Temporary increase in circulating replication-competent latent HIV-infected resting CD4+ T cells after switch to an integrase inhibitor based antiretroviral regimen

BACKGROUND

The principal barrier to an HIV cure is the presence of the latent viral reservoir (LVR), which has been understudied in African populations. From 2018 to 2019, Uganda instituted a nationwide rollout of ART consisting of Dolutegravir (DTG) with two NRTI, which replaced the previous regimen of one NNRTI and the same two NRTI.

METHODS

Changes in the inducible replication-competent LVR (RC-LVR) of ART-suppressed Ugandans with HIV (n = 88) from 2015 to 2020 were examined using the quantitative viral outgrowth assay. Outgrowth viruses were examined for viral evolution. Changes in the RC-LVR were analyzed using three versions of a Bayesian model that estimated the decay rate over time as a single, linear rate (model A), or allowing for a change at time of DTG initiation (model B&C).

FINDINGS

Model A estimated the slope of RC-LVR change as a non-significant positive increase, which was due to a temporary spike in the RC-LVR that occurred 0-12 months post-DTG initiation (p < 0.005). This was confirmed with models B and C; for instance, model B estimated a significant decay pre-DTG initiation with a half-life of 6.9 years, and an ∼1.7-fold increase in the size of the RC-LVR post-DTG initiation. There was no evidence of viral failure or consistent evolution in the cohort.

INTERPRETATION

These data suggest that the change from NNRTI- to DTG-based ART is associated with a significant temporary increase in the circulating RC-LVR.

FUNDING

Supported by the NIH (grant 1-UM1AI164565); Gilead HIV Cure Grants Program (90072171); Canadian Institutes of Health Research (PJT-155990); and Ontario Genomics-Canadian Statistical Sciences Institute.

Prevalence of sexually transmitted infections among transgender women living with and without HIV in the eastern and southern United States

BACKGROUND

Data on the epidemiology of sexually transmitted infections (STIs) among transgender women (TGW) with and without HIV are limited.

METHODS

We analyzed baseline data collected from a cohort of adult TGW across 6 eastern and southern US cities between March 2018-August 2020 (n = 1,018). Participants completed oral HIV screening, provided self-collected rectal and urogenital specimens for chlamydia and gonorrhea testing, and provided sera specimens for syphilis testing. We assessed associations with ≥1 prevalent bacterial STI using modified Poisson regression.

RESULTS

Bacterial STI prevalence was high and differed by HIV status: 32% among TGW with HIV and 11% among those without HIV (demographic-adjusted prevalence ratio = 1.91 [95%CI = 1.39-2.62]). Among TGW without HIV, bacterial STI prevalence differed by geographic region, race and ethnicity, and gender identity, and was positively associated with reporting >1 sexual partner, hazardous alcohol use, homelessness, having safety concerns regarding transit to healthcare, and no prior receipt of gender-affirming health services. Among TGW with HIV, older age was inversely associated with bacterial STI.

CONCLUSIONS

TGW had a high prevalence of bacterial STIs. The prevalence and correlates of bacterial STI differed by HIV status, highlighting the unique needs and risks of TGW with and without HIV. Tailored interventions may reduce sexual health-related inequities.

Temporary increase in circulating replication-competent latent HIV-infected resting CD4+ T cells after switch to an integrase inhibitor based antiretroviral regimen

The principal barrier to an HIV cure is the presence of a latent viral reservoir (LVR) made up primarily of latently infected resting CD4+ (rCD4) T-cells. Studies in the United States have shown that the LVR decays slowly (half-life=3.8 years), but this rate in African populations has been understudied. This study examined longitudinal changes in the inducible replication competent LVR (RC-LVR) of ART-suppressed Ugandans living with HIV (n=88) from 2015-2020 using the quantitative viral outgrowth assay, which measures infectious units per million (IUPM) rCD4 T-cells. In addition, outgrowth viruses were examined with site-directed next-generation sequencing to assess for possible ongoing viral evolution. During the study period (2018-19), Uganda instituted a nationwide rollout of first-line ART consisting of Dolutegravir (DTG) with two NRTI, which replaced the previous regimen that consisted of one NNRTI and the same two NRTI. Changes in the RC-LVR were analyzed using two versions of a novel Bayesian model that estimated the decay rate over time on ART as a single, linear rate (model A) or allowing for an inflection at time of DTG initiation (model B). Model A estimated the population-level slope of RC-LVR change as a non-significant positive increase. This positive slope was due to a temporary increase in the RC-LVR that occurred 0-12 months post-DTG initiation (p<0.0001). This was confirmed with model B, which estimated a significant decay pre-DTG initiation with a half-life of 7.7 years, but a significant positive slope post-DTG initiation leading to a transient estimated doubling-time of 8.1 years. There was no evidence of viral failure in the cohort, or consistent evolution in the outgrowth sequences associated with DTG initiation. These data suggest that either the initiation of DTG, or cessation of NNRTI use, is associated with a significant temporary increase in the circulating RC-LVR.

Evaluation of early de-escalation of empiric antimicrobial therapy in acute leukemia patients with febrile neutropenia at a large academic medical center

INTRODUCTION

Recent trials have shown early de-escalation of empiric antimicrobial therapy (EAT) in febrile neutropenia has led to less adverse effects with no difference in patient mortality. In 2019, our institution adjusted internal guidelines to de-escalate EAT after 7 days of intravenous anti-pseudomonal therapy in patients with signs of clinical recovery from febrile neutropenia and no evidence of infection.

METHODS

This was a retrospective, single-center, observational, cohort study. Eligible patients were adults with acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL) who received induction chemotherapy and developed febrile neutropenia without documented infection. Patients were separated based on EAT duration: ≤ 9 days and > 9 days. Empiric antimicrobial therapy was defined as the initiation of an anti-pseudomonal beta-lactam. The primary outcome was the difference in number of EAT-free days. Secondary outcomes included fever recurrence, ICU admissions, fever duration, infections post de-escalation, and Clostridioides difficile infection (CDI).

RESULTS

Forty-four encounters met inclusion. The EAT ≤ 9 days group had 7 more EAT-free days compared to the EAT > 9 days group (p < 0.001). No between-group differences were identified in terms of fever after EAT discontinuation (p = 0.335), ICU admission (p = 0.498), or CDI (p = 0.498). The EAT > 9 days group experienced longer initial fever (p < 0.001) and received addition of resistant Gram-positive coverage (p = 0.014). More patients receiving EAT > 9 days had a diagnosis of AML (p = 0.001).

