Synthesis and enzymatic evaluation of a P1 arginine aminocoumarin substrate library for trypsin-like serine proteases

A method for the solid-phase synthesis of P1 arginine containing peptides via attachment of the arginine side-chain guanidine group is described. This procedure is applied to the preparation of a tetrapeptide, P1 arginine aminocoumarin PS-SCL. This library was validated by using it to determine the P4-P2 specificity for thrombin and comparing the results to the known thrombin subsite specificity. This is the first reported example of a PS-SCL library containing a P1 arginine.

The discovery of non-basic atrial natriuretic peptide clearance receptor antagonists. Part 1

The cyclic peptide ANP 4-23 and the linear peptide analogue AP-811 have been shown to be selective ANP-CR antagonists. Via alanine scanning and truncation studies we sought to determine which residues in these molecules were important in their binding to the clearance receptor and the relationship between these two molecules. These studies show that several modifications to these compounds are possible which improve physical properties of these molecules while retaining high affinity for the ANP-CR.

C3 activation is inhibited by analogs of compstatin but not by serine protease inhibitors or peptidyl alpha-ketoheterocycles

C3 convertase is a key enzyme in the complement cascade and is an attractive therapeutic target for drug design. Recent studies have demonstrated that this enzyme is inhibited by compstatin (Morikis, D. , Assa-Munt, N., Sahu, A., Lambris, J.D., 1998. Solution structure of Compstatin, a potent complement inhibitor. Protein Sci. (7) 619-627; Sahu, A., Kay, B.K., Lambris, J.D., 1996. Inhibition of human complement by a C3-binding peptide isolated from a phage-displayed random peptide library. J. Immunol. (157) 884-891), a 13 amino acid cyclic peptide that binds to C3. Since the enzyme exhibits some homology to serine proteases, substrate-based design could be another avenue for drug design. In this study, we confirm the activity of compstatin using different sources of enzyme and different assay systems. We also tested the activity of substituted compstatin analogs and compared the selectivity and toxicity of these compounds to peptidyl alpha-ketoheterocyclic compounds. Our work confirms the activity of compstatin in both alternative and classical complement pathways, describes 11 new active analogs of this cyclic peptide, and provides evidence for key segments of the peptide for activity. Compstatin and related active analogs showed little or no inhibition of clotting or key enzymes in the clotting cascade nor did they appear to have significant cytotoxicity. The characteristics of compstatin suggest that this peptide and its analogs could be attractive candidates for further clinical development. By contrast, known serine protease inhibitors, including peptidyl alpha-ketoheterocycles, did not inhibit C3 convertase illustrating the atypical nature of this enzyme.

Spiral CT optimization for measurement of bronchial lumen diameter using an experimental model

The aim of the study was to determine optimal parameters for demonstrating sublobar bronchi on spiral CT. Measurements were obtained from five parallel polyethylene tubes embedded in foam matrix with similar radiographic characteristics to segmental and subsegmental bronchi and to lung parenchyma, respectively. Collimation widths of 1.5, 2, 3 and 4 mm were used, with a pitch of 1 or 1.5 and a reconstruction interval of 1 mm or 2 mm. Various slice planes were used. Images acquired orthogonally were viewed normally. Images acquired in planes oblique or parallel to the long axes of the tubes were reformatted into a plane orthogonal to the long axes of the tubes to be comparable with the directly acquired orthogonal images. Tube diameters were measured at lung window settings (L, -400; W, 1300) and compared with known true inner and outer tube diameters. Measurements from images acquired orthogonal to the tube long axes were accurate regardless of slice thickness. Images acquired obliquely or parallel only produced accurate measurements at the lowest slice thickness (1.5 mm). Pitch and reconstruction interval had no effect on measurement error in any scan plane. It is concluded that a slice thickness of 1.5 mm or less, with a pitch of 1.5, should be used when acquiring images at angles other than orthogonal to the long axes of experimental tubes equivalent to the segmental and subsegmental bronchi. It is suggested that similar parameters should be used in vivo and that the examination should be targeted to the area of the bronchial tree in question to reduce patient dose and length of breath-hold.

Molecular and mechanistic validation of delayed healing rat wounds as a model for human chronic wounds

The purpose of this study was to provide molecular and mechanistic evaluation of an ischemic wound model in rats to determine if it is a valid model for human chronic wounds. Compared to acute wounds, human chronic wounds contain markedly elevated levels of proinflammatory cytokines and matrix metalloproteinases, while matrix metalloproteinase inhibitors and growth factor activity are diminished. Accordingly, tissue from ischemic and normal rat wounds were analyzed for cytokine, proteases and growth factor levels. Dorsal full thickness punch wounds were created in rats using a reproducible template. The ischemic wound group (n = 10) had six uniformly placed wounds within a bipedicled dorsal flap. The control group (n = 10) had the same wounds created without elevation of a flap. On postwound days 3, 6 and 13 wounds were excised and analyzed. Protein levels for tumor necrosis factor-alpha were determined with a rat-specific enzyme-linked immunosorbent assay, while mRNA was determined by RNase protection assay. Matrix metalloproteinases and serine protease detection was done using gelatin and casein zymography, respectively. Significant delay in healing was achieved in the ischemic group: 50% healing for control wounds was at 7 days and 11 days for ischemic wounds (p < 0.001). No significant differences between wound groups were found for interleukin-1beta, and mRNA for tumor necrosis factor-alpha and interleukin-1beta. However, at day 13 ischemic wounds contained significantly more tumor necrosis factor-alpha than controls and normal skin (586 +/- 106 pg/biopsy vs. 79 +/- 7 pg/biopsy vs. 52 +/- 2 pg/biopsy; p < 0. 001). Zymography showed substantially greater quantities of matrix metalloproteinase-2, matrix metalloproteinase-9, and serine proteases in ischemic wounds. This model of delayed healing in rats shares many of the key biochemical, molecular and mechanistic characteristics found in human chronic wounds, namely elevated tumor necrosis factor-alpha and protease levels. As such, this model will likely prove to be useful in chronic wound research, particularly in developing novel therapeutics.

