On a path toward a broad-spectrum anti-viral: inhibition of HIV-1 and coronavirus replication by SR kinase inhibitor harmine

IMPORTANCE

This study highlights the crucial role RNA processing plays in regulating viral gene expression and replication. By targeting SR kinases, we identified harmine as a potent inhibitor of HIV-1 as well as coronavirus (HCoV-229E and multiple SARS-CoV-2 variants) replication. Harmine inhibits HIV-1 protein expression and reduces accumulation of HIV-1 RNAs in both cell lines and primary CD4+ T cells. Harmine also suppresses coronavirus replication post-viral entry by preferentially reducing coronavirus sub-genomic RNA accumulation. By focusing on host factors rather than viral targets, our study offers a novel approach to combating viral infections that is effective against a range of unrelated viruses. Moreover, at doses required to inhibit virus replication, harmine had limited toxicity and minimal effect on the host transcriptome. These findings support the viability of targeting host cellular processes as a means of developing broad-spectrum anti-virals.

Opioid use does not limit potent low-dose HIV-1 latency reversal agent boosting

The combined effects of the HIV-1 and opioid epidemics on virus reservoir dynamics are less well characterized. To assess the impact of opioid use on HIV-1 latency reversal, we studied forty-seven suppressed participants with HIV-1 and observed that lower concentrations of combination latency reversal agents (LRA) led to synergistic virus reactivation ex vivo, regardless of opioid use. The use of a Smac mimetic or low-dose protein kinase C agonist, compounds that did not reverse latency alone, in combination with low-dose histone deacetylase inhibitors generated significantly more HIV-1 transcription than phorbol 12-myristate 13-acetate (PMA) with ionomycin, the maximal known HIV-1 reactivator. This LRA boosting did not differ by sex or race and associated with greater histone acetylation in CD4+ T cells and modulation of T cell phenotype. Virion production and the frequency of multiply spliced HIV-1 transcripts did not increase, suggesting a post-transcriptional block still limits potent HIV-1 LRA boosting.

Opposing roles of CLK SR kinases in controlling HIV-1 gene expression and latency

BACKGROUND

The generation of over 69 spliced HIV-1 mRNAs from one primary transcript by alternative RNA splicing emphasizes the central role that RNA processing plays in HIV-1 replication. Control is mediated in part through the action of host SR proteins whose activity is regulated by multiple SR kinases (CLK1-4, SRPKs).

METHODS

Both shRNA depletion and small molecule inhibitors of host SR kinases were used in T cell lines and primary cells to evaluate the role of these factors in the regulation of HIV-1 gene expression. Effects on virus expression were assessed using western blotting, RT-qPCR, and immunofluorescence.

RESULTS

The studies demonstrate that SR kinases play distinct roles; depletion of CLK1 enhanced HIV-1 gene expression, reduction of CLK2 or SRPK1 suppressed it, whereas CLK3 depletion had a modest impact. The opposing effects of CLK1 vs. CLK2 depletion were due to action at distinct steps; reduction of CLK1 increased HIV-1 promoter activity while depletion of CLK2 affected steps after transcript initiation. Reduced CLK1 expression also enhanced the response to several latency reversing agents, in part, by increasing the frequency of responding cells, consistent with a role in regulating provirus latency. To determine whether small molecule modulation of SR kinase function could be used to control HIV-1 replication, we screened a GSK library of protein kinase inhibitors (PKIS) and identified several pyrazolo[1,5-b] pyridazine derivatives that suppress HIV-1 gene expression/replication with an EC₅₀ ~ 50 nM. The compounds suppressed HIV-1 protein and viral RNA accumulation with minimal impact on cell viability, inhibiting CLK1 and CLK2 but not CLK3 function, thereby selectively altering the abundance of individual CLK and SR proteins in cells.

CONCLUSIONS

These findings demonstrate the unique roles played by individual SR kinases in regulating HIV-1 gene expression, validating the targeting of these functions to either enhance latency reversal, essential for "Kick-and-Kill" strategies, or to silence HIV protein expression for "Block-and-Lock" strategies.

HIV-infected macrophages evade NK cell-mediated killing while driving inflammation