CONCLUSIONS

Shorter EAT duration did not lead to worse outcomes in patients with AML or ALL who received induction chemotherapy and developed febrile neutropenia without a documented infection source.

Development and Application of Endothelial Cells Derived From Pluripotent Stem Cells in Microphysiological Systems Models

The vascular endothelium is present in all organs and blood vessels, facilitates the exchange of nutrients and waste throughout different organ systems in the body, and sets the tone for healthy vessel function. Mechanosensitive in nature, the endothelium responds to the magnitude and temporal waveform of shear stress in the vessels. Endothelial dysfunction can lead to atherosclerosis and other diseases. Modeling endothelial function and dysfunction in organ systems in vitro, such as the blood–brain barrier and tissue-engineered blood vessels, requires sourcing endothelial cells (ECs) for these biomedical engineering applications. It can be difficult to source primary, easily renewable ECs that possess the function or dysfunction in question. In contrast, human pluripotent stem cells (hPSCs) can be sourced from donors of interest and renewed almost indefinitely. In this review, we highlight how knowledge of vascular EC development in vivo is used to differentiate induced pluripotent stem cells (iPSC) into ECs. We then describe how iPSC-derived ECs are being used currently in in vitro models of organ function and disease and in vivo applications.

Tuning bacterial hydrodynamics with magnetic fields

Magnetotactic bacteria are a group of motile prokaryotes that synthesize chains of lipid-bound, magnetic nanoparticles called magnetosomes. This study exploits their innate magnetism to investigate previously unexplored facets of bacterial hydrodynamics at surfaces. Through use of weak, uniform, external magnetic fields and local, micromagnetic surface patterns, the relative strength of hydrodynamic, magnetic, and flagellar force components is tuned through magnetic control of the bacteria's orientation. The resulting swimming behaviors provide a means to experimentally determine hydrodynamic parameters and offer a high degree of control over large numbers of living microscopic entities. The implications of this controlled motion for studies of bacterial motility near surfaces and for micro- and nanotechnology are discussed.

Genetic association of CD247 (CD3ζ) with SLE in a large-scale multiethnic study

A classic T-cell phenotype in systemic lupus erythematosus (SLE) is the downregulation and replacement of the CD3ζ chain that alters T-cell receptor signaling. However, genetic associations with SLE in the human CD247 locus that encodes CD3ζ are not well established and require replication in independent cohorts. Our aim was therefore to examine, localize and validate CD247-SLE association in a large multiethnic population. We typed 44 contiguous CD247 single-nucleotide polymorphisms (SNPs) in 8922 SLE patients and 8077 controls from four ethnically distinct populations. The strongest associations were found in the Asian population (11 SNPs in intron 1, 4.99 × 10(-4) < P < 4.15 × 10(-2)), where we further identified a five-marker haplotype (rs12141731-rs2949655-rs16859085-rs12144621-rs858554; G-G-A-G-A; P(hap) = 2.12 × 10(-5)) that exceeded the most associated single SNP rs858554 (minor allele frequency in controls = 13%; P = 4.99 × 10(-4), odds ratio = 1.32) in significance. Imputation and subsequent association analysis showed evidence of association (P < 0.05) at 27 additional SNPs within intron 1. Cross-ethnic meta-analysis, assuming an additive genetic model adjusted for population proportions, showed five SNPs with significant P-values (1.40 × 10(-3) < P< 3.97 × 10(-2)), with one (rs704848) remaining significant after Bonferroni correction (P(meta) = 2.66 × 10(-2)). Our study independently confirms and extends the association of SLE with CD247, which is shared by various autoimmune disorders and supports a common T-cell-mediated mechanism.

Host genetics and immune control of HIV-1 infection: fine mapping for the extended human MHC region in an African cohort

Multiple MHC loci encoding human leukocyte antigens (HLA) have allelic variants unequivocally associated with differential immune control of HIV-1 infection. Fine mapping based on single nucleotide polymorphisms (SNPs) in the extended MHC (xMHC) region is expected to reveal causal or novel factors and to justify a search for functional mechanisms. We have tested the utility of a custom fine-mapping platform (the ImmunoChip) for 172 HIV-1 seroconverters (SCs) and 449 seroprevalent individuals (SPs) from Lusaka, Zambia, with a focus on more than 6,400 informative xMHC SNPs. When conditioned on HLA and non-genetic factors previously associated with HIV-1 viral load (VL) in the study cohort, penalized approaches (HyperLasso models) identified an intergenic SNP (rs3094626 between RPP21 and HLA-E) and an intronic SNP (rs3134931 in NOTCH4) as novel correlates of early set-point VL in SCs. The minor allele of rs2857114 (downstream from HLA-DOB) was an unfavorable factor in SPs. Joint models based on demographic features, HLA alleles and the newly identified SNP variants could explain 29% and 15% of VL variance in SCs and SPs, respectively. These findings and bioinformatics strongly suggest that both classic and non-classic MHC genes deserve further investigation, especially in Africans with relatively short haplotype blocks.

Population screening of endangered horse breeds for the foal immunodeficiency syndrome mutation

The Fell and Dales are UK pony breeds that have small populations and may be at risk from in-breeding and inherited diseases. Foal immunodeficiency syndrome (FIS) is a lethal inherited disease caused by the recessive mutation of a single gene, which affects both Fell and Dales ponies and potentially other breeds that have interbred with either of these. FIS, previously known as Fell pony syndrome, is characterised by progressive anaemia and severe B lymphocyte deficiency. The identification of the causal mutation for this disease led to the recent development of a DNA-based carrier test. In this study, the authors used this test to estimate the prevalence of the FIS mutation in the Fell and Dales populations, revealing that approximately 18 per cent of adult Dales ponies and 38 per cent of adult Fell ponies are carriers of the FIS defect. In addition, a study of five potential at-risk breeds was conducted to assess the transfer of the FIS defect into these populations. Of the 192 coloured ponies tested, two were confirmed as FIS carriers: No carriers were found among 210 Clydesdales, 208 Exmoor ponies, 161 Welsh section D, 49 part-bred Welsh section D and 183 Highland ponies.