Bone age assessment: a large scale comparison of the Greulich and Pyle, and Tanner and Whitehouse (TW2) methods

PURPOSE

Comparison of bone age assessed using either the "atlas matching" method of Greulich and Pyle or the "point scoring system" of Tanner and Whitehouse (TW2).

MATERIALS AND METHODS

362 consecutive "bone age" radiographs of the left hand and distal radius performed in a large provincial teaching hospital. Data were analysed using the "method comparison" statistical technique. Ten per cent of the radiographs were re-analysed to assess intra-observer variation.

RESULTS

The 95% confidence interval for the difference between the two methods was 2.28 to -1.52 years. Intra-observer variation was greater for the Greulich and Pyle method than for the TW2 method (95% confidence limit, -2.46 to 2.18 v -1.41 to 1.43).

CONCLUSION

The two methods of bone age assessment as used in clinical practice do not give equivalent estimates of bone age and we suggest that one method only (preferably the TW2) should be used when performing serial measurements on an individual patient.

Application of gene therapy to acute inflammatory diseases

The application of gene therapy to acute inflammation has not received as much research attention as has the treatment of genetically-based diseases, cancer, and viral infections. However, gene therapy as a drug delivery system offers several theoretical and practical advantages over current protein delivery systems. These include the ability to target therapies to individual tissues or cell types, to locally produce proteins that can act intracellularly or in an autocrine, juxtacrine, or paracrine fashion, and to sustain new protein synthesis for periods up to several weeks after a single administration. Although retrovirus, herpes simplex, and adeno-associated virus have been proposed for gene therapy in cancer and in genetic diseases, nonviral and adenovirus approaches appear most applicable as drug delivery systems due to their rapid onset and short duration of transgene expression. The relative modest transduction efficiencies obtained at present with nonviral approaches, and the inherent inflammatory properties of first-generation adenovirus constructs, however, have limited their usefulness to date. The present review discusses the theoretical and practical benefits of specific gene therapy approaches for the treatment of acute inflammatory diseases, as well as our experiences with liposome:plasmid DNA and adenovirus-based approaches. Although a number of technical and theoretical hurdles remain before it can be evaluated in humans with acute inflammation, gene therapy offers a novel approach for the treatment of acute inflammation, and will likely enter the armamentarium of critical care physicians in the near future.

A new non-invasive test for the detection of compartment syndromes

Chronic exertional compartment syndrome (CECS) is currently diagnosed using invasive pressure measurements. We report the use of 99Tcm-methoxyisobutyl isonitrile (99Tcm-MIBI) scintigraphy as a new non-invasive method of diagnosis. Forty-six patients with suspected chronic compartment syndrome underwent graded treadmill exercise to reproduce the presenting symptoms. At peak exercise, 300 MBq of 99Tcm-MIBI were injected intravenously. Subsequent cross-sectional imaging provided by emission tomography demonstrated regional abnormalities in muscle perfusion in the calf. A repeat study was performed at rest the following day. All patients in whom there was a strong clinical suspicion of CECS were considered for invasive pressure measurements. Statistical analysis of the results for investigation of CECS using 99Tcm-MIBI versus pressure studies gave P = 0.06. A comparison of 99Tcm-MIBI versus outcome gave P < 0.0001. The sensitivity was 80% and the specificity 97% for 99Tcm-MIBI studies based on outcome. The positive predictive value was 89% and the negative predictive value 94%. Thus 99Tcm-MIBI can detect compartment syndromes with good positive and negative predictive values. It is relatively simple, cheap and less invasive than pressure measurements. This technique shows promise in the diagnosis of CECS.

CT measurement of main pulmonary artery diameter

The aim of this study was to determine the upper limit of the normal main pulmonary artery diameter using a modern CT system. This was measured at the level of the pulmonary artery bifurcation in 100 normal subjects using unenhanced contiguous 10 mm CT slices viewed at fixed mediastinal window settings (400/20). These normal subjects were then compared with similar unenhanced 10 mm images from 12 patients with proven pulmonary arterial hypertension (mean pulmonary artery pressure > 20 mmHg). The main pulmonary artery diameter in normal subjects was 2.72 cm (SD = 0.3). Main pulmonary artery diameter in patients with pulmonary arterial hypertension was significantly greater (p < 0.01) at 3.47 cm (SD = 0.33). A pulmonary artery diameter of 3.32 cm (main pulmonary artery diameter + 2 SD) had a 58% sensitivity and 95% specificity for the presence of pulmonary arterial hypertension. It is concluded that, using unenhanced axial 10 mm CT sections, the upper limit of normal main pulmonary artery diameter is 3.32 cm. Pulmonary arterial hypertension should be considered in patients with values above this level.

CT dimensions of the normal pericardium

Previous studies have suggested that the upper limit of the thinnest portion of the pericardium is 3-4 mm using 10 mm CT slices. However, these studies suffered from small sample sizes, long data acquisition times and unconventional viewing parameters. We have measured the width of the thinnest portion of the normal pericardium using 10 mm (100 patients) and 1 mm (100 patients) high resolution CT (HRCT) slices with modern CT equipment and fixed mediastinal window settings (400/20). The pericardium was identified in all patients and was best seen anterior to the heart. The pericardium is exceptionally well seen using 1 mm HRCT slices and this may be the optimal technique for visualization of the pericardium. The upper limit of the thinnest portion of the normal pericardium (mean value + 2 SD) was 1.2 mm (10 mm CT slices) and 0.7 mm (1 mm HRCT slices). These values are substantially lower than those previously reported and in line with anatomical findings.

