Intradural extramedullary metastasis of oncocytic carcinoma of the parotid gland: A first case report and review of the literature

We present an extremely infrequent case of intradural metastasis of a parotid tumour, responsible for motor deficit in legs. To our knowledge, this is the first reported case of an intradural metastasis of a malignant and rare parotid tumour, oncocytic carcinoma. It accounts for less than 1% of salivary gland tumours. Its management is not codified and its prognosis seems to be poor. Local recurrences are common, as are regional metastases. Distant metastases are present in less than 30% of cases and are poorly described, mainly involving the lung. Thanks to the surgical treatment, our patient has partially recovered his motor and sensory functions.

Diagnostic Value of an Additional Sequence (Large-Field Coronal Stir) in a Routine Lumbar Spine MR Imaging Protocol to Investigate Lumbar Radiculopathy

OBJECTIVE

Lumbar radiculopathy mainly originates in the spine (lumbar disc herniation or spine osteoarthritis) but can sometimes be explained by extra-spinal nerve compression or confused with referred pain mimicking radiculopathy. Our main objective was to demonstrate the clinical benefit of the large-field coronal STIR (coroSTIR) sequence in the etiological assessment of lumbar radiculopathy with a duration of more than six weeks.

MATERIALS AND METHODS

Six hundred consecutive lumbar MRI scans performed using the same protocol were retrospectively reviewed. Two musculoskeletal radiologists independently assessed the coroSTIR sequence for the presence of extra-spinal anomalies (ESA) that could explain or contribute to the lumbar radiculopathy. The presence of an ESA was then correlated with sex, age, topography and lateralization of radiculopathy, history of vertebral surgery, as well as the presence of a spinal cause explaining the symptoms. Extra-spinal incidentalomas (ESI) with potential clinical impact visible only on the coroSTIR sequence were also systematically reported.

RESULTS

An extra-spinal cause was detected on the coroSTIR sequence in 68 cases (11.3%), mainly gluteal tendinobursitis (30.9%), congestive hip osteoarthritis (25%), degenerative sacroiliac arthropathy (14.7%), or inflammatory sacroilitis (7.3%). Their prevalence was significantly correlated in multivariate regression with age (58 years vs. 53 years, p = 0.01), but not with the type of radiating pain (sciatica or cruralgia). The presence of ESI was also frequent (70 cases, 11.7%), including some potentially severe diagnoses (38% of tumor or pseudo-tumor mass requiring further assessment or monitoring).

CONCLUSIONS

Considering its acceptable acquisition time, the detection of a significant number of potentially symptom-related extra-spinal anomalies, and the discovery of a non-negligible number of extra-spinal incidentalomas with potential clinical impact, the coronal STIR should be performed systematically in routine MRI for lumbar radiculopathy.

Tofacitinib for celiac disease and microscopic colitis: killing two birds with one stone

Microscopic colitis is a chronic inflammatory condition of the colon. Firstline treatment consists of budesonide, with the consideration of biological agents in refractory cases. Celiac disease is a chronic immune mediated and gluten-induced enteropathy, with treatment consisting of a gluten-free diet. There is an association between microscopic colitis and instead of xand celiac disease, especially in refractory cases they can coincide. In this manuscript, we report for the first time the efficacy of tofacitinib, a pan Janus kinase inhibitor, in the treatment of concomitant microscopic colitis and celiac disease, resulting in persistent clinical and histological remission.

X-ray Microtomography to Assess Determinants of In Vivo N-Butyl Cyanoacrylate Glubran®2 Polymerization: A Rabbit-Model Study

Although introduced decades ago, few cyanoacrylate glues have been approved for endovascular use, despite evidence of their usefulness, notably for complex procedures suchas hemostatic embolization. Indications include massive bleeding requiring emergent hemostasis and prevention of severe bleeding during scheduled surgery to remove a hypervascular tumor. Adding radiopaque Lipiodol Ultra Fluid® (LUF) modulates glue polymerization and allows fluoroscopic guidance, but few comparative in vivo studies have assessed the impact of the resulting change in glue concentration or of other factors such as target-vessel blood flow. In a rabbit model, we used ex vivo X-ray microtomography to assess the results of in vivo renal-artery embolization by various mixtures of N-butyl cyanoacrylate (NBCA), metacryloxysulfolane, and LUF. Overall, penetration to the superficial interlobular arteries was achieved in about two-thirds of cases and into the capillaries in nearly half the cases, while cast fragmentation was seen in slightly more than half the cases. Greater NBCA dilution and the blocked-blood-flow technique were independently associated with greater distality of penetration. Blocked-blood-flow injection was independently associated with absence of fragmentation, capillary penetration, a shorter cast-to-capsule distance, and higher cast attenuation. A larger mixture volume was independently associated with higher indexed cast ratio and deeper penetration. Finally, microtomography is an adapted tool to assess ex vivo distribution of glue cast.

[Idiopathic intracranial hypertension: From physiopathological mechanisms to therapeutic decision]

Clinical features include visual disturbances, headaches, and pulsatile tinnitus that can be associated with reduced quality of life, and a risk of irreversible visual impairment in some cases. Obese women of childbearing age represent the main at-risk population, and the incidence of the disease is increasing because of rising prevalence of obesity worldwide. In addition, an imbalance in sex hormones is reported as a contributing risk factor. The pathophysiology of idiopathic intracranial hypertension involves a disturbance of the evacuation pathway of intracranial fluids caused by the increase in intracranial venous pressure. Brain imaging is useful for diagnosis with several signs including bilateral stenosis of the transverse sinuses that plays a major role in the pathogenesis of the disease by creating a positive feedback loop that increases intracranial venous hypertension and contributes to clinical manifestations. Treatment aims to relieve symptoms and prevent permanent visual impairment. Drug therapies including acetazolamide and topiramate have moderate effectiveness. Among invasive treatments, transverse sinus stenting seems to be the most interesting option to consider in drug-resistant patients. Weight loss remains essential to achieve a sustainable improvement by reducing central venous pressure. Future randomized trials are expected to reach a consensus on this treatment.

