Abdominal aortic aneurysm volume and relative intraluminal thrombus volume might be auxiliary predictors of rupture-an observational cross-sectional study

Objectives

The study aimed to identify differences and compare anatomical and biomechanical features between elective and ruptured abdominal aortic aneurysms (AAAs).

Methods

Data (clinical, anatomical, and biomechanical) of 98 patients with AAA, 75 (76.53%) asymptomatic (Group aAAA) and 23 (23.46%) ruptured AAA (Group rAAA), were prospectively collected and analyzed. Anatomical, morphological, and biomechanical imaging markers like peak wall stress (PWS) and rupture risk equivalent diameter (RRED), comorbid conditions, and demographics were compared between the groups. Biomechanical features were assessed by analysis of Digital Imaging and Communication in Medicine images by A4clinics (Vascops), and anatomical features were assessed by 3Surgery (Trimensio). Binary and multiple logistic regression analysis were used and adjusted for confounders. Accuracy was assessed using receiving operative characteristic (ROC) curve analysis.

Results

In a multivariable model, including gender and age as confounder variables, maximal aneurysm diameter [MAD, odds ratio (OR) = 1.063], relative intraluminal thrombus (rILT, OR = 1.039), and total aneurysm volume (TAV, OR = 1.006) continued to be significant predictors of AAA rupture with PWS (OR = 1.010) and RRED (OR = 1.031). Area under the ROC curve values and correct classification (cc) for the same parameters and the model that combines MAD, TAV, and rILT were measured: MAD (0.790, cc = 75%), PWS (0.713, cc = 73%), RRED (0.717, cc = 55%), TAV (0.756, cc = 79%), rILT (0.656, cc = 60%), and MAD + TAV + rILT (0.797, cc = 82%).

Conclusion

Based on our results, in addition to MAD, other important predictors of rupture that might be used during aneurysm surveillance are TAV and rILT. Biomechanical parameters (PWS, RRED) as valuable predictors should be assessed in prospective clinical trials. Similar studies on AAA smaller than 55 mm in diameter, even difficult to organize, would be of even greater clinical value.

siMS score- method for quantification of metabolic syndrome, confirms co-founding factors of metabolic syndrome

Background: Adipose tissue is a dynamic endocrine organ, a highly active metabolic tissue, and an important source of cytokines. Inflammatory factors play an important role in visceral obesity associated with insulin resistance (IR), metabolic syndrome (MS), hypertension, non-alcoholic fatty liver disease (NAFLD), diabetes mellitus type 2 (DM2), endothelial dysfunction (ED) and atherosclerosis. Objectives: To examine corelation of siMS score, as a quantification method for metabolic syndrome (MS), with insulin resistance, glucoregulation parameters, as with other co-founding factors of MS, inflammation and thrombosis factors, microalbuminuria, uric acid, fatty liver index (FLI) and homocysteine. Methods: The study included 451 obese individuals with pre-metabolic syndrome (pre-MS) and MS (age 16-75, body mass index (BMI) > 25kg/m²) classified into two groups: I-age 10-30 (167 patients); II-age 31-75 (284 patients). International Diabetes Federation (IDF) classification was applied for diagnosing metabolic syndrome. Patients with less than three criteria indicated below were considered pre-metabolic syndrome. siMS risk score was used. Results: siMS score increased with age: I-3.03 ± 0.87, II-3.27 ± 0.90. siMS score correlated with associated factors of MS: hyperinsulinemia and IR, ALT, gama-GT, FLI, uric acid in both groups and CRP (p < 0.01) in group I. Correlations in II group: siMS score with PAI-1 (p = 0.01), microalbuminuria (p = 0.006), homocysteine ​​(p = 0.076). Conclusion: Correlation of siMS score with HOMA-IR confirmed that hyperinsulinism and insulin resistance are in the basis of MS. Correlation of siMS score with parameters of NAFLD, CRP, PAI-1, uric acid, microalbuminuria and homocysteine indicates that they are significant co-founding factors of MS. Correlation of siMS score with PAI-1, microalbuminuria, homocysteine, indicates higher risk for progression of endothelial dysfunction and atherosclerosis with age.

Does the presence of an unerupted lower third molar influence the risk of mandibular angle and condylar fractures?

It has been suggested that unerupted lower third molars (M3) increase the fragility of the mandibular angle and simultaneously decrease the risk of condylar fracture. However, it is unknown whether this applies regardless of the direction and point of impact of the traumatic force. The aim of this study was to investigate the impact of an unerupted M3 on the fragility of the angle and condyle in terms of a force acting from different directions and affecting different regions of the mandible. Computed tomography scans of a human mandible and finite element methodology were used to obtain two three-dimensional models: a model with, and the other without an unerupted M3. A force of 2000N was applied to three different regions of the models: the symphysis, ipsilateral body, and contralateral body, respectively. When the force was applied to the mandibular body, the results revealed increased angle fragility in cases with unerupted M3. When the force was applied to the symphysis, the condyle region showed higher fragility, irrespective of the presence of an unerupted M3. In summary, fragility of the angle and condyle regions depends on the presence of an unerupted M3 and on the direction and point of impact of the force.

