Oncology clinical trial disruption during the COVID-19 pandemic: a COVID-19 and cancer outcomes study

Background

COVID-19 disproportionately impacted patients with cancer as a result of direct infection, and delays in diagnosis and therapy. Oncological clinical trials are resource-intensive endeavors that could be particularly susceptible to disruption by the pandemic, but few studies have evaluated the impact of the pandemic on clinical trial conduct.

Patients and methods

This prospective, multicenter study assesses the impact of the pandemic on therapeutic clinical trials at two large academic centers in the Northeastern United States between December 2019 and June 2021. The primary objective was to assess the enrollment on, accrual to, and activation of oncology therapeutic clinical trials during the pandemic using an institution-wide cohort of (i) new patient accruals to oncological trials, (ii) a manually curated cohort of patients with cancer, and (ii) a dataset of new trial activations.

Results

The institution-wide cohort included 4756 new patients enrolled to clinical trials from December 2019 to June 2021. A major decrease in the numbers of new patient accruals (−46%) was seen early in the pandemic, followed by a progressive recovery and return to higher-than-normal levels (+2.6%). A similar pattern (from −23.6% to +30.4%) was observed among 467 newly activated trials from June 2019 to June 2021. A more pronounced decline in new accruals was seen among academically sponsored trials (versus industry sponsored trials) (P < 0.05). In the manually curated cohort, which included 2361 patients with cancer, non-white patients tended to be more likely taken off trial in the early pandemic period (adjusted odds ratio: 2.60; 95% confidence interval 1.00-6.63), and substantial pandemic-related deviations were recorded.

Conclusions

Substantial disruptions in clinical trial activities were observed early during the pandemic, with a gradual recovery during ensuing time periods, both from an enrollment and an activation standpoint. The observed decline was more prominent among academically sponsored trials, and racial disparities were seen among people taken off trial.

AB0227 TREATMENT SEQUENCING PATTERNS AND COMPARATIVE EFFICACY IN PATIENTS WITH RHEUMATOID ARTHRITIS FROM A REAL-WORLD SETTING

Background

The European League Against Rheumatism (EULAR)1 recently provided updated guidelines regarding the initiation and modification of disease-modifying antirheumatic drug (DMARD) therapy in patients with Rheumatoid Arthritis (RA). Therefore, real-world evidence studies are warranted to provide insights into first-line DMARD utilization and durability of response in the second-line setting.

Objectives

To analyze RA treatment patterns in real-world data and compare durability of response between second-line DMARDs + anti-TNF (TNFi) therapies vs. TNFi monotherapy.

Methods

Electronic health records (EHRs) from a large health system in the Northeast US were used to identify RA patients. Lines of therapy were defined based on confirmed prescriptions for DMARDs and TNFi therapies. Time to next treatment (TTNT) was the primary outcome to estimate durability of response. Time-to-event analyses were performed using Kaplan-Meier and log-rank test methods. In addition, a Cox Proportional-Hazards (CoxPH) model was used to evaluate covariates as independent predictors of disease progression.

Results

Our study cohort consisted of 8,040 patients who had at least one line of therapy for RA. Conventional synthetic DMARDs (csDMARDs) were the predominant first line of therapy in this dataset (71.3%), followed by TNFi alone (11.1%) or TNFi combined with csDMARD (9.1%) (Figure 1).

For patients who had csDMARD as their first line of therapy, 22.93% progressed to second line treatment. Among them 36.2% patients were TNFi with or without in combination with csDMARDs. In the second-line, TNFi + csDMARDs were associated with a longer TTNT (median time: 13.1 months vs 6.1 months, P < 0.005) compared to TNFi monotherapy. The multiple variable CoxPH model (adjusted for age, gender, and race) demonstrated that second-line TNFi + csDMARDs had a lower hazard rate when compared to TNFi monotherapy (HR = 0.74, 95% CI: 0.36 - 1.12, p < 0.005).

Conclusion

We demonstrated the first comprehensive treatment sequencing patterns in RA from a real-world setting. As a second-line therapy for patients with inadequate response to csDMARDS, the TNFi + csDMARDs combination may improve duration of response when compared to TNFi monotherapy. Results from this study will inform future sequencing strategies to improve patient outcomes.