Intradural Small Bowel Herniation

Online supplemental material is available for this article.

Deep Learning-Based Reconstruction vs. Iterative Reconstruction for Quality of Low-Dose Head-and-Neck CT Angiography with Different Tube-Voltage Protocols in Emergency-Department Patients

Objective: To compare the image quality of computed tomography angiography of the supra-aortic arteries (CTSA) at different tube voltages in low doses settings with deep learning-based image reconstruction (DLR) vs. hybrid iterative reconstruction (H-IR). Methods: We retrospectively reviewed 102 patients who underwent CTSA systematically reconstructed with both DLR and H-IR. We assessed the image quality both quantitatively and qualitatively at 11 arterial segmental levels and 3 regional levels. Radiation-dose parameters were recorded and the effective dose was calculated. Eighty-six patients were eligible for analysis Of these patients, 27 were imaged with 120 kVp, 30 with 100 kVp, and 29 with 80 kVp. Results: The effective dose in 120 kVp, 100 kVp and 80 kVp was 1.5 ± 0.4 mSv, 1.1 ± 0.3 mSv and 0.68 ± 0.1 mSv, respectively (p < 0.01). Comparing 80 kVp + DLR vs. 120 and 100 kVp + H-IR CT scans, the mean overall arterial attenuation was about 64% and 34% higher (625.9 ± 118.5 HU vs. 382.3 ± 98.6 HU and 468 ± 118.5 HU; p < 0.01) without a significant difference in terms of image noise (17.7 ± 4.9 HU vs. 17.5 ± 5.2; p = 0.7 and 18.1 ± 5.4; p = 0.3) and signal-to-ratio increased by 59% and 33%, respectively (37.9 ± 12.3 vs. 23.8 ± 9.7 and 28.4 ± 12.5). This protocol also provided superior image quality in terms of qualitative parameters, compared to standard-kVp protocols with H-IR. Highest subjective image-quality grades for vascular segments close to the aorta were obtained with the 100 kVp + DLR protocol. Conclusions: DLR significantly reduced image noise and improved the overall image quality of CTSA with both low and standard tube voltages and at all vascular segments. CT that was acquired with 80 kVp and reconstructed with DLR yielded better overall image quality compared to higher kVp values with H-IR, while reducing the radiation dose by half, but it has limitations for arteries that are close to the aortic arch.

Endovascular Use of Cyanoacrylate-Lipiodol Mixture for Peripheral Embolization: Properties, Techniques, Pitfalls, and Applications

Endovascular embolization agents are particles and fluids that can be released into the bloodstream through a catheter to mechanically and/or biologically occlude a target vessel, either temporarily or permanently. Vascular embolization agents are available as solids, liquids, and suspensions. Although liquid adhesives (glues) have been used as embolic agents for decades, experience with them for peripheral applications is generally limited. Cyanoacrylates are the main liquid adhesives used for endovascular interventions and have a major role in managing vascular abnormalities, bleeding, and many vascular diseases. They can only be injected as a mixture with ethiodized oil, which provides radiopacity and modulates the polymerization rate. This review describes the characteristics, properties, mechanisms of action, modalities of use, and indications of the cyanoacrylate-Lipiodol® combination for peripheral embolization.

Simultaneous cardio-cerebral embolization. A prospective study

Background

Atrial Fibrillation (AF) is a common cause of ischemic stroke but also the most common cause of Coronary Artery Embolism (CE). Many previous case of coexistence of coronary and cerebral embolism have been reported in the literature but in specific situations were clinical signs of stroke but also indisputable clinical and/or electrocardiographic (ECG) signs leaded to the realization of coronarography in emergency.

Objectives

The aim of the study was to determine the existence of simultaneous cardio-cerebral embolization associated in patients with ischemic embolic stroke on de novo AF, in the absence of clinical and/or ECG signs evocative of myocardial infarction (MI).

Methods

We prospectively included patients hospitalized in our institution for ischemic embolic stroke on de novo AF. Patients with history of ischemic disease were excluded. All patients had: 1/ troponin assay; 2/ Cardiac Magnetic Resonance (CMR) imaging with Late-Gadolinium Enhancement (LGE) in order to detect myocardial infarction; 3/ coronary exploration by cardiac CT scan or coronarography to exclude patients with significant coronary lesion.

Results

Between January and December 2019, 32 patients were included. Of them, 15 had subendocardial or transmural LGE on CMR, evocative of MI. Among these 15 MIs we classified acute MIs according to the level of troponin at the admission in stroke unit, the coronarography and T2 hypersignal on cardiac MRI. Median delay of cardiac MRI was 6 days for acute MIs.

CE was clearly identified by coronarography for 4 patients with acute simultaneous cardio-cerebral infarction (56%). The MRI abnormalities showed that lesions of all MIs were transmural, relatively small (average 1.3±0.44 segments) and in most cases in the inferior cardiac wall (47%) and these abnormalities were comparable in sequelae and acute MI. Moreover, the left appendage morphology was a “cactus” in 62.7% of simultaneous acute cardio-cerebral infarction and only 33% in patients without MI or sequelae MI. Strokes were mainly localized in the superficial territory of the middle cerebral artery, and were similar in patients with or without MI. In addition, the rate of sequelae strokes was higher in isolated stroke group than “cardiocerebral infarction” (29.5% versus 13.3%).

Conclusion

Simultaneous acute cardio-cerebral infarction is not uncommon, diagnosed in 22% of our prospective cohort of embolic stroke. Cardiac MRI may help us to diagnose a concomitant cardiac embolization and evaluate the prognosis. Unfortunately optimal therapeutic strategy of these patients is still unknown.

