CHECK: Multi-level Real-World Pediatric Asthma Care Coordination: Results and Lessons Learned

OBJECTIVE

Because asthma health disparities in children remain common, innovative approaches to obtain asthma health equity are essential. Comprehensive care coordination programs may address the social determinants of health that influence these disparities. This analysis aims to ascertain if receipt of Coordination of Healthcare for Complex Kids (CHECK) program services was associated with changes in school absence, cost, healthcare utilization, and controller prescription in children with asthma.

METHODS

The CHECK program ran from December 1^st, 2014 through August 31^st, 2017. Engagement with Community Health Workers (CHW) was rolling and targeted based on risk level (low, medium or high determined by healthcare utilization). This analysis included school-aged children with asthma (n = 2,629) and sufficient Chicago Public Schools attendance data (n = 430).

RESULTS

Children engaged in CHECK were more likely to be female (p = 0.046) and to identify as Black and/or Hispanic/Latino than enrolled-only children. School absence was not different between the groups. Average total cost for engaged children was 21.3% more than enrolled-only children the first year (p = 0.027) but did not differ by the second year (p = 0.948). At baseline, 68.1% of the cohort had at least one ED visit 12-months prior to CHECK, this reduced to 49.5% post-1 and 41.9% post-2. Engaged children were 21% more likely to visit an ED (p = 0.010) and 40% more likely to have a controller.

CONCLUSIONS

CHECK program receipt was associated with reduced costs and improved healthcare utilization, and controller prescriptions. School attendance did not change. The CHECK model offers potential pathways to support low-income children with asthma.

Reliability of Tooth Width Measurements Delivered by the Clin-Check Pro 6.0 Software on Digital Casts: A Cross-Sectional Study

The purpose of this study was to assess the accuracy and reliability of tooth width measurements and Bolton Indices delivered by the Clin-Check Pro 6.0 software (Align Technology, San José, CA, USA). Fifty-four plaster casts were selected and measured with a manual calliper by a trained and calibrated observer. The data gathered were compared with those delivered by the software on the corresponding fifty-four virtual casts. The method reliability of the software was assessed by comparing the measurements performed by the software on 201 pairs of clin-checks corresponding to two consecutive treatment phases. Accuracy and reliability were statistically assessed using a mixed model. The software tends to provide larger widths compared with the manual method. Statistically significant differences were found in 23 teeth. At a global level, the mean difference between the methods was −0.19 mm, with a Dahlberg error of 0.24 mm and an intraclass correlation coefficient of 0.98. The Bolton Indices delivered by the two methods had a moderate correlation (ICC = 0.59; 0.69). The within method reliability of the software was extremely high. Tooth width measurements delivered by the software, despite the positive bias, can be considered accurate and clinically acceptable for all teeth except molars. The Bolton Indices made available by the software are not accurate and clinically acceptable, especially in the case of mandibular excess.

There is still room for improvement in the completeness of abstract reporting according to the PRISMA-A checklist: a cross-sectional study on systematic reviews in periodontology

BACKGROUND

To evaluate the completeness of reporting abstracts of systematic reviews (SRs) before and after the publication of the PRISMA-A checklist in 2013 and to assess if an association exists between abstract characteristics and the completeness of reporting.

METHODS

A systematic search of the literature was conducted in the PubMed and Scopus databases in March 2020. The search focused on the SRs of evaluations of interventions published since 2002 in the field of periodontology. The abstracts of the selected SRs were divided into two groups before and after publication of the PRISMA-A checklist in 2013, and compliance with the 12 items reported in the checklist was evaluated by three calibrated evaluators.

RESULTS

A set of 265 abstracts was included in the study. The total score before (mean score, 53.78%; 95% CI, 51.56-55.90%) and after (mean score, 56.88%; 95% CI, 55.39-58.44%) the publication of the PRISMA-A statement exhibited a statistically significant improvement (P = 0.012*). Nevertheless, only the checklist items included studies and synthesis of the results displayed a statistically significant change after guideline publication. The total PRISMA-A score was higher in the meta-analysis group and in articles authored by more than four authors.

CONCLUSIONS

The impact of the PRISMA-A was statistically significant, but the majority of the items did not improve after its introduction. The editors and referees of periodontal journals should promote adherence to the checklist to improve the quality of the reports and provide readers with better insight into the characteristics of published studies.

The online attention to orthodontic research: an Altmetric analysis of the orthodontic journals indexed in the journal citation reports from 2014 to 2018

Background

To describe the impact of research, beyond the limits of the academic environment, Altmetric, a new social and traditional media metric was proposed. The aims of this study were to analyze the online activity related to orthodontic research via Altmetric and to assess if a correlation exists among citations, Mendeley reader count, and the AAS (Altmetric Attention Score).

Method

The Dimensions App was searched for articles published in the orthodontic journals listed in the Journal Citation Reports (JCR) throughout the years 2014 to 2018. The articles with a positive AAS were collected and screened for data related to publication and authorship. The articles with an AAS higher than 5 were screened for research topic and study design. Citation counts were harvested from Web of Science (WOS) and Scopus.

Results

The best performing journals were Progress in Orthodontics and the European Journal of Orthodontics with a mean AAS per published item of 1.455 and 1.351, respectively and the most prevalent sources were Tweets and Facebook mentions. The most prevalent topic was Oral Health-Related Quality of Life (OHRQOL) and the study design was systematic reviews. The correlation between the AAS and the citations in both WOS and Scopus was poor (r = 0.1463 and r = 0.1508, p < .05). The correlation between citations count and Mendeley reader (r = 0.6879 and r = 0.697, p < .05) was moderate.

Conclusions

Few journals displayed a high level of web activity. Journals and editors should enhance online dissemination of the scientific outputs. The authors should report the impact of the findings to the general public in a convenient way to facilitate online dissemination but to avoid an opportunistic use of the research outputs. Despite the lack of correlation, a combination of the citation count and the AAS can give a more comprehensive assessment of research impact.

Trending topics in orthodontics research during the last three decades: A longitudinal bibliometric study on the top-cited articles

OBJECTIVE

To perform a bibliometric analysis on the top-cited articles over the last three decades from 1989 to 2018, using a longitudinal set-up, in order to analyse how articles' features have evolved over time.

SETTING AND SAMPLE POPULATION

A sample of 312 articles divided into three subgroups of 104 top-cited articles for each decade were included. The h-index value was used to determine the sample size.

MATERIALS AND METHODS

The articles were identified through a search in the category "dentistry oral surgery and medicine" of the Web of Science database. The information relative to the articles was collected. Descriptive statistics was used to describe the articles and the journals; selected parameters were analysed with the Kruskal-Wallis and the Mann-Whitney U test at the 0.05 level of significance.

RESULTS

The top-cited articles were published mainly by orthodontic journals. Along the last two decades, the scientific contribution of Asian and South American countries rose significantly. The trending topics varied in each decade. Skeletal anchorage-related articles dominated the production of the decade 1999-2008 while new technologies as CBCT displayed a higher prevalence in the last decade, where new topics such as corticotomy-assisted orthodontics started to appear. The number of multi-authored articles increased while the articles from no university institutions decreased.