Pharmacokinetics, immunogenicity, and efficacy of dimeric TNFR binding proteins in healthy and bacteremic baboon

Immunogenicity, pharmacokinetics, and therapeutic efficacy of three novel dimeric soluble tumor necrosis factor (TNF)-receptor I constructs [TNF-binding protein (bp)] were evaluated in 28 baboons, 12 of which were healthy and 16 were challenged with a lethal Escherichia coli bacteremia. The three constructs differed only in the number of extracellular domains of the TNF receptor I and were dimerized with polyethylene glycol. Although all three constructs had generally similar pharmacokinetics when administered to a naive animal, they differed quantitatively in their immunogenicity. Antibodies were detected more frequently, and titers were significantly higher (P < 0.05) in both healthy and septic baboons that received the 4.0-domain TNF-bp construct, compared with animals receiving the 2.6-domain construct. When the TNF-bp constructs were administered a second time (21 days later), the half-lives of the three constructs were significantly shorter in animals that had an antibody response after the first injection. In contrast, all three TNF-bp constructs were equally effective at improving outcome, blocking a systemic TNF-alpha response, and attenuating the cytokine responses when administered at a dose of 1.0 mg/kg body wt 1 h before a lethal E. coli infusion. The findings suggest that immunogenicity of TNF-bp constructs can be altered by changing the number of functional domains, without affecting their capacity to neutralize TNF-alpha and to abrogate TNF-mediated pathology.

Role of cytokines in the metabolic response to stress

Clinical trials with cytokine inhibitors have failed to show efficacy and confirm preclinical findings in sepsis and systemic inflammatory response syndromes. However, a better understanding of the pathogenesis of sepsis syndrome, and of proinflammatory cytokine signal transduction pathways, including the role of nuclear factor kappa B and inflammation-induced apoptosis, have provided new therapeutic opportunities for cytokine and anticytokine therapies.

Orally active trifluoromethyl ketone inhibitors of human leukocyte elastase

This paper describes the development a series of peptidyl trifluoromethyl ketone inhibitors of human leukocyte elastase which are found to have excellent pharmacological profiles. Methods have been developed that allow for the synthesis of these inhibitors in stereochemically pure form. Two of these compounds, 1k and 1l, have high levels of oral bioavailability in several species. Compound 1l has entered development as ZD8321 and is presently undergoing clinical evaluation. These compounds demonstrate that peptidyl trifluoromethyl ketone inhibitors can achieve high levels of oral activity and bioavailability, and therefore they may prove useful as therapeutic agents in the treatment of diseases in which elastase is implicated.

Gastric cancer in the bypassed segment after operation for morbid obesity

A case is reported in which two separate adenocarcinomas were detected in the bypassed distal stomach 13 years after gastric stapling with loop gastro-enterostomy was performed for the treatment of morbid obesity. Retrograde endoscopy via the afferent loop was used to establish the diagnosis. Although gastritis and metaplasia have been described in the bypassed stomach, only one case of carcinoma in this area has previously been reported.

Exogenously administered interleukin-10 decreases pulmonary neutrophil infiltration in a tumor necrosis factor-dependent murine model of acute visceral ischemia

INTRODUCTION

Visceral ischemia and reperfusion associated with thoracoabdominal aortic aneurysm (TAAA) repair results in lung injury, which appears to be mediated in part by proinflammatory cytokines. The purpose of this study was to determine the effect of exogenous administration of the antiinflammatory cytokine, recombinant human IL-10 (rhIL-10), on proinflammatory cytokine production (IL-6 and TNF alpha) and pulmonary neutrophil infiltration after acute visceral ischemia-reperfusion.

METHODS

Two hours before 25 minutes of supraceliac aortic occlusion, 80 C57BL/6 mice (20 to 22 g) received an intraperitoneal injection of rhIL-10 (0.2 microgram [n = 20], 2 micrograms [n = 20], 5 micrograms [n = 25], or 20 micrograms [n = 15]), and 16 mice received murine anti-IL-10 IgM 200 micrograms. Twenty-five additional mice underwent visceral ischemia-reperfusion without treatment (controls), and 16 mice underwent laparotomy without aortic occlusion (sham).

RESULTS

Pretreatment with exogenous rhIL-10 resulted in significant reductions in lung neutrophil infiltration with 0.2 microgram, 2 micrograms, and 5 micrograms per mouse of rhIL-10 compared with lung neutrophil levels in control mice that underwent acute visceral ischemia-reperfusion alone (p < 0.05). In addition, serum TNF alpha was detected in 50% of control mice and in 75% of mice that received murine anti-IL-10, but in none of the mice that received rhIL-10 (2 micrograms per mouse) or the mice that underwent sham operative procedures (p < 0.05 by chi 2 analysis).

CONCLUSION

Exogenous IL-10 limits pulmonary neutrophil recruitment and the appearance of TNF alpha in this model of visceral ischemia-reperfusion injury. Thus the use of exogenous IL-10 may offer a novel therapeutic approach to decrease the complications that are associated with TAAA repair.

Arginine-enhanced enteral nutrition augments the growth of a nitric oxide-producing tumor

BACKGROUND

Arginine-enhanced diets have been shown to be beneficial in tumor-bearing hosts, but no data exist regarding their effects in hosts bearing nitric oxide (NO)-producting tumors.

OBJECTIVE

To examine the effect of arginine supplementation on the growth of a NO-producing murine breast cancer cell line.