Flow Chart

Funding Acknowledgement

Type of funding source: None

Effects of body composition profiles on oncological outcomes and postoperative intraabdominal infection following colorectal cancer surgery

BACKGROUND

Anthropometric data as prognostic factors of colorectal cancer are promising but contradictory. The aim of this study was to assess the preoperative body composition profiles as predictive factors for postoperative, oncologic, and inflammation outcomes.

OBJECTIVES

We sought to assess the impact of body composition profiles on short- and long-term outcomes and on postoperative inflammatory response in a clinical setting for patients following curative intent surgery for colorectal cancer.

SETTING

University hopsital METHODS: We analyzed 122 patients from a prospective cohort (IMACORS) with colorectal cancer undergoing curative-intent surgery from 2011 to 2014. Musculature, total, visceral, and subcutaneous adiposity were measured from a preoperative CT scan and outcomes were compared between profiles.

RESULTS

Preoperative myopenia was an independent predictive factor of recurrence (HR = 3.3 95% CI = 1.6-6.9; P = .002) while subcutaneous adiposity was a protective factor (HR = .4 95% CI = .2-.9; P = .03). No anthropometric measurement was predictive of overall survival and postoperative intra abdominal infection was not determined by body composition profiles. Preoperative and D4 CRP levels were significantly higher in patients with subcutaneous adiposity.

CONCLUSIONS

Myopenia and subcutaneous adiposity seemed to have independent and opposite prognostic effects on recurrence. Muscle mass loss may represent a modifiable risk factor while the amount of subcutaneous adipose tissue reflects an energetic storage favorable to face this pathologic process.

Whipple's disease in a man of North African descent : case report and brief review of the literature

A 62-year-old man of North African descent presented with weight loss in the past year and diarrhea for three weeks. His medical history included erosive rheumatoid arthritis, treated with methotrexate and adalimumab. Histological examination of a duodenal biopsy showed foamy macrophages in the lamina propria, with PAS-positive cytoplasmatic inclusions. These findings are compatible with Whipple's disease, a rare chronic infectious disease caused by Tropheryma whipplei, an opportunistic bacterium. It is typically seen in middle-aged Caucasian men and the immunocompromised host. The classical presentation of Whipple's disease consists of intermittent migratory arthralgia, followed by intestinal symptoms which typically occur six to seven years later. The clinical image can be very variable, and this complicates the diagnostic process. PAS-staining and PCR are the diagnostic cornerstones. In our case, treatment consisted of a prolonged cure of antibiotics: intravenous ceftriaxone for two weeks, followed by an oral maintenance therapy of doxycycline and hydroxychloroquine for at least one year. A therapeutic dilemma arose as continued anti-TNF blockade was necessary to maintain remission of the rheumatoid arthritis. Lifelong follow-up is necessary because relapse is possible.

Coumarin-Ser-Asp-Lys-Pro-OH, a fluorescent substrate for determination of angiotensin-converting enzyme activity via high-performance liquid chromatography

N-Acetyl-Ser-Asp-Lys-Pro-OH (AcSDKP-OH), a negative regulator of hematopoietic stem cell proliferation, is shown to be a physiological substrate of angiotensin I-converting enzyme (ACE), a zinc-dipeptidyl carboxypeptidase, involved in cardiovascular homeostasis. Recently, a study carried out on captopril-treated volunteers revealed that the kinetics of [3H]AcSDKP-OH hydrolysis in vitro in the plasma of donors correlates closely to the plasmatic ratio angiotensin II/angiotensin I, which characterized the conversion activity of ACE. This prompted us to design a fluorescent substrate, 2-[7-(dimethylamino)-2-oxo-2H-chromen-4-yl]acetyl-SDKP-OH, or coumarin-SDKP-OH, which could be an alternative to the radiolabeled analogue used in that study, allowing an easier and more rapid determination of enzyme activity. We report here the synthesis and the determination of the kinetics constants of this fluorescent derivative compared with those of [3H]AcSDKP-OH with human plasma ACE (133 and 125 microM, respectively), which are in the same range as those of the physiological substrate angiotensin I. Furthermore, the hydrolysis of the fluorescent substrate shows the same sensitivity toward chloride concentration as the natural substrate, demonstrating its specificity for N-domain hydrolysis. This fluorescent derivative was used to develop a sensitive assay for the determination of ACE activity in human plasma.

Lisinopril, an angiotensin I-converting enzyme inhibitor, prevents entry of murine hematopoietic stem cells into the cell cycle after irradiation in vivo

The hemoregulatory peptide N-Acetyl-Ser-Asp-Lys-Pro (AcSDKP) has been shown in vivo to inhibit the cycling of murine hematopoietic stem cells triggered into S-phase by either cytotoxic drug administration or irradiation. This property, further confirmed using in vitro models, demonstrates that the peptide has an in vivo protective effect on the hematopoietic system. AcSDKP has been shown to be a physiological substrate of angiotensin I-converting enzyme (ACE), which catabolizes the peptide through a dipeptidasic activity. Thus, oral administration of ACE inhibitor to humans has led to an increase in the plasma AcSDKP concentration. In the present paper, we report on the in vivo effect of lisinopril, an ACE inhibitor, on the proliferative status of murine hematopoietic stem cells triggered into S-phase by irradiation. Administration of lisinopril (10 mg/kg) 1 hour after irradiation led to a 90 to 100% inhibition of murine plasma ACE activity as observed during the first 4 hours postirradiation. This inhibition was correlated with a 600% increase in the endogenous plasma AcSDKP level and a total suppression at 24 hours of entry of the hematopoietic stem cell into the cell cycle. We discuss the possible role of ACE in the regulation of hematopoietic stem cell proliferation through control of the AcSDKP concentration.