The primary targets for HIV infection are CD4 T cells, however macrophages (MΦ) are also infected and persist despite antiretroviral therapy, suggesting evasion of immune responses. Our previous work shows that while HIV-infected MΦ are recognized by cytolytic CD8 T lymphocytes (CTL), killing is inefficient and causes hypersecretion of CTL cytokines that propagate inflammation, emphasizing the need for rapid killing to limit inflammation. Thus, we hypothesized that NK cells would be able to rapidly kill HIV-infected MΦ while limiting inflammation. To test this hypothesis, innate interactions between NK cells and HIV-infected MΦ or CD4 T cells were assessed via flow cytometry-based recognition/killing assays. To characterize the potential for antibody-dependent cellular cytotoxicity (ADCC), HIV envelope expression on MΦ was characterized by flow cytometry and HIV-specific CAR T cells. Finally, ADCC responses against infected CD4 T cells and MΦ were assessed via flow cytometry. Despite similar levels of recognition of HIV-infected CD4 T cells and MΦ (degranulation and TNF-α production), NK responses to MΦ were significantly skewed towards non-cytolytic, cytokine production (p<0.0001), which was associated with poor elimination (p<0.0001). Surface HIV envelope is equally accessible on both MΦ and CD4 T cells, as determined by CAR T cell recognition. While ADCC enhanced NK cell responses to both cell types, responses to MΦ were significantly lower compared to that of CD4 T cells (p<0.05). Together, these data suggest HIV-infected MΦ employ a unique mechanism to evade cytolytic NK cell recognition while preserving inflammatory cytokine responses, emphasizing the need to develop alternative strategies to eliminate infected MΦ.

Trimeric HIV-1 gp140 fused with APRIL, BAFF, and CD40L on the mucosal gp140-specific antibody responses in mice

HIV-1 envelope (Env)-specific antibody present at mucosal surfaces can block entry of HIV-1 into these portals and thus should be elicited by an HIV-1 preventive vaccine. Since three molecules of tumor necrosis factor superfamily (TNFSF), APRIL, BAFF, and CD40L, could promote mucosal antibody responses, we made fusion constructs of them with an HIV-1 gp140 trimer and tested the mucosal gp140-specific antibody elicited by the fusion constructs in mice using a DNA prime-protein boost vaccination regimen. The fusion constructs formed trimers and displayed both broadly neutralizing antibody epitopes and non-broadly neutralizing antibody epitopes. Compared with the control construct, trimeric gp140, trimeric gp140-APRIL and gp140-BAFF fusion proteins mildly promoted B cell proliferation in vitro, enhanced HIV-1 gp140-binding IgG responses in vaginal lavage or fecal pellets, respectively, and decreased HIV-1 gp140-binding IgA in sera. Gp140-APRIL also augmented HIV-1 gp140-binding IgG in sera. Surprisingly, gp140-CD40L did not promote B cell proliferation in vitro and inhibited mucosal and systemic HIV-1 gp140-binding IgG or IgA. These results suggest that APRIL and BAFF should be further explored as molecular adjuvants for HIV-1 vaccines to enhance mucosal antibody responses, but covalent fusion of TNFSFs to gp140 may hinder their adjuvancy due to steric interactions.

Differential susceptibility to granzymes drives delayed apoptosis of HIV-infected macrophages and promotes CTL pro-inflammatory cytokine release

Although CD4+ T cells represent the main target cell for HIV/SIV infection, macrophages also contribute to viral reservoirs. Given CD8+ cytotoxic T lymphocytes (CTL) are essential for controlling viral replication, characterizing how they interact with HIV-infected targets will provide insights into mechanisms of reservoir persistence and cure strategies. CTL killing of SIV-infected macrophages is less efficient than CD4+ T cells, but the mechanism of this differential killing and whether this applies to HIV is not known. Here, we demonstrate that in contrast to infected CD4+ T cells, HIV-infected macrophages are intrinsically resistant to ex vivo CTL-mediated killing, resulting in inefficient suppression of viral infection. However, when macrophages are killed, apoptosis is delayed and caspase-3-dependent versus CD4+ T cell apoptosis, which is rapid and caspase-independent. Induction of these separate apoptosis pathways is a result of differential sensitivity to granzymes, specifically granzyme B, which is poorly expressed by ex vivo HIV-specific CTLs. Differential killing is not a consequence of poor recognition. On the contrary, CTL interaction with antigen-loaded macrophages is associated with longer effector-target contact time and increased CTL production of IFN-γ. This excess IFN-γ induces production of macrophage pro-inflammatory chemokines, CXCL9 and CXCL10, which recruit activated CD4+ T cell targets. These results suggest that inefficient CTL killing of HIV-infected macrophages may contribute to reservoir persistence, chronic inflammation, and recruitment of CD4+ T cells to sites of infection.

Soluble Tim-3 is shed from CD8+ T cells by the sheddase ADAM10, is increased in plasma during untreated HIV infection, and correlates with HIV disease progression (VIR6P.1165)

Chronic HIV infection results in a loss of HIV-specific CD8+ T cell effector function, termed “exhaustion”, mediated, in part, by the co-inhibitory receptor T cell immunoglobulin mucin domain-3 (Tim-3). Like many other receptors, a soluble form of this protein has been described in human blood plasma. However, soluble Tim-3 (sTim-3) is poorly characterized and its role in HIV disease is unknown. Here we show that Tim-3 is shed from the surface of responding CD8+ T cells by the matrix metalloproteinase, ADAM10, producing a soluble form of the co-inhibitory receptor. Despite previous reports in the mouse model, no alternatively spliced, soluble form of Tim-3 was observed in humans. Shed sTim-3 was found in human plasma, and was significantly elevated during early and chronic untreated HIV infection, but was not found differentially modulated in HAART treated HIV-infected subjects or in elite controllers, when compared to HIV-uninfected subjects. Plasma sTim-3 levels positively correlated with HIV viral load and negatively correlated with CD4 counts. Thus, plasma sTim-3 shedding correlated with HIV disease progression. Despite these correlations, we found that shedding Tim-3 did not improve the function of CD8+ T cells in terms of IFN-γ production or prevent their apoptosis through galectin-9. Further characterization studies of sTim-3 function are needed to understand the contribution of sTim-3 in HIV disease pathogenesis with implications for novel therapeutic interventions.