METHODS

EMT-6 cells were grown in various concentrations of arginine in the presence or absence of the inducible nitric oxide synthase (iNOS) inhibitor, aminoguanidine (1 mmol/L). Forty-eight hours later, nitrite accumulation and viable cell number were assessed. BALB/c mice were then pair-fed basal purified diets (n = 10), 4% casein diets (isonitrogenous control, n = 5), or 4% arginine-enhanced diets (n = 10). One week later, 10(5) EMT-6 cells were implanted subcutaneously into the dorsal flank. After tumor implantation, five mice fed basal purified diets and five mice fed arginine-enhanced diets also received aminoguanidine (100 mg/kg subcutaneously twice daily). Two weeks after tumor cell implantation, tumor size (mean diameter), animal weight, serum and tumor nitrite and nitrate levels were measured.

RESULTS

There was minimal nitrite accumulation in arginine-free media, while increasing the arginine concentration increased nitrite levels. Viable cell number did not increase in arginine-free media, but increased nearly twofold in 100 and 1000 mumol/L arginine. In 5000 and 10,000 mumol/L arginine, the difference in viable cell number was not statistically different than that seen in arginine-free media, whereas the addition of aminoguanidine blocked nitrite accumulation and increased viable cell number at these arginine concentrations. Arginine-enhanced diets stimulated tumor growth in vivo more than twofold over tumor growth in mice fed isonitrogenous control or basal purified enteral diets. Mice fed arginine-enhanced diets also had increased serum nitrite and nitrate levels over mice fed basal purified enteral diets, whereas tumors from mice fed arginine-enhanced diets had nitrite and nitrate levels similar to mice fed basal purified enteral diets. Aminoguanidine blocked the increase in serum nitrite and nitrate, but failed to block the increased tumor growth in mice receiving the arginine-supplemented diets.

CONCLUSIONS

Arginine concentration influences the growth of EMT-6 tumor cells in vitro and dietary arginine supplementation augments tumor growth in vivo. The mechanism of the growth modulation in vitro is NO-dependent whereas the enhanced tumor growth in vivo is NO-independent.

Discovery and biological activity of orally active peptidyl trifluoromethyl ketone inhibitors of human neutrophil elastase

Previously we had shown that tripeptidyl trifluoromethyl ketones (TFMKs) possessing an N-terminal diarylacylsulfonamide, such as ICI 200,880 and ICI 200,355, displayed unparalleled protection against the lung damage induced by human neutrophil elastase (HNE) when the inhibitors were administered intratracheally. Since the diarylacylsulfonamides were designed specifically to afford a long residence time in the lung, it was not unexpected that inhibitors from this class of TFMKs were not active when administered orally. Upon evaluating a large number of peptidyl TFMKs possessing a variety of N-terminal groups, several compounds were identified which demonstrated oral activity. Compounds were evaluated for their oral activity by measuring their ability to inhibit the increase in lung weight relative to body weight (Lw/Bw), the increase in red blood cells, and the increase in white blood cells induced by intratracheally administered HNE (100 micrograms/hamster). A number of tripeptidyl trifluoromethyl ketones containing neutral N-terminal groups displayed good oral activity, while those containing basic, acidic, or polar groups did not. Compound 50, possessing an N-terminal 4-(CH3O)C6H4CO group, was particularly effective, reducing Lw/Bw by 77%, red cells by 89%, and white cells by 91% when dosed at 37.5 mg/kg orally. Thus, by modifying the N-terminal group of tripeptidyl TFMKs, inhibitors can be designed which are effective in vivo when administered either orally or intratracheally.

Nitric oxide contributes to adriamycin's antitumor effect

Recently, several antitumor drugs have been shown to stimulate nitric oxide (NO) production.

PURPOSE

To determine if adriamycin induces NO production in breast cancer cells in vitro and whether NO contributes to adriamycin's antitumor effect in vivo.

METHODS

Murine breast cancer cells (EMT-6) were incubated with adriamycin (ADRIA, 0, 10, 100, 1000 microM) in the presence or absence of the NO synthase inhibitor aminoguanidine (AG, 1 mM). Twenty-four hours later nitrite accumulation (Greiss reagent) and cell viability (MTT assay) were assessed. Supernatants from adriamycin-stimulated cells were also analyzed at 6, 8, and 24 hr for TNF, IL-1, and IFN gamma (ELISA). For in vivo experiments, 10(5) EMT-6 cells were injected into the flank of BALB/c mice (n = 20) and 1 hr later mice received one of four treatments: (1) saline, (2) ADRIA (10 mg/kg ip), (3) AG (100 mg/kg sc BID), or (4) ADRIA (10 mg/kg ip) and AG (100 mg/kg sc BID). Two weeks later tumor size was measured and in situ tumor cell apoptosis was determined by fluorescent microscopy and flow cytometry.

RESULTS

Adriamycin was cytotoxic to EMT-6 cells with 100 microM resulting in nearly 100% killing (P < 0.01). Adriamycin also stimulated nitrite accumulation with 100 microM producing 6.5 +/- 0.26 microM nitrite (P < 0.001). AG blocked adriamycin-stimulated nitrite accumulation (P < 0.05), but did not inhibit cytotoxicity in vitro. In vivo, adriamycin inhibited tumor size by nearly 400% (P < 0.001), while AG attenuated adriamycin's effect on tumor growth (P < 0.05). There was no difference in the detection of apoptotic tumor cells between the adriamycin and adriamycin and AG groups as determined by immunohistochemistry and flow cytometry.

CONCLUSIONS

These findings suggest that adriamycin stimulated NO production in EMT-6 cells, but adriamycin's cytotoxicity in vitro was NO-independent. In vivo, adriamycin inhibited tumorigenesis partially via an NO-dependent, nonapoptotic mechanism.

