Biomedical subjects
Publications and source records attributed to M Wong.
The synthesis and optimization of a novel class of reversible and active-site directed dibasic inhibitors of human mast cell tryptase are described. The compounds were shown to be both remarkably potent and selective for tryptase with Ki values for optimized inhibitors in the picomolar range.
Detailed structure activity relationships (SARs) for a series of dibasic human tryptase inhibitors are presented. The structural requirements for potent inhibitory activity are remarkably broad with a range of core template modifications being well tolerated. Optimized inhibitors demonstrate potent anti-asthmatic activity in a sheep model of allergic asthma. APC-2059, a dibasic tryptase inhibitor with subnanomolar activity, has been advanced to phase II clinical trials for the treatment of both psoriasis and ulcerative colitis.
The present article describes the preparation and preliminary characterization of a novel phosphate-functionalized self-assembled monolayer (SAM) and the determination of the surface ionization states of the phosphate headgroup in aqueous solutions by chemical force microscopy (CFM). The phosphate headgroup used was PO(OH)2, a diprotic acid. The adhesion force between an AFM probe and a flat substrate, both of which were chemically modified with the same phosphate SAM, was also measured as a function of pH and ionic strength. At low ionic strength (10(-4) M), two peaks were observed in the force titration curve (adhesion force versus pH) at pH 4.5 and 8.4. The two peaks are positioned 2.4 and 1.2 pH units higher, respectively, than the acid dissociation constants obtained for the phosphate group free in aqueous solution. At high ionic strength (10(-1) M), the adhesion forces were reduced by 1 order of magnitude and the peaks were replaced by shoulders similar to those previously reported for acid force titrations. On the basis of JKR theory, the surface pKa values of the phosphate group in high ionic strength solutions were found to be 4.5 and 7.7, respectively. However, in light of the effects of ionic strength on the force titration curves, we discuss the applicability of JKR theory to nanoscopic measurements of adhesion force and surface pKa.
OBJECTIVE: To determine the effect of the ketone bodies beta-hydroxybutyrate (betaHB) and acetoacetate (AA) on excitatory and inhibitory neurotransmission in the mammalian CNS. BACKGROUND: The ketogenic diet is presumed to be an effective anticonvulsant regimen for some children with medically intractable seizures. However, its mechanism of action remains a mystery. According to one hypothesis, ketone bodies have anticonvulsant properties. METHODS: The authors examined the effect of betaHB and AA on excitatory and inhibitory synaptic transmission in rat hippocampal-entorhinal cortex slices and cultured hippocampal neurons. In cultured neurons, their effect was also directly assayed on postsynaptic receptor properties. Finally, their ability to prevent spontaneous seizures was determined in a hippocampal-entorhinal cortex slice model. RESULTS: betaHB and AA did not alter synaptic transmission in these models. CONCLUSIONS: The anticonvulsant properties of the ketogenic diet do not result from a direct effect of ketone bodies on the primary voltage and ligand gated ion channels mediating excitatory or inhibitory neurotransmission in the hippocampus.