Characterization of human soluble Tim-3 and its role in HIV infection (VIR1P.1002)

Chronic Human Immunodeficiency Virus Type-1 (HIV) infection results in a loss of HIV-specific CD8+ T cell effector function, termed “exhaustion”, which is mediated, in-part, by the co-inhibitory receptor T-cell immunoglobulin mucin domain-containing protein 3 (Tim-3). Like many other receptors, a soluble form of this protein has been described in human blood plasma. However, this soluble Tim-3 (sTim-3) is poorly characterized and it’s unclear whether it plays a role in HIV pathogenesis. Using a Tim-3 ELISA, we found that levels of sTim-3 were significantly elevated in HIV+ antiretroviral treatment naïve patient plasma compared to healthy controls or HIV+ antiretroviral treated patients, and significantly correlated positively with viral load but not with CD4+ T cell counts. To characterize this construct, we immunoprecipitated the protein from HIV+ patient plasma; western blotting analysis revealed that plasma sTim-3 is the approximate size of the Tim-3 ectodomain. Following detection of sTim-3 from activated PBMCs in culture, no alternatively spliced Tim-3 constructs were observed, however, levels of sTim-3 were abrogated with the inclusion of a matrix metalloproteinase, ADAM10, inhibitor. Further, we showed that this sTim-3 was produced from activated T cells treated with an ADAM10 agonist and was the approximate size of plasma sTim-3. Our results suggest that increasing levels of viral antigen result in increased Tim-3 shedding from the T cell surface during HIV infection.

IL-10-producing B cells are induced early in HIV-1 infection and suppress HIV-1-specific T cell responses

A rare subset of IL-10-producing B cells, named regulatory B cells (Bregs), suppresses adaptive immune responses and inflammation in mice. In this study, we examined the role of IL-10-producing B cells in HIV-1 infection. Compared to uninfected controls, IL-10-producing B cell frequencies were elevated in both blood and sigmoid colon during the early and chronic phase of untreated HIV-1 infection. Ex vivo IL-10-producing B cell frequency in early HIV-1 infection directly correlated with viral load. IL-10-producing B cells from HIV-1 infected individuals were enriched in CD19(+)TIM-1(+) B cells and were enriched for specificity to trimeric HIV-1 envelope protein. Anti-retroviral therapy was associated with reduced IL-10-producing B cell frequencies. Treatment of B cells from healthy donors with microbial metabolites and Toll-like receptor (TLR) agonists could induce an IL-10 producing phenotype, suggesting that the elevated bacterial translocation characteristic of HIV-1 infection may promote IL-10-producing B cell development. Similar to regulatory B cells found in mice, IL-10-producing B cells from HIV-1-infected individuals suppressed HIV-1-specific T cell responses in vitro, and this suppression is IL-10-dependent. Also, ex vivo IL-10-producing B cell frequency inversely correlated with contemporaneous ex vivo HIV-1-specific T cell responses. Our findings show that IL-10-producing B cells are induced early in HIV-1 infection, can be HIV-1 specific, and are able to inhibit effective anti-HIV-1 T cell responses. HIV-1 may dysregulate B cells toward Bregs as an immune evasion strategy.

Rapid Galectin-9 release occurs following HIV-1 acquisition in acute HIV-1 infection (P6165)

Despite successes with antiretroviral therapy, HIV infection continues to be a significant health burden with patients remaining at risk of non-AIDS defining events. The earliest immunological responses induced during HIV infection are key events in the control of HIV disease progression. Soluble biomarkers may aid in understanding HIV-immunopathogenesis, inflammation and prophylactic vaccine design. Galectin-9 (Gal-9) is a bidirectional immune regulator that promotes tissue inflammation and cell death but induces immune tolerance in part through engagement with the Tim-3 receptor. We measured circulating levels of Gal-9 in the plasma of 10 acute HIV-infected subjects at multiple time points over a 42-day period, before and after detectable HIV RNA. Plasma HIV RNA levels increased rapidly in all subjects. We found that Gal-9 levels rose with the first median elevation time of 5 days after detectable viremia and a median peak of 57.4 pg/ml. Overall Gal-9 levels generally tracked with viremia. In vitro, recombinant Gal-9 significantly increased IFN-γ production by CD8+ T cells compared to untreated cells (0.02% vs 1.2%) in cultures from early HIV-infected subjects and this was reversed by α-lactose blockade. Our findings reveal that Gal-9 is a novel plasma factor that is rapidly elevated during the first wave of the cytokine storm after HIV emergence and may have important roles in CD4+ T cell loss or the response to tissue damage.

