Quantitative multiple fragment monitoring with enhanced in-source fragmentation/annotation mass spectrometry

Analytical techniques with high sensitivity and selectivity are essential to the quantitative analysis of clinical samples. Liquid chromatography coupled to tandem mass spectrometry is the gold standard in clinical chemistry. However, tandem mass spectrometers come at high capital expenditure and maintenance costs. We recently showed that it is possible to generate very similar results using a much simpler single mass spectrometry detector by performing enhanced in-source fragmentation/annotation (EISA) combined with correlated ion monitoring. Here we provide a step-by-step protocol for optimizing the analytical conditions for EISA, so anyone properly trained in liquid chromatography-mass spectrometry can follow and apply this technique for any given analyte. We exemplify the approach by using 2-hydroxyglutarate (2-HG) which is a clinically relevant metabolite whose D-enantiomer is considered an 'oncometabolite', characteristic of cancers associated with mutated isocitrate dehydrogenases 1 or 2 (IDH1/2). We include procedures for determining quantitative robustness, and show results of these relating to the analysis of DL-2-hydroxyglutarate in cells, as well as in serum samples from patients with acute myeloid leukemia that contain the IDH1/2 mutation. This EISA-mass spectrometry protocol is a broadly applicable and low-cost approach for the quantification of small molecules that has been developed to work well for both single-quadrupole and time-of-flight mass analyzers.

Metabolic adaptation to calorie restriction

Calorie restriction (CR) enhances health span (the length of time that an organism remains healthy) and increases longevity across species. In mice, these beneficial effects are partly mediated by the lowering of core body temperature that occurs during CR. Conversely, the favorable effects of CR on health span are mitigated by elevating ambient temperature to thermoneutrality (30°C), a condition in which hypothermia is blunted. In this study, we compared the global metabolic response to CR of mice housed at 22°C (the standard housing temperature) or at 30°C and found that thermoneutrality reverted 39 and 78% of total systemic or hypothalamic metabolic variations caused by CR, respectively. Systemic changes included pathways that control fuel use and energy expenditure during CR. Cognitive computing-assisted analysis of these metabolomics results helped to prioritize potential active metabolites that modulated the hypothermic response to CR. Last, we demonstrated with pharmacological approaches that nitric oxide (NO) produced through the citrulline-NO pathway promotes CR-triggered hypothermia and that leucine enkephalin directly controls core body temperature when exogenously injected into the hypothalamus. Because thermoneutrality counteracts CR-enhanced health span, the multiple metabolites and pathways altered by thermoneutrality may represent targets for mimicking CR-associated effects.

Fluorinated Gold Nanoparticles for Nanostructure Imaging Mass Spectrometry

Nanostructure imaging mass spectrometry (NIMS) with fluorinated gold nanoparticles (f-AuNPs) is a nanoparticle assisted laser desorption/ionization approach that requires low laser energy and has demonstrated high sensitivity. Here we describe NIMS with f-AuNPs for the comprehensive analysis of metabolites in biological tissues. F-AuNPs assist in desorption/ionization by laser-induced release of the fluorocarbon chains with minimal background noise. Since the energy barrier required to release the fluorocarbons from the AuNPs is minimal, the energy of the laser is maintained in the low μJ/pulse range, thus limiting metabolite in-source fragmentation. Electron microscopy analysis of tissue samples after f-AuNP NIMS shows a distinct "raising" of the surface as compared to matrix assisted laser desorption ionization ablation, indicative of a gentle desorption mechanism aiding in the generation of intact molecular ions. Moreover, the use of perfluorohexane to distribute the f-AuNPs on the tissue creates a hydrophobic environment minimizing metabolite solubilization and spatial dislocation. The transfer of the energy from the incident laser to the analytes through the release of the fluorocarbon chains similarly enhances the desorption/ionization of metabolites of different chemical nature, resulting in heterogeneous metabolome coverage. We performed the approach in a comparative study of the colon of mice exposed to three different diets. F-AuNP NIMS allows the direct detection of carbohydrates, lipids, bile acids, sulfur metabolites, amino acids, nucleotide precursors as well as other small molecules of varied biological origins. Ultimately, the diversified molecular coverage obtained provides a broad picture of a tissue's metabolic organization.