References

[1]Smolen, Josef S., Robert B. M. Landewé, Johannes W. J. Bijlsma, Gerd R. Burmester, Maxime Dougados, Andreas Kerschbaumer, Iain B. McInnes, et al. 2020. “EULAR Recommendations for the Management of Rheumatoid Arthritis with Synthetic and Biological Disease-Modifying Antirheumatic Drugs: 2019 Update.” Annals of the Rheumatic Diseases 79 (6): 685–99.

Disclosure of Interests

Lei Ai: None declared, Mitchell Higashi: None declared, Kyeryoung Lee: None declared, Zongzhi Liu: None declared, Lan Jin: None declared, Kalpana Raja: None declared, Yun Mai: None declared, Tomi Jun: None declared, William Oh Consultant of: Janssen

Pfizer, Aviva Beckmann: None declared, Emilio Schadt: None declared, Zachary Schadt: None declared, Rick Wallsten: None declared, Ediz Calay: None declared, Andrew Kasarskis: None declared, Qi Pan: None declared, Eric Schadt Speakers bureau: Eli Lilly, Consultant of: SAB of Eli Lilly

Celgene, Xiaoyan Wang: None declared

0909 Sleep Duraion And Related Factors Amongchinese Children: Across-sectional Studyabstract

Introduction

It is known short sleep duration adversely affects children’s behavior and physical development. Sleep duration and sleep habit vary substantially in children with different ages, areas and races. However, our understanding on the sleep duration in Chinese children remains limited. The present study investigated the status of sleep durations in Chinese children and explored factors related to sleep loss.

Methods

A randomized, stratified, multi-stage cluster sampling method encompassed 11420 children in 25 schools from 7 districts in Beijing. Children aged 3 to 14 years were included, and their parents were invited to fill sleep habit related questionnaires about the performance of the last 3 months.

Results

The final cohort included 4736 boys and 4462 girls with a mean age of 8.8±3.8 years. The mean sleep duration of children ≥12 years of age was 9.4h, which was significantly lower than those &lt; 12 years old (9.7h); this was in agreement with the trend of sleep durations of weekdays. On weekends and holidays, the sleep duration was approximately 10h for most children and similar in all age groups. Gender (male), age (≥12-year group), overweight, and suburban residence were significantly correlated with sleep loss in children (p&lt; 0.001). A significantly high proportion of children with sleep loss displayed sleepiness during sitting and reading (19.1%), in the car (31.4%), in the afternoon (20.7%), and after lunch (17.5%).

Conclusion

The sleep duration reduced significantly in children ≥12 years of age as compared to younger children in Beijing. Factors such as gender (male), age (≥12-year group), overweight, and suburban residence are related to sleep loss. Children ≥12 years of age older with sleep loss were likely to experience daytime sleepiness.

Support

This work was supported by Beijing Municipal Science and Technology Project grant (Z161100000116050 and Z161100003216212) and Beijing Municipal Administration of Hospitals Clinical Technology Innovation Project grant (XMLX201701). .

Long non-coding RNA UCA1 regulates the proliferation, migration and invasion of human lung cancer cells by modulating the expression of microRNA-143

OBJECTIVE

Accounting for 25% of all the cancers and 20% of the cancer-related mortality, lung cancer is one of the devastating types of cancers. Due to an increase in the incidence of lung cancer and limited treatment options, there is a pressing need to look for novel drug options and to identify potential therapeutic targets. Long non-coding RNAs (LncRNAs) have been considered to be important therapeutic targets due to their plethora of cellular roles. Herein, we investigated the therapeutic potential of UCA1 in lung cancer and also attempted to examine the underlying mechanism through UCA1 exerts its growth inhibitory effects on cancer cells.

MATERIALS AND METHODS

The quantitative Reverse-Transcriptase Polymerase Chain Reaction (qRT-PCR) was used to perform the expression analysis. The CCK-8 assay was used to monitor the growth of the cells. The AO/EB assay was used to check apoptosis and flow cytometry was used for cell cycle distribution. The wound heal and transwell assays were used to monitor the cell migration and invasion.

RESULTS

It was found that the lncRNA UCA was significantly (p < 0.05) upregulated in the lung cancer cells and silencing of UCA1 could inhibit the proliferation of the SK-MES-1 lung cancer cells via induction of G2/M cell cycle arrest and apoptosis. Moreover, UCA1 silencing could also suppress the migration and invasion of the SK-MES-1 cells. The LncRNA UCA1 was also found to upregulate the expression of miR-143, and overexpression of miR-143 could also suppress the proliferation, migration, and invasion of the SK-MES-1 lung cancer cells. Both UCA1 silencing and miR-143 overexpression could cause a significant decrease in the expression of mitogen-activated protein kinase 1 (MAPK1). Therefore, it is concluded that UCA1 regulates the growth of the SK-MES-1 lung cancer by inhibition of MAPK1 via miR-143 upregulation.