Patient specific multiscale modelling for plaque formation and progression

We present a three-dimensional model of plaque formation and progression that was tested in a set of patients who underwent coronary Computed Tomography angiography (CTA) for anginal symptoms. The 3D blood flow is described by the Navier-Stokes equations, together with the continuity equation. Mass transfer within the blood lumen and through the arterial wall is coupled with the blood flow and is modeled by a convection-diffusion equation. The Low Density Lipoprotein (LDL) transports in lumen of the vessel and through the vessel tissue (which has a mass consumption term) are coupled by Kedem-Katchalsky equations. The inflammatory process is modeled using three additional reaction-diffusion partial differential equations. A full three-dimensional model was created. Furthermore, features potentially affecting plaque growth, such as patient risk score, circulating biomarkers, localization and composition of the initial plaque, and coronary vasodilating capability were also investigated. The proof of concept of the model effectiveness was assessed 6 months after the baseline evaluation.

The importance of timing in surgical treatment of unruptured symptomatic aneurysm of abdominal aorta

AIM OF STUDY

Aim of this study is to define an entity of unruptured symptomatic AAA, to examine the influence of timing of the surgical treatment and to analyze the results of the treatment of unruptured symptomatic AAA in acute expansion.

MATERIALS AND METHOD

The study is designed as retrospective analysis of 390 operatively treated patients in the last five years at the Clinics of Vascular Surgery in Novi Sad. All patients were grouped into four categories: elective operative surgical treatment, surgical treatment 24 hours after the admission through the Department of Urgent Surgery with an urgent CT diagnosis (in first 2 hours), surgical treatment within 24 hours since the admission through the Department of Urgent Surgery with an urgent CT diagnosis (in first 2 hours) and immediate surgical treatment of ruptured AAA.

RESULTS

In the period from Jan 1, 2005 to Dec 31, 2009, 390 patients with AAA were operatively treated. 89 patients had ruptured AAA, 52 were operated 24 hours after the urgent admission, 18 patients were operated in the first 24 hours after the urgent admission and 231 patients were planned for elective surgery. Mortality rates between the groups were as follows: elective surgery-5.1 %, patients operated 24 hours after the urgent admission 7.2 %, patients operated in the first 24 hours after the urgent admission 23 %, and patients who had ruptured AAA 34 %.

CONCLUSION

Considering the obtained data, it can be concluded that the treatment of unruptured symptomatic AAA is related to a higher risk of postoperative mortality in relation to an elective surgery. Moreover, surgical treatment in the first 24 hours after the urgent admission of unruptured symptomatic AAA has higher rate of mortality and morbidity compared to surgical treatment 24 hours after the urgent admission of the patients, so we can conclude that the early (semi) elective surgery is a method of choice for the treatment of unruptured symptomatic AAA in acute expansion (Tab. 2, Fig. 2, Ref. 21).

Gender and morphogenetic variability of patients with spina bifida occulta and spina bifida aperta: prospective population-genetic study

BACKGROUND

Aim of our study was to evaluate degree of genetic homozygosity in male and female gender of spina bifida (SB) occulta and SB aperta patients.

PATIENTS AND METHODS

We evaluated 95 patients with SB occulta and 51 with SB aperta. Degree of genetic homozygosity was evaluated by direct observation of 15 homozygously recessive characteristics (HRC) by HRC-test separately for SB occulta and SB aperta participants. Additionally 370 individuals without SB from Serbia were randomly selected and evaluated as control group. Male and female gender was separately evaluated for assessing degree of genetic homozygosity.

RESULTS

There was no significant difference in mean values of HRC between male and female gender in control group (male gender -3.9±1.2, female gender -4.0±1.4, z=0.39; p>0.05), SB occulta (male gender -4.1±1.5, female gender -4.7±1.4, z=1.87, p>0.05) and SB aperta patients (male gender -4.3±1.6, female gender -4.5±1.4, z=0.66, p>0.05), while there was significantly increased recessive homozygosity in female SB occulta group versus control female group (Females: SB occulta -4.7±1.4, Control group -4.0±1.4, z=3.16, p<0.01) and female SB aperta group versus control female group (Females: SB aperta -4.5±1.4, Control group -4.0±1.4, z=2.05, p<0.05).

CONCLUSION

There is increased recessive homozygosity in tested female SB occulta and female SB aperta individuals versus SB male participants and significantly increased recessive homozygosity in female groups of SB patients versus control female group. These findings could lead to the possible assumption that different genes in different degree might be expressed in SB occulta and SB aperta patients.

Double innominate osteotomy and the Smith-Petersen technique in the treatment of developmental hip disorder

PURPOSE

The purpose of our study was to present results of different surgical orthopaedic approaches in the treatment of children with developmental hip disorder.