Care management: automating the care process to improve consumer service

By implementing a care management system that is consumer-centric and service-oriented, the goal of providing high-quality care, controlling costs, and providing excellent service can be achieved through every interaction with the consumer. Care management broadens the consumer's access to service while coordinating and managing care across this extended web of access. This can only be achieved by implementing a system with a clinical usage model that care providers will actually use in their practices.

Gait parameters following stroke: a practical assessment

Mechanical methods of quantifying gait are more sensitive to change than is direct clinical inspection. To assess gait parameters and patterns of patients with stroke, and the temporal changes of these parameters, a foot-switch gait analyzer was used to test 49 ambulatory patients with stroke and 24 controls. Patients walked significantly slower than controls, with decreased cadence, increased gait cycle, and increased time in double limb support. Patients' hemiplegic limbs spent more time in swing and stance when compared to controls; their unaffected limbs spent significantly more time in stance and single limb support compared to controls. Patients' hemiplegic side, when compared with the unaffected side, spent less time in stance and more time in swing. A flatfoot pattern was typically noted on the affected side. General gait parameters improved over time, with the largest changes occurring in the first 12 months. However, the percentage of time spent in double and single limb support, stance and swing, parameters which describe the asymmetrical pattern of gait, did not change over time. Abnormal gait was due to difficulty in moving the body over an unstable limb. Gait analysis can be of importance in documenting abnormalities and determining the effects of therapeutic modalities.

Site-saturation mutagenesis and three-dimensional modelling of ROB-1 define a substrate binding role of Ser130 in class A beta-lactamases

Site-saturation mutagenesis was performed on the class A ROB-1 beta-lactamase at conserved Ser130, which is centrally located in the antibiotic binding site where it can participate in both protein-protein and protein-substrate hydrogen bonding. Mutation Thr130 gave a beta-lactamase hydrolysing penicillins and cephalosporins but which showed a 3-fold lower affinity (Km) for ampicillin and cephalexin, and a 30-fold lower hydrolytic (Vmax) activity for ampicillin. In contrast, the hydrolytic activity for cephalexin was similar to the wild-type for the Thr130 mutation. Mutation Gly130 gave a beta-lactamase hydrolysing only penicillins with an affinity and hydrolysis activity for these compounds approximately 15-fold lower than the wild-type, but no detectable activity against cephalosporins. Mutation Ala130 produced an enzyme capable of hydrolysing penicillins only at a low rate. Modelling the ROB-1 active site was done from the refined 2 A X-ray structure of the homologous Bacillus licheniformis beta-lactamase. Ampicillin and cephalexin were docked into the active site and were energy minimized with the CVFF empirical force field. Dockings were stable only when Ser70 was made anionic and Glu166 was made neutral. Interaction energies and distances were calculated for fully hydrated pre-acylation complexes with the Ser, Thr, Gly and Ala130 enzymes. The catalytic data from all mutations and the computed interactions from modelling confirmed that the Ser130 has a structural as well as a functional role in binding and hydrolysis of penicillins. This highly conserved residue also plays a substrate specificity role by hydrogen binding the carboxylic acid group of cephalosporins more tightly than penicillins.