Serratia marcescens strains implicated in adverse transfusion reactions form biofilms in platelet concentrates and demonstrate reduced detection by automated culture

BACKGROUND AND OBJECTIVES

Serratia marcescens is a gram-negative bacterium that has been implicated in adverse transfusion reactions associated with contaminated platelet concentrates. The aim of this study was to investigate whether the ability of S. marcescens to form surface-attached aggregates (biofilms) could account for contaminated platelet units being missed during screening by the BacT/ALERT automated culture system.

MATERIALS AND METHODS

Seven S. marcescens strains, including biofilm-positive and biofilm-negative control strains and five isolates recovered from contaminated platelet concentrates, were grown in enriched Luria-Bertani medium and in platelets. Biofilm formation was examined by staining assay, dislodging experiments and scanning electron microscopy. Clinical strains were also analysed for their ability to evade detection by the BacT/ALERT system.

RESULTS

All strains exhibited similar growth in medium and platelets. While only the biofilm-positive control strain formed biofilms in medium, this strain and three clinical isolates associated with transfusion reactions formed biofilms in platelet concentrates. The other two clinical strains, which had been captured during platelet screening by BacT/ALERT, failed to form biofilms in platelets. Biofilm-forming clinical isolates were approximately three times (P<0·05) more likely to be missed by BacT/ALERT screening than biofilm-negative strains.

CONCLUSION

S. marcescens strains associated with transfusion reactions form biofilms under platelet storage conditions, and initial biofilm formation correlates with missed detection of contaminated platelet concentrates by the BacT/ALERT system.

Is familial lupus different from sporadic lupus? Data from LUMINA (LXXIII), a multiethnic US cohort

The aim of this study was to characterize the clinical features of familial lupus, and determine its influence on damage accrual and survival using data from LUMINA, a longitudinal multiethnic US cohort. Familial lupus was defined as patients with a first-degree relative with systemic lupus erythematosus. Relative risks were estimated by logistic regression; odds ratios (ORs) and their 95% confidence intervals (CIs) were the measure of association for familial lupus. Hazard ratios were calculated using Cox proportional hazards adjusted for potential confounders for damage and survival. Of 644 patients, 32 had familial and 612 had sporadic lupus; both groups were of comparable age (~36 years). Patients with familial lupus were, in decreasing order of frequency, siblings, parents and children. In multivariable analyses, mucosal ulcers (OR = 1.92, 95% CI 0.65-5.70), mitral valve prolapse (OR = 1.74, 95% CI 0.50-6.10), cerebrovascular disease (OR = 4.18, 95% CI 0.98-17.76) and oral contraceptive use (ever/never; OR = 2.51, 95% CI 0.88-7.19) were more likely in familial lupus, but a history of low platelet count (<150,000/mm(3); OR=0.31, 95% CI 0.08-1.17) and pulmonary disease activity (OR=0.39, 95% CI 0.14-1.20) were less likely. However, none of these associations reached statistical significance. Familial lupus was not significantly associated with a shorter time to either damage accrual or death (HR = 0.77, 95% CI 0.37-1.59, p = 0.4746 and HR = 0.20, 95% CI 0.03-1.47, p = 0.2020, respectively). We conclude that although some clinical differences were observed between patients with familial and sporadic lupus, familial lupus was not associated with a significantly greater disease burden (damage, survival) than sporadic lupus.

Genetic associations of LYN with systemic lupus erythematosus

We targeted LYN, a src-tyosine kinase involved in B-cell activation, in case-control association studies using populations of European-American, African-American and Korean subjects. Our combined European-derived population, consisting of 2463 independent cases and 3131 unrelated controls, shows significant association with rs6983130 in a female-only analysis with 2254 cases and 2228 controls (P=1.1 x 10(-4), odds ratio (OR)=0.81 (95% confidence interval: 0.73-0.90)). This single nucleotide polymorphism (SNP) is located in the 5' untranslated region within the first intron near the transcription initiation site of LYN. In addition, SNPs upstream of the first exon also show weak and sporadic association in subsets of the total European-American population. Multivariate logistic regression analysis implicates rs6983130 as a protective factor for systemic lupus erythematosus (SLE) susceptibility when anti-dsDNA, anti-chromatin, anti-52 kDa Ro or anti-Sm autoantibody status were used as covariates. Subset analysis of the European-American female cases by American College of Rheumatology classification criteria shows a reduction in the risk of hematological disorder with rs6983130 compared with cases without hematological disorders (P=1.5 x 10(-3), OR=0.75 (95% CI: 0.62-0.89)). None of the 90 SNPs tested show significant association with SLE in the African American or Korean populations. These results support an association of LYN with European-derived individuals with SLE, especially within autoantibody or clinical subsets.

Fcgamma receptors: structure, function and role as genetic risk factors in SLE

Over 30 years ago, receptors for the Fc region of IgG (FcgammaR) were implicated in the pathogenesis of systemic lupus erythematosus (SLE). Since those pioneering studies, our knowledge of the structure and function of these FcgammaRs has increased dramatically. We now know that FcgammaR contributes to the regulation of acquired immunity and to the regulation of innate immune responses where FcgammaRs act as specific receptors for innate opsonins (CRP and SAP). Our understanding of the genomic architecture of the genes encoding the FcgammaR has also witnessed remarkable advances. Numerous functionally relevant single-nucleotide polymorphism (SNP) variants and copy number (CN) variants have been characterized in the FcgammaR genes. Many of these variants have also been shown to associate with risk to development of SLE and some have been associated with disease progression. This review will provide an overview of the FcgammaR in relation to SLE, including consideration of the role of genetic variants in FcgammaR in SLE pathogenesis. The difficulties in assessing genetic variation in these genes will be discussed. To enhance our understanding of the functional roles of these receptors in SLE, future research will need to integrate our knowledge of SNP variants, CN variants and the functional diversity of these receptors.

