Clinical impacts of the rapid diagnostic method on positive blood cultures

OBJECTIVE

This study aimed to evaluate the impact of short-term incubation (STI) protocol on clinical outcomes of bloodstream infection (BSI) patients.

METHODS

A total of 1363 positive blood culture records from January 2019 to December 2021 were included. The main clinical outcomes included pathogen identification turnaround time (TAT), antimicrobial susceptibility testing (AST) TAT, and length of total hospital stay.

RESULTS

The TAT of pathogen identification and AST significantly decreased after implementing the STI protocol (2.2 vs 1.4 days and 3.4 vs 2.5 days, respectively, with P < .001 for both). Moreover, for patients with Gram-negative bacteria (GNB)-infected BSIs, the length of total hospital stay decreased from 31.9 days to 27.1 days, indicating that these patients could be discharged 5 days earlier after implementing the STI protocol (P < .01).

CONCLUSION

The protocol led to a significant reduction in TAT and improved clinical outcomes, particularly for GNB organisms. The findings suggest that the STI protocol can improve patient outcomes and hospital resource utilization in the management of BSIs.

Sodium sulfate addition increases the bioresource of biologically active sulfated polysaccharides from Antrodia cinnamomea

Fungal sulfated polysaccharides (SPS) have been used in the pharmaceutical industry. In this study, sodium sulfate was employed as an elicitor to induce stress on the mycelia of Antrodia cinnamomea for the biosynthesis of SPS with high sulfate content. Sodium sulfate treatments increased the yield of SPS to 4.46 % and increased the sulfate content to 6.8 mmol/g of SPS. SPS were extracted from A. cinnamomea cultured with 500 mM sodium sulfate; these SPSs are denoted as Na500. Na500 exhibited the highest sulfate content and dose-dependent inhibitory activity against LPS-induced production of macrophage interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and interleukin 1β (IL-1β). Mechanistically, Na500 hindered the phosphorylation of transforming growth factor-β receptor II (TGFRII), extracellular signal-regulated kinases (ERK), and protein kinase B (AKT) expression. A purified 7.79 kDa galactoglucan, Na500 F3, augmented the anti-inflammation activity by inhibiting LPS-induced TGFβ release. Additionally, Na500 F3 restrained the LPS-induced phosphorylation of p-38, ERK, AKT, and TGFRII in RAW264.7 cells. Na500 F3 impeded the proliferation of lung cancer H1975 cells by inhibiting the phosphorylation of focal adhesion kinase, ERK, and Slug. The anti-inflammation and anticancer properties of Antrodia SPS contribute to its health benefits, suggesting its utility in functional foods.

Advanced culture strategy shows varying bioactivities of sulfated polysaccharides of Poria cocos

This study compares the bioactivity of six sulfated polysaccharides derived from glucose- and sucrose-feeding extracted from P. cocos. Anti-inflammatory potentials of these polysaccharides were evaluated by pretreating lipopolysaccharide (LPS)-induced inflammation in RAW264.7 cells. Of the tested polysaccharides, the sulfated polysaccharide derived from sucrose-feeding at the concentration of 40 g/l (referred to as "suc 40") exhibited the highest anti-inflammatory activity, of 83 %, and 33 % inhibition of IL-6 and TNF-α secretion, respetively. It achieved this by inhibiting the p-38 and c-Jun N-terminal kinase (JNK) MAPK signaling pathways. On the other hand, the sulfated polysaccharide derived from glucose-feeding at a concentration of 20 g/l (referred to as "glc 20") demonstrated the greatest anti-lung cancer activity. This was achieved by inducing apoptotic-related molecules, such as poly (ADP-ribose) polymerase (PARP) and CHOP. Furthermore, glc 20 had the highest contents of sulfate, fucose, and mannose compared to the other tested polysaccharides. This suggests that the composition of monosaccharide residues are critical factors influencing the anti-inflammatory and anti-cancer activities of these sulfated polysaccharides. Overall, this study highlights the potential of sulfated polysaccharides derived from P. cocos to function as bioactive compounds with anti-inflammatory and anti-cancer properties.