Involvement of 26-kDa cell-associated TNF-alpha in experimental hepatitis and exacerbation of liver injury with a matrix metalloproteinase inhibitor

TNF-alpha is a pleiotropic cytokine that exists both as a 26-kDa cell-associated and a 17-kDa soluble form. Recently, a class of matrix metalloproteinase inhibitors has been identified that can prevent the processing by TNF convertase of 26-kDa TNF-alpha to its 17-kDa form and can reduce mortality from normally lethal doses of D-galactosamine plus LPS (D-GalN/LPS). Here we report that a matrix metalloproteinase inhibitor, GM-6001, improves survival but does not protect against liver injury from D-GalN/LPS-induced shock in the mouse. In Con A-induced hepatitis, GM-6001 actually exacerbates hepatocellular necrosis and apoptosis despite greater than 90% reduction in plasma TNF-alpha concentrations. Treatment with GM-6001 also has minimal effect on the concentration of membrane-associated TNF-alpha in the livers of animals with Con A induced hepatitis. In contrast, a TNF binding protein (TNF-bp), which neutralizes both membrane-associated and soluble TNF-alpha, prevents D-GalN/LPS- and Con A-induced hepatitis. Our studies suggest that cell-associated TNF-alpha plays a role in the hepatocellular necrosis and apoptosis that accompany D-GalN/LPS- or Con A-induced hepatitis, and that matrix metalloproteinase inhibitors are ineffective in preventing this hepatic injury.

Involvement of 26-kDa cell-associated TNF-alpha in experimental hepatitis and exacerbation of liver injury with a matrix metalloproteinase inhibitor

TNF-alpha is a pleiotropic cytokine that exists both as a 26-kDa cell-associated and a 17-kDa soluble form. Recently, a class of matrix metalloproteinase inhibitors has been identified that can prevent the processing by TNF convertase of 26-kDa TNF-alpha to its 17-kDa form and can reduce mortality from normally lethal doses of D-galactosamine plus LPS (D-GalN/LPS). Here we report that a matrix metalloproteinase inhibitor, GM-6001, improves survival but does not protect against liver injury from D-GalN/LPS-induced shock in the mouse. In Con A-induced hepatitis, GM-6001 actually exacerbates hepatocellular necrosis and apoptosis despite greater than 90% reduction in plasma TNF-alpha concentrations. Treatment with GM-6001 also has minimal effect on the concentration of membrane-associated TNF-alpha in the livers of animals with Con A induced hepatitis. In contrast, a TNF binding protein (TNF-bp), which neutralizes both membrane-associated and soluble TNF-alpha, prevents D-GalN/LPS- and Con A-induced hepatitis. Our studies suggest that cell-associated TNF-alpha plays a role in the hepatocellular necrosis and apoptosis that accompany D-GalN/LPS- or Con A-induced hepatitis, and that matrix metalloproteinase inhibitors are ineffective in preventing this hepatic injury.

Visceral ischemia-reperfusion injury promotes tumor necrosis factor (TNF) and interleukin-1 (IL-1) dependent organ injury in the mouse

Acute visceral ischemia and subsequent reperfusion injury, which accompanies the surgical repair of a thoracoabdominal aorta aneurysm, is associated with high rates of morbidity and mortality. The purpose of the present study was to determine whether endogenous tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) production contributes to organ dysfunction in animals subjected to visceral ischemia secondary to 30 min of supraceliac aortic occlusion. C57BL6/j mice were treated with either a TNF binding protein (TNF-bp-10 mg/kg) or an anti-IL-1 receptor type 1 antibody (150 micrograms) 2 h prior to 30 min of supraceliac aortic occlusion. An additional group of mice received 30 min of infrarenal aortic occlusion to determine the contribution of lower torso ischemia-reperfusion injury to the changes seen following supraceliac aortic occlusion. Visceral organ ischemia for 30 min produced by supraceliac aortic occlusion followed by 2 h of reperfusion produced measurable TNF-alpha in 38% of untreated mice, but TNF-alpha was undetectable in both sham-operated mice and following infrarenal aortic occlusion. After 2 h of reperfusion, lung myeloperoxidase levels were significantly elevated in the mice experiencing visceral ischemia-reperfusion compared with either a sham operation or infrarenal ischemia-reperfusion (11.6 +/- 1.3 U/g vs. 3.4 +/- .2 U/g and 3.7 +/- 1.0 U/g, respectively, p < .05). Pretreatment with TNF-bp and anti-IL-1 antibody decreased lung neutrophil recruitment (7.2 +/- 1.2 U/g and 4.6 +/- 1.1 U/g) and capillary membrane permeability changes in mice following visceral ischemia-reperfusion. The present study demonstrates that brief (30 min) clinically relevant visceral ischemia produces TNF-alpha and IL-1 dependent lung injury.

Inhibitors of bacterial signal peptidase: a series of 6-(substituted oxyethyl)penems

A series of 6-(substituted oxyethyl)penem esters having the (5S) stereochemistry which are potent inhibitors of Escherichia coli leader peptidase is described. Structure-activity relationships are discussed.

Breast health. Challenges and promises

There has been significant improvement in breast health care in the United States over the past few decades primarily due to advances in health research by diverse teams of basic scientists, physicians, pharmacists, industries, nurses, and social workers. This research has involved inquiries about fundamental biological alterations in breast cancer, differences in diagnostic modalities, and treatment options and various outcome studies. Increase in public awareness of breast cancer, an interest in women's health issues, advances in radiologic imaging, development of new chemotherapeutic agents and the availability of molecular genetic testings have brought remarkable opportunities to a new insight in breast cancer. These efforts have resulted in earlier detection and prolonged disease-free intervals, however, the overall survival time has remained the same. This is mainly attributable to the wide range of individual therapy for breast cancer, which responds to a range of disease curable by surgery alone to one refractory to treatment and marked by rapid metastatic progression. Challenges remain in fostering adequate funding for biomedical, as well as behavioral and social research. Attempts should also be made to promote clinical and population-based studies and to emphasize the value of effective delivery of health-care services to all women with benign, high risk, premalignant and malignant breast disease.