OBJECTIVES: To define clinically relevant reference ("normal") values for cerebrospinal fluid (CSF) protein concentrations in pediatric patients who were evaluated for meningitis by traditional criteria and by enterovirus-polymerase chain reaction (EV-PCR). DESIGN AND PATIENTS: A cohort of 906 consecutive pediatric patients to receive CSF analysis at St Louis Children's Hospital, St Louis, Mo, from June 1, 1998, to December 31,1998, was studied for clinical and laboratory data. Age-dependent CSF protein concentrations were then derived from a reference group of 225 patients in whom meningitis and other neurologic diseases were excluded by traditional clinical or laboratory criteria (excluding EV-PCR). Available CSF samples from 132 patients of the reference group were subsequently tested for EV-PCR. RESULTS: In the reference group, the CSF protein concentration was highest and most variable in neonates, with a maximum of approximately 1.0 g/L. Cerebrospinal fluid protein concentration decreased rapidly to a nadir by 6 months and remained low throughout childhood, rarely exceeding 0.3 g/L and, finally, increasing in adolescence toward adult values. Enterovirus- polymerase chain reaction was positive in CSF of 11% of the reference group, with EV-PCR-positive patients having significantly higher CSF protein concentrations than EV-PCR-negative patients aged between 4 months and 14 years. CONCLUSIONS: Reference values for CSF protein exhibit a characteristic age dependence in pediatric patients. Continued standard use of adult reference values in the pediatric population is inappropriate. The unexpected finding of a positive EV-PCR in patients not diagnosed with meningitis by traditional criteria further emphasizes the importance of selecting the most clinically relevant reference group for age and other variables when defining normal laboratory values. Arch Pediatr Adolesc Med. 2000;154:827-831
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The objective of this study was to investigate how temporal and spatial patterns of characteristic extracellular matrix molecules are altered in the absence of normal functional skeletal muscle contractions during avian synovial joint development. By using in situ detection of protein and mRNA expression in developing avian feet and femorotibial joints from a wide range of developmental stages, we demonstrate that the morphological abnormalities that result from embryonic immobilization are associated with altered patterns of tenascin-C and collagen-XII expression within developing joint structures. As the joints fuse in immobilized embryos, the cells of the presumptive articular surface differentiate from flattened fibroblasts to more rounded chondrocytes and collagens XII and I are no longer detected at sites of complete joint fusion. Although the expression of collagen XII persists at normal levels elsewhere within the immobilized joint, tenascin-C expression is diminished within the chondroepiphysis, synovium, and tendons, as well as within the remains of the fibrous articular surface. This effect is most notable for the shortest tenascin variant (Tn190) within the chondroepiphysis and the largest variant (Tn230) within tendons, synovium, and the fibrous surface layer of the joint. This study thus provides in vivo support of previous in vitro work that suggests that tenascin expression is sensitive to external changes in mechanical loading environment. However, these data do not support a similar conclusion for collagen XII during early development.
Although no techniques are currently available that meet the needs of nutrition-support professionals, the future is promising. This article reviews various methods and techniques used to assess the metabolic and nutritional status of surgical patients. Technologic advances in bioengineering, molecular biology, and physiology are providing exciting new tools that may eventually replace or supplement traditional static indices of metabolic assessment. At the very least, an increased understanding of the cellular abnormalities associated with various diseases will likely change our view of illness and our approaches to nutritional and metabolic intervention.
The time-dependent lateral expansion and load relaxation of cartilage cylinders subjected to unconfined compression were simultaneously recorded. These measurements were used to (1) test the assumption of incompressibility for articular cartilage, (2) measure the Poisson's ratio of articular cartilage in compression and (3) investigate the relationship between stress relaxation and volumetric change. Mechanical tests were performed on fetal, calf, and adult humeral head articular cartilage. The instantaneous Poisson's ratio of adult cartilage was 0.49+/-0.08 (mean+S.D.), thus confirming the assumption of incompressibility for this tissue. The instantaneous Poisson's ratio was significantly lower for calf (0. 38+/-0.04) and fetal cartilage (0.36+/-0.04). The equilibrium Poisson's ratio, i.e. true Poisson's ratio of the solid matrix, was significantly higher for the adult tissue (0.26+/-0.11) compared to both the fetal (0.09+/-0.02) and calf (0.11+/-0.03) cartilage. A linear relationship between time-matched load and lateral expansion after the first minute of stress relaxation was observed.
