Mechanism-based inhibitors of serine proteinases based on the Gabriel-Colman rearrangement

Neutrophil-derived mediators such as, for example, the serine proteinase elastase, cathepsin G and proteinase 3, play a critical role in inflammatory lung disease. This report describes the design, synthesis and in vitro inhibitory activity of some novel mechanism-based inhibitors of human leukocyte elastase and cathepsin G. The design of the inhibitors is based on the Gabriel-Colman rearrangement. The behavior of the synthesized compounds toward elastase and cathepsin G with respect to inhibitory prowess, mode of interaction, specificity, etc., has been found to be dependent on the recognition and reactivity elements present in each inhibitor.

Visualisation of arterial structure in vivo with intravascular ultrasound

BACKGROUND

Contrast angiography provides a silhouette of the arterial lumen, but does not give information about arterial wall structure. Catheter-tip ultrasound transducers can now provide a cross-sectional image of the arterial wall. This study examined the pathological correlation of intravascular ultrasound images and the accuracy of ultrasound measurements of vascular geometry.

METHODS

Intravascular ultrasound images were obtained with a mechanically rotated catheter-tip transducer and recorded on videotape. Initial validation studies were performed in fresh, post-mortem arterial specimens, which were filled with saline at physiological pressures. Ultrasound images at specific sites were compared with the pathological findings at that site and measurements of luminal diameter were compared with corresponding angiographic measurements. Subsequently, intravascular ultrasound was employed to examine the aorta, ilio-femoral and coronary arteries in patients undergoing balloon angioplasty.

RESULTS

The pathological correlations showed that intravascular ultrasound can detect early initial thickening and mild atherosclerotic lesions that do not result in luminal deformation. Ultrasound images provided definition of calcified, fibrotic and lipid-filled lesions. Ultrasound measurements of luminal diameter correlated well with pathology measurements (r = 0.93), as did ultrasound measurements of plaque area (r = 0.89). The in vivo studies demonstrated that intravascular ultrasound can define atheroma lesions not evident on contrast angiography and permits detailed evaluation of the results of interventions such as balloon angioplasty.

CONCLUSIONS

Intravascular ultrasound provides a unique window upon arterial structure and pathology in humans. Ultrasound images allow accurate measurements of vascular geometry and define early atheromatous lesions that are not evident with angiography.

On the structure of calonyctin A, a plant growth regulator

The plant growth regulator calonyctin A, isolated from the dried leaves of Calonyction aculeatum L. House (Yue-Guang-Hua), was separated into two pure components by high performance liquid chromatography. By use of mass spectrometry based on various ionization techniques, one- and two-dimensional NMR spectroscopy, IR spectrometry, and chemical methods the molecular structures of the two homologous glycosides were determined. Each molecule contains two hydroxy fatty acid residues and four 6-deoxyhexose units. The fatty acids are 3-hydroxy-2-methylbutanoic acid and 11-hydroxytetradecanoic acid or 11-hydroxyhexadecanoic acid. The 6-deoxyhexose residues (three of quinovose and one of rhamnose) comprise a tetrasaccharide having the following structure: [formula: see text] The long-chain hydroxy acid is linked glycosidically through its O-11 to Qui D and esterified to O-2 of Qui C, forming a macrocyclic lactone. The 3-hydroxy-2-methylbutanoic acid is ester-linked to O-3 of Qui C.

Mechanism of the preserving effect of aprotinin on platelet function and its use in cardiac surgery