CONCLUSIONS

UCA1, as well as miR-143, may be essential therapeutic targets for the management of lung cancer and warrant further investigations.

Suppression of long non-coding RNA UCA1 inhibits proliferation and invasion and induces apoptosis in human lung cancer cells

OBJECTIVE

Lung cancer is one of the deadliest cancers responsible for significant mortality and morbidity across the globe. The unavailability of efficient treatments, lack of reliable biomarkers and potent therapeutic targets, limit the treatment of lung cancer. In this study, we explored the potential of long non-coding RNA (lncRNA) urothelial carcinoma-associated 1 (UCA1) as the therapeutic target for lung cancer.

MATERIALS AND METHODS

The expression analysis was carried out by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Cell viability was monitored by cell counting kit 8 (CCK-8) assay. The 4',6-diamidino-2-phenylindole (DAPI), annexin-V/Propidium iodide staining and comet assays were used to detect apoptosis. Boyden chamber and wound heal assays were used for cell to asses cell invasion and migration respectively. Protein expression was determined by immunoblotting.

RESULTS

The expression of lncRNA UCA1 was determined by qRT-PCR in six different types of lung cancer cell lines. It was observed that lncRNA UCA1 was significantly (p < 0.05) upregulated in all the lung cancer cell lines. To investigate the role of lncRNA UCA1 in lung cancer, its expression was suppressed by transfection of the lung cancer NCI-H23 cells by si-UCA1. The results showed that suppression of lncRNA UCA1 significantly (p < 0.05) reduced the viability of NCI-H23 cancer cells via induction of the apoptosis. Furthermore, the lncRNA UCA1 suppression (p < 0.05) significantly inhibited the migration and invasion of the NCI-H23 lung cancer at least in part via inhibition of mitogen-activated protein kinase 1 (MAPK1). Additionally, the suppression of MAPK1 exhibited similar effects on the proliferation, migration, and invasion of the NCI-H23 cells as that of UCA1 silencing. Finally, the co-suppression of lncRNA UCA1 and MAPK1 exhibited synergistic effects on cell proliferation, migration, and invasion.

CONCLUSIONS

We demonstrated that lncRNA UCA1 could be an important therapeutic target for curbing lung cancer.

Monitoring and assessing heavy metals in topsoils as potential diffuse pollutants in the Pyeongchang River Basin, Korea

Topsoils, mainly from crop fields, orchards, forests, and barns around the Pyeongchang River, were collected to investigate their heavy metal concentrations. Pollution load index, ecological risk index, and enrichment factor were applied to assess levels of heavy metal contamination for topsoils. The concentrations of cadmium (Cd) (1.7 mg/kg) and chromium (Cr) (4.1 mg/kg) exceeded the troublesome level in one site, whereas zinc (Zn) (396.7 to 711.1 mg/kg) and nickel (Ni) (40.1 to 95.3 mg/kg) in several topsoils exceeded the troublesome to countermeasure levels, according to soil contamination standards for the study areas. A significant risk of contamination was observed for mercury (Hg) by all indices, although the concentration in most of the topsoils was below the guideline. As expected, a positive linear correlation was observed for the values of pollution load index and ecological risk index, demonstrating lower heavy metal contamination in upstream areas compared to those downstream. High to extremely high ecological risk was observed in several samples for Zn and Ni, while all of the soils were unpolluted to slightly polluted, according to the pollution load index. A baseline study was not performed earlier for these sites, so these assessed values of heavy metals should be used as reference values for further assessment.

An open pilot trial of olanzapine for delirium in the Korean population

This study was performed to assess the efficacy and safety of olanzapine for the treatment of delirium in a Korean population. An open trial of olanzapine was conducted in Korean patients with delirium caused by multiple medicosurgical conditions. All subjects were evaluated by Delirium Rating Scale (DRS), which is known to be one of the most sensitive scales for delirium. In addition, other data for profiles of side-effects were collected and analyzed. Twenty patients were treated by olanzapine with doses of 5.9 +/- 1.5 mg/day. The initial dose was 4.6 +/- 0.9 mg/day and maximal dose of olanzapine was 8.8 +/- 2.2 mg/day. The average duration of treatment was 6.6 +/- 1.7 days and the day of maximal response was 3.8 +/- 1.7 treated days. The scores of DRS were significantly improved from 20.0 +/- 3.6 at the time of pretreatment to 9.3 +/- 4.6 at the post-treatment. All subjects showed no definite serious side-effects including anticholinergic and extrapyramidal symptoms. Olanzapine treatment for patients with delirium was effective and safe. This newer drug may be a useful alternative agent to classical antipsychotics in the treatment of delirium.