MATERIAL AND METHODS

At the University Childrens Hospital in Belgrade, 21 young adults diagnosed with developmental hip disorder were treated with double osteotomy and with a modified Smith-Peterson approach during a period of 10 years, from 1997 to 2007. All patients were clinically and radiographically evaluated.

RESULTS

We were successful with 23 hips in 20 patients, since some patients underwent surgery of both hips. The evaluation of improvement was done according to the Merle d'Aubigne and Postel system which indicated very satisfied outcome in five patients, satisfied in 8, fair in 7 and poor in one patient.

CONCLUSIONS

In this paper we discuss the advantages and disadvantages of double osteotomy procedures compared with others that are used in the correction of developmental hip disorder. The best solution is adequate and timely diagnosis with proper correction of the deformity.

Congenital muscular torticollis in children: distribution, treatment duration and out come

AIM

The aim of the study was to evaluate the proportion of left and right congenital muscular torticollis (CMT) in both genders and age groups of the patients as well as to evaluate the duration of physical therapy and treatment outcome in observed population.

METHODS

In our study, 980 children with CMT without hematoma were treated at University children's Hospital of Belgrade (Serbia). They were divided into 2 groups: group with left torticollis and group with right torticollis. Boys and girls were separately evaluated. Patients were classified into 5 age groups: group of children less than one month of life, group above one to 3 months, group above 3 months to 6 months, group above 6 months to 12 months and group of children above 12 months of life. Optimal time for physical therapy was analyzed in every age group.

RESULTS

We diagnosed 496 torticollis in boys and 484 torticollis in girls. There were 458 children with left torticollis and 522 children with right torticollis. In group of children less than one month of life median duration of physical therapy was 1.5+/-0.3 months, in group above one to 3 months of life 5.9+/-0.6, in group above 3 to 6 months 7.2+/-0.6, in group above 6 to 12 months 9.8+/-0.6 and in group of children above 12 months of life 10.3+/-0.8 months.

CONCLUSION

Right torticollis is frequent in both genders and age groups. Younger children have lower treatment duration and better treatment outcome. Boys have longer treatment duration and not significantly better treatment outcome.

Physical therapy of non-neurogenic voiding dysfunction in children with occult spinal dysraphism

BACKGROUND

In children with occult spinal dysraphism one of the symptoms is disbalance in bladder emptying and filling. Goal of our study was to estimate the correlation of medicamentous treatment alone and combined medicamentous and physical treatment in patients that are diagnosed with occult spinal dysraphism with non-neurogenic bladder dysphunction.

METHODS

We evaluated 69 patients aged from 4 to 12 years treated at the University children's Hospital in Belgrade during 2005-2008 years period. In the first group of 29 patients only medicamentous therapy was implemented. In the second group of 40 patients combined medicamentous and physical therapy were applied. Physical therapy methods that were used included: transcutaneal electric nerve stimulation and exponential current. We monitored daily enuresis, enuresis nocturna, urgency and frequency. Urodynamic evaluation included: bladder capacity, onset of unstable contractions, residual urine and detrusor sphincter dyssynergia.

RESULTS

Statistical analysis showed that there is significant improvement (p < 0.001) in all evaluated symptoms after 6 months and for urgency there was significant improvement (p < 0.05) after 3 months from the beginning of the treatment with combined therapy. Our study pointed out significant improvement in the group treated with combined therapy for detrusor sphincter dyssynergia and unstable contractions after 3 months while after 6 months from the beginning of the treatment there was significant improvement (p < 0.001) for all urodynamic parameters.

CONCLUSIONS

Combined medicamentous and physical treatment is more beneficial for patients with non-neurogenic bladder instead of medicamentous treatment alone (Tab. 2, Ref. 11).

Evaluation of cerebrovascular insult types and their localization in patients due to the presence of elevated body temperature

BACKGROUND

The Aim of our study was to present and analyze the distribution of cerebrovascular insult types and their localization in patients with normal body temperature by means of computerized tomography, and in those with elevated body temperature by means of neuroradiographic findings.

METHODS

In our study we evaluated 103 patients that suffered a cerebrovascular insult and were treated at Special Hospital for Cerebrovascular disorders "Saint Sava" in Belgrade. All patients were divided into two groups due to the presence of elevated body temperature.

RESULTS

Fever as a complication in period after acute cerebrovascular insult is presented in almost every fifth patient. In the group of patients with fever, the most common presentation was acute ischemic cerebrovascular insult, namely in 45.63%, while in the group of patients with normal body temperature, the most common presentation was lacunar infarction, namely in 46.60% of participants. The most frequent localization of cerebrovascular insult is in cortex and subcortex regions.

CONCLUSIONS

It should be stated that some patients with specific types of cerebrovascular insult as well as their localization are at higher risk for development of complications. This study suggests that appropriate diagnostics as well as prevention and management of in-hospital complications could improve the short-term and long-term prognoses after stroke (Tab. 3, Ref. 14).