A branched 2-O sulfated 1,3-/1,4-galactoglucan from Antrodia cinnamomea exhibits moderate antiproliferative and anti-inflammatory activities

A sulfated galactoglucan (3-SS) was discovered in Antrodia cinnamomea with antiproliferative and anti-inflammatory activities. Chemical identification of 3-SS resulted in the determination of a partial repeat unit as a 2-O sulfated 1,3-/1,4-linked galactoglucan with a two-residual 1,6-O-β-Glc branch on the 3-O position of a Glc. by monosaccharide analysis and 1D and 2D NMR spectroscopy. The anti-inflammation effects of 3-SS on RAW264.7 macrophage cells, such as IL-6 inhibition, restoration of LPS-induced IκB protein degradation, and inhibited LPS-induced TGFRII protein degradation, were confirmed to occur via AKT, ERK1/2, and p-38. In addition, 3-SS impaired the proliferation of H1975 lung cancer cells through EGFR/ERK/slug signaling. This is the first finding of 2-O sulfated 1,3-/1,4-galactoglucan with 1,6-β-Glc branches with dual functions of anti-inflammatory and antiproliferative activities.

SPS, a sulfated galactoglucan of Laetiporus sulphureus, exhibited anti-inflammatory activities

Laetiporus sulphureus is an edible and medicinal mushroom. A sulfated galactoglucan (SPS) was isolated by the papain method. Polysaccharides (PS) were isolated by hot water and ethanol precipitation. The medium molecular weight SPS of 100 to 1000 kDa accounted for over half of the SPS mixture. Fucose, galactose, glucose, and mannose were the major monosaccharides in SPS and PS. The amount of sulfate in SPS was 1.09 mmol/g. SPS showed inhibition of tumor necrosis factor-α (TNF-α) release and reversed IκB degradation in LPS-induced RAW264.7 macrophages. The suppression of TNF-α secretion by SPS was through inhibiting the phosphorylation of AKT/extracellular signal-regulated kinases (ERK), p38, and c-Jun N-terminal kinase (JNK). A purified SPS, named SPS-3, was proven to inhibit the LPS-induced phosphorylation of AKT, ERK, and p-38 in RAW264.7 cells. The suppression of interleukin 6 (IL-6) and transforming growth factor beta (TGFβ) secretion by PS was through inhibiting LPS-induced phosphorylation of p-38 and TGF-β receptor II (TGFRII) signaling pathways. This study demonstrates that the isolated SPS and PS from L. sulphureus possessed good anti-inflammatory activity for dietary supplements and functional food.

Structural changes, and anti-inflammatory, anti-cancer potential of polysaccharides from multiple processing of Rehmannia glutinosa

Polysaccharides play important roles in the bioactivities of Rehmannia glutinosa. This study examined the physiochemical structure and biological activity of the polysaccharides of R. glutinosa during nine steps of processing. Characteristic study showed galactose, glucose, and fructose were the major sugars in the polysaccharides. The percentage of the high-molecular weight polysaccharide increased after processing. In addition, polysaccharides from repeated steam and dry processing of R. glutinosa can effectively increase the anti-inflammatory activity. Secretions of tumor necrosis factor (TNF-α), interleukin (IL)-6, and transforming growth factor (TGF)β after lipopolysaccharide (LPS) stimulation were detected in RAW264.7 macrophages because of its anti-inflammatory activity. RG-B9, a polysaccharide of the ninth steam and dry processing, showed the strongest inhibitory activity on bacterial LPS-induced macrophage IL-6 and TGFβ production. Mechanically, RG-B9 down-regulated the phosphorylation of AKT/ERK. The anti-inflammation of RG-B9 involved AKT/ERK/JNK signaling. In addition, RG-B9 inhibited the viability of lung cancer cells via EGFR/AKT signaling.