Complement receptor 2 polymorphisms associated with systemic lupus erythematosus modulate alternative splicing

Genetic factors influence susceptibility to systemic lupus erythematosus (SLE). A recent family-based analysis in Caucasian and Chinese populations provided evidence for association of single-nucleotide polymorphisms (SNPs) in the complement receptor 2 (CR2/CD21) gene with SLE. Here we confirmed this result in a case-control analysis of an independent European-derived population including 2084 patients with SLE and 2853 healthy controls. A haplotype formed by the minor alleles of three CR2 SNPs (rs1048971, rs17615, rs4308977) showed significant association with decreased risk of SLE (30.4% in cases vs 32.6% in controls, P=0.016, OR=0.90 (0.82-0.98)). Two of these SNPs are in exon 10, directly 5' of an alternatively spliced exon preferentially expressed in follicular dendritic cells (FDC), and the third is in the alternatively spliced exon. Effects of these SNPs and a fourth SNP in exon 11 (rs17616) on alternative splicing were evaluated. We found that the minor alleles of these SNPs decreased splicing efficiency of exon 11 both in vitro and ex vivo. These findings further implicate CR2 in the pathogenesis of SLE and suggest that CR2 variants alter the maintenance of tolerance and autoantibody production in the secondary lymphoid tissues where B cells and FDCs interact.

Bone morphogenetic protein as an adjuvant in the treatment of Kienbock's disease by vascular pedicle implantation

This case report documents the first use of bone morphogenetic protein (BMP) as an adjuvant to revascularisation with a first dorsal metacarpal arterio-venous pedicle in the treatment of a patient with Stage III Kienbock's disease. The patient had complete relief of her symptoms of wrist pain by 8 months postoperatively, when X-rays showed no further evidence of lunate collapse and an MRI scan demonstrated islands of revascularisation. It is impossible to prove unequivocably that BMP contributed to the result seen in this one patient, but this adjuvant concept is based on experimental evidence demonstrating that optimal bioengineering of vascularised bone is dependent on four factors - a structural matrix, progenitor cells, BMP and a vascular supply, and BMP may play a future role in promoting new bone formation in Kienbock's disease.

The neurobiology of cocaine-induced reinforcement

Cocaine has potent pharmacological actions on a number of monoaminergic systems in the brain, including those that use noradrenaline, dopamine and serotonin as neurotransmitters. There is growing evidence that cocaine's effects on dopaminergic neurons, particularly those that make up the mesolimbic system, are closely associated with its rewarding properties. For example, low doses of dopamine receptor antagonists reliably influence cocaine self-administration, whereas noradrenaline and serotonin receptor antagonists are without consistent effects. Similarly, selective lesions of dopaminergic terminals in the nucleus accumbens, a major target of the mesolimbic dopamine projection, disrupt cocaine self-administration in a manner that is consistent with loss of cocaine-induced reward. The introduction of in vivo brain microdialysis as a tool with which to investigate the neurochemical correlates of motivated behaviour has provided new opportunities for investigating the role of dopamine in the nucleus accumbens in the acquisition and maintenance of cocaine self-administration. Although the body of literature that has been generated by this approach appears to contain some important inconsistencies, these probably reflect the use of inappropriate microdialysis conditions by some investigators. A critical review of the literature suggests that microdialysis results are generally consistent with a role for mesolimbic dopamine in cocaine-induced reward, although it does not seem to be the case that animals will work to maintain consistent increases in extracellular concentrations of dopamine in the nucleus accumbens in all experimental conditions. Elucidation of the complete neural circuitry of cocaine-induced reward remains an important priority for future research.

The Canadian Plastic Surgery Workforce Survey: Interpretation and Implications

BACKGROUND

Few studies have monitored physician supply in Canada, and no studies have specifically examined the Canadian plastic surgery workforce.

METHODS

In this study, data were gathered by three methods. A survey was distributed to all members of the Canadian Society of Plastic Surgeons in October of 2004. Opinions on the availability of plastic surgery services were solicited. A second survey that focused on demographics and workload was distributed in December of 2004. Finally, the locations of all Canadian trainees graduating between 1995 and 2005 were reviewed.

RESULTS

The response rate to the first survey was 42 percent. Seventy-eight percent of respondents felt that there was a shortage of plastic surgeons in their community. The response rate to the second survey was 40 percent. Twenty-eight percent of respondents were within 5 years of retirement and 3.2 percent stated that they planned to emigrate by 2010. The mean waiting time for an elective consultation was 32 +/- 33 weeks. Review of all 179 plastic surgery graduates over the past 10 years revealed that 23 percent now practice outside of Canada.

CONCLUSIONS

When these results are projected to the total workforce, they indicate that there will be a future shortage of plastic surgeons in Canada. To prevent a further deficit, there is a need to increase the number of plastic surgery trainees in Canada, to offer incentives for graduates to stay in Canada, and to possibly recruit more foreign-trained plastic surgeons to practice within Canada.

Temporary arteriovenous loop between the saphenous vein and the first plantar metatarsal artery in toe-to-hand transfers

We describe a technique for creating a temporary arteriovenous loop by anastomosing the saphenous vein to the first plantar metatarsal artery to facilitate harvesting and subsequent anastomosis of a great or second toe transfer. This technique has been used in 9 patients: 6 pediatric toe-to-hand transfers for congenital hand differences and 3 adult toe transfers for a thumb amputation. All 9 toe transfers survived. The advantages of this technique are that it allows precise determination of the exact length of the loop to reach the recipient artery, it facilitates palmar positioning of the arterial pedicle, and, if necessary, the saphenous vein can be anastomosed directly to the lateral digital artery of a great toe transfer or the medial digital artery of a second toe transfer rather than the first plantar metatarsal artery itself, thereby minimizing more proximal dissection of the first plantar metatarsal artery, which is more difficult and time consuming.

Social relations and depressive symptomatology: self-efficacy as a mediator

This study investigates general and social self-efficacy as possible mediators of the relationship between quantity and quality of social relations and depressive symptomatology. Mediation models were examined using a regionally representative sample of middle-aged (35-59) and older adults (60+). Hierarchical regression analyses, controlling for age, race, sex, education, health, and family composition, revealed partial mediation for several social relations predictor variables. Whereas general self-efficacy acted as a partial mediator for only middle-aged adults, social self-efficacy was a partial mediator between social relations and depressive symptomatology only among older adults. Findings suggest that self-efficacy may function as a mechanism through which social relations influence depressive symptoms, and that the importance of this mechanism as domain-specific or domain-general may vary with age.

Iatrogenic arteriovenous fistula after revascularization of the hand

This is the first report of an iatrogenic arteriovenous fistula complicating revascularization of an incomplete amputation of the hand, due to inadvertent anastomosis of the proximal radial artery to the distal cephalic vein. This resulted in a severely painful, massively swollen hand, which was initially diagnosed as an infection or poor venous outflow and eventually required a below-elbow amputation. This complication of replantation or revascularization should be preventable by carefully matching the thickness of the vessel wall and the diameter of the lumen, to avoid anastomosing a proximal artery to a distal vein.