The deficiency of platelet function is the main defect of the hemostatic mechanism during cardiopulmonary bypass, which greatly exacerbates the postoperative bleeding complications. In this study, we assessed, from basic and clinical perspectives, the mechanism of relieving platelet damage by means of aprotinin. In vitro research confirmed that the addition of urokinase (40 U/ml) to platelet-rich plasma and the addition of plasmin (0.3 U/ml) to washed platelets made ristocetin-induced agglutination decline to 31.6% and 38.5% of control values, respectively. The extent of decline was positively correlated with the concentration of urokinase and plasmin. In addition, the platelet membrane glycoprotein Ib decreased to 76.4% of control value. With the addition of urokinase or plasmin to aprotinin-pretreated platelet-rich plasma or washed platelets, the changes in agglutination are not statistically significant and the decrement in glycoprotein Ib is much less marked. Further in vivo research revealed that cardiopulmonary bypass caused a decrease in plasma alpha 2-antiplasmin, indicating the fibrinolytic system activation. Meanwhile, ristocetin-induced agglutination decreased to 39.6% and platelet glycoprotein Ib decreased to 50% of preoperative values. However, with the administration of aprotinin, plasma alpha 2-antiplasmin during cardiopulmonary bypass did not change; platelet agglutination was improved, platelet glycoprotein Ib was preserved, and this consequently resulted in 46% lower blood loss after the operation. The results showed that fibrinolysis impaired platelet function, and this effect may be associated with the hydrolysis of glycoprotein Ib. Fibrinolytic activation occurred during cardiopulmonary bypass and contributed to postoperative platelet dysfunction to a great extent. Aprotinin may inhibit fibrinolysis during cardiopulmonary bypass and thus relieve the platelet damage and improve the postoperative hemostatic mechanism.

A positive correlation between the precursor frequency of cytotoxic lymphocytes to autologous Epstein-Barr virus-transformed B cells and antibody titer level against Epstein-Barr virus-associated nuclear antigen in healthy seropositive individuals

A limiting dilution analysis was established to determine the precursor frequency (PF) of cytotoxic lymphocytes against autologous B cells transformed with the Epstein-Barr virus (EBV). This method was found to detect mainly self-restricted T-cell activity and little non-self-restricted cytotoxicity. The mean PF in 21 healthy EBV-seropositive persons was 1.4 x 10(-3) (range: 0.03 x 10(-3) to 8.7 x 10(-3)) for peripheral blood mononuclear cells, whereas 4 samples of mononuclear cells obtained from umbilical cord blood had PFs below 0.007 x 10(-3). A positive correlation was observed between the PF and serum antibody titers against EBV-associated nuclear antigen among the seropositive persons.

Mortality from lung cancer among copper miners

A cohort mortality study of lung cancer in 7088 copper miners was made from 1 January 1969 to 31 December 1988. There was an excess of deaths from lung cancer in the copper miners. The standardised mortality ratio (SMR) was 147 (p < 0.01). The SMR increased with calendar period. There was a higher risk of deaths from lung cancer in the miners employed in the 1950s. Age at the start of exposure had no effect on the risk of lung cancer. The risk of death from lung cancer increased with the duration of exposure and the time since first exposure. The SMR for lung cancer was 173 in underground miners and 193 for drilling miners (both p < 0.01). These data show that exposure to dust is associated with an excess of deaths from lung cancer in copper miners whereas exposure to radiation does not seem to carry such risk.

Regulation of angiotensin II receptors on ventricular myocytes after myocardial infarction in rats

To determine the effects of acute myocardial infarction on the regulation of angiotensin II (Ang II) receptors and contractile performance of left and right ventricular myocytes, coronary artery ligation was surgically induced in rats, and Ang II receptor density and affinity and the mechanical properties of surviving muscle cells were examined 1 week later. Physiological determinations of cardiac pump function revealed the presence of ventricular failure, which was associated at the cellular level with a depression in the velocity of myocyte shortening and relengthening, a prolongation of time to peak shortening, and a reduction in the extent of cell shortening. These abnormalities in single-cell function were more prominent in left than in right ventricular myocytes. Cellular hypertrophy was documented by increases in cell length and width, which were also greater in the spared myocytes of the infarcted left ventricle. Reactive hypertrophy was accompanied by a 1.84- and 1.85-fold increase in the density of Ang II receptors on left and right myocytes, respectively. On the other hand, the affinity of Ang II receptors for the radiolabeled antagonist was not altered. However, Ang II-stimulated phosphoinositol turnover was enhanced by 3.7- and 2.5-fold in left and right myocytes, respectively, after infarction. Ventricular myocytes were found to possess the AT1 receptor subtype exclusively. In conclusion, myocardial infarction leads to impairment in the contractile behavior of the remaining cells and to the activation of Ang II receptors and effector pathway associated with these receptors, which may be involved in the reactive growth adaptation of the viable myocytes.