Dobutamine stress echocardiography for the diagnosis of myocardial viability: assessment of left ventricular systolic velocities in longitudinal axis by pulsed Doppler tissue imaging

Dobutamine (DOB) stress two-dimensional echocardiography is an established method for the detection of viable myocardium, but conventional assessment of wall motion is subjective. We measured quantitatively the left ventricular systolic velocities along the longitudinal axis by pulsed Doppler tissue imaging (DTI). In 30 patients with previous myocardial infarction, pulsed DTI focused on the infarct area was performed from an apical two- or four-chamber view before and during DOB (10 microg/kg/min) stress one day before coronary angioplasty. We calculated peak systolic velocity (S), regional pre-ejection period (PEP, the time interval from the onset of QRS to the onset of systolic wave) and regional ejection time (ET). Left ventriculography was obtained before and 3 months after coronary angioplasty to assess regional wall motion. Improvement of abnormal wall motion was observed in 19 patients (group P) but not in 11 (group N). Group P had significantly larger S and smaller PEP/ET than group N during DOB stress, although there were no significant differences in these indices between the groups at baseline. As a consequence, group P had a significantly larger percent change in S and a smaller percent change in PEP/ET than group N (164+/-39 vs 117+/-20% and 88+/-17 vs 116+/-29%, respectively, p < 0.01). It is suggested that the quantitative measurement of longitudinal systolic velocities during DOB stress by DTI is useful for the precise assessment of myocardial viability.

Lack of NO Formation Is Involved in the Vasodilative Response to Contrast Media

Intravascular injection of angiographic contrast media results in peripheral vasodilation and hypotension. The mechanisms underlying these hemodynamic changes are not entirely clear. We hypothesized that increased formation of nitric oxide (NO) could be involved in the vasodilatory response to contrast media. To address this assumption we have investigated whether N(G)-monomethyl-L-arginine (L-NMMA, 200 mg/kg) and N(G)-nitro-L-arginine methyl ester (L-NAME, 50 mg/kg), two specific NO formation inhibitors, can abolish the hypotensive response to intravascular injection of isopaque amin (1 g/kg), a contrast medium, as well as bradykinin (10 µg/kg), a NO-dependent vasodilator, in anaesthetized normotensive rats. In rats before pretreatment with L-NMMA and L-NAME, the absolute values of the average fall in mean arterial pressure (MAP) induced by intravascular injection of isopaque amin and bradykinin were 21.3 +/- 2.1 and 37.2 +/- 4.4 mmHg, respectively. Pretreatment with L-NMMA and L-NAME failed to affect the hypotensive response to isopaque amin; by administering isopaque amin in rats pretreated with L-NMMA and L-NAME the absolute values of the average fall in MAP were 25.6 +/- 4.9 and 23.4 +/- 3.9 mmHg, respectively, similar to the average fall in MAP before treatment with NO formation inhibitors. In contrast, the hypotensive response to bradykinin was significantly inhibited; by administering bradykinin in rats pretreated by L-NMMA and L-NAME, the absolute values of the average fall in MAP were 10.2 +/- 2.8 and 7.2 +/- 2.2 mmHg, respectively, much less than the average fall in MAP before treatment with NO formation inhibitors. We conclude that intravascular injection of isopaque amin causes reduction in systemic arterial pressure. However, this vasodilative effect seems unrelated majorly to augmented endothelium-derived NO formation.

Tangled webs: evidence of cross-talk between c-Raf-1 and Akt

The apparent cross-communication that can occur between different cell signaling pathways indicates that some signaling mechanisms may be more complex than originally envisaged. Jun et al. discuss recent studies suggesting that two signaling pathways that can be activated by the same growth factor receptor, the Ras-Raf pathway and the phosphatidylinositol 3-kinase (PI3K)--Akt (protein kinase B) pathway, can integrate with each other to generate a particular response, depending on the cell type and the stage of cell differentiation.