Defining a Role for G-Protein Coupled Receptor/cAMP/CRE-Binding Protein Signaling in Hair Follicle Stem Cell Activation

Manipulation of adrenergic signaling has been shown experimentally and clinically to affect hair follicle growth. In this study, we provide direct evidence that canonical cAMP/CRE-binding protein signaling through adrenergic receptors can regulate hair follicle stem cell (HFSC) activation and hair cycle. We found that CRE-binding protein activation is regulated through the hair cycle and coincides with HFSC activation. Both isoproterenol and procaterol, agonists of adrenergic receptors, show the capacity to activate the hair cycle in mice. Furthermore, deletion of ADRB2 receptor, which is thought to mediate sympathetic nervous system regulation of HFSCs, was sufficient to block HFSC activation. Downstream, stimulation of adenylyl cyclase with forskolin or inhibition of phosphodiesterase to increase cAMP accumulation or direct application of cAMP was each sufficient to promote HFSC activation and accelerate initiation of hair cycle. Genetic induction of a Designer Receptors Exclusively Activated by Designer Drug allele showed that G-protein coupled receptor/GαS stimulation, specifically in HFSCs, promoted the activation of the hair cycle. Finally, we provide evidence that G-protein coupled receptor/CRE-binding protein signaling can potentially act on HFSCs by promoting glycolytic metabolism, which was previously shown to stimulate HFSC activation. Together, these data provide mechanistic insights into the role of sympathetic innervation on HFSC function.

Effect of carbohydrate-feeding strategy on the production, physiochemical changes, anti-inflammation activities of polysaccharides of Poria cocos

The aim of this research was to physiochemically characterize the structure and study the pharmaceutical benefits of the polysaccharide (PS) produced by Poria cocos using two selected carbohydrates (sucrose, and potato dextrose broth) in the in vitro culture system. A direct dosage effect was shown as sucrose- or PDB-based medium on the PS yield of Paragalago cocos. Very low-molecular-weight PS (<1 kDa) were largely synthesized by sucrose and PDB feeding. Sucrose-feeding mycelia of P. cocos results in a direct dosage effect in the fructose component in the PS. Sucrose and PDB feeding increased the glucose content but decreased the galactose content of PS. This study examined the anti-inflammatory activities of PS in lipopolysaccharide (LPS)-induced RAW264.7 macrophages. At 100 μg/mL and 50 μg/mL, PS from 10 g/L PDB- treatment, denoted as PDB 10, pretreatment showed maximal inhibition of TNF-α and IL-6 release, respectively. Mechanically, PDB10 attenuated IκB from degradation in LPS-induced macrophages, and down-regulated LPS-induced phosphorylation of ERK/AKT/p-38. PDB10 showed dose-dependent inhibition of the LPS induced TGFRII signaling pathways.

Structural sequencing and anti-inflammatory, anti-lung cancer activities of 1,4-α/β-sulfomalonoglucan in Antrodia cinnamomea

Antrodia cinnamomea is a precious Polyporaceous fungus with various bioactivities. This study reports the chemical identification and biological activities of sulfomalonoglucan, a sulfated polysaccharide (SPS), from the sodium sulfate enriched medium of the title fungus. The SPS-containing fraction was separated by gel filtration chromatography (GFC) to give the title SPS (denoted as Na10_SPS-F3). By analyzing the evidence for key inter-glycosidic linkages in the 1D and 2D NMR spectroscopic data, one possible repeat unit was proposed as: Na10_SPS-F3 inhibited the secretion of tumor necrosis factor (TNF-α) and interleukin (IL)-6 after lipopolysaccharide (LPS) stimulation in RAW264.7 macrophages. Mechanistically, Na10_SPS-F3 downregulated TGFRII also attenuated the LPS-induced IκB-α degradation. Moreover, Na10_SPS-F3 inhibited lung cancer cell H1975 EGFR/ERK signaling. This is the first paper reporting a 3-O-sulfomalonyl glucan (Na10_SPS-F3) with eight 1,4-β-Glc moieties connected with ten 1,4-α-Glc moieties from Antrodia cinnamomea and its anti-inflammatory and anti-cancer activities.