Glutathione as a cellular defence against arsenite toxicity in cultured Chinese hamster ovary cells

The cytotoxic effect of arsenite seems to be inversely related to the intracellular glutathione (GSH) content, and GSH seems to facilitate the metabolism of arsenic in cell. Arsenite is also known to induce chromosome aberration, to enhance the cytotoxicity and clastogenicity of ultraviolet (UV) light, and to inhibit UV-induced DNA repair. We have investigated whether these toxic effects of arsenite and the cellular arsenic content are also modulated by the intracellular GSH. A 2-h pretreatment of the cultured ovary (CHO) cells with GSH reduced the clastogenicity and cytotoxicity of arsenite. The enhancing effects of arsenite on chromosome aberrations and cell destruction induced by UV were also reduced by a 2-h pretreatment with GSH. The inhibitory effect of arsenite on the strand-break rejoining during UV-induced DNA repair was reduced by GSH pretreatment and was enhanced by pretreatment with buthionine sulfoximine, which is known to deplete the cellular GSH. The cellular arsenic content was reduced by GSH pretreatment and increased by buthionine sulfoximine pretreatment. GSH given before or simultaneously with arsenite, effectively reduced the clastogenicity and coclastogenicity of arsenite. GSH given after treatment with arsenite decreased the cellular arsenic content, and increased the cell survival, but did not reduce the clastogenicity or the coclastogenicity of arsenite.

The natural history of aortic dilatation in Marfan syndrome

OBJECTIVES

To determine the relationship between age and aortic dilatation in patients with Marfan syndrome and to define the rate of progression of aortic dilatation in these patients.

DESIGN

All patients were evaluated in a multidisciplinary clinic to establish a firm diagnosis of Marfan syndrome. Aortic dimensions were measured by echocardiography and patients with Marfan syndrome were followed up with annual physical and echocardiographic examinations to detect any change in aortic diameter over the subsequent four years.

PATIENTS

One hundred and fifty-seven patients were referred to the clinic for assessment, of whom 40 exhibited diagnostic features of Marfan syndrome. Only 24 of these patients had previously been diagnosed with Marfan syndrome, while 17 other patients, previously diagnosed with Marfan syndrome, had insufficient clinical features to justify the diagnosis.

RESULTS

Among the 40 patients (19 male, 21 female) with Marfan syndrome (mean age, 28 +/- 15 years), the prevalence of cardiovascular abnormalities was 90%. Aortic root dilatation was present in 78% of patients, aortic regurgitation in 28%, mitral valve prolapse in 65% and mitral regurgitation in 35%. Mean aortic root diameter in the Marfan patients (21.4 +/- 4.0 mm/m2 body surface area) markedly exceeded that of age and sex matched controls without Marfan syndrome (14.9 +/- 2.2 mm/m2) and that of first-degree relatives without Marfan syndrome (15.3 +/- 2.9 mm/m2). The occurrence of aortic dilatation in Marfan syndrome was variable, with patients as young as 20 years exhibiting severe dilatation. All patients with Marfan syndrome exhibiting aortic dilatation were advised to take beta-adrenergic blocking drugs, unless contraindicated, in an effort to retard the rate of aortic dilatation. Among 33 patients followed up for at least one year, 14 (42%) exhibited an increase in aortic diameter of at least 2 mm, while 16 of 23 patients (70%) followed up for at least three years exhibited similar progression of aortic dilatation. The overall mean rate of dilatation in the Marfan patients was 1.9 mm per year. Nine patients developed aortic dilatation of more than 50 mm diameter during four years' follow-up and required surgical repair of the aorta. Each of these patients is well at between three months' and four years' follow-up.