Radial artery compliance in patients with peripheral vascular disease

Compliance in largely central arteries of patients with peripheral vascular disease (PVD) has been reported to be reduced. However, the arterial tree is an inhomogeneous system, and there remains uncertainty about whether the peripheral arteries (e.g. the medium-sized muscular radial artery) undergo a similar change to the central arteries. The aim of this study was to investigate the radial artery elasticity in 19 patients with PVD compared with 18 normal subjects of comparable age and sex. Using a noninvasive high-resolution echo-tracking device coupled to a photoplethysmograph (Finapres system) allowing simultaneous arterial diameter and finger blood pressure monitoring, we measured the radial artery compliance by determining the diameter-pressure, compliance-pressure and distensibility-pressure curves. The results showed that the diameter of the radial artery was similar in the two groups, but that the compliance and distensibility were not further reduced in patients with PVD than in the normal controls at 100 mmHg and for a common blood pressure range. The present studies demonstrate that in patients with PVD the radial arterial compliance is not reduced, which indicates that the change in arterial elasticity is not identical. The potential mechanisms involved in this change in radial artery compliance are discussed.

Basal nitric oxide production is not reduced in patients with noninsulin-dependent diabetes mellitus

Vascular disease is the leading cause of morbidity, disability and death in patients with noninsulin-dependent diabetes mellitus. Abnormalities in endothelium-derived nitric oxide (NO) have been demonstrated to be involved in the pathogenesis of vascular disease. By measuring hemodynamic responses to a NO synthase agonist or antagonist, previous studies have shown the presence of NO deficiency in patients with noninsulin-dependent diabetes mellitus, a method of assessing bioactive NO formation. However, direct biochemical evidence that this is the case, has not been produced. In vivo NO is metabolized into nitrate, an end breakdown product of NO, which can be used as an index of endogenous NO formation. To investigate further whether decreased basal synthesis of NO may be a major cause of endothelium-mediated vascular dysfunction in patients with noninsulin-dependent diabetes mellitus, the plasma nitrite/nitrate levels of 15 patients were examined and compared with 13 normal controls. The results showed that in basal conditions plasma nitrite/nitrate levels were not reduced in diabetic patients compared with normal controls (37.3 +/- 14.7 versus 29.4 +/- 8.6 mumol/l). It was concluded that in noninsulin-dependent diabetes mellitus patients, endothelium-derived basal NO formation is not impaired. This study, taken with previous observations, suggests that factors other than diminished basal NO production, such as reduced bioavailability of NO probably due to the augmented production of superoxide anion with subsequently increased inactivation of NO, contribute to the high incidence of vascular disease in patients with noninsulin-dependent diabetes mellitus.

Involvement of endothelins in immediate and late asthmatic responses of guinea pigs

To explore the pathophysiological roles of endothelin isopeptides and receptor subtypes in asthmatic responses, a guinea pig model for asthma was used to test the effects of antiendothelin (ET) serum and selective ET receptor antagonists for antigen-induced specific airway conductance changes as measured by whole-body plethysmography. In this model, all of the animals so far tested demonstrated both the immediate and late asthmatic responses. Although preimmune serum had no apparent effects, anti-ET antiserum suppressed the maximal reduction of specific airway conductance in both the immediate and late asthmatic responses, which suggested that ET(s) are involved in the pathophysiology of both the immediate and late asthmatic responses. The ETB selective antagonists, BQ788 and RES701-1, blocked the immediate asthmatic response but not the late asthmatic response, whereas the ETA antagonists, BQ123 and (Shionogi) 97-139, suppressed only the late asthmatic response without influencing the immediate asthmatic response. In vitro constrictive responses of isolated tracheas and bronchi to ET1 were inhibited mainly by BQ123 and BQ788, respectively, which suggested that distribution of ETA and ETB receptors for bronchoconstriction are topographically distinct along airways. Furthermore, thromboxane A2 and platelet activating factor (PAF) antagonists were effective in suppressing the late asthmatic response but not the immediate asthmatic response. Taken together, our present observations suggest that ET(s) influences pulmonary functions by constricting airway smooth muscle via ETB receptors during the immediate asthmatic response and by modulating pulmonary inflammation via ETA receptors during the late asthmatic response, respectively.