A human tumor necrosis factor p75 receptor agonist stimulates in vitro T cell proliferation but does not produce inflammation or shock in the baboon

Tumor necrosis factor (TNF) is a potentially useful adjunct to anticancer therapies. However, the clinical utility of TNF has been limited by generalized toxicity and hypotension. Recently, studies have begun to dissect the individual proinflammatory and immunologic responses that result from TNF binding to its two cellular receptors, p55 and p75, in an attempt to develop TNF receptor agonists with reduced systemic toxicity. To evaluate a p75 receptor selective TNF mutant (p75TNF), TNF and p75TNF were administered to healthy anesthetized baboons. Intravenous infusion of the p75TNF produced none of the hemodynamic changes seen after the infusion of TNF. Infusion of p75TNF also failed to induce the plasma appearance of interleukins 6 and 8. However, p75TNF enhanced in vitro baboon thymocyte proliferation to concanavalin A, and infusion of p75TNF resulted in increased soluble p55 and p75 receptor plasma concentrations. Local skin necrosis and tissue neutrophil infiltration were seen after subcutaneous injections of TNF and p55TNF. Subcutaneous injection of p75TNF did not result in skin necrosis but did result in a modest dermal infiltration of lymphocytes and macrophages. The findings suggest that p75TNF may stimulate T cell proliferation without the systemic and local toxicity seen with TNF.

Increased soluble interleukin-1 type II receptor concentrations in postoperative patients and in patients with sepsis syndrome

Plasma interleukin-1 (IL-1) activity is modulated in part through the simultaneous appearance of several inhibitors of IL-1 action, including interleukin-1 receptor antagonist (IL-1ra) and the soluble IL-1 type II receptor (IL-1RII). However, little is known concerning the plasma appearance of these inhibitors in patients following operative trauma or those with sepsis syndrome. In the present report, plasma IL-1beta, IL-1ra, and soluble IL-1RI and IL-1RII concentrations were evaluated in 118 patients with sepsis syndrome or after elective operative trauma. Plasma concentrations of IL-1ra increased significantly following elective operative repair of thoraco-abdominal and abdominal aortic aneurysms, and after bowel resection for inflammatory bowel disease, but did not increase after laparoscopic cholecystectomy. Plasma IL-1ra levels were also elevated in patients with sepsis syndrome. In contrast, soluble IL-1RII levels were only increased in patients after operative repair of thoraco-abdominal aortic aneurysms and in sepsis syndrome, whereas concentrations were unaffected by the other more modest surgical procedures. Plasma IL-1RI concentrations decreased in all postoperative patients in the first 24 hours after surgery. We conclude that both plasma IL-1ra and soluble IL-1RII concentrations often increase in sepsis and following some operative trauma. Less severe operative trauma increases the plasma concentration of only IL-1ra, whereas both IL-1ra and soluble IL-1RII are increased in patients with sepsis syndrome or following thoraco-abdominal aneurysm repair.

Nonpeptidic inhibitors of human neutrophil elastase. 7. Design, synthesis, and in vitro activity of a series of pyridopyrimidine trifluoromethyl ketones

Using molecular modeling and the information derived from X-ray crystal structures of human neutrophil elastase (HNE) and porcine pancreatic elastase (PPE) complexed to peptidic ligands, we have developed a new series of nonpeptidic inhibitors of HNE, the pyridopyrimidine trifluoromethyl ketones (TFMKs). These bicyclic inhibitors were designed to extend the concept of the related pyridone trifluoromethyl ketones by incorporating a rigidly positioned carbonyl group to participate in a hydrogen bonding interaction with the backbone NH groups of Gly-218 and Gly-219 of the enzyme. In addition, the pyrimidine ring serves as a scaffold to vector substituents toward the S5-S4 subsites of the enzyme's extended binding pocket. Furthermore, the heteroatoms of the pyrimidine ring generally increase the aqueous solubility of the pyridopyrimidines relative to pyridone TFMKs. Pyridopyrimidine TFMKs containing a 6-phenyl substituent afforded potent inhibitors of elastase, and several inhibitors from this class of compounds possessed aqueous solubilities of > 0.1 mg/mL and Ki values of < or = 10 nM.

Finite element analysis of a total knee replacement by using Gauss point contact constraints

Finite element methods have been applied extensively and with much success in the analysis of orthopaedic hip and knee implants. Very recently a burgeoning interest has developed, in the finite element community, in how numerical models can be constructed for the solution of problems in contact mechanics. New developments in this area are of paramount importance in the design of implants for orthopaedic surgery. Modern techniques are described for finite element contact analysis and applied to two problems of stress analysis in a plastic tibial component. In the former, results are compared with a previous finite element analysis and with Hertzian solutions. In the latter, an estimate of the extent of convergence of the finite element solutions is provided.