Orthopaedic patterns of retroperitoneal tumors in pediatric population

The paper presents three children of various ages with tumors of different histology localized in the retroperitoneum. The children underwent investigation as orthopedic cases at the Orthopedic Department of the Belgrade University Childrens' Hospital. All children had orthopedic symptoms and several similar clinical findings: high or increased red blood cell (RBC) sedimentation, increased lactate dehydrogenase (LDH) and hypochromic anemia. Retroperitoneal tumors were diagnosed by echosonography. Further investigations were targeted towards histological verification and treatment protocol for retroperitoneal tumor. Since the children were presented chronologically to the deparmtent, diagnosis was reached more rapidly. It is our aim to draw attention to the possibility that various retroperitoneal tumors can be presented as orthopedic diseases. If symptomatology of retroperitoneal tumors is suspected and particularly in insufficiently clear cases, one should always perform echsonography of the retroperitoneum as a non-agressive, simple, readily available and reliable diagnostic method. This reduces examination time, direction of patients to further treatment according to pathology and also in reduction of risk both for patient and orthopedic surgeon who normally are presented with such diseases (Fig. 2, Ref. 10). Full Text (Free, PDF) www.bmj.sk.

Rehabilitation protocols in children with corrected congenital heart defects due to the presence of pulmonary complications

BACKGROUND

The Aim of our study was to present early rehabilitation protocols for children with and without pulmonary complications after the correction of congenital heart defects and to estimate the optimal time for the initiation of early rehabilitation in both groups of children.

METHODS

In our study, 176 children treated at the University Children's Hospital in Belgrade were evaluated during the period 2003-2007. All patients were children with the corrected congenital heart defects from birth to 12 months of life.

RESULTS

In the group of patients without pulmonary complications we administered 3.64 +/- 1.02 exercises and in the group with present pulmonary complications we implemented 2.71 +/- 0.79 exercises. The optimal time for the initiation of early rehabilitation is 1.54 +/- 1.37 days for the group of children that did not have pulmonary complications, but for the other group the period was longer: 2.27 +/- 1.68 days.

DISCUSSIONS

The optimal number of exercises in children younger than one year of life is from 2 to 4 and the early rehabilitation should start as soon as possible. A desirable time for beginning of such program is within 24 to 48 hours post surgery but it cannot be limited to this interval due to possible complications stating that every child should have an individual approach (Tab. 3, Ref. 14).

Light-emitting-diode-based light source for calibration of an intensified charge-coupled device detection system intended for galvanoluminescence measurements

A spectrally tunable light source utilizing three light-emitting diodes (LEDs) for calibration of a highly sensitive intensified charge-coupled device (ICCD) optical detection system intended for time-resolved galvanoluminescence (GL) measurements is described. The source has been conceived as a low-cost substitute for standard tungsten lamps usually used for relative and absolute calibration of optical detection systems. Three LEDs with different spectral characteristics in conjunction with a system of two integrating spheres as light mixers and light reducers are used. This construction provides control over the source spectrum by changing individual LED contributions. The use of integration spheres eliminated angular distribution of light intensities of LEDs as well as angular dependence of their spectral contributions. Moreover, by using the source we have avoided the problem of stray and diffuse light of higher wavelengths, as well as different light intensities for different wavelengths (up to three orders of magnitude in the range from 400 nm to 750 nm), which we have with standard tungsten lamps. A complete calibration procedure for the LED source and ICCD detection system is described. Finally, for the first time, we have performed time-resolved spectral GL measurements during aluminum anodization in porous film-forming electrolyte phosphoric acid in a transient regime. Two peaks at 425 nm and 595 nm are recognized, confirming the same mechanism of GL in both transient and steady-state regimes of anodization.

Human fetal islet transplantation in type 1 diabetics: comparison of immunological effects between multiple implantation regimens

Previous studies have suggested that the multiple transplants might be equally metabolically efficient to a single regimen for human adult islets. The aim of this study was to compare immunological and metabolic parameters after each of the two regimens of human fetal islets (HFI). Group A single transplants (n = 9) had 180 +/- 20 x 1000 HFI equivalents (IEQs) implanted via a single intramuscular injection. In group B multiple transplants (n = 8) islets were implanted by three consecutive injections of 60 +/- 10 x 1000 IEQs at 7-day intervals. We analyzed the immunological parameters of CD4/CD8 T lymphocyte ratios; islet cell antibodies (ICAs) and insulin antibodies (IAs). We estimated insulin secreting capacity (ISC) as the metabolic parameter. We observed that the CD4+/CD8+ T-cell ratio increased, peaking on day 90, in similar fashion in both groups: day -1: A = 1.18 +/- 0.03 versus B = 1.19 +/- 0.04; on day 90: A = 1.79 +/- 0.09, versus B = 1.75 +/- 0.08 (P = NS) immediately before the decrease in C-peptide levels. Thereafter the ratios rapidly decreased without statistical differences. The levels of ICAs did not change. The levels of IAs, which were increased before transplant, then decreased without statistical differences between the groups. The values of ISC increased after transplant and then decreased similar to the T-cell ratio. Our results demonstrated that regimens of multiple and single HFIs did not show differences in the kinetics of the immunological response presumably mediating graft destruction. The CD4/CD8 ratio increased as the C-peptide level decreased, peaking on day 90 at the time of a decrease in C-peptide. These results may be useful for clinical studies of HFIs for type 1 diabetic patients.