CONCLUSION

The publications in the three studied decades were significantly different in terms of numbers and characteristics. A longitudinal set-up allows to study the evolution of the scientific production and how the area of interest has developed over time.

The online attention to research in periodontology: An Altmetric study on the most discussed articles on the web

AIM

To assess the online attention to research in the field of Periodontology. To assess the correlation between the Altmetric Attention Score (AAS) and the citations count in Web of Science (WOS), Scopus and Dimensions.

MATERIAL AND METHODS

The articles were identified by a search performed through the Dimensions Free App. The search included the six journals related to periodontology listed in the Journal Citation Report (JCR) in the year 2017. The 200 articles with the highest AAS were collected and screened for data related to publication, authorship and research. Citations were harvested from WOS, Scopus and Dimensions.

RESULTS

The Journal of Clinical Periodontology was the most prevalent publication accounting for the 51, 5% of the published items followed by the Journal of Periodontology that published the 34, 5% of the 200 articles with the highest AAS. 65% of these articles were published between 2013 and 2018. The mean AAS was 33, 81 being Tweets and news outlets the most frequent Altmetric resources. Systematic reviews were the most prevalent study design. The correlation between the AAS and the citations in WOS, Dimensions and Scopus was poor. A strong correlation exists between the citations in WOS, Dimensions and Scopus.

CONCLUSIONS

Online attention to periodontal research is high. Systemic interaction studies had a significantly higher visibility. The classic citations count in combination with the AAS can offer a more comprehensive insight into research by highlighting what is valuable for the researcher and for the lay persons. The online profile of journals should be edited to facilitate spread of research information in non-scholar audiences.

Measuring the social impact of research in Paediatric Dentistry: An Altmetric study

BACKGROUND

Traditional metrics have been extensively used to evaluate the scientific performance. Despite being widespread accepted, citation-based metrics are not able to describe the social impact of research. A diverse metric, Altmetric, was proposed to overcome those limitations.

AIM

This study aims to analyse the social impact of research in the field of paediatric dentistry and to assess if a correlation exists between the JCR citations, the AAS score, and the recently released Dimensions citation count.

DESIGN

A bibliometric study was conducted on the four journals related to Paediatric Dentistry listed in the JCR from 2014 to 2017. Descriptive statistics was used to describe the articles and the journals. Pearson's correlation analysis was used to explore the relationship among JCR citations, AAS, and Dimensions.

RESULTS

The percentage of articles with an AAS presents a huge variability and was significantly higher in the International Journal of Paediatric Dentistry. In our sample, the correlation between the JCR citation count and the AAS was poor in the years 2014, 2015, and 2016 and low in 2017. The correlation between JCR citation and Dimensions citation count was strong.

CONCLUSIONS

The social impact of research in paediatric dentistry can be increased. Dimensions could be an alternative to the JCR. Both the editors and the researcher should change their vision and facilitate the access to research information to scholar and non-scholar audiences.

Space Regaining Made Easy: The Case of a Severely Infraoccluded Primary Molar

Infraocclusion of deciduous molars is a quite common but challenging clinical situation that a paediatric dentist has to face in his everyday practice. This anomaly can lead to space loss, eruption disturbances of the permanent successor, and deformation of the occlusal plane. A case of a severely infraoccluded primary molar is presented. The treatment was carried out using a compressed NiTi wire applied only to the adjacent teeth. In three months, the space was recovered, and the infraoccluded temporary molar was extracted. After one year, the permanent successor erupted without any complication. The technique presented can be considered minimally invasive, and it involves cost- and time-efficient mechanics.

Redefining the therapeutic objective in psoriatic patients candidates for biological therapy

The advances in psoriasis management currently allow achieving a good control of the disease. In particular, with the latest developed molecules, available evidence suggests that it is possible to pose an ambitious therapeutic goal, such as a Dermatology Life Quality Index 0/1, a Physician Global Assessment 0/1, or a Psoriasis Area and Severity Index 90/100 response. However, patients often fail to achieve the complete clearance of their cutaneous lesions or the improvement of disease factors that impair their quality of life. To optimize the treatment of psoriasis, it is not enough to define precisely the therapeutic objective, but also to adapt the therapeutic strategy to make the necessary modifications in case of not achieving it at the time point (at the end of the induction phase, or every 3-6 months) to be agreed with the patient (the so-called treat-to-target approach). In the present report, based on the Delphi methodology, 11 dermatologists from the Spanish Psoriasis Group addressed key issues that could be involved in the achievement and maintenance of the therapeutic goals of patients with moderate to severe psoriasis. The document provides 27 consensus statements intended to support clinical decision-making by healthcare professionals for patients who might be candidates to receive biologic therapy.

Clinical Pharmacogenetics Implementation Consortium Guidelines for HLA-B Genotype and Abacavir Dosing: 2014 update

The Clinical Pharmacogenetics Implementation Consortium (CPIC) Guidelines for HLA-B Genotype and Abacavir Dosing were originally published in April 2012. We reviewed recent literature and concluded that none of the evidence would change the therapeutic recommendations in the original guideline; therefore, the original publication remains clinically current. However, we have updated the Supplementary Material online and included additional resources for applying CPIC guidelines to the electronic health record. Up-to-date information can be found at PharmGKB (http://www.pharmgkb.org).

Natural disease course and genotype-phenotype correlations in Complex I deficiency caused by nuclear gene defects: what we learned from 130 cases

Mitochondrial complex I is the largest multi-protein enzyme complex of the oxidative phosphorylation system. Seven subunits of this complex are encoded by the mitochondrial and the remainder by the nuclear genome. We review the natural disease course and signs and symptoms of 130 patients (four new cases and 126 from literature) with mutations in nuclear genes encoding structural complex I proteins or those involved in its assembly. Complex I deficiency caused by a nuclear gene defect is usually a non-dysmorphic syndrome, characterized by severe multi-system organ involvement and a poor prognosis. Age at presentation may vary, but is generally within the first year of life. The most prevalent symptoms include hypotonia, nystagmus, respiratory abnormalities, pyramidal signs, dystonia, psychomotor retardation or regression, failure to thrive, and feeding problems. Characteristic symptoms include brainstem involvement, optic atrophy and Leigh syndrome on MRI, either or not in combination with internal organ involvement and lactic acidemia. Virtually all children ultimately develop Leigh syndrome or leukoencephalopathy. Twenty-five percent of the patients died before the age of six months, more than half before the age of two and 75 % before the age of ten years. Some patients showed recovery of certain skills or are still alive in their thirties . No clinical, biochemical, or genetic parameters indicating longer survival were found. No clear genotype-phenotype correlations were observed, however defects in some genes seem to be associated with a better or poorer prognosis, cardiomyopathy, Leigh syndrome or brainstem lesions.