Peptidyl alpha-ketoheterocyclic inhibitors of human neutrophil elastase. 3. In vitro and in vivo potency of a series of peptidyl alpha-ketobenzoxazoles

A series of peptidyl alpha-ketobenzoxazoles were synthesized and evaluated for their in vitro and in vivo inhibition of human neutrophil elastase (HNE). These compounds inhibit HNE by forming both a covalent bond between the ketone carbonyl carbon atom and the hydroxyl group of Ser-195 and a hydrogen bond between the benzoxazole nitrogen atom and His-57. Appending to the parent benzoxazole ring a variety of substituents which spanned a range of physicochemical properties had only a modest effect on in vitro potency (Ki = 3-0.4 nM). This apparent lack of a significant effect is believed to result from the fact that any increased ketone carbonyl activation by the ring substituent is counter balanced by a corresponding decrease in the hydrogen-bonding ability of the benzoxazole nitrogen atom. In contrast to the results in vitro, maximizing in vivo activity was critically dependent upon the choice of the benzoxazole ring substituent. Several substituted peptidyl alpha-ketobenzoxazoles effectively inhibited HNE-induced lung injury when administered intratracheally 24 h prior to the enzyme.

Peptidyl alpha-ketoheterocyclic inhibitors of human neutrophil elastase. 2. Effect of varying the heterocyclic ring on in vitro potency

A series of peptidyl alpha-ketoheterocycles were synthesized and evaluated for their in vitro inhibition of human neutrophil elastase (HNE). Several heterocycles, including oxazoline and benzoxazole, afforded extremely potent inhibitors of HNE (1p-r) with nanomolar to subnanomolar Ki values. The structure-activity relationships revealed that for compounds with a Ki < 1000 nM potency tends to be positively correlated with the sigma I value of the heterocycle. Furthermore, the results in this study support the hypothesis that, in the covalent enzyme-inhibitor adduct, the azole nitrogen atom of the inhibitor heterocycle participates in a hydrogen-bonding interaction with the active-site His-57.

Nonpeptidic inhibitors of human leukocyte elastase. 3. Design, synthesis, X-ray crystallographic analysis, and structure-activity relationships for a series of orally active 3-amino-6-phenylpyridin-2-one trifluoromethyl ketones

A series of nonpeptidic inhibitors of human leukocyte elastase (HLE) is reported. These trifluoromethyl ketone-based inhibitors contain a 3-amino-6-phenylpyridone group as a central template. The effect of varying the N-3 substituent in these inhibitors on in vitro potency, physical properties, and oral activity in a hamster based, HLE-induced lung damage model is described. The variety of substituents at this position that have little effect on in vitro potency supports the idea that this region of the molecule does not interact strongly with the enzyme. One exception to this generality is 13k, which is substituted with a (4-acetamidophenyl)sulfonyl group. This compound has a K(i) of 0.7 nM and is, in vitro, the most potent inhibitor in the series. In contrast, variation of the N-3 substituent was found to have a dramatic effect on activity after oral administration. Several analogs, including the parent amine, 7, formamide, 2u, benzyl sulfamide, 13e, and benzyl sulfonamide, 13f, show significant activity when administered at an oral dose of 2.5 mg/kg. Support for the modeling-based design concepts was obtained through in vitro SAR results and X-ray crystallographic analysis of the complex between 13d and porcine pancreatic elastase (PPE), a closely related enzyme.

Nonpeptidic inhibitors of human leukocyte elastase. 2. Design, synthesis, and in vitro activity of a series of 3-amino-6-arylopyridin-2-one trifluoromethyl ketones

A series of potent nonpeptidic inhibitors of the enzyme human leukocyte elastase (HLE) is reported. These inhibitors contain a 3-amino-2-pyridone ring as a central template in which the pyridone carbonyl and 3-position NH group are thought to form important hydrogen bonding interactions with the Val-216 residue of HLE. Substitution of the 6-position of the pyridone ring by various alkyl and aryl groups was found to afford increases in the in vitro potency of these inhibitors. A 6-position phenyl group, compound 10f, was found to result in a large increase in binding affinity, which was not obtained when the phenyl group was placed in either the 4- or 5-position of the molecule. Compound 10f was found to have good selectivity for HLE over other proteolytic enzymes, with the exception of bovine pancreatic chymotrypsin (BPC). Substitution of the 6-phenyl group in these molecules was found to decrease binding affinity for BPC without adversely affecting affinity for HLE.

Synthetic inhibitors of elastase

For more than two decades investigators around the world, in both academic and industrial institutions, have been developing inhibitors of human neutrophil elastase. A number of very elegant and insightful strategies have been reported. In the case of reversible peptidic inhibitors, this has resulted in the identification of some extremely potent compounds with dissociation constants in the 10(-11) M range. This is quite an accomplishment considering that these low molecular-weight inhibitors are only tri- and tetrapeptides. In the case of the heterocyclic-based inhibitors, the challenge of balancing the heterocycle's inherent reactivity and aqueous stability with the stability of the enzyme-inhibitor adduct has been meet by either using a latent, reactive functionality which is only activated within the enzyme, or by incorporating features which selectively obstruct deacylation but have little effect on the enzyme acylation step. The underlying goal of this research has been the identification of agents to treat diseases associated with HNE. Several animal models have been developed for evaluating the in vivo activity of elastase inhibitors, and compounds have been shown to be effective in all of these models by the intravenous, intratrachael or oral routes of administration. However, only a very small percentage of compounds have possessed all the necessary properties, including lack of toxicity, for progression into the clinic. The peptidyl TFMK ICI 200,880 (25-12) has many of the desired characteristics of a drug to treat the diseases associated with HNE: chemical stability, in vitro and in vivo activity, a long duration of action, and adequate metabolic stability. Currently ICI 200,880 is the only low molecular-weight HNE inhibitor known to be undergoing clinical trials, and may be the compound which finally demonstrates the clinical utility of a synthetic HNE inhibitor.