Healing of a scaphoid nonunion using human bone morphogenetic protein

A chronic nonunion of a proximal pole fracture of the scaphoid was treated by curettage of the nonunion, single K-wire fixation, and implantation of 50 mg of human bone morphogenetic protein followed by 12 weeks of cast immobilization without any conventional corticocancellous bone grafting or rigid screw fixation. Radiographs showed signs of bony healing by 12 weeks and a magnetic resonance imaging scan 6 years after surgery showed no signs of avascular necrosis. The potential future applications of human bone morphogenetic protein in hand surgery are discussed.

Clarithromycin potentiates glucocorticoid responsiveness in patients with asthma: results of a pilot study

BACKGROUND

Selected macrolide antibiotics have steroid-sparing effects in patients with steroid-dependent asthma. In addition to inhibiting methylprednisolone clearance, macrolides may also display anti-inflammatory effects.

OBJECTIVE

To determine whether clarithromycin, by virtue of its anti-inflammatory effects, enhances glucocorticoid sensitivity.

DESIGN

Open-label, pilot study in a paired design (pre- and posttreatment).

PARTICIPANTS

Seven patients, mean age 27 (range 15 to 42 years), with mild to moderate asthma under good control.

METHODS

Clarithromycin (500 mg) was administered twice daily for 10 days with blood drawn for lymphocyte stimulation assays at baseline, and again upon completion of therapy. Lymphocytes were stimulated with phytohemagglutinin in the presence and absence of increasing concentrations of clarithromycin and dexamethasone (DEX).

RESULTS

At baseline, clarithromycin alone did not cause a significant degree of suppression of T-lymphocyte activation, yet clarithromycin significantly enhanced the sensitivity of lymphocytes to suppression by DEX as measured by a shift in the DEX dose-response curve by at least 6-fold (P = 0.04). In addition, a 10-day course of clarithromycin resulted in: 1) a significant decrease in the inhibitory concentration which results in a 50% reduction in proliferation for DEX alone, thereby increasing glucocorticoid sensitivity (P = 0.04); 2) heightened inhibitory effect of clarithromycin alone (P = 0.03); and 3) a sustained suppressive effect with the combination of clarithromycin and DEX on the inhibition of lymphocyte stimulation (P = 0.01).

CONCLUSIONS

Clarithromycin acts synergistically with DEX in suppressing lymphocyte activation. In addition, a 10-day course resulted in a significant treatment effect as evidenced by lower inhibitory concentration which results in a 50% reduction in proliferation value for DEX, a heightened response to clarithromycin alone, and a consistent degree of suppression of lymphocyte stimulation when clarithromycin and DEX were used together.

Inhibition of methylprednisolone elimination in the presence of clarithromycin therapy

BACKGROUND

Macrolide antibiotics have long been used as steroid-sparing agents in patients with severe steroid-dependent asthma. Their efficacy and their propensity to potentiate glucocorticoid adverse effects have been attributed in part to their ability to delay glucocorticoid clearance.

OBJECTIVE

We sought to determine whether clarithromycin, a newer macrolide antibiotic, can alter the pharmacokinetic profile of oral glucocorticoids and thereby increase the risk of steroid-induced adverse effects.

METHODS

An open-label study in a paired design (before and after treatment) was conducted in a hospital-based outpatient clinic. Participants were 6 adult patients (mean age, 30 years) with mild-to-moderate asthma. Prednisone (40 mg/1.73 m2) and methylprednisolone (40 mg/1.73 m2) were given as single randomized doses on consecutive study days before and on days 8 and 9 of a clarithromycin (500 mg twice daily) course. Twelve-hour pharmacokinetic profiles with measurement of plasma methylprednisolone and prednisolone levels were taken before and after clarithromycin therapy.

RESULTS

Clarithromycin therapy resulted in a 65% reduction of methylprednisolone clearance and significantly higher mean plasma methylprednisolone concentrations compared with preclarithromycin concentrations but had no significant effect on prednisolone clearance or mean prednisolone plasma concentrations.

CONCLUSIONS

Clinicians must be aware of potential drug interactions that could place patients at increased risk for steroid-induced adverse effects. Such an effect has been demonstrated between clarithromycin and methylprednisolone, two drugs that may be administered concomitantly in asthma. To avoid potential steroid-enhancing effects, prednisone should be substituted for methylprednisolone during prolonged courses of clarithromycin therapy.

The significance of hypersialylation of dipeptidyl peptidase IV (CD26) in the inhibition of its activity by Tat and other cationic peptides. CD26: a subverted adhesion molecule for HIV peptide binding

The functionality of DPP-IV, purified from human placenta and isolated from CD4+/CD26+ T cells of noninfected and HIV-1-infected individuals, was investigated as to its ability to bind certain specific peptides. Using isoelectric focusing and the specificity of substrate-impregnated overlay membranes, we found that DPP-IV from term placenta and from T cells of HIV-infected individuals was significantly more sialylated compared with enzyme isozyme patterns of other tissues. We report here that (1) the number of isoforms of DPP-IV and extent of sialylation are critical to function and peptide binding; (2) the number of sialylated isoforms isolated from PBMCs increases significantly with age greater than 40 years; (3) hypersialylation by extreme anionic isoforms is highly associated with HIV infection and pathognomonic to remaining CD4+ cells in overt AIDS; and (4) highly sialylated DPP-IV is more significantly inhibited by Tat and cationic peptides. We conclude that hypersialylation of DPP-IV modifies surface charge of the CD26 antigen, promoting binding of HIV peptides through their cationic domains to the sialic acid residues of DPP-IV, and that certain HIV moieties are likely to engage this phenomenon as an auxiliary adhesion mechanism to fuse with cells. Furthermore, as a consequence of this occurrence, DPP-IV enzymatic activity can be significantly reduced, competitively.

Requirement for microtubules in new membrane formation during cytokinesis of Xenopus embryos

In cleaving Xenopus eggs, exposure to nocodazole or cold shock prevents the addition of new plasma membrane to the cleavage plane and causes furrows to recede, suggesting a specific role for microtubules in cytokinesis. Whole-mount confocal immunocytochemistry reveals a ring of radially arranged, acetylated microtubule bundles at the base of all advancing cleavage furrows, from the first cleavage through the midblastula stage. We hypothesize that this novel microtubular structure is involved in transporting maternal stores of membrane in the subcortex to a site of membrane addition near the leading edge of the furrow.