Living donor liver transplantation: usefulness of hemostatic and prothrombotic screening in potential donors

Bleeding and thrombosis are serious complications of living donor liver transplantation (LDLT). The aim of this paper was to describe the results of a screening for coagulation disorders, including for thrombophilic factors, in potential living liver graft donors and to evaluate thrombotic and bleeding events in donors and recipients, during and after the procedure. From January 2001 to January 2007, 41 LDLTs were performed at our institution. We performed systematic screening for bleeding or prothrombotic states among 188 potential donors, 38 (20.2%) of whom showed at least one abnormality. We rejected potential donors with factor V Leiden, prothrombin mutation G20210A, and deficiencies in anticoagulant proteins (protein C, protein S, and antithrombin) or coagulation factors. Bleeding and thrombotic events in donors and recipients of the 41 LDLTs were evaluated during 7 days to 70 months follow-up. No major bleeding events were detected in the donors. Neither donor nor recipient experienced venous thrombosis or pulmonary embolism. Among all recipients, six suffered hepatic artery thrombosis including five in the first month probably related to surgery. Deep venous thrombosis and pulmonary embolism are well-known complications of hepatic surgery; Prothrombotic abnormalities in the donor can be transmitted to the recipient, leading to increased risk of serious postoperative events. Although the cost-effectiveness is not definitely established, we recommend systematic screening for hemostatic and prothrombotic disorders to prevent more morbidity of a procedure that already has high risks of bleeding and thrombosis.

The use of fluorescent probes in pharmaceutical analysis

Even though many pharmaceuticals show native fluorescence, there is also an important group of compounds which is not fluorescent. A main object of studies is to make them fluorescent, principally by using fluorescent probes through derivatisation reactions. An account of the fluorescent probes more widely used for the determination of drugs and related compounds is presented in this review paper. A wide variety of fluorescent probes is described on the basis of their ability to react specifically with various functional groups. Attention is focused on derivatisation reactions used in spectrofluorimetry and chromatographic techniques (HPLC, TLC) with fluorimetric detection. The review covers only those fluorescent probes whose use involves a chemical reaction with the analyte, and not those methods that involve physico-chemical interactions such as sensitised or charge transfer processes. Many of these derivatisation reactions have been widely used in the detection of primary and secondary amines. Reagents such as dansyl chloride, fluorescamine, o-phtalaldehyde are very well known. Other reagents have also been developed for other functional groups, for example dansyl hydrazine for compounds with a carbonyl function or 4-bromomethyl-7-methoxy-coumarin for acidic compounds . Acid chlorides such as dansyl chloride may also react with different functional groups carrying active hydrogens as do phenols. The use and development of new fluorescent probes in pharmaceutical analysis is a subject for further studies.

Novel mutations in patients with McArdle disease by analysis of skeletal muscle mRNA

OBJECTIVE

To identify pathogenic mutant alleles of the PYGM gene in "genetic manifesting heterozygous" patients with McArdle disease-that is, those in whom we could only find a sole mutant allele by genomic DNA analysis.

METHODS

We studied four unrelated patients. PCR-RFLP, gene sequencing, and muscle cDNA analysis were performed to search for mutations in the PYGM gene. The effects of the mutations were evaluated by in silico analysis, and gene expression was assessed by real-time polymerase chain reaction (PCR).

RESULTS

Patient 1 was a compound heterozygous for the p.G205S missense mutation and for a novel "in frame" mutation, p.Q176_M177insVQ, resulting from a retention of six nucleotides from the 3'-end sequence of intron 4. Patient 2 was heterozygous for the common nonsense mutation p.R50X, and for a 1094 bp, c.1969+214_2177+369del mutation, spanning from intron 16 to intron 17 sequences. Furthermore, mRNA expression level was dramatically reduced consistent with nonsense mediated decay. Patient 3 was heterozygous for the p.R50X substitution, and patient 4 was heterozygous for the relatively common private Spanish mutation p.W798R. These two patients harboured a heterozygous exonic synonymous variant, p.K215K. Quantification of gene transcripts in patient 3 revealed a drastic decrease in the relative expression of the gene, which strongly supports the possibility of nonsense mediated decay.

CONCLUSIONS

Our results indicate that skeletal muscle cDNA studies in "genetic manifesting heterozygous" patients with McArdle disease are prone to identify their second mutant allele.

Genotype distributions in top-level soccer players: a role for ACE?

We determined the genotype and allelic frequency of several genetic polymorphisms (ACE I/D, GDF-8K153R [and also E164K, P198A and I225T] and AMPD1 C34T) that are candidates to influence sports performance in a group of 54 male professional soccer players. Their results were compared with those of elite endurance male athletes (52 runners) and 123 sedentary, healthy men (controls). We found statistical significance for the ACE ID (chi (2)((2))=8.176, P=0.017) and II genotypes (chi(2)((2))=16.137, P<0.001) with a higher and lower frequency of ID ( P=0.005) and II (P<0.001), respectively, in soccer players than in endurance runners. Statistical significance was also reached for AMPD1 (with a higher frequency of the CT genotype in soccer players than in runners [chi(2)((2))=7.538, P=0.006]) but not for GDF-8 K153R. Since the ACE II genotype is associated with improved potential for endurance performance but with decreased training gains in muscle mass and strength, these findings together with previous results support the notion that elite soccer players tend to have a power/strength oriented genotype.

Can patients with McArdle's disease run?

Patients with McArdle's disease commonly adopt a sedentary lifestyle. This sedentary behaviour, however, usually worsens the limited exercise capacity of these patients. Although eccentric muscle work can be associated with rhabdomyolysis, supervised eccentric training with gradually increasing loads has important advantages compared with conventional concentric work, particularly for patients with a poor cardiorespiratory system. We report the beneficial effects (particularly, increased VO(2peak) (from 14.6 to 30.8 ml/kg/min) and increased gross muscle efficiency (from 13.8% to 17.2%)) induced by a supervised aerobic training programme of 7 months duration including 3-4 running sessions (< or =60 min/session) per week in a 38-year-old patient. These preliminary data suggest the potential therapeutic value of this type of exercise in these patients.

Exercise capacity in a 78 year old patient with McArdle's disease: it is never too late to start exercising

The case is reported of a 78 year old man with McArdle's disease and a history of treated coronary heart disease. Despite the pre-exercise administration of sucrose allowing the patient to exercise with normal physiological responses, and without typical McArdle's symptoms or biochemical evidence of muscle damage, his exercise capacity was very low (V(O2)peak = 10.7 ml/min/kg), probably attributable to his lifetime of sedentary living. The data suggest that, with pre-exercise sucrose administration, such patients may be candidates for systematic reconditioning, which may improve functional capacity and quality of life.

Mobilisation of mesenchymal cells into blood in response to skeletal muscle injury

Mesenchymal cells recruited to damaged tissues must circulate through the bloodstream. The absolute numbers of circulating mesenchymal stem cells (cMSCs) in two different models of acute and chronic skeletal muscle injury were determined. cMSCs were present in significantly higher numbers in both models than in healthy controls. These results support the hypothesis that MSCs are mobilised into the bloodstream after skeletal muscle tissue damage. These two models (acute and chronic) would be of value in the search for molecular mediators of mobilisation of MSCs into the circulation.