Catabolism of the hemoregulatory peptide N-Acetyl-Ser-Asp-Lys-Pro: a new insight into the physiological role of the angiotensin-I-converting enzyme N-active site

The tetrapeptide N-Acetyl-Ser-Asp-Lys-Pro (AcSDKP) was first isolated from bone marrow extracts and shown to be involved in the negative control of hematopoiesis by preventing the recruitment of primitive stem cells into S-phase. In vitro studies on AcSDKP catabolism in human plasma revealed that AcSDKP was cleaved by plasmatic angiotensin-I converting enzyme (ACE). The evaluation of the respective involvement of the two active sites of ACE in AcSDKP degradation in vitro revealed that the N-active site was preferentially involved in this catabolism. Moreover, an in vivo study on healthy volunteers of the catalytic efficiency of ACE towards AcSDKP after administration of Captopril demonstrated that AcSDKP was a physiological substrate of ACE. AcSDKP might represent the first natural specific substrate of the N-active site of the enzyme. These results pose the question of a potential role of ACE in the control of hematopoiesis as well as possible applications of ACE inhibitors to cope with dysfunctions in which AcSDKP might exert physiological control.

Acute angiotensin-converting enzyme inhibition increases the plasma level of the natural stem cell regulator N-acetyl-seryl-aspartyl-lysyl-proline

Angiotensin I-converting enzyme (ACE) has two homologous active NH2- and COOH-terminal domains and displays activity toward a broad range of substrates. The tetrapeptide N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) has been shown to be hydrolyzed in vitro by ACE and to be a preferential substrate for its NH2-terminal active site. This peptide is a regulatory factor of hematopoiesis which reversibly stem cells and normal early progenitors into S-phase. We found that a single oral dose of 50 mg of the ACE inhibitor, captopril, when administered to eight healthy subjects in a double-blind, crossover, placebo-controlled study, massively increased the plasma level of Ac-SDKP. ACE inhibition by captopril induced a 90-99% inhibition of in vitro [3H]Ac-SDKP hydrolysis and a long-lasting 5.5-fold (range: 4-8.5-fold) increase in the plasma levels of Ac-SDKP. These results demonstrate that Ac-SDKP is the first natural peptide hydrolyzed by the NH2-terminal domain of ACE not only in vitro but also in vivo, confirming that both catalytic sites of ACE are physiologically active. Our data suggest that ACE may also be implicated in the process of hematopoietic stem cell regulation, by permanently degrading this natural circulating inhibitor of cell entry into S-phase.

The hemoregulatory peptide N-acetyl-Ser-Asp-Lys-Pro is a natural and specific substrate of the N-terminal active site of human angiotensin-converting enzyme

Angiotensin I-converting enzyme (ACE) is a zinc-dipeptidyl carboxypeptidase, which contains two similar domains, each possessing a functional active site. Respective involvement of each active site in the degradation of the circulating peptide N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP), a negative regulator of hematopoietic stem cell proliferation, was studied by using wild-type recombinant ACE and two full-length mutants containing a single functional site. Both the N- and C-active sites of ACE exhibit dipeptidyl activity toward AcSDKP, with Km values of 31 and 39 microM, respectively. However, the N-active site hydrolyzes the peptide 50 times faster compared with the C-active site, with kcat/Km values of 0.5 and 0.01 microM-1.s-1, respectively. The predominant role of the N-active site in AcSDKP hydrolysis was confirmed by the inhibition of hydrolysis using a monoclonal antibody specifically directed against the N-active site. The N-domain specificity for AcSDKP will aid the identification of specific inhibitors for this domain. This is the first report of a highly specific substrate for the N-active site of ACE, with kinetic constants in the range of physiological substrates, suggesting that ACE might be involved via its N-terminal active site in the in vivo regulation of the local concentration of this hemoregulatory peptide.

Interaction of G-actin with thymosin beta 4 and its variants thymosin beta 9 and thymosin beta met9

Thymosin beta 4 is a major actin sequestering peptide in vertebrate cells and plays a role in the regulation of actin monomer/polymer ratio. Thymosin beta 9 and thymosin beta met9 are minor variants of thymosin beta 4. The possible function of these peptides has been investigated by comparing the actin binding properties of these beta-thymosins. Thymosin beta 9 and thymosin beta met9 were found to inhibit polymerization of ATP-actin with identical KDs of 0.7-0.8 microM (as compared to 2 +/- 0.3 microM for thymosin beta 4); like thymosin beta 4, they bound to ADP-G-actin with a 100-fold lower affinity than to ATP-G-actin. The interaction of thymosin beta 4 and thymosin beta met9 with G-actin was weakened 20-fold upon oxidation of methionine-6 into methionine sulfoxide. Binding of thymosin beta 4 to G-actin was accompanied by a 15% increase in the fluorescence intensity of actin tryptophans, and a 10 nm emission blue shift. Methionine-6 played an important role in this effect. The fluorescence change was used to monitor the kinetics of thymosin beta 4 binding to G-actin in the stopped-flow. The reaction was bimolecular, with association and dissociation rate constants of approximately 1.5 microM-1 s-1 and 2 s-1 respectively, under physiological conditions. The possible physiological significances of methionine-6 oxidation and of the relatively slow binding kinetics in regulating thymosin beta 4 function in vivo is discussed.