HERV-K-specific T cells eliminate diverse HIV-1/2 and SIV primary isolates

The genetic diversity of HIV-1 represents a major challenge in vaccine development. In this study, we establish a rationale for eliminating HIV-1-infected cells by targeting cellular immune responses against stable human endogenous retroviral (HERV) antigens. HERV DNA sequences in the human genome represent the remnants of ancient infectious retroviruses. We show that the infection of CD4+ T cells with HIV-1 resulted in transcription of the HML-2 lineage of HERV type K [HERV-K(HML-2)] and the expression of Gag and Env proteins. HERV-K(HML-2)-specific CD8+ T cells obtained from HIV-1-infected human subjects responded to HIV-1-infected cells in a Vif-dependent manner in vitro. Consistent with the proposed mode of action, a HERV-K(HML-2)-specific CD8+ T cell clone exhibited comprehensive elimination of cells infected with a panel of globally diverse HIV-1, HIV-2, and SIV isolates in vitro. We identified a second T cell response that exhibited cross-reactivity between homologous HIV-1-Pol and HERV-K(HML-2)-Pol determinants, raising the possibility that homology between HIV-1 and HERVs plays a role in shaping, and perhaps enhancing, the T cell response to HIV-1. This justifies the consideration of HERV-K(HML-2)-specific and cross-reactive T cell responses in the natural control of HIV-1 infection and for exploring HERV-K(HML-2)-targeted HIV-1 vaccines and immunotherapeutics.

Group art therapy as an adjunctive treatment for people with schizophrenia: a randomised controlled trial (MATISSE)

OBJECTIVE

To examine the clinical effectiveness and cost-effectiveness of referral to group art therapy plus standard care, compared with referral to an activity group plus standard care and standard care alone, among people with schizophrenia.

DESIGN

A three-arm, parallel group, single-blind, pragmatic, randomised controlled trial. Participants were randomised via an independent and remote telephone randomisation service using permuted blocks, stratified by study centre.

SETTING

Study participants were recruited from secondary care mental health and social services in four UK centres.

PARTICIPANTS

Potential participants were aged 18 years or over, had a clinical diagnosis of schizophrenia, confirmed by an examination of case notes, and provided written informed consent. We excluded those who were unable to speak sufficient English to complete the baseline assessment, those with severe cognitive impairment and those already receiving arts therapy.

INTERVENTIONS

Group art therapy was delivered by registered art therapists according to nationally agreed standards. Groups had up to eight members, lasted for 90 minutes and ran for 12 months. Members were given access to a range of art materials and encouraged to use these to express themselves freely. Activity groups were designed to control for the non-specific effects of group art therapy. Group facilitators offered various activities and encouraged participants to collectively select those they wanted to pursue. Standard care involved follow-up from secondary care mental health services and the option of referral to other services, except arts therapies, as required.

MAIN OUTCOME MEASURES

Our co-primary outcomes were global functioning (measured using the Global Assessment of Functioning Scale - GAF) and mental health symptoms (measured using the Positive and Negative Syndrome Scale - PANSS) at 24 months. The main secondary outcomes were level of group attendance, social functioning, well-being, health-related quality of life, service utilisation and other costs measured 12 and 24 months after randomisation.

RESULTS

Four hundred and seventeen people were recruited, of whom 355 (85%) were followed up at 2 years. Eighty-six (61%) of those randomised to art therapy and 73 (52%) of those randomised to activity groups attended at least one group. No differences in primary outcomes were found between the three study arms. The adjusted mean difference between art therapy and standard care at 24 months was -0.9 [95% confidence interval (CI) -3.8 to 2.1] on the GAF Scale and 0.7 (95% CI -3.1 to 4.6) on the PANSS Scale. Differences in secondary outcomes were not found, except that those referred to an activity group had fewer positive symptoms of schizophrenia at 24 months than those randomised to art therapy. Secondary analysis indicated that attendance at art therapy groups was not associated with improvements in global functioning or mental health. Although the total cost of the art therapy group was lower than the cost of the two comparison groups, referral to group art therapy did not appear to provide a cost-effective use of resources.

CONCLUSIONS

Referring people with established schizophrenia to group art therapy as delivered in this randomised trial does not appear to improve global functioning or mental health of patients or provide a more cost-effective use of resources than standard care alone.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN 46150447.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 16, No. 8. See the HTA programme website for further project information.