Does the C34T Mutation in AMPD1 Alter Exercise Capacity in the Elderly?

Ageing does affect functional capacity through several changes at the peripheral muscle level that impair the muscles capacity to produce energy and generate force. The skeletal muscle-specific isoform of AMP deaminase (AMPD) plays an important regulatory role in muscle metabolism and in determining energy charge. Since nearly 20 % of the general Caucasian population is heterozygous (CT) for the most common C34T mutation of the gene (AMPD1) encoding for this enzyme, it would be worthwhile to study if such a condition further increases the effects of ageing. Twenty-one women (61 - 80 yrs) served as subjects, and depending on the results of previous genotyping, were assigned to a group with the C34T mutation (heterozygous; n=4; mean+/-SEM age: 71+/-1 yrs) or with no mutation (n=17; 68+/-1 yrs). Several indices of maximal (peak oxygen uptake [V.O (2 peak)], peak power output) and submaximal endurance performance (ventilatory threshold, mechanical efficiency) and functional tests (one-mile walk test and a specific test of lower-body functional performance [sit-stand test]) were compared between the two groups. No significant differences were found in exercise capacity between both groups, e. g. V.O (2 peak) of 19.1+/-1.0 vs. 20.1+/-1.9 ml . kg (-1) . min (-1), V.O (2) at the VT of 11.9+/-0.6 vs. 12.9+/-1.0 ml . kg (-1) . min (-1), or time to complete the one-mile walk test (951+/-18 s vs. 962+/-61 s) and sit-stand test (9.9+/-0.2 vs. 9.2+/-0.2) (no mutation vs. C34T mutation, respectively). Although more research is necessary, it seems that the C34T mutation of the AMPD1, at least in heterozygous individuals, does not affect functional capacity in the elderly.

C34T mutation of the AMPD1 gene in an elite white runner

The case is reported of an elite, male, white endurance runner (28 years of age), who is one of the best non-African runners in the world despite carrying the C34T mutation in the gene (AMPD1) that encodes the skeletal muscle specific isoform of AMP deaminase, an enzyme that plays an important role in muscle metabolism. The frequency of the mutant allele in sedentary white people is 8-11%. Previous research has shown that this mutation, at least in homozygotes, can impair the exercise capacity of untrained people and their trainability. The maximum oxygen uptake of the study subject was exceptionally high (83.6 ml/kg/min), whereas his ammonia and lactate concentrations at high submaximal running speeds were lower than those of other world class runners who are not carriers of the mutation. The partial metabolic deficiency of the study subject is possibly compensated for by his exceptionally favourable anthropometric characteristics (body mass index 18.2 kg/m2).

Applying a moving total mortality count to the cities in the NMMAPS database to estimate the mortality effects of particulate matter air pollution

OBJECTIVES

To apply a new method for estimating the association between daily ambient particulate matter air pollution (PM) and daily mortality to data from over 100 United States cities contained in the National Morbidity, Mortality, and Air Pollution Study (NMMAPS) database and to see whether the results from the 90 cities NMMAPS analysis are robust to this different modelling approach. This new method has recently been shown to provide improved estimates for the association between PM and daily mortality when every-day PM data are unavailable. It avoids the need for selecting a lag of PM at which the mortality effects of PM are to be investigated.

METHODS

With the aid of analytical methods and databases developed for NMMAPS, Poisson log linear models controlling for long term trends and weather effects were used to estimate the association between PM and mortality for cities in the NMMAPS database using the new method. A two stage Bayesian hierarchical model was then used to combine city specific estimates to form a national average PM mortality effect estimate.

RESULTS

A 10 microg/m3 increase in PM was associated with a 0.12% increment in total mortality and a 0.17% increment in cardiovascular and respiratory mortality. These results are consistent with those found in the NMMAPS analysis.

CONCLUSIONS

There is a statistically significant association between short term changes in PM and mortality on average for the cities contained in the NMMAPS database. These findings are further evidence that this widespread pollutant adversely affects public health.

Tumour dose enhancement using modified megavoltage photon beams and contrast media

This study examines the magnitude of tumour dose enhancement achieved by injection of gadolinium or iodine contrast media (CM) and treatment using modified x-ray photon spectra from linear accelerators. Monte Carlo modelling of the linear accelerator and patient geometry was used to explore the effect of removing the flattening filter for various beam qualities and the resultant effect on dose enhancement. In addition, ionization measurements were conducted to observe dose enhancement within a phantom containing CM. Simulation results indicate that for flattened 6-24 MV photon beams and realistic CM tumour concentrations, the dose enhancement remains below 5%. However, if the flattening filter is removed, dose enhancement is increased significantly. For a 30 mg ml(-1) gadolinium CM tumour concentration, for example, 8.4%, 10.8%, 13.7% and 23.1% dose enhancements are achieved for 18 MV, 6 MV, 4 MV and 2 MV unflattened beams, respectively. In contrast to the phototherapy technique, which uses the orthovoltage beam from a modified CT scanner to achieve dose enhancement, all unflattened spectra preserve the dose build-up at the surface, and thus the skin and bone are spared.

Economic considerations for the adoption of transgenic crops: the case of bt corn

Biotechnology is offering farmers new crop production opportunities and challenges. Prior to selecting a transgenic variety, farmers must consider the cost of the technology fee, possible yield drag, potential pest infestations, possible reductions in pesticide costs, refuge requirements to minimize the development of insect resistance, and adjustments in cultural practices. Moreover, crop segregation in the field, storage, and shipment may be necessary to capture potential price premiums for nontransgenic varieties. As farmers consider these various production and marketing factors, they find that Bt corn is a more profitable control method for European corn borer in the Western Corn Belt relative to the Eastern Corn Belt. This is primarily due to higher infestation probabilities in the Western Corn Belt, coupled with greater demand for manufacturing and export uses in the Eastern Corn Belt where several buyers do not accept transgenic corn.

Thyroid hormone regulates oxidative phosphorylation in the cerebral cortex and striatum of neonatal rats

We have previously shown that thyroid hormone (T(3)) regulates mitochondrial gene expression, morphology and transmembrane potential in the developing brain. Here, we have analysed the effect of thyroid hormone on mitochondrial function in different brain regions. For this purpose we have determined, in control, hypothyroid and T(3)-treated hypothyroid neonatal rats, the rate of oxidative phosphorylation in isolated mitochondria and the activity of the respiratory complexes in tissue homogenates. Our results showed a decrease in oxidative phosphorylation rate (only in the presence of NADH-generating substrates) and mitochondrial complexes I and III activity in the cerebral cortex and striatum of hypothyroid neonates, but not in the other areas analysed (hippocampus, cerebellum, thalamus, mid brain and brain stem). In parallel with mitochondrial activity, the levels of mitochondrially encoded transcripts were decreased only in the cerebral cortex and striatum of hypothyroid rats. The administration of T(3) corrected all these parameters. In summary, this study showed a down-regulation of mitochondrial gene expression accompanied by a decrease in mitochondrial activity in the cerebral cortex and striatum of developing hypothyroid neonatal rats.