Involvement of human plasma angiotensin I-converting enzyme in the degradation of the haemoregulatory peptide N-acetyl-seryl-aspartyl-lysyl-proline

The degradation of N-Ac-Ser-Asp-Lys-Pro (AcSDKP), a negative regulator controlling the proliferation of the haematopoietic stem cell, by enzymes present in human plasma, has been investigated. Radiolabelled AcSD[4-3H]KP ([3H]AcSDKP, 1 mM) was completely metabolized in human plasma with a half-life of 80 min, leading exclusively to the formation of radiolabelled lysine. The cleavage of AcSDKP was insensitive to classical proteinase inhibitors including leupeptin, but sensitive to metalloprotease inhibitors. The degradation was completely blocked by specific inhibitors of angiotensin I-converting enzyme (ACE; kininase II; peptidyldipeptide hydrolase, EC 3.4.15.1), showing that the first step of the hydrolysis was indeed due to ACE. In dialysed plasma, the hydrolysis proceeded at only 17% of the maximal rate, whereas addition of 20 mM NaCl led to the recovery of the initial rate observed with normal plasma. Hydrolysis of AcSDKP by commercial rabbit lung ACE generated the C-terminal dipeptide Lys-Pro. Thus, ACE cleaves AcSDKP by a dipeptidyl carboxypeptidase activity. In fact the formation of Lys-Pro was observed when AcSDKP was incubated in human plasma in the presence of HgCl2. These results suggest that ACE is involved in the first limiting step of AcSDKP degradation in human plasma. The second step seems to be under the control of a leupeptin- and E-64-insensitive, HgCl2-sensitive plasmatic enzyme.

The molecular specificity of action of the tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (AcSDKP) in the control of hematopoietic stem cell proliferation

The hemoregulatory tetrapeptide Acetyl-N-Ser-Asp-Lys-Pro (AcSDKP, M(r) = 487 amu) prevents the recruitment of hematopoietic stem cells into S phase. AcSDKP does not possess inherent inhibitory activity against hematopoietic stem cells, rather it appears to act by "blocking" the action of a hematopoietic stem cell proliferation stimulator present in extracts of regenerating hematopoietic tissue. The molecular specificity of this action was investigated using a number of peptide analogues of AcSDKP and evaluating their ability to "block" the recruitment of a primitive murine hematopoietic precursor (high proliferative potential colony forming cell HPP-CFC) into S phase following incubation with a hematopoietic stem cell proliferation stimulator. The capacity of AcSDKP to compromise the action of the hematopoietic stem cell proliferation stimulator was not evident for either AcSDDKP or AcSD beta KP, two structurally distinct forms of the molecule; similar no stimulator-"blocking" activity was observed for the tripeptide Ala-Asp-Lys (ADK, M(r) = 332 amu), while the tripeptide Ser-Asp-Lys (SDK, M(r) = 348 amu) was active. It would appear that the hemoregulatory action of AcSDKP is specific and that the tripeptide sequence SDK may be a significant component of the molecule.

The tetrapeptide AcSerAspLysPro (Seraspenide), a hematopoietic inhibitor, may reduce the in vitro toxicity of 3'-azido-3'-deoxythymidine to human hematopoietic progenitors

3'-azido-3'-deoxythymidine (AZT), the main antiviral drug used in AIDS treatment, is known to induce anemia and neutropenia. These effects have been attributed to its toxicity to hematopoietic progenitors. In this report, we present a new approach to reduce AZT hematotoxicity by using an inhibitory factor of the hematopoietic stem cells, the tetrapeptide AcSerAspLysPro (AcSDKP, Seraspenide), which has been shown to increase the survival of mice subjected to high doses of chemotherapy and to block reversibly the cycling of human granulocyte-macrophage colony forming unit (CFU-GM) and burst forming unit erythroid (BFU-E) progenitors. Normal bone marrow mononuclear cells (BMMNC) from 14 subjects were incubated with or without AcSDKP (10(-10) M) for 20 h and with or without AZT (100 microM) for another 2 h. After washing, cells were plated in methylcellulose in the presence of interleukin 3 (IL-3), granulocyte-macrophage colony stimulating factor (GM-CSF) and erythropoietin (EPO). Under these conditions, the preincubation of cells with AcSDKP reduced significantly the toxicity of AZT to both BFU-E and CFU-GM at least in 3 out of 8 and 4 out of 10 cases, respectively. A careful statistical analysis of these observations indicates that AcSDKP may be an efficient factor in preserving progenitors against AZT-induced hematopoietic toxicity.

Modulation of the interaction between G-actin and thymosin beta 4 by the ATP/ADP ratio: possible implication in the regulation of actin dynamics

The interaction of G-actin with thymosin beta 4 (T beta 4), the major G-actin-sequestering protein in motile and proliferating cells, has been analyzed in vitro. T beta 4 is found to have a 50-fold higher affinity for MgATP-actin than for MgADP-actin. These results imply that in resting platelets and neutrophils, actin is sequestered by T beta 4 as MgATP-G-actin. Kinetic experiments and theoretical calculations demonstrate that this ATP/ADP dependence of T beta 4 affinity for G-actin can generate a mechanism of desequestration of G-actin by ADP, in the presence of physiological concentrations of T beta 4 (approximately 0.1 mM). The desequestration of G-actin by ADP is kinetically enhanced by profilin, which accelerates the dissociation of ATP from G-actin. Whether a local drop in the ATP/ADP ratio can allow local, transient desequestration and polymerization of actin either close to the plasma membrane, following platelet or neutrophil stimulation, or behind the Listeria bacterium in the host cell, while the surrounding cytoplasm contains sequestered ATP-G-actin, is an open issue raised by the present work.

Catabolism of the tetrapeptide N-Ac-Ser-Asp-Lys-Pro (AcSDKP), an inhibitor of hematopoietic stem cell (CFU-S) proliferation, following in vitro incubation with hematopoietic tissues from normal and leukemic mice

The comparative degradation of N-Ac-Ser-Asp-Lys-Pro (AcSDKP), a negative regulator controlling the proliferation of the hematopoietic pluripotent stem cell, was investigated following incubation with plasma, bone marrow and spleen cells from normal mice and mice bearing a transplantable myeloid leukemia. Using the tetrapeptide, specifically radiolabelled in the lysyl residue, degradation of [3H]AcSDKP was followed by measurement of [3H]Lys formation resulting from its catabolism. It was shown that already after 1 h the degradation of AcSDKP in plasma from leukemic mice was higher compared to that following incubation in plasma from normal mice, whereas incubation with bone marrow cells exhibits a small difference only after 4 hours incubation. However, no increase of AcSDKP catabolic activity was observed following incubation with spleen cells from leukemic animals when compared with incubation of normal spleen cells.