In vitro assessment of intestinal permeability and hepatic metabolism of 4'-bromoflavone, a promising cancer chemopreventive agent

1. The intestinal permeability and hepatic metabolism of the investigational cancer chemoprevention agent 4'-bromoflavone were investigated in vitro using human intestinal Caco-2 cell monolayers, human liver microsomes and human hepatocytes. Liquid chromatography-mass spectrometry and tandem mass spectrometry were used for quantitative analysis in support of the Caco-2 cell studies and for the characterization of metabolites of 4'-bromoflavone. 2. The Caco-2 cell model indicated that 4'-bromoflavone would be absorbed by the intestine at a moderate rate by means of direction-independent, passive diffusion. There was no indication of active transport or efflux. 3. Three monohydroxylated metabolites and one monohydroxylated, hydrated metabolite of 4'-bromoflavone were detected at relatively low levels in the human liver microsomal and hepatocyte incubations. The structures of these metabolites were confirmed by comparison with synthetic standards. Hydroxylation occurred on the A-ring of 4'-bromoflavone but not on the B-ring, probably due to deactivation of the B-ring by bromine. No phase II metabolites were detected following incubation of 4'-bromoflavone in these in vitro systems. 4. In conclusion, these studies predict that 4'-bromoflavone should show moderate oral bioavailability, and that it would probably be excreted as unchanged compound and monohydroxylated metabolites. The results might be helpful in the design of clinical trials and in the interpretation of pharmacokinetic studies of 4'-bromoflavone.

Human fetal islet transplantation in type 1 diabetic patients: Comparison of metabolic effects between single and multiple implantation regimens

Previous studies suggest that multiple transplantations might be equally efficient to a single regimen for human adult islets. The aim of this study was to compare metabolic parameters after each of the two regimens of human fetal islet (HFI) transplantation in type 1 diabetics. In group A (single transplant, n = 9), 180 +/- 20 x 1000 HFI equivalents (IEQs) were implanted by a single IM injection; in group B (multiple transplants, n = 8) islets were implanted as three consecutive injections (60 +/- 10 x 1000 IEQs) at 7-day intervals. We analyzed the metabolic parameters on days -1, 30, 60, 90, 120, 150, and 180 after the procedure. Among the metabolic parameters, we evaluated insulin secretion capacity-ISC (C peptide, RIA), metabolic control (HbA1c, chromatography), and insulin daily dose IDD. We found that C peptide levels increased, peaking on day 90 (A: 0.38 +/- 0.15; B: 0.34 +/- 0.19 nmol/L, P = NS) and then rapidly decreasing without differences, the HbA1c levels and IDD decreased in the same manner without differences between the groups. Our results demonstrate that multiple and single islet transplant regimens are equally efficient to temporarily restore a significant ISC with improvement of metabolic and clinical parameters. The results imply that the two regimens have an equal clinical value.

Isolation of linoleic acid as an estrogenic compound from the fruits of Vitex agnus-castus L. (chaste-berry)

A methanol extract of chaste-tree berry (Vitex agnus-castus L.) was tested for its ability to displace radiolabeled estradiol from the binding site of estrogen receptors alpha (ERalpha) and beta (ERbeta). The extract at 46 +/- 3 microg/ml displaced 50% of estradiol from ERalpha and 64 +/- 4 microg/ml from ERbeta. Treatment of the ER+ hormone-dependent T47D:A18 breast cancer cell line with the extract induced up-regulation of ERbeta mRNA. Progesterone receptor (PR) mRNA was upregulated in the Ishikawa endometrial cancer cell line. However, chaste-tree berry extract did not induce estrogen-dependent alkaline phosphatase (AP) activity in Ishikawa cells. Bioassay-guided isolation, utilizing ER binding as a monitor, resulted in the isolation of linoleic acid as one possible estrogenic component of the extract. The use of pulsed ultrafiltration liquid chromatography-mass spectrometry, which is an affinity-based screening technique, also identified linoleic acid as an ER ligand based on its selective affinity, molecular weight, and retention time. Linoleic acid also stimulated mRNA ERbeta expression in T47D:A18 cells, PR expression in Ishikawa cells, but not AP activity in Ishikawa cells. These data suggest that linoleic acid from the fruits of Vitex agnus-castus can bind to estrogen receptors and induce certain estrogen inducible genes.