N-linked glycosylation sites adjacent to and within the V1/V2 and the V3 loops of dualtropic human immunodeficiency virus type 1 isolate DH12 gp120 affect coreceptor usage and cellular tropism

The envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1) is extensively glycosylated, containing approximately 23 asparagine (N)-linked glycosylation sites on its gp120 subunit. In this study, specific glycosylation sites on gp120 of a dualtropic primary HIV-1 isolate, DH12, were eliminated by site-directed mutagenesis and the properties of the resulting mutant envelopes were evaluated using a recombinant vaccinia virus-based cell-to-cell fusion assay alone or in the context of viral infections. Of the glycosylation sites that were evaluated, those proximal to the V1/V2 loops (N135, N141, N156, N160) and the V3 loops (N301) of gp120 were functionally critical. The glycosylation site mutations near the V1/V2 loop compromised the use of CCR5 and CXCR4 equally. In contrast, a mutation within the V3 loop preferentially inhibited the usage of CCR5; although this mutant protein completely lost its CCR5-dependent fusion activity, it retained 50% of the wild-type fusion activity with CXCR4. The replication of a virus containing this mutation was severely compromised in peripheral blood mononuclear cells, MT-4 cells, and primary monocyte-derived macrophages. A revertant virus, which acquired second site changes in the V3 loop that resulted in an increase in net positive charge, was isolated. The revertant virus fully recovered the usage of CXCR4 but not of CCR5, thereby altering the tropism of the parental virus from dualtropic to T-tropic. These results suggest that carbohydrate moieties near the V1/V2 and the V3 loops play critical roles in maintaining proper conformation of the variable loops for optimal interaction with receptors. Our results, combined with those of previously reported studies, further demonstrate that the function of individual glycans may be virus isolate dependent.

Polyvalent envelope glycoprotein vaccine elicits a broader neutralizing antibody response but is unable to provide sterilizing protection against heterologous Simian/human immunodeficiency virus infection in pigtailed macaques

The great difficulty in eliciting broadly cross-reactive neutralizing antibodies (NAbs) against human immunodeficiency virus type 1 (HIV-1) isolates has been attributed to several intrinsic properties of their viral envelope glycoprotein, including its complex quaternary structure, extensive glycosylation, and marked genetic variability. Most previously evaluated vaccine candidates have utilized envelope glycoprotein from a single virus isolate. Here we compare the breadth of NAb and protective immune response following vaccination of pigtailed macaques with envelope protein(s) derived from either single or multiple viral isolates. Animals were challenged with Simian/human immunodeficiency virus strain DH12 (SHIV(DH12)) following priming with recombinant vaccinia virus(es) expressing gp160(s) and boosting with gp120 protein(s) from (i) LAI, RF, 89.6, AD8, and Bal (Polyvalent); (ii) LAI, RF, 89.6, AD8, Bal, and DH12 (Polyvalent-DH12); (iii) 89.6 (Monovalent-89.6); and (iv) DH12 (Monovalent-DH12). Animals in the two polyvalent vaccine groups developed NAbs against more HIV-1 isolates than those in the two monovalent vaccine groups (P = 0.0054). However, the increased breadth of response was directed almost entirely against the vaccine strains. Resistance to SHIV(DH12) strongly correlated with the level of NAbs directed against the virus on the day of challenge (P = 0.0008). Accordingly, the animals in the Monovalent-DH12 and Polyvalent-DH12 vaccine groups were more resistant to the SHIV(DH12) challenge than the macaques immunized with preparations lacking a DH12 component (viz. Polyvalent and Monovalent-89.6) (P = 0.039). Despite the absence of any detectable NAb, animals in the Polyvalent vaccine group, but not those immunized with Monovalent-89.6, exhibited markedly lower levels of plasma virus than those in the control group, suggesting a superior cell-mediated immune response induced by the polyvalent vaccine.

Recent economic evaluations of antenatal screening: a systematic review and critique

A systematic review of recent economic evaluations of antenatal screening was conducted. Relevant studies were identified from a number of sources including computerised databases, bibliographies of economic evaluations, and searches of unpublished manuscripts. Each study identified by the literature searches was categorised on the basis of its title and abstract. Studies considered relevant to the systematic review were obtained from libraries. The methodology, results, and policy implications of studies categorised as economic evaluations upon full review were documented. A total of 566 studies were identified by the literature searches, 41 of which were categorised as economic evaluations upon full review. The economic evaluations covered a range of antenatal screening practices, aimed mainly at the prevention of infectious diseases and fetal anomalies. The review highlighted the poor methodological quality of the bulk of economic evaluations of antenatal screening. The study design, data collection methods, and analysis and interpretation of results frequently violated methodological guidelines adopted by health economists. The review also highlighted the narrow definition of benefits adopted by this body of literature, with most studies reporting outcomes in terms of cases detected, cases of particular disorders prevented or, most often, costs averted. The conclusions arrived at differed by area of antenatal screening. There appeared to be clear economic arguments in favour of some forms of antenatal screening, for example, triple test screening for Down's syndrome. Other economic evaluations pertained to specific locations, which suggests that the results may not necessarily be generalizable to different settings. For all areas of antenatal screening, an updating of published economic evaluations may be required to account for evolving economic, epidemiological, and clinical effectiveness evidence.

Macrophage are the principal reservoir and sustain high virus loads in rhesus macaques after the depletion of CD4+ T cells by a highly pathogenic simian immunodeficiency virus/HIV type 1 chimera (SHIV): Implications for HIV-1 infections of humans

The highly pathogenic simian immunodeficiency virus/HIV type 1 (SHIV) chimeric virus SHIV(DH12R) induces a systemic depletion of CD4(+) T lymphocytes in rhesus monkeys during the initial 3-4 weeks of infection. Nonetheless, high levels of viral RNA production continue unabated for an additional 2-5 months. In situ hybridization and immunohistochemical analyses revealed that tissue macrophage in the lymph nodes, spleen, gastrointestinal tract, liver, and kidney sustain high plasma virus loads in the absence of CD4(+) T cells. Quantitative confocal immunofluorescence analysis indicated that greater than 95% of the virus-producing cells in these tissues are macrophage and less than 2% are T lymphocytes. Interestingly, the administration of a potent reverse transcriptase inhibitor blocked virus production during the early T cell phase but not during the later macrophage phase of the SHIV(DH12R) infection. When interpreted in the context of HIV-1 infections, these results implicate tissue macrophage as an important reservoir of virus in vivo. They become infected during the acute infection, gradually increase in number over time, and can be a major contributor to total body virus burden during the symptomatic phase of the human infection.