Production, characterization, and functions of sulfated polysaccharides from zinc sulfate enriched cultivation of Antrodia cinnamomea

This research utilized zinc sulfate enriched cultural conditions to produce sulfated polysaccharides from Antrodia cinnamomea (denoted as ZnFSPS) and physiochemically characterize functional and mechanical investigations of ZnFSPS. The maximum SPS yield reached a value of 6.68% when A. cinnamomea was fed zinc sulfate with 250 mM (denoted as Zn250). Zn250 had a maximal inhibitory effect on LPS-induced tumor necrosis factor (TNF-α) release in RAW264.7 macrophage. Zn250 contained the highest area percentage of molecular weight of 178.5, 105.1, and 1.56 kDa at values of 19.08, 15.09, and 5.04. Zn250 contained three times the sulfate content as compared with the control. Mechanism studies revealed a novel finding that Zn250 inhibited the LPS-induced RAW264.7 macrophage inflammation and selectively blocked pAKT, pERK and p38. Zn250 also attenuated the LPS-induced IkB-α degradation. In addition, ZnFSPS interfered with lung cancer cell H1975 TGFRI/FAK/Slug signaling. These results suggest ZnFSPS plays roles in regulating inflammatory and anti-lung cancer activity.

Comparison of knee biomechanical characteristics during exercise between pinnacle and step trainers

BACKGROUND

A novel stair-climber called a pinnacle trainer (PT) provides both sagittal and frontal plane exercise, making it different from a step trainer (ST), which provides only sagittal plane exercise. Exercise with different trajectories may produce different biomechanical responses. There are currently no guidelines for choosing between a PT and a ST for different training or rehabilitation purposes.

RESEARCH QUESTIONS

Are there differences in the electromyographic patterns of lower extremity musculature and biomechanical responses of the knee joint during exercise between using a PT and a ST?

METHODS

This study utilizes a prospective observational study design. Eighteen healthy males participated in the study. A six-axis force and torque transducer embedded in the machine pedal synchronized with a three-dimensional motion capture system were utilized to measure kinematic and kinetic data of the right knee during the stepping movement. The activities of six lower extremity muscles of the same limb were captured with surface electromyography during exercise on the two trainer types.

RESULTS

The co-activation index of the vastus lateralis (VL) and the biceps femoris (BF) recorded during ST exercise was significantly greater than that for the PT exercise. Moreover, exercise using the ST produced a significantly greater knee downward force compared to that for the PT. Exercise with the PT produced a significantly greater internal knee varus moment compared to that for the ST.

SIGNIFICANCE

The ST provided greater co-activation of the BF and VL and a greater knee joint downward force, which may decrease the antero-posterior displacement of the tibia relative to the femur. Exercise with the PT produced a significant internal knee varus moment and a more balanced muscular activation on the vastus medialis and VL compared to that for the ST, which may decrease the maltracking of the patella.

Risk of post-contrast acute kidney injury in emergency department patients with sepsis

INTRODUCTION

Although computed tomography (CT) is a useful tool for exploring occult infection in patients with sepsis in the emergency department, the potential nephrotoxicity of contrast media is a major concern. Our study aimed to investigate the association between use of contrast-enhanced CT and the risks of acute kidney injury and other adverse outcomes in patients with sepsis.

METHODS

In total, 587 patients with sepsis who underwent CT scan (enhanced CT group: 105, non-enhanced CT group: 482) from January 2012 to December 2016 at a tertiary referral centre were enrolled in this retrospective analysis, and propensity score matching was performed to minimise the selection bias. The length of stay, incidences of acute kidney injury and emergent dialysis, and short-term mortality were compared between the two groups.

RESULTS

Compared with patients in the non-enhanced CT group, patients in the contrast-enhanced CT group did not have increased risks of acute kidney injury (odds ratio [OR]=1.38, 95% confidence interval [CI]=0.55-3.43; P=0.489), emergent dialysis (OR=1.31, 95% CI=0.47-3.68; P=0.602), or short-term mortality (OR=0.90, 95% CI=0.48-1.69; P=0.751). In addition, there was no significant difference in the median length of hospital stay between survivors in the two groups (20 vs 19 days, P=0.742).

CONCLUSIONS

Intravenous contrast administration during CT scanning was not associated with prolonged length of hospital stay in patients with sepsis in an emergency setting. Moreover, the use of contrast-enhanced CT was not associated with increased risks of acute kidney injury, emergent dialysis, or short-term mortality.