CONCLUSIONS

Aneurysmal dilatation of the aorta is a common complication of Marfan syndrome and may become manifest at an early age. Furthermore, aortic dilatation can progress rapidly, even in the absence of symptoms. Individuals with Marfan syndrome should have annual echocardiographic examinations to monitor aortic root dimensions, and those exhibiting rapid progression of aortic dilatation or an aortic root diameter in excess of 50 mm, should be considered for elective composite graft repair of the aorta.

Angiotensin-converting enzyme inhibition does not suppress plasma angiotensin II increase during exercise in humans

Physical effort stimulates the reninangiotensin system (RAS). We studied the effect of an angiotensin-converting enzyme inhibitor (ACE inhibitor) in a double-blind placebo-controlled study, on eight volunteers undergoing physical stress on an ergometric bicycle. The effects of captopril (C) (50 mg, three times daily for 3 days) on arterial pressure (AP), O2 consumption (VO2), variations in auricular natriuretic factor (ANF), renin, angiotensin II (AII) plasma levels, as well as glomerular filtration rate (GFR) and microalbuminuria (MA) were evaluated. The different parameters were compared by analysis of variance (ANOVA). The pressure profile and VO2 were not modified by ACE inhibitor. Exercise stimulates release of renin; this action was greater with captopril administration (treatment effect: p < 10(-4), indicating blockade of the RAS. This inhibition was incomplete because AII levels increased markedly when captopril was given (no treatment effect: p < 0.37). Finally, ACE inhibitor resulted in decreased GFR (p = 115 +/- 5.8 ml/mn-1, C = 91.1 +/- 4, p < 0.05) with exercise without modification of MA. ACE inhibitor administration does not modify the physical performance of nonathletic subjects; AII is significantly increased with exercise despite captopril treatment; ACE inhibitor decreases GFR significantly but does not influence MA with prolonged physical effort.

Analysis of two gene regions involved in the expression of the imipenem-specific, outer membrane porin protein OprD of Pseudomonas aeruginosa

A Tn501 mutant of Pseudomonas aeruginosa resistant to imipenem and lacking the imipenem-specific outer membrane porin protein OprD was isolated. The mutation could be complemented to imipenem susceptibility and OprD-sufficiency by a cloned 6-kb EcoRI-PstI fragment of DNA from the region of chromosome of the wild-type strain surrounding the site of Tn501 insertion. However, this fragment did not contain the oprD structural gene as judged by its inability to hybridize with an oligonucleotide corresponding to the N-terminal amino acid sequence of OprD. DNA sequencing of 3.9 kb of the region surrounding the Tn501 insertion site revealed three large open reading frames, one of which would be interrupted by the Tn501 insertion in the mutant. This latter open reading frame, named opdE (for putative regulator of oprD expression), predicted a hydrophobic protein of M(r) 41,592. Using the above-mentioned oligonucleotide, the oprD structural gene was cloned and expressed in Escherichia coli on a 2.1-kb Bam HI-KpnI fragment. DNA sequencing predicted a 420 amino acid mature OprD protein with a 23 amino acid signal sequence.

Direct, simplified, and sensitive assay of angiotensin II in plasma extracts performed with a high-affinity monoclonal antibody

A very simple, fast, and sensitive RIA of angiotensin (Ang) II has been developed, based on a monoclonal antibody with high affinity and specificity, making possible the direct measurement of circulating Ang II in human plasma after solid-phase extraction. The purified monoclonal antibody 4D8 has an association constant of 1.3 x 10(11) L/mol with Ang II and a cross-reactivity of < 1% for Ang I. The assay can detect as little as 0.8 fmol of Ang II in 2 mL of plasma and is not influenced by the presence of Ang I. Analytical recoveries between 112% and 116% were obtained for Ang II added to human plasma at physiological concentrations. Comparison of the RIA with a reversed-phase, high-performance liquid chromatographic method followed by RIA to measure Ang II in human plasma samples from normal and hypertensive subjects--and from normotensive subjects before and after an acute inhibition of angiotensin-converting enzyme with captopril (50 mg)--showed a high degree of correlation (r2 = 0.93) between the two methods.