Identifying priority patients for coronary angiography

We conducted an open observational study with blinded endpoint evaluation to validate the use of the Duke treadmill score in identifying patients likely to require coronary intervention. We studied 101 consecutive patients referred for coronary angiography from a cardiology clinic. All patients had a Bruce protocol exercise test. A 70% stenosis was regarded as significant. Patients were referred for percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG) surgery, if indicated. The Duke score was calculated as follows: exercise time (min) - (5 x ST segment deviation [mm]) - (4 x angina index [text]). Patients were classified into low, medium and high risk. The patients at high risk are more likely to have a significant stenosis (53/58 vs 30/43: p = 0.01 [OR 4.59 95% CI 1.34-16.6]) and require CABG or PTCA (47/58 vs 16/43: p < 0.001 [OR 7.21 95% CI 2.69-19.8]) than those at medium/low risk. Multiple logistic regression analysis, including ST segment depression, exercise time and symptoms shows that the score independently predicts a significant stenosis (p = 0.002) and the need for coronary intervention (p = 0.001). Introducing the score can help to identify those patients who need priority investigation.

Associations between alcohol consumption and insulin sensitivity and cardiovascular disease risk factors: the Insulin Resistance and Atherosclerosis Study

OBJECTIVE

Light-to-moderate alcohol consumption has been associated with reduced cardiovascular disease (CVD) mortality, which may be explained by increased insulin sensitivity (SI) and an improved lipoprotein and blood pressure profile. Prior research has shown improved SI with light-to-moderate alcohol intake even though somewhat imprecise measures of SI were used.

RESEARCH DESIGN AND METHODS

Relationships between alcohol use and SI and CVD risk factors were assessed in a cross-sectional analysis of 1,196 white, African-American, and Hispanic men and women from the Insulin Resistance and Atherosclerosis Study (IRAS). Five categories of previous-year alcohol use (never, <0.5 drinks/day, 0.5-0.99 drinks/day, 1-2.99 drinks/day, and > or =3 drinks/day) and log SI + 1 (frequently sampled intravenous glucose tolerance test with Bergman minimal model analysis), log fasting insulin, log triglycerides, HDL cholesterol, and systolic/diastolic blood pressure were examined using analysis of variance.

RESULTS

Univariate analysis showed an inverse U-shaped relationship between SI and alcohol intake, with a peak at the 0.5-0.99 drinks/day category. A U-shaped relationship was observed between fasting insulin and the lipid and blood pressure measures. After adjustment for demographic (clinic, sex, ethnicity, age), lifestyle (smoking, dietary energy/fat intake, physical activity), and physical (BMI, waist circumference) variables, the alcohol/insulin association was attenuated, but the association with lipids and blood pressure remained for high-intake categories.

CONCLUSIONS

These data suggest that the enhanced SI associated with light-to-moderate alcohol consumption may be a function solely of a BMI and central adiposity profile more favorable to higher SI.

Identification of gp120 regions targeted by a highly potent neutralizing antiserum elicited in a chimpanzee inoculated with a primary human immunodeficiency virus type 1 isolate

We have previously reported that a chimpanzee infected with a primary human immunodeficiency virus type 1 (HIV-1) isolate (HIV-1(DH12)) developed an extremely potent virus-neutralizing antibody. Immunoglobulin G purified from this animal conferred sterilizing immunity following passive transfer to macaques which were subsequently challenged with simian immunodeficiency virus/HIV-1 chimeric virus strain DH12. In addition to being highly strain specific, the chimpanzee antiserum did not bind to the V3 loop peptide of HIV-1(DH12), nor did it block the interaction of gp120 with the CD4 receptor. When neutralization was examined in the context of virus particles carrying chimeric envelope glycoproteins, the presence of all five hypervariable regions (V1 to V5) was required for optimal neutralization. Virions bearing chimeric gp120 containing the V1-V2 and V4 regions of HIV-1(DH12) could also be neutralized, but larger quantities of the chimpanzee antiserum were needed to block infection. These results indicate that the HIV-1 gp120 epitope(s) targeted by the chimpanzee antiserum is highly conformational, involving surface elements contributed by all of the hypervariable domains of the envelope glycoprotein.

Short- and long-term clinical outcomes in rhesus monkeys inoculated with a highly pathogenic chimeric simian/human immunodeficiency virus

A highly pathogenic simian/human immunodeficiency virus (SHIV), SHIV(DH12R), isolated from a rhesus macaque that had been treated with anti-human CD8 monoclonal antibody at the time of primary infection with the nonpathogenic, molecularly cloned SHIV(DH12), induced marked and rapid CD4(+) T cell loss in all rhesus macaques intravenously inoculated with 1.0 50% tissue culture infective dose (TCID(50)) to 4.1 x 10(5) TCID(50)s of virus. Animals inoculated with 650 TCID(50)s of SHIV(DH12R) or more experienced irreversible CD4(+) T lymphocyte depletion and developed clinical disease requiring euthanasia between weeks 12 and 23 postinfection. In contrast, the CD4(+) T-cell numbers in four of five monkeys receiving 25 TCID(50)s of SHIV(DH12R) or less stabilized at low levels, and these surviving animals produced antibodies capable of neutralizing SHIV(DH12R). In the fifth monkey, no recovery from the CD4(+) T cell decline occurred, and the animal had to be euthanized. Viral RNA levels, subsequent to the initial peak of infection but not at peak viremia, correlated with the virus inoculum size and the eventual clinical course. Both initial infection rate constants, k, and decay constants, d, were determined, but only the latter were statistically correlated to clinical outcome. The attenuating effects of reduced inoculum size were also observed when virus was inoculated by the mucosal route. Because the uncloned SHIV(DH12R) stock possessed the genetic properties of a lentivirus quasispecies, we were able to assess the evolution of the input virus swarm in animals surviving the acute infection by monitoring the emergence of neutralization escape viral variants.

Vaginal clindamycin and oral metronidazole for bacterial vaginosis: a randomized trial

OBJECTIVE

To compare the efficacy and safety of clindamycin vaginal ovules with oral metronidazole for treatment of bacterial vaginosis.

METHODS

Women with bacterial vaginosis received either 100-mg ovules of clindamycin (intravaginally for 3 consecutive days) plus placebo capsules (orally twice daily for 7 days) or metronidazole 500 mg (two 250-mg capsules orally twice daily for 7 days) plus placebo ovules (intravaginally for 3 consecutive days). The sample was determined prospectively to provide a probability of.84 of correctly concluding that the rate of success for clindamycin is not more than 15% less than the expected 75% success rate for metronidazole. Clinical outcome was determined on the basis of vaginal fluid amine odor and clue cells.

RESULTS

Of the 399 patients enrolled, 233 could be evaluated for efficacy. Of those, 77 (68.1%) of 113 patients were cured with clindamycin, compared with 80 (66. 7%) of 120 who were cured with metronidazole (95% confidence interval -10.6%, 13.4%; P =.810). Treatment-related adverse events were reported more frequently in the metronidazole treatment group. Systemic symptoms, such as nausea and taste perversion, accounted for most of the difference between groups.

CONCLUSION

A 3-day regimen of clindamycin, given as intravaginal ovules, was as effective as and better tolerated than a 7-day regimen of oral metronidazole 500 mg, given twice daily, for treatment of bacterial vaginosis.