Evaluation of the sphincter pharyngoplasty

The results of the sphincter pharyngoplasty were evaluated in 139 patients with velopharyngeal incompetence (VPI) who demonstrated active velar elevation. All patients underwent perceptual speech evaluation and lateral phonation radiographic study; select patients underwent multiview videofluoroscopic, flexible nasendoscopic, and pressure-flow studies. All but one patient demonstrated improvement and 109/139 (78.42%) demonstrated resolution of VPI. Sixteen of thirty failed pharyngoplasties were revised. Revision was successful in 8/16 patients yielding an overall success rate of 117/139 (84.17%). Success rate was 67.65 percent for patients managed during the first 5 years and improved to 84.78 percent for patients managed during the last 5 years of this 15-year series. Analysis revealed that younger patients were treated more successfully than older patients, large velopharyngeal areas were treated as successfully as smaller ones, and circular closure patterns were treated more successfully than coronal patterns. The primary cause of failure was insertion of the flap below the point of attempted velopharyngeal contact.

Helicobacter pylori-associated gastritis is rare in AIDS: antibiotic effect or a consequence of immunodeficiency?

Helicobacter pylori is the principal cause of type B histologic gastritis. AIDS is associated with increased susceptibility to Gram-negative enteric infections. Using a retrospective study design, we have determined the prevalence of H. pylori-associated histologic gastritis (based on gastric histopathology) in 201 patients with AIDS. These data were compared with H. pylori prevalence rates (based on serology) from healthy HIV-negative, age-matched Australian controls (n = 785) and a cohort (n = 137) of HIV-negative, dyspeptic patients undergoing panendoscopy and antral biopsy, at a community endoscopy center. Twenty-five of 201 (12.5%) patients with AIDS had histologic gastritis and, of these, six (25%) had H. pylori. The 3% (six of 201) H. pylori prevalence rate in the AIDS patients was significantly less than age-matched HIV-negative controls (22%) p = 0.001 and endoscopy center controls (59%) p = 0.009. The explanation for this unexpectedly low prevalence of H. pylori is not possible from these data. It may be a consequence of antimicrobial therapy. Other potential explanations may include specific HIV-related host factors, including hypochlorhydria or an inadequate mucosal inflammatory response, which may impair successful colonization of H. pylori.

6-(substituted methylene)penems, potent broad spectrum inhibitors of bacterial beta-lactamase. IV. Kidney stability, serum binding and additional biological evaluation of racemic derivatives

Sodium (5RS)-Z-6-(substituted methylene)penem-3-carboxylates (3) are extremely potent inhibitors of bacterial beta-lactamases, but some members of this group of compounds are highly bound to human serum, while others are readily degraded by renal dehydropeptidase I enzyme. Consequently, the stability of a variety of 6-(substituted methylene)penems (3) to human kidney homogenate, their binding to human serum and their activity in a mouse infection model was investigated at an early stage, and were instrumental in the selection of the 1,2,3-triazolylmethylene derivatives (e.g. 3k) as a class of compounds worthy of further evaluation.

Mechanism of slow-binding inhibition of human leukocyte elastase by trifluoromethyl ketones

Kinetics of inhibition have been determined for the interaction of human leukocyte elastase (HLE) with two series of peptide trifluoromethyl ketones (TFMKs): X-Val-CF3,X-Pro-Val-CF3,X-Val-Pro-Val-CF3, and X-Lys(Z)-Val-Pro-Val-CF3, where X is MeOSuc or Z. These compounds are "slow-binding" inhibitors of HLE and, thus, allow the determination of Ki, the dissociation constant for the stable complex of inhibitor and enzyme, as well as kon and koff, the rate constants for formation and decomposition of this complex. Maximal potency is reached with Z-Lys(Z)-Val-Pro-Val-CF3, which displays a Ki less than 0.1 nM. Upon binding to HLE, these compounds undergo addition by the hydroxyl of the active site serine to form a hemiketal. The evidence supporting a hemiketal intermediate includes Ki values of 1.6 and 80,000 nM for Z-Val-Pro-Val-CF3 and its alcohol analogue, linear free energy correlations between inhibitory potency and catalytic efficiency for structurally related TFMKs and substrates, and the pH dependence of kon for the inhibition of HLE by Z-Val-Pro-Val-CF3, which is sigmoidal and displays a pKa of 6.9. Hemiketal formation is probably not rate limiting, however. Kinetic solvent isotope effects of unity suggest that kon cannot be rate limited by a reaction step, like hemiketal formation, that is subject to protolytic catalysis. A general mechanism that is consistent with these results is one in which formation of the hemiketal is rapid and is followed or preceded by a slow step that rate limits kon.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of retinoic acid receptor (RAR) status of bladder tumours on the course of the disease

Retinoids influence bladder tumour development in animals and tumour recurrence in man. Some human tumours contain intracellular receptor proteins for retinoids. The effect of the presence of such retinoic acid receptors (RAR) on tumour response to conventional therapy has been studied in 59 patients. Thirty-two of 36 RAR+ve and 11 of 23 RAR-ve tumour patients were alive after a mean follow-up period of 2.6 years. Higher stage and grade were more commonly associated with RAR-ve tumours. Independent of stage, recurrence was more common in RAR-ve tumours. These studies suggest that RAR-ve tumours are more likely to recur and more likely to become invasive. However, further studies are required to determine the clinical value of RAR receptor status as a prognostic indicator.

Chorea, polycythaemis, and cyanotic heart disease

Two cases of polycythaemic chorea are described, both of which were complicated by severe heart disease. The first was a child with patent ductus arteriosus and coarctation of the aorta causing severe cyanosis and secondary polycythaemia. Chorea began intermittently at an early age, becoming continuous by his fifth birthday. The second was a middle-aged male with tight mitral stenosis and a story of paralytic chorea in his teens. Polycythaemia rubra vera was eventually diagnosed two years after mitral valvotomy, some seven years after the onset of chorea.