OBJECTIVE: To assess the effects of raloxifene, estrogen, and placebo on quality of life in healthy, asymptomatic, postmenopausal women. METHODS: In a multicenter, double-blind, 12-month study, 398 women were assigned randomly to one of four groups: raloxifene HCl, 60 (n = 97) or 150 mg/day (n = 100); conjugated equine estrogens, 0. 625 mg/day (n = 96); or placebo (n = 105). The Women's Health Questionnaire, a validated quality-of-life instrument for perimenopausal and postmenopausal women, was administered at baseline and 3-month intervals. RESULTS: Overall, quality of life from baseline to end point was preserved equally in all treatment groups. Six domains (depressed mood, somatic symptoms, memory/concentration, sexual behavior, sleep problems, and perceived attractiveness) were unchanged in all groups. Three domains (menstrual symptoms, vasomotor symptoms, and anxiety/fears) were statistically significantly different among groups. Mean scores for menstrual symptoms significantly worsened and vasomotor symptoms significantly improved from baseline to end point in the estrogen group. Mean scores for vasomotor symptoms did not worsen at any point in the raloxifene 60 mg/day group. Mean anxiety/fears scores improved significantly during raloxifene 60 mg/day administration throughout treatment (P <.05), irrespective of previous hormone replacement therapy, baseline estradiol (E2) levels, or years postmenopause. CONCLUSION: Most quality-of-life domains were not affected by treatment with estrogen or raloxifene. Estrogen provided relief from vasomotor symptoms but caused menstrual symptoms. Raloxifene 60 mg/day improved anxiety levels in postmenopausal women.
Orthopoxvirus infections in mice have been effectively treated with cidofovir, a clinically approved drug given by intravenous infusion to treat cytomegalovirus infections. In a bioterrorist scenario it would be technically difficult to give this drug to a large number of exposed individuals. New treatment approaches are being sought, which include giving cidofovir by alternative routes or designing oral prodrugs of cidofovir. In this report, intranasal cidofovir was investigated as a treatment of pulmonary cowpox virus infections in BALB/c mice. Ninety to 100% of animals given a single intranasal drug treatment (10, 20 or 40 mg/kg) 24 h after virus challenge survived the infection, whereas all placebo-treated mice died. Doses of 2.5 and 5 mg/kg resulted in 60 and 80% survival, respectively. Single treatments of 20 and 40 mg/kg could be given up to 3 days after virus inoculation and still be 80-90% protective. A single 40 mg/kg treatment of infected mice given 1 or 2 days after infection also resulted in statistically significant decreases in virus titer in lungs and nose/sinus compared to the placebo group. Drug efficacy was found to be contingent upon treatment volume. A 10 mg/kg intranasal dose given 24 h after virus challenge was 100 and 50% effective in volumes of 40 and 20 microl, respectively. The same dose in 5 and 10 microl volumes caused no decrease in mortality. The results of these studies establish the utility of cidofovir treatment of poxvirus infections in mice by intranasal route. The data suggest the possibility that aerosol delivery of cidofovir to human lungs may be a viable alternative to intravenous dosing.
BACKGROUND: The echocardiographic substudy of the Vasodilator-Heart Failure Trial III (V-HeFT III) aimed to determine if felodipine treatment in patients with heart failure who were taking an angiotensin-converting enzyme inhibitor had a favorable effect on left ventricular (LV) structure and function. Earlier V-HeFT trials showed that hydralazine-isosorbide dinitrate improved ejection fraction (EF) and survival, whereas enalapril achieved greater survival with smaller increases in EF. Would the combination of a potent vasodilator and enalapril produce greater improvements in function and survival? METHODS AND RESULTS: Doppler-echocardiographic data were collected from 260 males with heart failure who were randomized to felodipine or a placebo. Mean intrasubject differences between baseline, at 3 months, and at 12 months were compared. Intersite and intrareader reproducibilities were measured from duplicate recordings and readings. At 3 months, no changes in ultrasound variables from baseline occurred in either group. At 12 months, felodipine patients achieved greater increases in EF, shortening of LV end-systolic length, and increases in stroke volume index. Reproducibility coefficients of variation were 7.4% (EF), 6.0% (end-diastolic length), and 13.0% (stroke volume index). CONCLUSIONS: The echocardiographic substudy showed that felodipine, added to heart failure therapy, increased EF, shortened end-systolic length, and increased stroke volume index. The changes were small and confirmed that reproducibility from multiple laboratories can be coordinated into a useful research tool.