Higher western blot immunoreactivity of glycoprotein 120 from R5 HIV type 1 isolates compared with X4 and X4R5 isolates

The envelope glycoprotein of human immunodeficiency virus 1 (HIV-1) plays important roles in viral life cycle and pathogenesis. Understanding the immune responses the protein elicits during the course of a viral infection in patients is important in designing an effective vaccine candidate against the virus or for better diagnosis of the disease. In this study, we report that gp120 of R5 isolates have higher Western blot (WB) immunoreactivity to antibodies elicited against the protein in virus-infected human patients compared with that of X4 and X4R5 isolates. Analyses of WB immunoreactivity of chimeric gp120s constructed between R5 (AD8) and X4R5 (DH12) HIV-1 isolates indicate that there are complex tertiary interdomain interactions even after a complete denaturation of the protein. Our data suggest that the determinant(s) responsible for the high WB immunoreactivity might be present in all gp120s, but are accessible to antibodies only for R5 gp120s in the WB assay. The V1/V2 and/or V3 regions of X4 and X4R5 gp120s likely interfere with either the formation or surface exposure of the WB immunoreactive determinant. Supplementing HIV-1 WB diagnosis kits with purified R5 gp120 could improve their sensitivity and facilitate earlier diagnosis of virus infection.

Quantification of thymic function by measuring T cell receptor excision circles within peripheral blood and lymphoid tissues in monkeys

The thymus is the primary organ responsible for the production of mature TCR alpha / beta T cells. Quantification of a DNA excision circle that is produced during TCR rearrangement, termed a signal joint TCR rearrangement excision circle (sjTREC) can be used as a measure of thymic function. Here sjTREC measurement has been applied to two monkey species used as animal models of human disease, rhesus macaques (Asian origin) and sooty mangabeys (African origin). Initial PCR analysis determined that the TCR deltaRec-PsiJalpha rearrangement leading to sjTREC formation occurs in both species. Primers to a DNA sequence conserved in macaques, mangabeys and humans were used in a quantitative competitive PCR assay to quantify sjTREC. We found that as in humans, sjTREC in these two monkey species decline with age. sjTREC are first generated in thymocytes during the early stages of TCR rearrangement. Lymph node CD4(+) and CD8(+) T cells contain more sjTREC than peripheral blood T cell populations, suggesting that recent thymic emigrants home to the lymphoid tissues. The sjTREC level is significantly higher within the peripheral blood CD4(+) and CD8(+) T cells of mangabeys compared to macaques. Removal of the thymus in four macaques led to a profound decrease in peripheral blood sjTREC level by 1 year post-thymectomy, indicating the lack of a significant extra-thymic source of peripheral naive T cells in macaques. Our results indicate that production, trafficking, and proliferation of recent thymic emigrants in these two monkey species represents a useful animal model system for understanding human immunological disorders.

Effect of ABC transporters on HIV-1 infection: inhibition of virus production by the MDR1 transporter

The MDR1 multidrug transporter P-gp (P-glycoprotein) is an efflux pump that extrudes diverse hydrophobic drugs and peptides from cells. Since the entry of HIV-1 into cells involves an initial interaction of the viral gp41 hydrophobic peptide with the plasma membrane, a potential effect of P-gp on HIV-1 infectivity was explored. Virus production was greatly decreased when P-gp was overexpressed at the surface of a continuous CD4(+) human T-leukemic cell line (12D7) infected with HIV-1(NL4-3), a T-tropic molecular clone of HIV-1. P-gp overexpression did not significantly alter the surface expression or distribution of either the HIV-1 receptor CD4 or the coreceptor CXCR4. Reduction of HIV-1 infectivity in P-gp-expressing cells occurred both during the fusion of viral and plasma membranes and at subsequent step(s) in the HIV-1 life cycle.

Emergency coronary artery bypass graft surgery in abciximab-treated patients

BACKGROUND

Although the platelet antiaggregant abciximab is frequently used with percutaneous coronary interventions, results of emergency coronary artery bypass graft operations in patients recently treated with abciximab are poorly characterized.

METHODS

During a 29-month period, 12 patients required emergency coronary artery bypass grafting within 12 hours (mean, 1.9 hours) of abciximab therapy. Our full standard heparin dose regimen was used (mean heparin dose, 53,000 U per patient). Each patient received a single platelet transfusion dose after protamine administration, and further blood products were transfused as necessary. Clinical outcome and transfusion requirements were compared with predicted results based on risk-adjusted historical patients.

RESULTS

No patients died and none were returned to the operating room for coagulopathy-related bleeding. Per patient transfusion requirements were as follows: red blood cells, 3.6 units; apheresis platelets, 1.4 units; and fresh frozen plasma, 1.5 units. As compared with predicted values, there was no excessive incidence of mortality, stroke, or red blood cell transfusion requirements.

CONCLUSIONS

Emergency coronary artery bypass graft operations using full-dose heparin can be performed successfully in acutely ischemic abciximab-treated patients. Prophylactic transfusion of platelets after protamine administration appears to be useful.

Kinesins in the nervous system

Both the development and the maintenance of neurons require a great deal of active cytoplasmic transport. Much of this transport is driven by microtubule motor proteins. Membranous organelles and other macromolecular assemblies bind motor proteins that then use cycles of adenosine 5'-triphosphate hydrolysis to move these 'cargoes' along microtubules. Different sets of cargoes are transported to distinct locations in the cell. The resulting differential distribution of materials almost certainly plays an important part in generating polarized neuronal morphologies and in maintaining their vectorial signalling activities. A number of different microtubule motor proteins function in neurons; presumably they are specialized for accomplishing different transport tasks. Questions about specific motor functions and the functional relationships between different motors present a great challenge. The answers will provide a much deeper understanding of fundamental transport mechanisms, as well as how these mechanisms are used to generate and sustain cellular asymmetries.

Muscle dysfunction in elderly individuals with hip fracture

OBJECTIVE

To investigate muscle metabolism in elderly people with hip fracture.

METHODS

Free carnitine, carnitine esters, and respiratory chain enzyme activity were measured in muscle tissue from 54 patients over 65 years who underwent surgery for hip fracture, and from 40 healthy controls.

RESULTS

Eighty-five percent of patients older than 85 have either abnormal carnitine distribution or defects in the respiratory chain.

CONCLUSION

Elderly patients with hip fracture have muscle metabolic alterations that may contribute to neuromuscular impairment and be amenable to therapy.

Advantages of concurrent biochemotherapy modified by decrescendo interleukin-2, granulocyte colony-stimulating factor, and tamoxifen for patients with metastatic melanoma

PURPOSE

Concurrent biochemotherapy results in high response rates but also significant toxicity in patients with metastatic melanoma. We attempted to improve its efficacy and decrease its toxicity by using decrescendo dosing of interleukin-2 (IL-2), posttreatment granulocyte colony-stimulating factor (G-CSF), and low-dose tamoxifen.