Increased superoxide anion production in humans: a possible mechanism for the pathogenesis of hypertension

Although endothelium-dependent vasodilation is impaired in human hypertension, the mechanism underlying this abnormality is not yet completely elucidated. It has been suggested that accelerated inactivation of nitric oxide (NO) due to superoxide anion, which is rapidly removed by superoxide dismutase (SOD) in physiological condition, may be related to hypertension. Therefore, SOD deficiency following an increase in superoxide anion production contributes to a rise in arterial blood pressure (BP). We hypothesized that there is defective endogenous SOD in patients with essential hypertension. To examine this assumption we measured the SOD activities of the erythrocytes in 335 healthy Chinese volunteers (age 2-76 years) and 30 hypertensive patients (age 60-75 years). The SOD activities of the healthy volunteers exhibited decreased trend with advancing aging. There was no significant difference in the SOD activities between men and women in each group. There is significant difference in the SOD activities (1814.35 +/- 250.00 vs 1584.06 +/- 126.19 u/Hb.g; P < 0.001) between the two groups (age 20-59 years; mean age 34 years vs age 60-76 years; mean age 67 years). The SOD activities in patients with essential hypertension were 1322.4 +/- 139.5 u/Hb.g and significantly lower than the corresponding healthy controls (P < 0.05). In the hypertensives, the SOD activities against systolic and diastolic arterial pressure seem to be shown the trend of negative correlation but did not reach the statistical significance. We conclude that the SOD activities in the erythrocytes are reduced in subjects with essential hypertension and increasing aging. The present findings, in a limited data, could suggest that the fall in SOD activities following an increased superoxide anion production with subsequently augmented NO inactivation is, at least in part, involved in the pathogenesis of human hypertension, although the evidence is indirect. The decrease in erythrocyte SOD activities may serve as a function of human aging.

Downregulation of Lck-mediated signal transduction by tip of herpesvirus saimiri

A protein, called tip, of herpesvirus saimiri associates with Lck in transformed T cells. To investigate the effects of complex formation on cellular signal transduction, we constructed human Jurkat-T-cell lines expressing tip. The expression of tip in Jurkat-T cells dramatically suppressed cellular tyrosine phosphorylation and surface expression of lymphocyte antigens. The expression of tip also blocked the induction of tyrosine phosphorylation by anti-CD3 stimulation. The expression of tip in fibroblast cells suppressed the transforming activity of oncogenic F505 Lck. Binding assays showed that the SH3 domain of Lck is sufficient to form a stable complex with tip in vitro. These results demonstrate that tip acts at an early stage of the T-cell signal transduction cascade by associating with Lck and downregulating Lck-mediated activation. Inhibition of Lck-mediated signal transduction by tip in T cells appears to be analogous to the inhibition of Lyn/Syk-mediated signal transduction in B cells by LMP2A of the B-cell-tropic Epstein-Barr virus.

The insulin secretory response to intravenous glucose in the rat is independent of NO formation

In isolated pancreative beta cells from rats the insulin secretory response to glucose is amplified by L-arginine. Since this effect is inhibited by NO synthesis inhibitors, and since L-arginine is precursor of NO, the observation indicates a role for NO in insulin secretion from beta cells. We recently reported that i.v. L-arginine elicited insulin secretion in anaesthetized rats by a mechanism that was partly NO dependent. The aim of the present study was to assess if the insulin secretory response to an intravenous infusion of glucose also requires an intact NO formation. Anaesthetized rats were given D-glucose (100 mg kg-1 min-1 i.v. for 30 min). Plasma insulin (PI), blood glucose (BG) levels and mean arterial blood pressure (MAP) were assessed from before and until 15 min after the end of the infusion. One group of rats were untreated and served as controls. The two other groups were pretreated with either of the NO synthase inhibitors NW-nitro-L-arginine methyl ester (L-NAME, 50 mg kg-1 i.v.), or NG-monomethyl-L-arginine (L-NMMA, 100 mg kg-1 i.v.). In controls infusion of glucose elevated PI by up to 25 +/- 3 U L-1, and BG by up to 27 +/- 1 mmol L-1. Pretreatment with L-NAME elevated MAP from 74 +/- 6 to 132 +/- 4 mmHg, indicating that NO synthase was inhibited.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of Lck-binding elements in tip of herpesvirus saimiri