The changes in intramuscular pressure and femoral vein flow with continuous passive motion, pneumatic compressive stockings, and leg manipulations

Intramuscular pressure was measured continuously in the deep compartment of the calf and anterior thigh of volunteers while their legs were cyclically moved from 0 degrees to 90 degrees back to 0 degrees (angle of knee flexion) in an anatomic continuous passive motion (CPM) device and a nonanatomic CPM device. Femoral venous flow was measured continuously using a thermodilution technique in volunteers while their legs were moved in both CPM devices, during inflation of a pneumatic stocking, and during several leg manipulations. Baseline intramuscular pressures in the deep calf and anterior thigh were 10.0 +/- 1.9 mmHg and 4.9 +/- 1.9 mmHg, respectively (mean +/- standard error). Both the anatomic and nonanatomic CPM devices produced a statistically significant maximal increase in pressure in the calf. By contrast, only a decrease in pressure occurred in the thigh with both devices. Baseline femoral vein flow measured by the thermodilution technique was 311 +/- 38 ml per minute. Significant increases in femoral vein flow were seen with both CPM devices. The maximal flow produced by the anatomic CPM was 1199 ml per minute and was approximately four times higher than baseline flow and approximately 1.4 times the maximal flow change seen with the nonanatomic CPM (836 ml per minute). The greatest net increase in flow was observed between 60 degrees and 90 degrees of knee flexion with both devices. Overall, passive straight-leg elevation produced the largest flow (1524 ml per minute), followed by the anatomic CPM and nonanatomic CPM, and then by active ankle dorsiflexion(640 ml per minute), pneumatic stocking inflation (586 ml per minute), manual calf compression (532 ml per minute), and passive dorsiflexion (385 ml per minute)(ABSTRACT TRUNCATED AT 250 WORDS)

Collagenase activity in anterior cruciate ligament: protective role of the synovial sheath

To evaluate the protective role of the synovial sheath of the anterior cruciate ligament (ACL), we have developed a synovectomy model that exposes the ACL substance to the intra-articular environment with and without hemarthrosis. Histology and the level of collagenase activity were studied to assess intrinsic ligament alterations. The treatment groups studied were as follows: ACLs of sham-operated knees receiving arthrotomy only, ACLs of knees receiving arthrotomy and acute hemarthrosis, ACLs of knees that underwent synovectomy, and ACLs of knees that underwent both synovectomy and acute hemarthrosis. All animals were killed 10 days postoperatively for gross, histological, and biochemical assessment. Histologically at 10 days ACLs experiencing synovectomy and ACLs having synovectomy plus hemarthrosis revealed marked hypocellular areas. Biochemical results indicate that synovectomy is the treatment mainly responsible for the observed increase in ACL collagenase activity. Hemarthrosis alone clearly had no effect, although hemarthrosis coupled with synovectomy appeared to further increase the amount of active collagenase present in the ACLs. This study indicates that, with exposure of the ACL substance to the synovial fluid or with hemarthrosis after synovectomy, there is an increase in the degradative activity of the ACL. The protective role of the synovial sheath suggests that the synovial sheath injury associated with acute ACL rupture may allow for exposure of the ligament substance to the degradative effects of the synovial environment and associated hemarthrosis.

Cartilage resurfacing of the rabbit knee. The use of an allogeneic demineralized bone matrix-autogeneic perichondrium composite implant

A full-thickness articular-cartilage defect was created in the medial femoral condyles of 32 adult rabbits. The defects were filled with demineralized bone or a composite of demineralized bone and perichondrium. Results of cartilage repair were assessed after 12 weeks of implantation. We conclude that demineralized bone matrix used as a subchondral matrix in a cartilage repair model 1) stimulates and induces subchondral bone ingrowth, 2) provides a surface on which cartilage repair can proceed, and 3) can be utilized as a platform on which perichondrium can be fixed to provide a cellular source for cartilage repair. Repair tissue that developed from perichondrium was thicker, more closely resembled normal articular cartilage, and was of a less fibrous nature than the repair tissue that developed de novo on the demineralized bone matrix.