PATIENTS AND METHODS

Forty-five patients with poor prognosis metastatic melanoma were treated at a community hospital inpatient oncology unit affiliated with the John Wayne Cancer Institute (Santa Monica, CA) between July 1995 and September 1997. A 5-day modified concurrent biochemotherapy regimen of dacarbazine, vinblastine, cisplatin, decrescendo IL-2, interferon alfa-2b, and tamoxifen was repeated at 21-day intervals. G-CSF was administered beginning on day 6 for 7 to 10 days.

RESULTS

The overall response rate was 57% (95% confidence interval, 42% to 72%), the complete response rate was 23%, and the partial response rate was 34%. Complete remissions were achieved in an additional 11% of patients by surgical resection of residual disease after biochemotherapy. The median time to progression was 6.3 months and the median duration of survival was 11.4 months. At a maximum follow-up of 36 months (range, 10 to 36 months), 32% of patients are alive and 14% remain free of disease. Decrescendo IL-2 dosing and administration of G-CSF seemed to reduce toxicity, length of hospital stay, and readmission rates. No patient required intensive care unit monitoring, and there were no treatment-related deaths.

CONCLUSION

The data from this study indicate that the modified concurrent biochemotherapy regimen reduces the toxicity of concurrent biochemotherapy with no apparent decrease in response rate in patients with poor prognosis metastatic melanoma.

Telomere dynamics in monkeys: increased cell turnover in macaques infected with chimeric simian-human immunodeficiency viruses

To address the question of how cell turnover is affected by retroviral infections, we used the telomeric terminal restriction fragments (TRFs) as markers of cell replicative history and measured their length in macaques infected with chimeric simian-human immunodeficiency viruses (SHIVs). The TRF lengths of mononuclear cells in 104 samples, including longitudinal samples from nine cynomolgus and ten pig-tailed macaques infected with SHIV, and in samples from 26 uninfected macaques, were quantitated by an improved method, based on two-dimensional calibration of DNA sizes, pulsed field electrophoresis, and high-resolution Southern blot images. The average TRF lengths of peripheral blood mononuclear cells (PBMCs) from uninfected pig-tailed (14.9+/-1.6 kbp) and cynomolgus (14.1+/-1.8 kbp) macaques were about 3 and 5 kbp longer than those of human infants and 30-year-old adults, respectively. The rate of TRF length shortening in infected pig-tailed macaques was significantly (P = 0.035) higher (2.2-fold) than in uninfected monkeys. The TRFs in SHIV-infected cynomolgus monkeys, which, in general, had lower viral loads than pig-tailed macaques, shortened on average more rapidly (1.6-fold) than in uninfected animals, but the difference was not statistically significant. The TRFs of mononuclear cells from the lymph nodes of two rapidly progressing SHIV-infected macaques that developed AIDS and died also shortened in parallel but somewhat more rapidly than in the PBMCs. These results suggest that the rate of PBMC turnover in macaques could be increased several-fold during infections by immunodeficiency viruses, likely due to immune activation by SHIV antigens.

Human immunodeficiency virus type 1 neutralizing antibodies accelerate clearance of cell-free virions from blood plasma

The concentration of human immunodeficiency virus type 1 (HIV-1) particles in blood plasma is very predictive of the subsequent disease course in an infected individual; its measurement has become one of the most important parameters for monitoring clinical status. Steady-state virus levels in plasma reflect a balance between the rates of virions entering and leaving the peripheral blood. We analyzed the rate of virus clearance in the general circulation in rhesus macaques receiving a continuous infusion of cell-free particles in the presence and absence of virus-specific antibodies. Here we show, by measuring virion RNA, particle-associated p24 Gag protein and virus infectivity, that the clearance of physical and infectious particles from a primary, dual-tropic virus isolate, HIV-1DH12, is very rapid in naive animals, with half-lives ranging from 13 to 26 minutes. In the presence of high-titer HIV-1DH12-specific neutralizing antibodies, the half-life of virion RNA was considerably reduced (to 3.9-7.2 minutes), and infectious virus in the blood became undetectable. Although physical virus particles were eliminated extravascularly, the loss of virus infectivity in the blood reflected the combined effects of extravascular clearance and intravascular inactivation of HIV-1 infectivity due to antibody binding.

Vasa vasorum: another cause of the carotid string sign

BACKGROUND AND PURPOSE

Our purpose was to describe a variant of the carotid string sign that may be associated with a completely occluded vessel and to consider possible pathophysiological mechanisms for this observation.

METHODS

Carotid angiography was performed in three patients with suspected carotid stenosis and in a fourth with carotid dissection. Surgery was performed in one of the patients with carotid stenosis.

RESULTS

On all angiograms, instead of a single linear or curvilinear contrast "string," either single or multiple serpiginous channels were seen. In one case, such a channel was seen emanating from below the origin of an occluded internal carotid stump, reconstituting the distal portion of the vessel. Surgery revealed a completely occluded lumen with a small intramural vessel bypassing the obstruction.

CONCLUSION

We propose that these channels are either atherosclerotically induced neovessels connecting bridging vasa vasorum or recanalized luminal thrombus. We review the literature associated with this subject.

Neutralizing antibody directed against the HIV-1 envelope glycoprotein can completely block HIV-1/SIV chimeric virus infections of macaque monkeys

Virus-specific antibodies protect individuals against a wide variety of viral infections. To assess whether human immunodeficiency virus type 1 (HIV-1) envelope-specific antibodies confer resistance against primate lentivirus infections, we purified immunoglobulin (IgG) from chimpanzees infected with several different HIV-1 isolates, and used this for passive immunization of pig-tailed macaques. These monkeys were subsequently challenged intravenously with a chimeric simian-human immunodeficiency virus (SHIV) bearing an envelope glycoprotein derived form HIV-1DH12, a dual-tropic primary virus isolate. Here we show that anti-SHIV neutralizing activity, determined in vitro using an assay measuring loss of infectivity, is the absolute requirement for antibody-mediated protection in vivo. Using an assay that measures 100% neutralization, the titer in plasma for complete protection of the SHIV-challenged macaques was in the range of 1:5-1:8. The HIV-1-specific neutralizing antibodies studied are able to bind to native gp120 present on infectious virus particles. Administration of non-neutralizing anti-HIV IgG neither inhibited nor enhanced a subsequent SHIV infection.

Sequential determination of free and total cyanide by flow injection

This study presents a flow injection system for the sequential determination of free (CN(-)) and total (CN(-)+ HCN) cyanide using a potentiometric method which employs two different processes for the determination of these two chemical species. The first process is based on direct detection of CN(-) using an ion-selective electrode for cyanide. In the second process, the sample is mixed with acid, and the released HCN is transferred across a PTFE membrane. The flow system employs three solenoid valves, a gas diffusion chamber, an ion-selective electrode, a potentiometer, and a computer with an AID conversion card. A Turbo Pascal computer program automatically performs all the steps involved in data acquisition and processing. The standard deviation for the results obtained with the proposed method was 0.5%.