Inactivation of C30A trimethylamine dehydrogenase by N-cyclopropyl-alpha-methylbenzylamine, 1-phenylcyclopropylamine, and phenylhydrazine

Trimethylamine dehydrogenase (TMADH) from the bacterium Methylophilus methylotrophus (sp. W(3)A(1)) and its C30A mutant were inactivated with three known inactivators of monoamine oxidase, namely, phenylhydrazine, N-cyclopropyl-alpha-methylbenzylamine, and 1-phenylcyclopropylamine. All three compounds irreversibly inactivated both the wild-type and C30A mutant enzymes, although phenylhydrazine was 10 times more potent than N-cyclopropyl-alpha-methylbenzylamine, which was much more potent than 1-phenylcyclopropylamine. The change in the UV--visible absorption spectra upon modification indicated that the flavin was modified. In the case of the C30A mutant, the absence of a covalent attachment of the flavin to the polypeptide has permitted LC-electrospray mass spectrometry of the reaction product to be undertaken, demonstrating new mass peaks corresponding to various chemically modified forms of the flavin cofactor. In the case of N-cyclopropyl-alpha-methylbenzylamine, masses corresponding to hydroxy-FMN and hydroxyriboflavin were detected. 1-Phenylcyclopropylamine inactivation of the C30A mutant produced three modified flavins, as evidenced by the electrospray mass spectrum: hydroxy-FMN, FMN plus C(6)H(5)COCH(2)CH(2), and hydroxy-FMN plus C(6)H(5)COCH(2)CH(2). Phenylhydrazine inactivation of the C30A mutant gave at least seven different modified flavins: hydroxyriboflavin, hydroxy-FMN, two apparently isomeric compounds corresponding to hydroxy-FMN plus one phenyl group, two apparently isomeric compounds corresponding to FMN plus one phenyl group, and FMN plus two phenyl groups. Covalent flavin adduct formation appears to be the only modification because dialysis of the inactive enzyme followed by reconstitution with FMN restores the enzyme activity to that of a noninactivated control.

Inactivation of monoamine oxidase B by 1-phenylcyclopropylamine: mass spectral evidence for the flavin adduct

Incubation of 1-phenylcyclopropylamine with bovine liver MAO (MAO B), followed by complete enzymatic digestion to single amino acid residues and subsequent analysis by on-line liquid chromatography-electrospray ionization mass spectrometry, was used to investigate the resulting flavin adduct structure.

Spectrometric evidence for the flavin-1-phenylcyclopropylamine inactivator adduct with monoamine oxidase N

1-Phenylcyclopropylamine (1-PCPA) is shown to be an inactivator of the fungal flavoenzyme monoamine oxidase (MAO) N. Inactivation results in an increase in absorbance at 410 nm and is accompanied by the concomitant loss of the flavin absorption band at 458 nm. The spectral properties of the covalent adduct formed between the flavin cofactor of MAO N and 1-PCPA are similar to those reported for the irreversible inactivation product formed with 1-PCPA and mammalian mitochondrial monoamine oxidase B [Silverman, R. B., and Zieske, P. A. (1985) Biochemistry 24, 2128-2138]. There is a hypsochromic shift of the 410 nm band upon lowering the pH to 2, indicating that an N(5)-flavin adduct formed upon inactivation. Use of the fungal enzyme, MAO N, which lacks the covalent attachment to the flavin adenine dinucleotide (FAD) cofactor present in the mammalian forms MAO A and MAO B, has allowed for the isolation and further structural identification of the flavin-inactivator adduct. The incorporation of two (13)C labels into the inactivator, [2,3-(13)C(2)]-1-PCPA, followed by analysis using on-line liquid chromatography/electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy, provided a means to explore the structure of the flavin-inactivator adduct of MAO N. The spectral evidence supports covalent attachment of the 1-PCPA inactivator to the cofactor as N(5)-3-oxo-3-phenylpropyl-FAD.

DNA oxidation induced by cyclooxygenase-2

The inducible form of cyclooxygenase, COX-2, has been shown to be overexpressed in various types of tumors, including colon and prostate cancer. Several studies indicate that COX-2 inhibition can be beneficial for the prevention of these types of cancer. Since COX-2 reactions involve production of reactive oxygen radicals that can potentially damage biological macromolecules, we explored the possibility that DNA and/or nucleosides can be oxidized during cyclooxygenase reactions. When DNA or nucleosides were incubated with COX-2 and arachidonic acid, a significant increase in the amount of 8-oxo-2'-deoxyguanosine was observed. This increase was enzyme-dependent and could be prevented by COX-2 inhibitors as well as by antioxidants. These data indicate that peroxyl radicals or other oxidized species formed during conversion of arachidonic acid to prostaglandin G(2) might be responsible for the observed oxidation. These results suggest also that overexpression of COX-2 in inflammatory diseases places an additional burden on antioxidative defenses of the cell, which might contribute to DNA oxidation and the induction of mutations.