P5388N-cadherin promotes cardiac regeneration by stabilizing beta-catenin

Background

Although the adult mammalian heart fails to regenerate after injury, it is known that newborn mice within a week have full cardiac regenerative capacity. The molecular determinants underlying the disparate regenerative capacity between neonatal and adult mice, however, remain incompletely understood. Exploiting RNA sequencing in isolated cardiomyocytes from neonatal and adult mouse heart, we identified Cdh2, which encodes the adherence junction protein N-cadherin, as a potential novel mediator of cardiac regeneration. Cdh2 expression levels were much higher in neonatal, compared with adult, cardiomyocytes and showed a strong positive correlation with that of multiple cell cycle genes. N-cadherin has been reported to be essential for embryonic cardiac development; its role in cardiac regeneration, however, remains unknown.

Purpose

To determine the role of Cdh2 (N-cadherin) in cardiac regeneration and to investigate the underlying molecular mechanisms.

Methods

Apical resection in postnatal day 1 mice was used as a cardiac regenerative model. The in vitro gain/loss-of function studies of Cdh2/N-cadherin was performed in postnatal day 1 neonatal mouse cardiomyocytes (P1CM) and human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM). N-cadherin inhibitor exherin was used to study the effects of N-cadherin in vivo.

Results

Comparing to sham-operated control, Cdh2 was significantly upregulated in mouse cardiac apex and border zone following apical resection, which was accompanied with increased cardiomyocyte proliferation activity. In vitro, knocking down Cdh2 or inhibition of N-cadherin activity with exherin in P1CM significantly reduced the proliferative activity of cardiomyocytes, whereas overexpression of Cdh2 markedly increased the proliferation of P1CM. In addition, forced expression of Cdh2 resulted in significant upregulation of multiple cell cycle genes, including Ccnd1 (Cyclin D1) and Pcna (proliferating cell nuclear antigen), in P1CM. In vivo inhibition of N-cadherin in P1 neonatal mice with exherin following apical resection impaired cardiac regeneration and increased scar formation (Figure). Knocking down CDH2 in human iPSC-CMs significantly reduced the proliferative activity and the expression levels of cell cycle gene CCND1 in iPSC-CMs. Mechanistically, we demonstrated that the pro-mitotic effects of N-cadherin in cardiomyocytes were mediated, at least partially, by stabilizing β-catenin, a pro-mitotic transcription factor, through direct interaction with its cytoplasmic domain and/or inactivation of GSK3β, a critical component of β-catenin destruction complex.

N-Cad blocker impairs heart regeneration

Conclusion

Our study uncovered a previously unrecognized role of Cdh2 (N-cadherin) in cardiomyocyte proliferation and cardiac regeneration. Enhancing cardiac expression or activity of N-cadherin, therefore, could be a potential novel therapeutic approach to promote cardiac regeneration and restore cardiac function in adult heart following injury.

Spin-splitting calculation for zincblende semiconductors using an atomic bond-orbital model

We develop a 16-band atomic bond-orbital model (16ABOM) to compute the spin splitting induced by bulk inversion asymmetry in zincblende materials. This model is derived from the linear combination of atomic-orbital (LCAO) scheme such that the characteristics of the real atomic orbitals can be preserved to calculate the spin splitting. The Hamiltonian of 16ABOM is based on a similarity transformation performed on the nearest-neighbor LCAO Hamiltonian with a second-order Taylor expansion k at the Γ point. The spin-splitting energies in bulk zincblende semiconductors, GaAs and InSb, are calculated, and the results agree with the LCAO and first-principles calculations. However, we find that the spin-orbit coupling between bonding and antibonding p-like states, evaluated by the 16ABOM, dominates the spin splitting of the lowest conduction bands in the zincblende materials.

Current development and patents on high-brightness white LED for illumination

In this paper, we reviewed the current development and patents for the application of high-brightness and high-efficiency white light-emitting diode (LED). The high-efficiency GaN nanostructures, such as disk, pyramid, and rod were grown on LiAlO(2) substrate by plasma-assisted molecular-beam epitaxy, and a model was developed to demonstrate the growth of the GaN nanostructures. Based on the results, the GaN disk p-n junction was designed for the application of high brightness and high efficiency white LED.