Hyaluronan in flexor tendon repair

This study assesses the effect of a preparation of hyaluronan (hyaluronic acid) applied topically at the time of flexor tendon repair in a well-established model. The hypothesis is that hyaluronic acid applied topically at the time of flexor tendon repair will decrease adhesions, and will improve clinically the gliding function of the repaired flexor tendon. After transection and repair of the second and fifth flexor tendons of the left forepaw of four mongrel dogs, the second flexor tendon was treated with hyaluronic acid of molecular weight 3.6 x 10(6) daltons applied topically between the synovial sheath and the repair site. The left forepaws were completely immobilized for 5 weeks to optimize the formation of adhesion ingrowth. After death, the repaired tendons and sheaths were removed en bloc, fixed, and dissected. Gross inspection and histologic evaluation of all tendons showed that the quality and quantity of adhesions from the wound repair to the synovial sheath appeared to have been consistently affected by hyaluronan. Hyaluronic acid had a beneficial effect on both the repair site and synovial sheath by decreasing the peripheral inflammatory response and promoting a contact healing process via epitenon and endotenon cell involvement in the repair process.

Historical review and present status of free fat graft autotransplantation in plastic and reconstructive surgery

Free fat graft autotransplantation for soft-tissue replacement has been a neglected subject in recent years. In a review of the literature, investigations of the various uses of free fat autotransplantation in animals and humans provide an understanding of the problems associated with the use of fat as a free graft. Results of free fat autotransplantation were found to be quite unpredictable, with wide variations in the resulting bulk of the graft. Microscopic studies of this behavior led to controversy as to whether the graft ultimately was made of surviving graft adipocytes (cell survival theory) or host adipocytes (host replacement theory). Studies revealed a "fibroblast-like" mesenchymal cell within adipose tissue that was believed to be an immature adipocyte precursor or preadipocyte. Further characterization of the preadipocyte and its complete differentiation was accomplished using tissue-culture techniques. These investigations provide evidence of the dynamic nature of adipose tissue that strongly supports the cell survival theory and gives explanation to the unpredictable behavior of free fat autografts. Many conditions treated by plastic surgeons require soft-tissue augmentation. Autogenous adipose tissue is the most appropriate and natural replacement material. With new culturing techniques, preadipocytes in a single cell suspension may provide an injectable soft-tissue replacement. This subject appears ripe for investigation.

Laser treatment of macular holes

Macular holes have not been treated with the laser because of the rarity of subsequent total retinal detachment (RD). The authors attempted to clear the subretinal fluid of the halo by laser coagulation of the rim of the hole. Eighteen eyes with visual acuity of 20/200 or less were treated with a laser and followed for a mean of 34.8 months. Ten eyes (55.6%) improved three to eight lines, five eyes (27.8%) remained the same, and the vision of three (16.6%) deteriorated three to five lines. The best visual results noted in three eyes (20/400-20/70, 20/200-20/80, and 20/200-20/60) correlated with the least late loss of pigment epithelium and pigment migration.

Recurrence of keratoconus in donor cornea 22 years after successful keratoplasty

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Prospective clinical study of radial keratotomy

A prospective clinical study of radial keratotomy was conducted at the University of Maryland. Results of surgery on 33 eyes of 19 patients with a minimum follow-up of seven months and a mean of 13.8 months are reported. There were eight patients (15 eyes) who needed adequate unaided visual acuity for occupational purposes. Preoperative visual acuity was 20/400 in 79% of eyes. Postoperative visual acuity was 20/50 or better in 48% of cases. However, in patients with preoperative refractive errors of 5 diopters or less, postoperative visual acuity was 20/50 or better in 84% of cases. Average decrease in myopia was 2.5 diopters. Decrease in myopia following radial keratotomy did not correlate with corneal curvature or whether 8 or 16 incision technique was used. However, there was a very significant (P = 0.001) difference in postoperative visual acuity of patients with refractive error of 5 diopters or less, as compared to those with greater than 5 diopters of myopia. Complications included corneal scarring, vascularization, and glare. No microperforation or endothelial cell loss was observed.