The late effects of proton irradiation on cell growth, cell cycle arrest and apoptosis in a human melanoma cell line

The aim of this work is the in vitro study of the late effects of single proton irradiation on HTB63 human melanoma cell growth, cell cycle and cell death. The experimental conditions were focused on analyzing the effects of irradiation on the periphery of tumour that can be, in clinical practice, close to critical organs. Confluent cell monolayers were irradiated with single doses ranging from 1 - 20 Gy, using proton beams having an energy of 22.6 MeV at the target. Antiproliferative effect of protons, cell cycle analysis and initiation of cell death, were followed 48 hours after irradiation. The inhibition of melanoma cell growth was observed, especially after single application of 12 and 16 Gy. Cell cycle analysis and cell viability have shown the G2/M and G1/G0 arrest of irradiated cells correlating with the increase of the applied dose. The flow cytometric analysis has shown presence of apoptotic nuclei. These data demonstrate that irradiation with protons, under the chosen experimental conditions, have significant effects on melanoma cell growth inhibition being dose dependent, G2/M cell cycle arrest and appearance of apoptotic nuclei, even 48 hours after irradiation. The results obtained may help the understanding of the relationship between cell proliferation, death and cell cycle regulation of melanomas after proton irradiation.

Evaluation of cyclooxygenase-2 inhibitors using pulsed ultrafiltration mass spectrometry

Since selective inhibition of the inducible form of cyclooxygenase (COX-2) might retain all the benefits of classical nonsteroidal antiinflammatory agents while avoiding the major side effects associated with inhibition of the constitutive isoform COX-1, COX-2 has become an important target for the discovery and development of new antiinflammatory drugs. To aid in the discovery and characterization of such selective inhibitors, we have applied a mass spectrometry-based screening technique, pulsed ultrafiltration mass spectrometry, using COX-2 as the target. In a blind study, 18 samples enriched with one or more inhibitors of COX-2 were evaluated. The matrixes for the test samples consisted of DMSO, r DMSO solutions of a plant extract, or a bacterial fermentation broth extract. The composition of the samples was unknown during the assays, as were the concentrations of the COX-2 inhibitors. A soluble recombinant form of human COX-2 was incubated with each sample, and then an aliquot of each mixture was injected into the stirred ultrafiltration chamber fitted with a 30000 MW cutoff ultrafiltration membrane. After the unbound and weakly bound compounds were washed away, the ligand-receptor complexes were disrupted using an acidified 10% methanol solution. The released ligands were trapped on a C18 cartridge and then identified using liquid chromatography-negative ion electrospray mass spectrometry with the trapping cartridge as the HPLC column. Neither the plant matrix nor the fermentation broth extract were found to interfere with the assay. Two or three ligands for COX-2 were identified in each sample, which included polar and nonpolar compounds and inhibitors with IC50 values ranging from 100 microM to 10 nM.

Primary surgical treatment of war injuries of the foot

Presented are the results of primary surgical treatment of war injuries of the foot in 250 patients wounded in the territory of former Yugoslavia in the period June 1991-October 1995. Total number of feet treated was 275. Aetiologically, the most frequent injuries were those inflicted by the effect of mine blasts (65.2%) and by bullets from firearms (30.8%). Injuries to a single foot were present in 140 (56.0%), combined injuries in 107 (42.8%) and associated with burn injuries in three (1.2%) patients. Soft tissue injuries were present in 25 (9.1%) and injuries to bone structures and joints in 250 (90.9%) feet. Injuries resulting from solid blasts were found in nine (3.2%) feet. Postoperative bone fragment stabilization was required in 115 (41.8%) feet. Stabilization was by plaster of Paris in 87 (75.6%) and by external fixation in 23 (20. 0%) feet. Amputations were performed in 73 (26.5%) feet. Covering of soft tissue and bone defects was required in 84 (33.6%) patients.

Thrombin-induced growth cone collapse: involvement of phospholipase A(2) and eicosanoid generation

The studies presented here explore intracellular signals resulting from the action of repellents on growth cones. Growth cone challenge with thrombin or thrombin receptor-activating peptide (TRAP) triggers collapse via a receptor-mediated process. The results indicate that this involves activation of cytosolic phospholipase A(2) (PLA(2)) and eicosanoid synthesis. The collapse response to repellents targets at least two functional units of the growth cone, the actin cytoskeleton and substratum adhesion sites. We show in a cell-free assay that thrombin and TRAP cause the detachment of isolated growth cones from laminin. Biochemical analyses of isolated growth cones reveal that thrombin and TRAP stimulate cytosolic PLA(2) but not phospholipase C. In addition, thrombin stimulates synthesis of 12- and 15-hydroxyeicosatetraenoic acid (HETE) from the released arachidonic acid via a lipoxygenase (LO) pathway. A selective LO inhibitor blocks 12/15-HETE synthesis in growth cones and inhibits thrombin-induced growth cone collapse. Exogenously applied 12(S)-HETE mimics the thrombin effect and induces growth cone collapse in culture. These observations indicate that thrombin-induced growth cone collapse occurs by a mechanism that involves the activation of cytosolic PLA(2) and the generation of 12/15-HETE.