BACKGROUND: Reflex activation of the sympathetic nervous system by short-acting dihydropyridine calcium channel antagonists has been reported to harm hypertensive patients. Different neurohormonal profiles and their response to treatment may influence the effectiveness of dihydropyridine vasodilator treatment of heart failure. METHODS: Four hundred fifty men with left ventricular (LV) systolic dysfunction were administered standard heart failure treatment and felodipine extended release (ER) or placebo in the Vasodilator Heart Failure Trial III (V-HeFT III). Plasma norepinephrine (PNE) levels, atrial natriuretic peptide (ANP) levels, exercise capacity, LV ejection fraction (EF), cardiac dimensions and function, and arrhythmia frequency were measured. Hospital-free survival for baseline neurohormonal classes was assessed. RESULTS: Distributions of ANP and PNE levels at baseline in patients with heart failure of ischemic and nonischemic causes were virtually identical. ANP levels at baseline were inversely related to LVEF (r = -0.39; P = .0001), exercise duration (r = -0.19; P = .0001), and peak oxygen consumption (r = -0.27; P = .008) and directly related to LV (r = 0.23; P = .0006) and right ventricular dilatation (r = 0.23; P = .0008). The increase in ANP levels between baseline and 3 months (P = .02) and 1 year (P = .03) was significantly less in the felodipine-ER group than in the placebo group, but PNE levels did not differ between treatment groups. Hospital-free survival was directly related to baseline ANP (P = .0002) and PNE levels (P = .004). All-cause mortality was related to baseline PNE levels (P = .02) but not baseline ANP levels. CONCLUSION: Levels of ANP and PNE hormones are related to LV dysfunction, exercise performance, and hospital-free survival in heart failure and PNE levels are related to all-cause mortality. Treatment with felodipine ER did not adversely affect survival in any neurohormone subclass.
Human interleukin 2 (IL-2; Proleukin) is an approved therapeutic for advanced-stage metastatic cancer; however, its use is restricted because of severe systemic toxicity. Its function as a central mediator of T-cell activation may contribute to its efficacy for cancer therapy. However, activation of natural killer (NK) cells by therapeutically administered IL-2 may mediate toxicity. Here we have used targeted mutagenesis of human IL-2 to generate a mutein with approximately 3,000-fold in vitro selectivity for T cells over NK cells relative to wild-type IL-2. We compared the variant, termed BAY 50-4798, with human IL-2 (Proleukin) in a therapeutic dosing regimen in chimpanzees, and found that although the T-cell mobilization and activation properties of BAY 50-4798 were comparable to human IL-2, BAY 50-4798 was better tolerated in the chimpanzee. BAY 50-4798 was also shown to inhibit metastasis in a mouse tumor model. These results indicate that BAY 50-4798 may exhibit a greater therapeutic index than IL-2 in humans in the treatment of cancer and AIDS.
BACKGROUND: The aggressiveness of familial non-medullary thyroid cancer (FNMTC) has been a subject of debate. The purpose of the study was to determine whether FNMTC is more aggressive than sporadic thyroid cancer. METHODS: A multicenter retrospective matched-case control study of FNMTC versus sporadic non-medullary thyroid cancer was conducted. Disease-free survival (time to recurrence) for both groups was compared. RESULTS: Forty-eight familial cases were compared with 144 age-, gender-, and stage-matched controls. Patients with FNMTC had a significantly shorter disease-free survival compared with sporadic non medullary thyroid cancer. Patients with FNMTC who presented with evidence of distant metastasis, or who were from families with more than 2 thyroid cancer-affected members, had the worst prognosis. The available staging systems were less likely to predict the outcome in patients with FNMTC than in patients with sporadic non-medullary thyroid cancer unless one accounted for the strength of family history in the staging system. CONCLUSIONS: FNMTC is more aggressive than sporadic non-medullary thyroid cancer. The best predictors of a poor outcome in patients with FNMTC are the number of family members affected by thyroid cancer and evidence of distant metastasis.