Particular ability of cytochrome P-450 CYP3A to reduce glyceryl trinitrate in rat liver microsomes: subsequent formation of nitric oxide

Glyceryl trinitrate was denitrated in rat hepatic subcellular fractions, with formation of glyceryl dinitrates and glyceryl mononitrates. Among differently treated-rat liver microsomes, the highest microsomal activity was obtained under anaerobic conditions with microsomal preparations from dexamethasone-treated rats and NADPH. The reaction was inhibited by O2, CO, miconazole, dihydroergotamine and troleandomycin showing that it was catalyzed by cytochrome P-450 CYP3A isoforms. The formation of a transient cytochrome P-450 Fe(II)-NO complex during this reaction was shown by visible spectroscopy. The cytosolic activity was shown to be dependent on glutathione and glutathione transferase and was not inhibited by dioxygen. In the hepatic 9000 x g supernatant containing both NADPH and cytochrome P-450 and glutathione and glutathione transferase, the cytochrome P-450-dependent reaction accounts for 30-40% of the total denitration activity observed under anaerobic conditions, using 100 microM GTN.

Optimization of cell culture conditions for the evaluation of the biological activities of the tetrapeptide N-Acetyl-Ser-Asp-Lys-Pro, a natural hemoregulatory factor

The present study attempts to define the difficulties in evaluating the properties of the hemoregulatory peptide AcSDKP using in vitro assays. In fact, in the presence of sera, which are generally added to basic culture media, AcSDKP is catabolized by proteases present in the serum. The kinetics of AcSDKP degradation depends on the nature and on the concentration of the added serum. In in vitro conditions, the half life of this peptide can be increased by the addition of 1 microM captopril, a metalloprotease inhibitor. Thus, these points need to be considered in designing experiments to study the effects of AcSDKP.

The mechanism of action of the tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (AcSDKP) in the control of haematopoietic stem cell proliferation

The mechanism of action of the haemoregulatory tetrapeptide Acetyl-N-Ser-Asp-Lys-Pro (AcSDKP, M(r) = 487 amu), was investigated using an in vitro assay of a murine high proliferative potential colony-forming cell (HPP-CFC) which responds to proliferation regulators of the haematopoietic stem cell population. AcSDKP had no direct inhibitory effect on the number, or the proportion in S phase, of the committed granulocyte-macrophage progenitor (GM-CFC), or cycling HPP-CFC populations. However, AcSDKP blocked the action of a stimulator of haematopoietic stem cell proliferation, preventing the switching of quiescent HPP-CFC into cell cycle. It would appear that AcSDKP exerts its inhibitory haemoregulatory role indirectly, by preventing stimulator action on haematopoietic stem cells.

Multiple enzymatic pathways involved in the metabolism of glyceryl trinitrate in Phanerochaete chrysosporium

A study of glyceryl trinitrate metabolism by a filamentous fungus, Phanerochaete chrysosporium, carried out with the 14C-labeled substrate, provides evidence for a multienzymatic system leading to di- and mononitrate derivatives. At least two independent enzymatic activities were detected in the cytosolic fraction: an aerobic glutathione S-transferase activity and an anaerobic NADPH-dependent soluble cytochrome P450-like activity. Other hemoproteins with enzymatic activities dependent upon the presence of NADPH or ferrous ions were also detected in the microsomal fraction. Electron paramagnetic resonance spectra characteristic of an interaction between a hemoprotein and nitric oxide appeared in these two subcellular fractions during the anaerobic metabolism of glyceryl trinitrate.

Nitroglycerin metabolism by Phanerochaete chrysosporium: evidence for nitric oxide and nitrite formation

We have demonstrated that a filamentous fungus Phanerochaete chrysosporium converts glyceryl trinitrate (GTN) into its di- and mononitrate derivatives concurrently with the formation of nitric oxide detected by electron paramagnetic resonance (EPR), and the formation of nitrite. The metabolisms of nitrite and nitrate by the fungus are evaluated and taken into account when considering GTN degradation. Lack of evidence for nitrate formation from GTN suggests that an esterase-type activity is not involved. Furthermore, the kinetics of appearance of the hemoprotein-NO and non-heme protein-NO (FeS-NO) complexes indicate that an enzymatic process producing NO directly from GTN may be involved concurrently with a glutathione transferase-like system.

Formation of acetyl-Ser-Asp-Lys-Pro, a new regulator of the hematopoietic system, through enzymatic processing of thymosin beta 4

The demonstration that AcSDKP, a new regulator of the hematopoietic system, is formed in the bone marrow by a one-step enzymatic maturation processing of thymosin beta 4 (T beta 4) is presented. AcSDKP and T beta 4 were both detected in bone marrow cells (BMC). Incubation of [3H]T beta 4 with either intact or lysed BMC led to the formation of [3H]AcSDKP, whereas the labeled tetrapeptide was not degraded under these conditions. Model enzymatic degradation of T beta 4 carried out with bacterial enzymes suggests that a mammalian endoproteinase Asp-N might be involved in the formation of AcSDKP through the specific cleavage of the Pro4-Asp5 peptidic bond of T beta 4. In contrast, alpha-prolyl-endopeptidase was ineffective in carrying out a similar processing.

Involvement of thymosin beta 4 and endoproteinase Asp-N in the biosynthesis of the tetrapeptide AcSerAspLysPro a regulator of the hematopoietic system

It is shown that AcSDKP a new regulator of the hematopoietic system can be generated from thymosin beta 4 by a one-step enzymatic cleavage in vitro and in vivo. AcSDKP and T beta 4 were both detected in bone marrow cells (BMC). Incubation of [3H]T beta 4 with either intact or lysed BMC led to the formation of [3H]AcSDKP whereas the labelled tetrapeptide was not degraded under these conditions. Model enzymatic degradation of T beta 4 carried out with bacterial enzymes suggests that a mammalian endoproteinase Asp-N might be involved in the formation of AcSDKP through the specific cleavage of the 4Pro-5 Asp peptide bond of T beta 4.