Antigen-independent induction of Tim-3 expression on human T cells by the common γ-chain cytokines IL-2, IL-7, IL-15, and IL-21 is associated with proliferation and is dependent on the phosphoinositide 3-kinase pathway

T cell Ig mucin domain-containing molecule 3 (Tim-3) is a glycoprotein found on the surface of a subset of CD8(+) and Th1 CD4(+) T cells. Elevated expression of Tim-3 on virus-specific T cells during chronic viral infections, such as HIV-1, hepatitis B virus, and hepatitis C virus, positively correlates with viral load. Tim-3(+) cytotoxic T cells are dysfunctional and are unable to secrete effector cytokines, such as IFN-γ and TNF-α. In this study, we examined potential inducers of Tim-3 on primary human T cells. Direct HIV-1 infection of CD4(+) T cells, or LPS, found to be elevated in HIV-1 infection, did not induce Tim-3 on T cells. Tim-3 was induced by the common γ-chain (γc) cytokines IL-2, IL-7, IL-15, and IL-21 but not IL-4, in an Ag-independent manner and was upregulated on primary T cells in response to TCR/CD28 costimulation, as well as γc cytokine stimulation with successive divisions. γc cytokine-induced Tim-3 was found on naive, effector, and memory subsets of T cells. Tim-3(+) primary T cells were more prone to apoptosis, particularly upon treatment with galectin-9, a Tim-3 ligand, after cytokine withdrawal. The upregulation of Tim-3 could be blocked by the addition of a PI3K inhibitor, LY 294002. Thus, Tim-3 can be induced via TCR/CD28 costimulation and/or γc cytokines, likely through the PI3K pathway.

HCV-specific T cells in HCV/HIV co-infection show elevated frequencies of dual Tim-3/PD-1 expression that correlate with liver disease progression

Co-infection of HCV with HIV has been associated with more rapid progression of HCV-related disease. HCV-specific T-cell immune responses, which are essential for disease control, are attenuated in co-infection with HIV. T-cell exhaustion has recently been implicated in the deficient control of chronic viral infections. In the current study, we investigated the role of programmed death-1 (PD-1) and T-cell immunoglobulin and mucin domain-containing molecule-3 (Tim-3) expression in T-cell exhaustion during HCV/HIV co-infection. We show that in HCV/HIV co-infection, both total and HCV-specific T cells co-express Tim-3 and PD-1 in significantly higher frequencies, compared with HCV mono-infection. Co-expression of these two markers on HCV-specific CD8(+) T cells positively correlated with a clinical parameter of liver disease progression. HCV-specific CD8(+) T cells showed greater frequencies of Tim-3/PD-1 co-expression than HIV-specific CD8(+) T cells, which may indicate a greater degree of exhaustion in the former. Blocking Tim-3 or PD-1 pathways restored both HIV- and HCV-specific CD8(+) T-cell expansion in the blood of co-infected individuals. These data demonstrate that co-expression of Tim-3 and PD-1 may play a significant role in HCV-specific T-cell dysfunction, especially in the setting of HIV co-infection.

A study of amsalog (CI-921) administered orally on a 5-day schedule, with bioavailability and pharmacokinetically guided dose escalation

PURPOSE

Amsalog is a derivative of 9-aminoacridine. Phase I studies using intravenous (i.v.) amsalog have shown the dose-limiting toxicity (DLT) to be phlebitis and myelosuppression. Phase II studies using a variety of schedules have shown evidence of activity in patients with large-cell lung, breast, and head and neck cancers. Preclinical studies demonstrated that amsalog is active orally: a clinical study of the oral bioavailability of amsalog was therefore performed.

METHODS

A group of 20 patients with refractory malignancies were treated. There were two phases of the study: a pharmacokinetic comparison of i.v. against oral amsalog, followed by a pharmacokinetically guided oral dose escalation study. In the first phase of the study, 11 patients were treated. Amsalog 50 mg/m2 was administered i.v., and 50 mg/m2 and 200 mg/m2 orally. In the second phase of the study, 9 patients were treated in three cohorts of three. On day 1 of a 5-day schedule, amsalog was administered i.v. at the maximum tolerated dose (MTD) of 200 mg/m2. Subsequent doses were given orally, starting at a dose of 200 mg/m2 per day, with intrapatient dose escalation of up to 100% for the second cycle. Doses were escalated further in subsequent cohorts, based on oral bioavailability and toxicity.

RESULTS

Oral bioavailability of 50 mg/m2 amsalog was 34%. In the dose escalation phase, DLT was neutropenia; other toxicities included malaise and nausea. The MTD was 1600 mg/m2 per day for 5 days. The plasma AUC using 1600 mg/m2 by the oral route was higher than that achieved using 200 mg/m2 by the i.v. route.

CONCLUSION

Amsalog can be tolerated orally on a 5-day schedule at doses up to 1600 mg/m2. The recommended dose for further evaluation is 800 mg/m2 daily for 5 days, repeated three weekly.