PURPOSE: Cyclosporine (CSA) toxicity represents a common cause of seizures in transplant patients, but the specific mechanisms by which CSA induces seizures are unknown. Although CSA may promote seizure activity by various metabolic, toxic, vascular, or structural mechanisms, CSA also has been hypothesized to modulate neuronal excitability directly. The objective of this study was to determine if CSA exerts direct epileptogenic actions on neurons in an in vitro seizure model. METHODS: Combined hippocampal-entorhinal cortex slices from juvenile rats were exposed directly to artificial cerebrospinal fluid (ACSF) containing either (a) 1.0 mM magnesium sulfate (control), (b) 1.0 mM sodium sulfate (low-magnesium), or (c) 1.0 mM magnesium sulfate + CSA (1,000-10,000 ng/ml). Spontaneous and evoked extracellular field potentials were recorded simultaneously from the dentate gyrus (DG) and CA3 hippocampal regions. Evoked synaptic responses were elicited by stimulation of the entorhinal cortex/perforant pathway. RESULTS: CSA elicited spontaneous or stimulation-induced epileptiform activity in the DG or CA3 region of approximately 40% of slices, consisting of brief repetitive "interictal" discharges or prolonged stereotypical "ictal" discharges. Mean latency to epileptiform activity was approximately 100 min after onset of CSA application. The interictal discharges were inhibited by the non-NMDA antagonist, NBQX. Similar epileptiform activity was observed in low-magnesium ACSF without CSA. In control ACSF alone, epileptiform activity was not seen, except for rare spontaneous potentials in the DG. CONCLUSIONS: Direct effects of CSA on neuronal excitability and synaptic transmission may contribute to seizures seen in clinical CSA neurotoxicity.
PURPOSE: As a preliminary step in the development of an implantable Peltier device to abort focal neocortical seizures in vivo, we have examined the effect of rapid cooling on seizures in rodent hippocampal-entorhinal slices. METHODS: Seizure-like discharges were induced by exposing the slices to extracellular saline containing 4-aminopyridine (50 micromol/L). RESULTS: When we manually activated a Peltier device that was in direct contact with the slice, seizures terminated within seconds of the onset of cooling, sometimes preceding a detectable decrease in temperature measured near the top of the slice. However, activation of the Peltier device did not stop seizures when slices were no longer in direct physical contact with the device, indicating that this was not a field effect. When cooling was shut off and temperature returned to 33 degrees C, bursting sometimes returned, but a longer-term suppressive effect on seizure activity could be observed. In two of our experiments, a custom computer program automatically detected seizure discharges and triggered a transistor-transistor logic pulse to activate the Peltier device. In these experiments, the Peltier device automatically terminated the slice bursting in less than 4 seconds. When the Peltier device was placed in contact with the normal, exposed cortex of a newborn pig, we found that the cortical temperature decreased rapidly from 36 degrees C to as low as 26 degrees C at a depth of 1.7 mm below the cooling unit. CONCLUSIONS: These experiments show that local cooling may rapidly terminate focal paroxysmal discharges and might be adapted for clinical practice.
Candida dubliniensis is an opportunistic fungal pathogen that has been linked to oral candidiasis in AIDS patients, although it has recently been isolated from other body sites. DNA sequence analysis of the internal transcribed spacer 2 (ITS2) region of rRNA genes from reference Candida strains was used to develop molecular beacon probes for rapid, high-fidelity identification of C. dubliniensis as well as C. albicans. Molecular beacons are small nucleic acid hairpin probes that brightly fluoresce when they are bound to their targets and have a significant advantage over conventional nucleic acid probes because they exhibit a higher degree of specificity with better signal-to-noise ratios. When applied to an unknown collection of 23 strains that largely contained C. albicans and a smaller amount of C. dubliniensis, the species-specific probes were 100% accurate in identifying both species following PCR amplification of the ITS2 region. The results obtained with the molecular beacons were independently verified by random amplified polymorphic DNA analysis-based genotyping and by restriction enzyme analysis with enzymes BsmAI and NspBII, which cleave recognition sequences within the ITS2 regions of C. dubliniensis and C. albicans, respectively. Molecular beacons are promising new probes for the rapid detection of Candida species.