therapy does not directly increase the number of resistant strains in the population but, by eradicating susceptible strains, allows greater opportunity for carriage and spread of resistant strains.

Efficacy and safety of troglitazone in the treatment of lipodystrophy syndromes

BACKGROUND

Troglitazone promotes adipocyte differentiation in vitro and increases insulin sensitivity in vivo. Therefore, troglitazone may have therapeutic benefit in lipoatrophic diabetes.

OBJECTIVE

To determine whether troglitazone ameliorates hyperglycemia and hypertriglyceridemia or increases fat mass in lipoatrophic patients.

DESIGN

Open-labeled prospective study.

SETTING

United States and Canada.

PATIENTS

20 patients with various syndromes associated with lipoatrophy or lipodystrophy.

INTERVENTION

6 months of therapy with troglitazone, 200 to 600 mg/d.

MEASUREMENTS

Levels of hemoglobin A1c triglycerides, free fatty acids, and insulin; respiratory quotient; percentage of body fat; liver volume; and regional fat mass.

RESULTS

In the 13 patients with diabetes who completed 6 months of troglitazone therapy, hemoglobin A1c levels decreased by a mean of 2.8% (95% CI, 1.9% to 3.7%; P < 0.001). In all 19 study patients, fasting triglyceride levels decreased by 2.6 mmol/L (230 mg/dL) (CI, 0.7 to 4.5 mmol/L [62 to 398 mg/dL]; P = 0.019) and free fatty acid levels decreased by 325 micromol/L (CI, 135 to 515 micromol/L; P = 0.035). The respiratory quotient decreased by a mean of 0.12 (CI, 0.08 to 0.16; P < 0.001), suggesting that troglitazone promoted oxidation of fat. Body fat increased by a mean of 2.4 percentage points (CI, 1.3 to 4.5 percentage points; P = 0.044). Magnetic resonance imaging showed an increase in subcutaneous adipose tissue but not in visceral fat. In one patient, the serum alanine aminotransferase level increased eightfold during the 10th months of troglitazone treatment but normalized 3 months after discontinuation of treatment Liver biopsy revealed an eosinophilic infiltrate, suggesting hypersensitivity reaction as a cause of hepatotoxicity.

CONCLUSION

Troglitazone therapy improved metabolic control and increased body fat in patients with lipoatrophic diabetes. The substantial benefits of troglitazone must be balanced against the risk for hepatotoxicity, which can occur relatively late in the treatment course.

The internal phosphodiesterase RegA is essential for the suppression of lateral pseudopods during Dictyostelium chemotaxis

Dictyostelium strains in which the gene encoding the cytoplasmic cAMP phosphodiesterase RegA is inactivated form small aggregates. This defect was corrected by introducing copies of the wild-type regA gene, indicating that the defect was solely the consequence of the loss of the phosphodiesterase. Using a computer-assisted motion analysis system, regA(-) mutant cells were found to show little sense of direction during aggregation. When labeled wild-type cells were followed in a field of aggregating regA(-) cells, they also failed to move in an orderly direction, indicating that signaling was impaired in mutant cell cultures. However, when labeled regA(-) cells were followed in a field of aggregating wild-type cells, they again failed to move in an orderly manner, primarily in the deduced fronts of waves, indicating that the chemotactic response was also impaired. Since wild-type cells must assess both the increasing spatial gradient and the increasing temporal gradient of cAMP in the front of a natural wave, the behavior of regA(-) cells was motion analyzed first in simulated temporal waves in the absence of spatial gradients and then was analyzed in spatial gradients in the absence of temporal waves. Our results demonstrate that RegA is involved neither in assessing the direction of a spatial gradient of cAMP nor in distinguishing between increasing and decreasing temporal gradients of cAMP. However, RegA is essential for specifically suppressing lateral pseudopod formation during the response to an increasing temporal gradient of cAMP, a necessary component of natural chemotaxis. We discuss the possibility that RegA functions in a network that regulates myosin phosphorylation by controlling internal cAMP levels, and, in support of that hypothesis, we demonstrate that myosin II does not localize in a normal manner to the cortex of regA(-) cells in an increasing temporal gradient of cAMP.

CD28-B7 blockade prevents the development of experimental autoimmune glomerulonephritis

Experimental autoimmune glomerulonephritis (EAG), an animal model of Goodpasture's disease, can be induced in Wistar Kyoto (WKY) rats by a single injection of rat glomerular basement membrane (GBM) in adjuvant. EAG is characterized by circulating and deposited anti-GBM antibodies, accompanied by focal necrotizing glomerulonephritis with crescent formation. The role of T cells in the pathogenesis of EAG remains unclear. T-cell costimulation is provided by ligation of CD28 with either B7.1 (CD80) or B7.2 (CD86) on antigen-presenting cells, and can be inhibited by a soluble form of CTLA4 (CTLA4-Ig) that binds to both B7.1 and B7.2. We examined the effect of CD28-B7 blockade on the development of EAG using native CTLA4-Ig or mutant CTLA4-Ig (Y100F-Ig), which selectively blocks B7.1. Native CTLA4-Ig treatment ameliorated EAG by several measures, including the levels of circulating anti-GBM antibodies, albuminuria, the deposition of IgG and fibrin in the glomeruli, the severity of glomerular abnormalities, and the numbers of infiltrating T cells and macrophages. Y100F-Ig resulted in a similar reduction in the severity of nephritis, but produced no overall reduction in circulating anti-GBM antibodies, although there was a reduction in IgG2a antibodies. We concluded that CD28-B7 blockade reduced autoantibody production and cellular infiltration of glomeruli, and prevented target organ injury. Our results suggest a key role for B7. 1 in costimulation of Th1-like autoimmune responses in the rat, and show that glomerular injury in EAG is largely dependent on cell-mediated mechanisms.