Modulations in gene expression and mapping of genes associated with cyst nematode infection of soybean

Infection of the soybean root by the soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) induces a well-documented, yet poorly understood, response by the host plant. The plant response, involving the differentiation of a feeding structure, or "syncytium," facilitates the feeding and reproduction of the nematode to the detriment of the host. We used a genetic system involving a single dominant soybean gene conferring susceptibility to an inbred nematode strain, VL1, to characterize the nematode-host interaction in susceptible line PI 89008. The restriction fragment length polymorphism marker pB053, shown to map to a major SCN resistance locus, cosegregates with resistance among F2 progeny from the PI 89008 x PI 88287 cross. Cytological examination of the infection process confirmed that syncytium development in this genetic system is similar to that reported by others who used noninbred nematode lines. Our study of infected root tissue in the susceptible line PI 89008 revealed a number of genes enhanced in expression. Among these are catalase, cyclin, elongation factor 1alpha, beta-1,3-endoglucanase, hydroxy-methylglutaryl coenzyme A reductase, heat shock protein 70, late embryonic abundant protein 14, and formylglycinamidine ribonucleotide synthase, all of which we have genetically positioned on the public linkage map of soybean. Formylglycinamidine ribonucleotide synthase was found to be tightly linked with a major quantitative trait locus for SCN resistance. Our observations are consistent with the hypothesis proposed by others that feeding site development involves the dramatic modulation of gene expression relative to surrounding root cells.

Pulmonary nodule detection: low-dose versus conventional CT

PURPOSE

To quantitate the effectiveness of low-dose computed tomography (CT) in the identification of pulmonary nodules while controlling for anatomic nodule characteristics and to establish what factors lead to reduced diagnostic sensitivity at low-dose CT.

MATERIALS AND METHODS

Each of six participating radiologist independently rated 200 image panels by using a four-point confidence scale. Conventional images were obtained at 200 mAs; low-dose images were obtained at 20 mAs. To fully control their characteristics, nodules were simulated with a given diameter, shape, and section thickness while preserving the resolution, noise level, and reconstruction artifacts of the original images. Panels were matched so that nodules on low-dose and conventional images had equivalent sizes, locations, and relationships to blood vessels.

RESULTS

Among 864 positive panels, 259 (60%) of 432 low-dose panels and 272 (63%) of 432 conventional panels were correctly interpreted (P = .259). Lowering the x-ray dose significantly reduced the detectability of peripheral nodules (P = .019) and nodules separated from blood vessels (P = .044). Surprisingly, 3-mm nodules were detected with approximately equal sensitivity (P = .181) at conventional and low-dose CT. The specificity of low-dose images was 88% (148 of 168 panels) versus 91% (153 of 168 panels) for conventional images (P = .372).

CONCLUSION

Low-dose CT is acceptable for pulmonary nodule identification, making it suitable for primary screening. These results confirm the strong effect of size, location, and angiocentricity on the sensitivity of nodule detection with conventional CT.

The relationship between overnight GH levels and insulin concentrations in adolescents with insulin-dependent diabetes mellitus (IDDM) and the impact of recombinant human insulin-like growth factor I (rhIGF-I)

OBJECTIVE

We examined the relationship between GH concentrations and free insulin concentrations, used as an index of insulin sensitivity, before and after recombinant human insulin-like growth factor I (RhIGF-I) administration in adolescents with insulin-dependent diabetes mellitus (IDDM).

DESIGN AND PATIENTS

Growth hormone concentrations were assessed by a peak detection programme (Pulsar) on a control night (2000 h-0800 h) and a night when rhIGF-I administered in a subcutaneous dose of 40 micrograms/kg at 1800 h to 16 adolescent subjects. Stable euglycaemia was maintained by a continuous intravenous insulin infusion and changes in free insulin levels on the two nights were compared with growth hormone data.

RESULTS

Mean overnight GH concentrations (2000 h-0800 h) on the control night were positively related to glycated haemoglobin (Hba1) concentrations (r = 0.63; P < 0.01) and were reduced following rhIGF-I administration (24.9 +/- 3.6 mU/I on the control night versus 17.4 +/- 2.2 mU/I after administration, P = 0.01). The mean GH pulse amplitude on the control night was related to the change in GH levels after rhIGF-I (rs = -0.66, P < 0.001). Multiple regression analysis revealed that mean GH pulse amplitude was the only determinant of free insulin concentrations (0500 h-0700 h on both study nights (P < 0.01). The percentage change in mean growth hormone pulse amplitude between the two nights was related to the percentage reduction in free insulin concentrations (r = 0.53, P = 0.03).

CONCLUSIONS

Growth hormone pulse amplitude is related to early morning insulin sensitivity in adolescents with IDDM on control nights and after rhIGF-I administration. The reduction in insulin levels following rhIGF-I may be linked to the change in GH pulse amplitude and not just to direct insulin-like actions. Individuals with the higher GH (and thus HbA1 levels) were most sensitive to the GH-suppressive effects of rhIGF-I.