A protein called Tip (tyrosine kinase interacting protein) of herpesvirus saimiri associates with Lck in virus-transformed human T cells and is an in vitro substrate for Lck kinase. Mutational analyses of a GST-Tip fusion protein revealed that binding to Lck requires putative SH3 binding sequences and a sequence homologous to the carboxyl terminus of Src-related kinases. These sequences are referred to as SH3-Binding (SH3B) and C-terminal Src-related Kinase Homology (CSKH) elements. Peptide fragments as short as 37 amino acids containing both SH3B and CSKH elements were sufficient to form a stable complex with Lck in vitro. Furthermore, these same sequences of Tip were necessary for in vivo association with Lck when Tip and Lck were expressed transiently in COS-1 cells or stably in Rat-1 cell lines. These results demonstrate that the CSKH element of Tip participates in the binding of sequences within Lck. Tip of herpesvirus saimiri has apparently acquired such CSKH and SH3B elements for the purpose of targeting cellular protein kinases. The interaction of Tip with Lck may influence Lck kinase activity or its binding to other cellular proteins and thereby alter Lck function in T cells infected by h. saimiri.

L-arginine-induced hypotension in the rat: evidence that NO synthesis is not involved

L-Arginine is the biological precursor for nitric oxide (NO). NO is formed continuously in endothelial cells and maintains a certain degree of vasodilator tone under physiological conditions. Although the formation of NO is not primarily controlled by precursor availability, the extent to which extra supplementation with L-arginine may affect endothelial NO formation, and hence, vasodilator tone and systemic blood pressure, is not entirely clear. To address this issue, we infused L-arginine i.v. in anaesthetized normotensive rats pretreated with NG-nitro-L-arginine methyl ester (L-NAME, 50 or 200 mg-1) and in untreated controls, under continued recording of mean arterial pressure (MAP). In control animals L-arginine (25 or 100 mg kg-1 min-1) had no effect on systemic MAP (111 +/- 3 mm Hg), while L-arginine (200 mg kg-1 min-1) lowered MAP (to 70 +/- 6 mm Hg). D-Arginine (200 mg kg-1 min-1) also induced hypotension; during infusion of D-arginine MAP fell from 106 +/- 4 to 64 +/- 4 mm Hg. Pretreatment with L-NAME (50 and 200 mg kg-1) elevated MAP to 140 +/- 2 and 147 +/- 3 mm Hg, respectively, but failed to affect the hypotensive response to L-arginine; during infusion of L-arginine (200 mg kg-1 min-1) in rats pretreated with L-NAME (50 and 200 mg kg-1) MAP fell to 86 +/- 9 and 104 +/- 6 mm Hg, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

NO-dependent and -independent elevation of plasma levels of insulin and glucose in rats by L-arginine

1. L-Arginine elevates plasma insulin in man. Recent in vitro data indicate that this is based on stimulation of endogenous nitric oxide (NO) with subsequent pancreatic release of insulin by L-arginine. L-Arginine also raises plasma glucose. 2. We studied plasma levels of insulin, glucose and NO metabolites, as well as systemic blood pressure, in anaesthetized rats during i.v. infusion of L-arginine (25-200 mg kg-1 min-1) or glucose (55 mg kg-1 min-1), before and after administration of the NO synthesis inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME, 50 mg kg-1). 3. Before L-NAME, L-arginine elevated plasma insulin from about 15 to 65 ul-1 and glucose from 5.2 to 6.7 mmol l-1. These effects of L-arginine were not dose-related. 4. L-NAME alone had no effect on plasma insulin and glucose levels, but diminished the effects of a low dose (25 mg kg-1 min-1) of L-arginine on plasma insulin by about 40%, and that on plasma glucose by more than 90%. In contrast, the effects of a high dose (200 mg kg-1 min-1) of L-arginine on plasma insulin and glucose levels were not affected by L-NAME. 5. L-NAME elevated systemic blood pressure by about 35 mmHg. L-Arginine (25-100 mg kg-1 min-1) had no effect on systemic blood pressure, either before or after L-NAME. L-Arginine (200 mg kg-1 min-1) lowered systemic blood pressure, both before and after L-NAME. 6. Glucose infusion elevated plasma glucose from about 5.5 to 6.8 mmol l-1, and plasma insulin from about 18 to 26 ul-1. 7. The basal plasma levels of the NO metabolite nitrate (18 +/- 4 mumol l-1) were not affected by L-arginine (200 mg kg-1 min-1). Plasma nitrosohaemoglobin was likewise unaffected by L-arginine (200 mg kg-1 min-1). 8. We conclude that L-arginine separately elevates plasma insulin and glucose levels, both by NO-dependent and -independent mechanisms.