Provisional bilateral symmetry in Xenopus eggs is established during maturation

Dorsal-ventral patterning in the Xenopus egg becomes established midway through the first cell cycle during a 30 degree rotation of the subcortical yolk mass relative to the egg cortex. This 'rotation of symmetrisation' is microtubule dependent, and its direction is thought to be cued by the usually eccentric sperm centrosome. The fact that parthenogenetically activated eggs also undergo a directed rotation, despite the absence of a sperm centrosome, suggests that an endogenous asymmetry in the unfertilised egg supports the directed polymerisation of microtubules in the vegetal cortex, in the way that an eccentric sperm centrosome would in fertilised eggs. Consistent with this idea, we noticed that the maturation spot is usually located an average of more than 15 degrees from the geometric centre of the pigmented animal hemisphere. In parthenogenetically activated eggs, this eccentric maturation spot can be used to predict the direction of rotation. Although in most fertilised eggs the yolk mass rotates toward the sperm entry point (SEP) meridian, occasionally this relationship is perturbed significantly; in such eggs, the maturation spot is never on the same side of the egg as the SEP. In oocytes tilted 90 degrees from upright during maturation in vitro, the maturation spot developed 15 degrees or more from the centre of the pigmented hemisphere, always displaced towards the point on the equator that was up during maturation. This experimentally demonstrated lability is consistent with an off-axis oocyte orientation during oogenesis determining its eccentric maturation spot position, and, in turn, its endogenous rotational bias.

Deep cytoplasmic rearrangements in ventralized Xenopus embryos

Following fertilization in Xenopus, dramatic rearrangements of the egg cytoplasm relocalize maternally synthesized egg components. During the first cell cycle the vegetal yolk mass rotates relative to the egg surface, toward the sperm entry point (SEP) (J. P. Vincent, G. F. Oster, and J. C. Gerhart, 1986, Dev. Biol. 113, 484-500), while concomitant deep cytoplasmic rearrangements occur in the animal hemisphere (M. V. Danilchik and J. M. Denegre, 1991, Development 111, 845-856). In this paper we examine the role of vegetal yolk mass rotation in producing the animal cytoplasmic rearrangements. We inhibited rotation by uv-irradiating embryos during the first cell cycle, a treatment that yields an extremely ventralized phenotype. Both uv-irradiated embryos and unirradiated control embryos show cytoplasmic rearrangements in the animal hemisphere during the first cell cycle. Cytoplasmic rearrangements on the SEP side of the embryo associated with the path of the sperm pronucleus, plus a swirl on the anti-SEP (dorsal) side, are seen, whether or not yolk mass rotation has occurred. This result suggests a role for the expanding sperm aster in directing animal hemisphere cytoplasmic movements. In unirradiated control embryos the anti-SEP (dorsal) swirl is larger than that in uv-irradiated embryos and often extends into the vegetal hemisphere, consistent with the animal cytoplasm having been pulled dorsally and vegetally by the sliding vegetal yolk mass. Thus the yolk mass rotation may normally enhance the dorsalward cytoplasmic movement, begun by the sperm aster, enough to induce normal axis formation. We extended our observations of unirradiated control and uv-irradiated embryos through early cleavages. The vegetal extent of the anti-SEP (dorsal) swirl pattern seen in control embryos persists through the early cleavage period, such that labeled animal cytoplasm extends deep into dorsal third-tier blastomeres at the 32-cell stage. Significantly, in uv-irradiated embryos, which have not undergone vegetal rotation, most of this labeled material remains more equatorial.

ECS-induced dopamine release: effects of electrode placement, anticonvulsant treatment, and stimulus intensity

Although electroconvulsive therapy (ECT) remains an important therapy for severe depression, its mechanism of action remains elusive. We previously demonstrated that there is a significant increase of interstitial dopamine of neuronal origin in the rat striatum after electroconvulsive shock (ECS) but not after chemically (flurothyl) induced seizures. The present studies examined how electrode placement, stimulus intensity, and the administration of an anticonvulsant affect ECS-induced dopamine release in the rat striatum. Bilateral electrode placement resulted in greater dopamine release than that produced by a unilaterally applied stimulus. Pretreatment with sodium pentobarbital markedly decreased seizure duration but had no effect on the magnitude of the increase in interstitial dopamine. Finally, a higher voltage applied longer resulted in greater dopamine release without a concomitant increase in seizure duration. These data suggest that the passage of current may be directly responsible for certain ECS-induced chemical changes. These findings are discussed in the context of clinical observations that challenge the traditional view that the production of generalized seizures of adequate duration is both necessary and sufficient for a therapeutic response to ECT.

Differential effects of excitotoxic lesions of the amygdala on cocaine-induced conditioned locomotion and conditioned place preference

The reinforcing properties of cocaine can readily become associated with salient environmental stimuli that acquire secondary reinforcing properties. This type of classical conditioning is of considerable clinical relevance, as intense drug craving can be evoked by the presentation of stimuli previously associated with the effects of cocaine. Given the large body of evidence that implicates the amygdaloid complex in the learning of stimulus-reward associations, the present experiments examined the effects of quinolinic acid lesions of the amygdala on cocaine-induced conditional locomotion and conditioned place preference (CPP). Destruction of the amygdala did not affect basal or cocaine-induced locomotion, suggesting that the amygdala does not mediate the unconditioned psychomotor stimulant effects of this drug. Preconditioning lesions also failed to affect cocaine-induced conditional locomotion. Specifically, exposure of both lesioned and non-lesioned rats to a cocaine-paired environment produced significant conditional increases in locomotion. This lack of effect was contrasted by a complete blockade of cocaine-induced CPP by the amygdaloid lesions. These data demonstrate that cocaine-induced stimulus-reward conditioning can be differentially affected by lesions of the amygdala.