Intensive care of patients with HIV infection: utilization, critical illnesses, and outcomes. Pulmonary Complications of HIV Infection Study Group

To examine intensive care unit (ICU) admission rates and diagnoses of patients with HIV infection, and to determine the outcomes of different critical illnesses, we analyzed data derived from the 63 patients who were admitted to an ICU from among the 1,130 adults with HIV infection who did not have AIDS at the time of enrollment in a multicenter prospective study. Patients were admitted and treated according to the judgment of their physicians. During 4,298 patient-years of follow-up for the entire cohort, there were 1,320 hospital admissions, of which 68 (5%) included admission to an ICU. Twenty-five (40%) of the patients admitted to the ICU died during that admission. Twenty-four patients (38%) were admitted with a principal diagnosis of lung disease; 11 had Pneumocystis carinii pneumonia (PCP), one of whom was coinfected with Aspergillus fumigatus and Legionella pneumophilia, and six of them (55%) died. Four had bacterial pneumonia, two had pulmonary edema caused by renal failure, and one each had pulmonary tuberculosis, pulmonary Kaposi's sarcoma, pneumothorax, adult respiratory distress syndrome, severe pulmonary fibrosis, cytomegalovirus pneumonitis, and metastatic adenocarcinoma to the lungs. Eleven of these 14 patients (79%) died. Thirty-nine patients had 44 admissions for nonpulmonary diagnoses, including gastrointestinal disorders (14 admissions), cardiovascular disorders (nine), sepsis syndrome (six), neurologic disorders (four), monitoring and ICU nursing care during or after a procedure (four), metabolic disorders (three), trauma (two), drug overdose (one), and unknown reasons (one). Nine (23%) of these patients died. Twenty-eight patients underwent mechanical ventilation, and 16 (57%) died. Seven (25%) had PCP (five died), seven had other primary pulmonary diseases (six died), and 14 were placed on mechanical ventilation for nonpulmonary disorders (five died). Survival did not correlate with CD4 count determined within 6 mo of admission to the ICU. In conclusion, the range of indications for critical care in patients with HIV infection is diverse. PCP accounted for only 16% of the ICU admissions, and mechanical ventilation for PCP and other pulmonary disorders was associated with a high mortality rate. In contrast, mechanical ventilation for nonpulmonary disorders, and admission to the ICU for nonpulmonary diagnoses was associated with a more favorable outcome.

The effects of repeated daily recombinant human insulin-like growth factor I administration in adolescents with type 1 diabetes

Reduced insulin-like growth factor bioactivity has been linked to poor metabolic control and growth hormone hypersecretion in adolescents with Type 1 diabetes. The safety and efficacy of recombinant human insulin-like growth factor I administered subcutaneously in a dose of 40 micrograms kg-1 for 28 days was studied in a group of 6 adolescent male subjects with Type 1 diabetes (aged 13.6-19.4 years, puberty stage 3-5). After a 4-week run-in period (week -4 day 0) recombinant human insulin-like growth factor I was administered for 4 weeks (day 0 to week +4) before a run-out of a further 4 weeks duration (week +4 to +8). HbA1c levels were measured throughout the study and overnight profiles were undertaken to study levels of insulin-like growth factor 1, insulin-like growth factor binding protein-3, and growth hormone concentrations (week -1, day 0, and week +4). The injections were well tolerated and hypoglycaemia was not problematic at any stage of the study. Recombinant insulin-like growth factor I administration appeared to lead to a sustained increase in insulin-like growth factor I levels (week -1; 198 +/- 16 ng ml-1, week +4; 422 +/- 18 ng ml-1, mean +/- SEM; p = 0.03). Insulin-like growth factor binding protein-3 concentrations (n = 6) increased in 5 subjects (week -1; 4.5 +/- 0.3 micrograms ml-1, week +4; 5.1 +/- 0.4 micrograms ml-1) and mean overnight growth hormone decreased (week -1; 14.0 +/- 3.1 mUI-1, week +4; 7.6 +/- 1.7 mUI-1) during the period of study but these differences were not statistically significant. HbA1c levels fell significantly at the time of rhIGF-I administration (day 0; 10.4 +/- 1.9% vs week +4; 9.4 +/- 1.9%; p = 0.03) despite a reduction in subcutaneous isophane insulin dose from 0.50 +/- 0.02 U kg-1 to 0.41 +/- 0.02 U kg-1 (p = 0.03). There was no significant change in biochemical and haematological indices, glomerular filtration rate or urinary albumin excretion. The restoration of IGF-I levels in adolescents with Type 1 diabetes may have a beneficial impact on glycaemic control.