Synthesis and activity of NAcSerAspLysPro analogues on cellular interactions between T-cell and erythrocytes in rosette formation

Analogues of NAcSerAspLysPro (AcSDKP), a natural regulator of hematopoiesis isolated from fetal calf bone marrow, were synthesized. The biological activity of these molecules were evaluated in vitro in the rosette assay, which measures the interaction between human Jurkat T-cells and sheep red blood cells. In this test, the tripeptide SerAspLys was the most efficient. Inhibitory activity was detected at the concentration 10(-14) M for the analogue and at 10(-9) M for the parent tetrapeptide. The dipeptide NAcSerAsp still showed activity but at much higher doses (10(-6) M). Substitution of polar amino acids led mostly to inactive molecules. Thus, replacement of Ser by Ala, or Lys by Orn yielded completely inactive compounds and replacement of Asp by Glu decreased the activity (10(-6) M). The present study gives an insight into the role of individual amino acids of AcSDKP in the inhibition of the rosette formation which implicates interactions with T-cell CD2 glycoprotein.

Formation of glyceryl 2-mononitrate by regioselective bioconversion of glyceryl trinitrate: efficiency of the filamentous fungus Phanerochaete chrysosporium

Various microorganisms have been evaluated for their ability to hydrolyze glyceryl trinitrate (GTN) to glyceryl dinitrates and mononitrates. Provided that the GTN extracellular concentration was under the lethal dose, metabolite formation and regioselectivity depend on the nature of the strain used. In particular, Phanerochaete chrysosporium at a sublethal dose (3 mM) converts GTN into 1,2-glyceryl dinitrate and 2-glyceryl mononitrate (2-GMN) with a 80% regioselectivity in both steps. This bioconversion, when carried out in fermentors at 28 degrees C, allowed formation of 2-GMN at a rate of 12 mumol/h/g of dried mycelium. Successive batches of 3 mM GTN could be converted into 2-GMN as long as consecutive additions of glycerol or glucose were effected to ensure cell survival and the efficiency of the enzymatic system involved.

AcSDKP, an inhibitor of CFU-S proliferation, is synthesized in mice under steady-state conditions and secreted by bone marrow in long-term culture

The peptide AcSDKP, isolated from fetal calf bone marrow, is able to prevent DNA synthesis in mouse CFU-S in vivo and in vitro. The molecule is demonstrated here to be constitutively produced in mice and synthesized by bone marrow cells in long term culture.

In vivo effect of the tetrapeptide, N-acetyl-Ser-Asp-Lys-Pro, on the G1-S transition of rat hepatocytes

The synthetic molecule N-Acetyl-Ser-Asp-Lys-Pro (Ac-SDKP), corresponding to the low molecular weight inhibitory factor preventing in vivo haematopoietic stem cell (CFU-S) entry into DNA synthesis, was tested in two heterologous systems in vivo: adult regenerating rat liver and 10-day-old rat hepatocytes synchronized by an irritating trigger. In both systems, it was shown that doses of 2-8 micrograms kg-1 of tetrapeptide inhibited 50-70% of the hepatocyte G1-S transitions.

Bioconversion of glyceryl trinitrate into mononitrates by Geotrichum candidum

Glyceryl trinitrate (GTN) 2 mM was quantitatively converted into its 1 and 2 mononitrate derivatives by Geotrichum candidum, with consumption of the nitrite ions produced. The conversion proceeded at a rate independent of the addition of either organic carbon or organic nitrogen sources. Eight batches of nitrate ester, which were added every 24 hours, were successfully converted as far as during the bioconversion process GTN concentration did not exceed 2 mM. When those limiting conditions were not observed, dramatic toxicity of GTN was noticed.

Nitric oxide formation during microsomal hepatic denitration of glyceryl trinitrate: involvement of cytochrome P-450

Glyceryl trinitrate was denitrated by rat liver microsomes in the presence of NADPH with formation of a mixture of glyceryl dinitrates and glyceryl mononitrates. The highest activity was obtained under anaerobic conditions and the reaction was inhibited by O2 indicating that it is a reductive denitration. It was also inhibited by CO, metyrapone and miconazole showing that it was catalyzed by cytochrome P-450. Finally the formation of the cytochrome P-450-Fe(II)-NO complex during this reaction was shown by visible spectroscopy. These data demonstrate that microsomal reductive denitration of glyceryl trinitrate is catalyzed by cytochrome P-450 and can be involved in the formation of the endothelium-derived relaxing factor (EDRF = nitric oxide).

Enhancement of the adherence of hematopoietic stem cells to mouse bone marrow-derived stromal cell line MS-1-T by a tetrapeptide acetyl-N-Ser-Asp-Lys-Pro

The tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (AcSDKP) has been shown to inhibit in vivo the hematopoietic stem cell (spleen colony-forming unit; CFU-S) entry into cell cycle in cytosine arabinoside-treated mice. Our data showed that AcSDKP has no effect on interleukin 3 (IL-3)-dependent DA-1 cell proliferation or on granulocyte-macrophage colony-forming cell and mast cell colony formation, whereas it enhances the adherence of CFU-S to the bone marrow-derived hematopoietic supportive stromal cell line MS-1-T. AcSDKP suppresses MS-1-T proliferation but does not modify granulocyte-macrophage colony-stimulating activity secretion by these cells. This suggests that the peptide does not counteract the activity of the IL-3 receptor on CFU-S but acts on MS-1-T and in particular at the level of CFU-S/MS-1-T interactions.