Neurochemical effects of electrically and chemically induced seizures: an in vivo microdialysis study in the rat hippocampus

This study examined the effects of electroconvulsive shock (ECS) on interstitial concentrations of serotonin (5-HT), its metabolite 5-hydroxyindoleacetic acid (5-HIAA), acetylcholine and choline, and the dopamine metabolite homovanillic acid (HVA) in the hippocampus of freely moving rats using online brain microdialysis. The effects of ECS on 5-HT, 5-HIAA, and HVA were compared to the effects of seizures induced by the convulsant agent flurothyl. Interstitial concentrations of 5-HT increased several fold in response to ECS and this increase was accompanied by a significant increase in the concentration of HVA. Acetylcholine and choline concentrations were also increased significantly by ECS. The ECS-induced increase in interstitial 5-HT was markedly reduced when the voltage-dependent sodium channel blocker tetrodotoxin (1 mumol/L) was added in the perfusion solution, indicating that the observed increase was of neuronal origin. Interstitial concentrations of 5-HT also increased in response to flurothyl-induced seizures and this increase was accompanied by a significant increase in the concentration of HVA. These results provide direct in vivo evidence that interstitial concentrations of 5-HT increase several fold in response to both ECS- and flurothyl-induced seizures. These observations are discussed in relation to the hypothesized role of 5-HT in ECS-induced memory deficits.

Human focal cerebral ischemia: evaluation of brain pH and energy metabolism with P-31 NMR spectroscopy

The authors investigated early human focal ischemia with phosphorus-31 nuclear magnetic resonance spectroscopy at 1.89 T to characterize the temporal evolution and relationship of brain pH and phosphate energy metabolism. Data from 65 symptomatic patients were prospectively studied; none of the patients had had ischemic stroke in the internal carotid artery territory before. Twenty-eight neurologically normal individuals served as control subjects. Serial ischemic brain pH levels indicated a progression from early acidosis to subacute alkalosis. When acidosis was present there was a significant elevation in the relative signal intensity of inorganic phosphate (Pi) and significant reductions in signal intensities of alpha-adenosine triphosphate (ATP) and gamma-ATP compared with those of control subjects. Ischemic brain pH values directly correlated with the relative signal intensity of phosphocreatine (PCr) and the PCr index and inversely correlated with the signal intensity of Pi. There was a general lack of correlation between either ischemic brain pH or phosphate energy metabolism and the initial clinical stroke severity. The data suggest a link between high-energy phosphate metabolism and brain pH, especially during the period of ischemic brain acidosis, and the authors propose that effective acute stroke therapy should be instituted during this period.

Evidence for conditional neuronal activation following exposure to a cocaine-paired environment: role of forebrain limbic structures

The reinforcing properties of cocaine can readily become associated with salient environmental stimuli that acquire secondary reinforcing properties. This form of classical conditioning is of considerable clinical relevance as intense craving can be evoked by the presentation of stimuli previously associated with the effects of cocaine. To understand better the neurobiology of cocaine-induced environment-specific conditioning, Fos expression was examined in the forebrain of rats exposed to an environment in which they had previously received cocaine. These results were compared to those observed following an acute injection of cocaine. Consistent with its stimulant actions, cocaine produced an increase in locomotion that was accompanied by an increase in Fos expression within specific limbic regions (cingulate cortex, claustrum, piriform cortex, lateral septal nucleus, paraventricular nucleus of the thalamus, lateral habenula, and amygdala) as well as the basal ganglia (dorsomedial striatum and nucleus accumbens). Exposure of rats to the cocaine-paired environment also produced an increase in locomotion, as compared to various control groups. In addition to this behavioral effect, conditioned subjects exhibited a significant increase in Fos expression within the cingulate cortex, claustrum, lateral septal nucleus, paraventricular nucleus of the thalamus, lateral habenula, and the amygdala, suggesting increased neuronal activity within these regions. In contrast to the dramatic effects observed within these structures, no conditional activation was observed within the piriform cortex, nucleus accumbens, or dorsal striatum, suggesting that these brain areas are not involved in the conditioned response. The present findings indicate that specific limbic regions exhibit increased neuronal activation during the presentation of cocaine-paired cues and may be involved in the formation of associations between cocaine's stimulant actions and the environment in which the drug administration occurred. Although the nucleus accumbens is necessary for the reinforcing and locomotor effects of cocaine, it does not exhibit a conditional Fos response, suggesting that different neural circuits are involved in the unconditioned and conditioned effects of cocaine.

Cocaine-induced conditioned locomotion: absence of associated increases in dopamine release

The potent reinforcing effects of cocaine can readily become associated with salient environmental stimuli that acquire secondary reinforcing properties. This phenomenon is of considerable significance as intense craving can be evoked by stimuli previously associated with the effects of cocaine. It has been proposed that the reinforcing properties of these conditional stimuli are due to their ability to elicit neural events that are similar to those produced by the drug itself. Given the large body of evidence that implicates the mesolimbic dopaminergic projection in the unconditioned behavioural properties of cocaine, the present study used in vivo microdialysis to determine whether stimuli paired with cocaine elicit increases in interstitial dopamine in the nucleus accumbens that are similar to the unconditioned effects of this drug. When administered acutely, cocaine (10 mg/kg, i.p.) produced a potent unconditioned increase in interstitial dopamine concentrations (300% of basal values) in the nucleus accumbens. The results from two separate experiments indicate that the administration of cocaine (10 mg/kg for seven days) in association with a specific environment produced significant locomotion in that environment. Compared to subjects that received saline in both settings, rats that received cocaine in their home cage (pseudoconditioned group) did not exhibit increased locomotion on the test day. Although repeated pairing of cocaine with a specific environment produced conditioned locomotion, there was no concomitant conditional increase in dopamine release. Specifically, the modest increase in dopamine (10-15% above basal values) observed after exposure to the conditional environment was equal in the conditioned and pseudoconditioned groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Cocaine self-administration differentially alters mRNA expression of striatal peptides

The influence of cocaine self-administration on the expression of messenger RNAs for dynorphin, enkephalin and substance P was analyzed in the rat striatum with in situ hybridization histochemistry. Cocaine, an indirect dopamine agonist, was found to differentially affect the levels of mRNA encoding these neuropeptides in different subregions of the striatum. Following a 7 day period of variable free access to cocaine, dynorphin and substance P mRNA levels were elevated throughout the striatum, but the increases were substantially greater in the dorsal striatum than in the nucleus accumbens. Enkephalin mRNA was not significantly altered in the dorsal striatum but was slightly elevated in the nucleus accumbens. These results suggest that cocaine self-administration has differential effects on striatonigral and striatopallidal projection neurons, and that these effects vary in subregions of the striatum.