Assays of ligand-human serum albumin binding using pulsed ultrafiltration and liquid chromatography-mass spectrometry

Two approaches were utilized to increase the throughput of pulsed ultrafiltration assays of ligand binding to human serum albumin, reducing the volume of the ultrafiltration chamber and combining pulsed ultrafiltration with high performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-MS). Affinity constants for binding of ligands to human serum albumin were determined using pulsed ultrafiltration with ultraviolet absorbance detection. The first affinity constants (Ka1) were measured for the binding of dansylsarcosine, dansylamide, 7-anilinocoumarin-4-acetic acid and warfarin, and were determined to be 1.8 x 105, 5 x 104, 8 x 104, and 2.0 x 105 M-1, respectively. The throughput of pulsed ultrafiltration analyses was tripled compared to previous pulsed ultrafiltration measurements by reducing the volume of the chamber. In addition, the use of LC-MS with pulsed ultrafiltration permitted the simultaneous comparison and rank ordering of ligand mixtures for binding to serum albumin. For example, the throughput of these pulsed ultrafiltration measurements was tripled by analyzing three ligands as a mixture.

The apparent inhibition of inosine monophosphate dehydrogenase by mycophenolic acid glucuronide is attributable to the presence of trace quantities of mycophenolic acid

BACKGROUND

Mycophenolic acid glucuronide, the primary metabolite of the immunosuppressive agent mycophenolic acid, affords weak inhibition of proliferating and resting lymphocytes and recombinant human inosine monophosphate dehydrogenase in comparison to the active drug. We evaluated the hypothesis that mycophenolic acid is a trace contaminant of the glucuronide metabolite preparation and that this accounts for the observed effects of mycophenolic acid glucuronide on human inosine monophosphate dehydrogenase catalytic activity both in lymphocytes and the pure enzyme.

METHODS

We used negative ion electrospray HPLC-mass spectrometry (HPLC-MS) and HPLC-tandem MS (HPLC-MS-MS) to identify mycophenolic acid as a contaminant of mycophenolic acid glucuronide. Quantification of the mycophenolic acid contaminant was achieved using a negative ion electrospray HPLC-MS method in the selected-ion monitoring mode.

RESULTS

Trace amounts of mycophenolic acid were detected and definitively identified in the mycophenolic acid glucuronide preparation by the HPLC-MS-MS analysis. In addition to having identical HPLC retention times, pure mycophenolic acid and the contaminant produced the following major fragments upon HPLC-MS-MS analysis: deprotonated molecular ion, m/z 319; and fragment ions, m/z 275, 243, 205, and 191 (the most abundant fragment ion). Using the negative ion electrospray HPLC-MS procedure in the selected-ion monitoring mode, the quantity of the contaminant mycophenolic acid was determined to be 0.312% +/- 0.0184% on a molar basis.

CONCLUSION

These data provide strong support for the proposal that the apparent inhibition of the target enzyme inosine monophosphate dehydrogenase by mycophenolic acid glucuronide is attributable to the presence of trace amounts of contaminant mycophenolic acid.

Screening for xenobiotic electrophilic metabolites using pulsed ultrafiltration-mass spectrometry

A pulsed ultrafiltration-mass spectrometric screening assay has been developed to generate and identify electrophilic metabolites of xenobiotic compounds formed by hepatic cytochrome P450 enzymes. This assay would be suitable for the early identification of potentially toxic compounds during the initial phase of drug development. Rat liver microsomes were trapped by an ultrafiltration membrane in a stirred flow-through chamber, and substrates for microsomal cytochrome P450 including hydroxychavicol, 3-methylindole, cyproheptadine and 2-tert-butyl-4,6-dimethylphenol were flow-injected individually through the chamber along with the cofactors, NADPH and glutathione. Metabolites and glutathione conjugates were detected on-line using electrospray mass spectrometry. Alternatively, the ultrafiltrate was concentrated on a reversed phase HPLC column and analyzed using electrospray LC-MS or LC-MS-MS to separate and characterize isomeric metabolites and metabolites present at low concentration. Enzymatic activation of each xenobiotic substrate produced highly electrophilic metabolites such as quinones, quinone methides and imine methides that reacted with glutathione on-line to produce glutathione conjugates which were detected by using electrospray mass spectrometry. Although epoxides such as cyproheptadine epoxide were generated, it is likely that these compounds were insufficiently reactive to form glutathione conjugates in the absence of cytosolic glutathione S-transferases. Pulsed ultrafiltration-electrospray mass spectrometry offers an efficient method for in vitro formation and mass spectrometric characterization of activated microsomal drug metabolites and is suitable for use during the drug discovery process for the early identification and screening out of potentially toxic lead compounds.