Inhibitor of hematopoietic pluripotent stem cell proliferation: purification and determination of its structure

We report here a five-step purification procedure that led to the isolation from fetal calf bone marrow extract of a tetrapeptide, Ac-Ser-Asp-Lys-Pro (Mr 487), exerting a high inhibitory activity on the proliferation of hematopoietic pluripotent stem cells [defined here as spleen colony-forming units (CFU-S)]. The structure of this molecule was established from amino acid analysis, fast atom bombardment mass spectrometry, and 1H nuclear magnetic resonance spectral data. This structure was confirmed by comparison with the corresponding synthetic molecule, which presents identical physiochemical characteristics and biological properties. Natural and synthetic peptides administered to mice (at a dose of 100 ng per mouse) after one injection of cytosine arabinonucleoside prevent CFU-S recruitment into DNA synthesis.

Suppression of mast cell colony formation by a low molecular weight fraction of fetal calf bone marrow extract

A semi-purified fraction extracted from fetal calf bone marrow was previously shown to contain a tetrapeptide N-Ac-Ser-Asp-Lys-Pro which inhibits in mice, hematopoietic stem cell entry into the cell cycle. This peptide however, did not exhibit any effect on either IL-3 nor GM-CSF dependent cell growth. We report herein that a semi-purified fraction also contains another activity which is antagonistic to IL-3. Addition of the fraction in vitro decreased IL-3 dependent mast cell colony formation. Growth of IL-3 dependent cell lines (DA-1 and FDC-P2) was also suppressed. No effect was observed in the same dose range on granulocyte-macrophage colony formation nor on IL-3 independent cell growth.

Ca2+-channel blockers modulate the oxidative burst induced with arachidonic acid in macrophage-like P 388D1 cells. Interaction with peripheral benzodiazepines

Ca2+-channel blockers are shown to modulate, like peripheral benzodiazepines, the oxidative burst induced by arachidonic acid in the macrophage-like P 388D1 cell line. Nifedipine (1 and 10 nM) enhanced the cellular response to arachidonate; this stimulation by nifedipine was reversed by PK 1195, a specific antagonist for the peripheral benzodiazepine binding site. Verapamil (5 microM), on the other hand, antagonized the stimulation of the oxidative burst by benzodiazepines. The data suggest some possible interaction of Ca2+-channel blockers at the benzodiazepine binding site or at a secondary step in the activation mechanism. None of the molecules modulated the calcium influx triggered by arachidonate. Instead, the oxidative response of P 388D1 cells to arachidonate was inhibited by K+-channel blockers, quinidine and tetraethylammonium bromide.

Fluoride effects on 31P NMR spectra of macrophages

31P High resolution nuclear magnetic resonance studies have been carried out on the P388D1 tumoral cell line and the BCG elicited alveolar rabbit macrophages both in sedimented cells and in perfused agarose-embedded cells. When the cells were sufficiently oxygenated, the phosphorylated sugars and ATP concentrations attained high levels. The intensity of the peak representing phosphorylated sugars varied inversely with ATP level when macrophagic cells were treated by NaF. The identities of the phosphorylated sugars were revealed by 1H and 31P NMR studies of the P 388D1 cells perchloric extracts.

Peripheral benzodiazepines enhance the respiratory burst of macrophage-like P388D1 cells stimulated by arachidonic acid

P388D1, a murine cell with macrophage properties, responds to exogenous arachidonic acid with superoxide anion production. This oxidative burst is enhanced by peripheral and mixed type benzodiazepines and this stimulation is specifically reversed by the peripheral antagonist PK 11195. In contrast, PK 11195 is unable to antagonize a stimulation caused by a non-benzodiazepine ligand such as the chemotactic peptide fMet-Leu-Phe. The optimal concentrations were close to 10 nM and corresponded to the affinities of the compounds for the peripheral benzodiazepine receptor detected on these cells. Compared to other tissues where peripheral benzodiazepines acted only at micromolar concentrations, the macrophage with its functional receptor appears as a privileged site of action for these molecules.

Structure activity relationship in heparin: stimulation of non-vascular cells by a synthetic heparin pentasaccharide in cooperation with human acidic fibroblast growth factors

Heparin enhances strongly the mitogenic properties of human acidic fibroblast growth factor (h-aFGF) on hamster fibroblast (CCL 39) or bovine lens epithelial cells (BEL). We report here that a synthetic heparin pentasaccharide with high affinity for antithrombin III has the same effect as heparin at about the same concentration. Thus a pentasaccharidic sequence may represent the shortest heparin structure which interacts with h-aFGF.

Effect of heparin on the stimulation of non-vascular cells by human acidic and basic FGF

We have purified acidic and basic fibroblast growth factors from human brain (h-aFGF, h-bFGF) and studied the effect of heparin on the growth stimulation by these factors of hamster fibroblast CC139 cells and bovine epithelial lens (BEL) cells. In both the presence and the absence of foetal calf serum (FCS) heparin cooperates with h-aFGF in a dose dependent manner to stimulate both types of cells. The cooperation with h-bFGF is much less. An unpurified human brain fraction containing both factors behaves differently: in the absence of FCS, heparin enhances the activity of the crude fraction on BEL cells, while in the presence of FCS, it decreases this activity. These results indicate that heparin cooperates strongly with h-aFGF to stimulate non-vascular cell proliferation while in a partially purified extract and in the presence of serum it can induce the opposite effect.

In vivo immunomodulating activity of PK 1195, a structurally unrelated ligand for "peripheral" benzodiazepine binding sites--I. Potentiation in mice of the humoral response to sheep red blood cells

PK 11195, an isoquinoline carboxamide compound with the highest affinity for the peripheral type benzodiazepine binding site has been shown to enhance the humoral response of mice to sheep red blood cells, a T cell dependent antigen. The compound was active when administered i.p. 1 day following immunization. The active doses ranged from 10 ng to 1 mg/kg. Such an immunomodulating activity might be related to the presence of peripheral type benzodiazepine binding sites, previously detected on the macrophage.