Chronic desipramine enhances the effect of locally applied amphetamine on interstitial concentrations of dopamine in the nucleus accumbens

In vivo microdialysis was used to study the effect of chronic desipramine (DMI, 5 mg/kg, twice daily for 21 days) on increases in interstitial dopamine (DA) produced by local administration of d-amphetamine (1.0, 3.3 and 10.0 microM) in the nucleus accumbens. Locally applied amphetamine increased interstitial DA in a dose-dependent manner. The amphetamine-induced increase was significantly greater in the DMI treated animals. These data suggest that chronic DMI may directly influence the functional status of the DA terminals in the nucleus accumbens.

Interstitial 3-methoxytyramine reflects striatal dopamine release: an in vivo microdialysis study

Previous ex vivo studies have provided indirect evidence that the dopamine (DA) metabolite 3-methoxytyramine (3-MT) may be a useful index of DA release in vivo. In the present study, in vivo microdialysis was utilized to assess directly the relationship between extracellular DA and 3-MT in the striatum of rats following a variety of pharmacological manipulations. Apomorphine, a DA receptor agonist, produced a rapid, transient decrease in both DA and 3-MT. Conversely, the DA receptor antagonist haloperidol produced a concomitant increase in extracellular DA and 3-MT. Increases in DA and 3-MT were also noted following the administration of the DA uptake inhibitor, bupropion. Local application of tetrodotoxin resulted in the complete elimination of measurable amounts of DA and 3-MT in the dialysate, gamma-Butyrolactone also greatly decreased DA and 3-MT. Finally, d-amphetamine produced a large increase in DA and 3-MT in animals that had been treated previously with gamma-butyrolactone. The Pearson correlation coefficients for DA and 3-MT following these manipulations ranged from 0.87 to 0.97. These data indicate that interstitial 3-MT is an accurate index of DA release. However, when compared with previous ex vivo findings, the present results also suggest that changes in tissue concentrations of 3-MT may not reliably reflect DA release following certain pharmacological manipulations.

Behavioral and neurochemical interactions between cocaine and buprenorphine: implications for the pharmacotherapy of cocaine abuse

Intravenous self-administration studies in nonhuman primates suggest that the opioid receptor agonist-antagonist buprenorphine may be useful in the pharmacotherapy of cocaine abuse. In the present studies, behavioral and neurochemical interactions between cocaine and buprenorphine were examined using a conditioned place preference (CPP) procedure and in vivo microdialysis. Cocaine-induced CPP was linearly related to the dose administered (0-5.0 mg/kg). Buprenorphine (0-0.9 mg/kg) also elicited CPP in a dose-related manner; an inverted U-shaped function was obtained. Subthreshold doses of cocaine (1.5 mg/kg) and buprenorphine (0.01 mg/kg), themselves incapable of eliciting CPP, produced a significant CPP when given together. Moderate doses of cocaine (5.0 mg/kg) and buprenorphine (0.075 mg/kg), which were individually capable of eliciting CPP, produced a significantly larger CPP when given in combination. In the in vivo microdialysis studies, a low dose of buprenorphine (0.01 mg/kg) produced a progressive increase in extracellular dopamine in the nucleus accumbens, reaching approximately 200% of basal levels after 5 hr. Cocaine (5.0 mg/kg) rapidly increased extracellular dopamine concentrations (180% of basal values within 20 min), which returned to baseline in 2 to 3 hr. This effect of cocaine was significantly potentiated by coadministering buprenorphine (0.01 mg/kg); under this condition the peak increase in extracellular dopamine reached 260% of baseline values. These neurochemical findings are consistent with the CPP results and indicate that buprenorphine can interact with cocaine in a synergistic manner. In contrast to previous speculations, these results suggest that buprenorphine may enhance rather than attenuate the rewarding properties of cocaine.

Regulation of larval cuticle protein gene expression in Drosophila melanogaster

Genes that encode 3rd instar larval cuticle proteins (LCP's) of Drosophila melanogaster are located in at least two chromosomal sites. The genes encoding four of the five predominant LCP's are located in a cluster at the chromosomal region 44D. They are organized in pairs that are transcribed divergently, and expressed with different timing during the third larval instar. Towards understanding the basis of gene regulation within the 44D cluster, we have analyzed genetic variants, including the 2-3 variant, which has an insertion of a copia-like transposable element, H.M.S. Beagle, within the 44D cluster. The Beagle element appears to inactivate the LCP-3 gene by inserting into its TATA box, but also may cause the precocious expression of two other LCP genes, LCP-1 and LCP-f2, in the cluster. The long terminal repeat (LTR) of the Beagle element apparently contains a sequence, perhaps an enhancer-like element, which causes altered expression of these genes. We have also investigated the cis-regulatory elements involved in expression of the LCP-2 gene in wild-type larvae. We have identified two upstream regions that may contain separate cis-regulatory elements. The region between -252 bp and -515 bp may be essential for any expression of LCP-2. Additionally, the region between -515 bp and -795 bp appears to be required for the normal level of expression of the LCP-2 gene.

Prepupal differentiation of Drosophila imaginal discs: identification of four genes whose transcripts accumulate in response to a pulse of 20-hydroxyecdysone

We have isolated and initially characterized a novel set of four genes expressed during the prepupal differentiation of imaginal discs of Drosophila melanogaster. These four ecdysone-dependent genes are named EDG-42A, EDG-64CD, EDG-78E and EDG-84A-1 based on their respective chromosomal locations. Their expression is like that expected for genes encoding proteins that participate in the formation of the pupal cuticle. Transcripts complementary to these genes accumulate in imaginal discs during an 18-hr in vitro culture period that begins with a 6-hr pulse of 20-hydroxyecdysone (20-HE). Transcripts for three of these genes were not detected in imaginal discs following culture in the absence or the continuous presence of 20-HE (1 microgram/ml). Transcripts corresponding to EDG-64CD exhibit delayed accumulation in the continuous presence of 20-HE. Transcripts corresponding to three of the genes are only detected in the prepupal stage of development. Only EDG-64CD is complementary to transcripts present at other stages of development. One of the genes, EDG-78E, encodes a pupal cuticle protein. This is the first reported isolation of a set of steroid hormone-responsive genes that require first the presence, then removal of hormone for transcript accumulation.