Genetic mapping of soybean cyst nematode race-3 resistance loci in the soybean PI 437.654

Resistance to the soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) is difficult to evaluate in soybean [Glycine max (L.) Merr.] breeding. PI 437.654 has resistance to more SCN race isolates than any other known soybean. We screened 298 F6∶7 recombinant-inbred lines from a cross between PI 437.654 and 'BSR101' for SCN race-3 resistance, genetically mapped 355 RFLP markers and the I locus, and tested these markers for association with resistance loci. The Rhg 4 resistance locus was within 1 cM of the I locus on linkage group A. Two additional QTLs associated with SCN resistance were located within 3cM of markers on groups G and M. These two loci were not independent because 91 of 96 lines that had a resistant-parent marker type on group G also had a resistant-parent marker type on group M. Rhg 4 and the QTL on G showed a significant interaction by together providing complete resistance to SCN race-3. Individually, the QTL on G had greater effect on resistance than did Rhg 4, but neither locus alone provided a degree of resistance much different from the susceptible parent. The nearest markers to the mapped QTLs on groups A and G had allele frequencies from the resistant parent indicating 52 resistant lines in this population, a number not significantly different from the 55 resistant lines found. Therefore, no QTLs from PI 437.654 other than those mapped here are expected to be required for resistance to SCN race-3. All 50 lines that had the PI 437.654 marker type at the nearest marker to each of the QTLs on groups A and G were resistant to SCN race-3. We believe markers near to these QTLs can be used effectively to select for SCN race-3 resistance, thereby improving the ability to breed SCN-resistant soybean varieties.

The effects of recombinant human insulin-like growth factor-I (IGF-I) administration on the levels of IGF-I, IGF-II and IGF-binding proteins in adolescents with insulin-dependent diabetes mellitus

Insulin-dependent diabetes mellitus (IDDM) during puberty is associated with a reduction in circulating concentrations of insulin-like growth factor-I (IGF-I) and low IGF bioactivity. Altered levels of the IGF-binding proteins (IGFBPs), including low IGFBP-3 and elevated IGFBP-1, have also been described. These abnormalities have been linked to poor growth and deteriorating blood glucose control. We have therefore examined the effects of recombinant human IGF-I (rhIGF-I) administration on the levels of IGF-I, IGF-II, IGFBP-1, IGFBP-3 and IGF bioactivity in a group of 9 late-pubertal adolescents with IDDM. This was a double-blind placebo controlled study with each individual admitted on two occasions when either rhIGF-I (40 micrograms/kg) or placebo was administered by subcutaneous injection in the thigh at 1800 h. Blood samples were then taken for the subsequent 22 h. The half-life of administered rhIGF-I (12.1-22.2 h) was similar to that previously described in normal subjects. There was a small increase in IGFBP-3 concentrations overnight following rhIGF-I administration when compared to placebo, whereas the levels of IGF-II decreased. Under strict euglycaemic conditions, the relationship between insulin and IGFBP-I did not appear to be affected by rhIGF-I administration although the levels of IGFBP-1 tended to be higher overnight. IGF bioactivity was low during the placebo study, and although within the normal adult range following administration of IGF-I, was still relatively low for adolescents in late puberty.(ABSTRACT TRUNCATED AT 250 WORDS)

The perception of natural contour

The observation that natural curves and surfaces are often fractal suggests that people may be sensitive to their statistical properties. The perceptual protocols that underlie discrimination between fractals and between other types of random contour and fractals are examined. Discrimination algorithms that have precisely the same sensitivities as human observers are constructed. These algorithms do not recognize the integrated scale hierarchy intrinsic to fractal form and operate by imposing a metatheory of structure that is based on a signal-noise distinction. The success of the algorithms implies that (a) self-affinity in random fractals is not perceptually recovered and (b) people have a natural disposition to view contour in terms of signal and noise. The authors propose that this disposition be understood as a principle of perceptual organization.

Extradural vein puncture--an avoidable complication

Accidental cannulation of an extradural vein is a troublesome and potentially serious complication of extradural catheter insertion. This study was conducted to assess the influence of posture, catheter size and the injection of saline before catheter insertion, on its occurrence. Eight different techniques were studied based on combinations of these three factors. There was no difference in incidence with respect to posture. The use of 18-gauge catheters, after injection of 10 ml of 0.9% saline, resulted in a significant (p less than 0.01) reduction in the incidence of extradural vein cannulation. This technique is recommended in obstetric patients as a means of avoiding accidental intravenous injection of local analgesic.

Spinal bracing in the institutionalized person with scoliosis

Twenty institutionalized children with scoliosis were treated with a spinal bracing program for an average of two years. The Boston brace with or without superstructure was employed. These children generally had neuromuscular disease and were often functional sitters only. Seizure disorders were common. Fifteen thoracolumbar curves were improved from a prebracing mean curvature of 4.25 degrees to a postbracing mean curvature of 31 degrees. The three lumbar curves improved from 39 degrees to 30 degrees. On patient was termed a failure. The program is considered to be of definite benefit.