Hoffa fracture: should precautions be taken during fixation and rehabilitation?

A coronal fracture of a femoral condyle (Hoffa fracture) is an unusual injury and there are only a handful of reports discussing it. We report a case of a 52-year-old worker who fell from a height, suffering lower limb injuries, including a Hoffa fracture with comminution, and had problems with malunion during the postoperative period. Clinicians should be aware that rehabilitation programmes need to be tailored to the method of fixation used to manage this uncommon fracture pattern.

Effects of passivation treatments on titanium alloy with nanometric scale roughness and induced changes in fibroblast initial adhesion evaluated by a cytodetacher

Passivation treatments of titanium alloy alter not only its nanosurface characteristics of oxides and ion release but also surface roughness (Ra), and wettability as well, where nanosurface characteristics of oxides include chemistries of oxides, amphoteric-OH groups adsorbed on oxides, and oxide thickness. Consequently, the passivation treatment affects the alloy's cyto-comparability. In this study, we polish specimens to achieve nanometric scale roughness. In addition, treatment effects are evaluated for surface topology, roughness, wettability, and responses of fibroblasts consisting of MTT assay, initial adhesion strength, and morphology. The initial adhesion strength is measured using a cyto-detacher that achieves nano-Newton resolution. Results reveal that (1) the treatment effects on the percentage of Ti--OH basic groups and wettability are nearly collinear; (2) the Ra of passivated Ti-6Al-4V ranges from 1.9 to 7.4 nm; (3) the initial adhesion strength of fibroblast ranges from 58 to 143 nN, and it is negatively correlated to the Ra; (4) the passivation results in distinguishable morphologies, which further substantiate the negative correlation between cell initial adhesion force and Ra; and (5) our results fall short of confirming previous reports that found positively charged functional groups promoting fibroblast attachment and spread. Potential causes of the inconsistency are addressed.

Effects of nano-surface properties on initial osteoblast adhesion and Ca/P adsorption ability for titanium alloys

Titanium alloys (Ti6Al4V), while subjected to high temperature surface treatment, experience altered nano-surface characteristics. The effects of such surface treatments are examined, including the initial adhesion force experienced by osteoblasts, the Ca/P adsorption capability, and the nano-surface properties, including the amounts of amphoteric Ti-OH groups, surface topography, and surface roughness. The initial adhesion force is considered a quantitative indicator of cyto-compatibility in vitro. Previously, a cyto-detacher was applied in a pioneer attempt measuring the initial adhesion force of fibroblasts on a metal surface. Presently, the cyto-detacher is further applied to evaluate the initial adhesion force of osteoblasts. Results reveal that (1) titanium alloys subjected to heat treatment could promote the adsorption capability of Ca and P; (2) titanium alloys subjected to heat treatment could have higher initial osteoblast adhesion forces; (3) the adhesion strength of osteoblasts, ranging from 38.5 to 58.9 nN (nanonewtons), appears stronger for rougher surfaces. It is concluded that the heat treatment could have impacted the biocompatibility in terms of the initial osteoblast adhesion force and Ca/P adsorption capability.

Antibiotic-loaded cement articulating spacer for 2-stage reimplantation in infected total knee arthroplasty: a simple and economic method

We presented a simple and economic method of preparing articulating antibiotic-loaded cement spacers for treatment of infection after total knee arthroplasty. From 1996 to 2004, 28 infected total knee arthroplasties were treated with 2-stage reimplantation. Static spacers were used in 7 knees, and articulating spacers were used in 21 knees. A minimum of 2 years' follow-up after final treatment was evaluated. In the static group, 1 (14%) knee had recurrence of infection. In the articulating group, 2 (9%) knees had recurrence of infection with the original organism. Patients receiving articulating spacer had better range of motion, better knee score, and less bone loss than patients with static spacer.

Magnolol protects against cerebral ischaemic injury of rat heatstroke

1. Free radicals mediate cerebral ischaemic injury associated with heatstroke. Magnolol, an active component of Magnolia officinalis, is 1000-fold more potent than alpha-tocopherol in inhibiting lipid peroxidation in rat mitochondria. The aim of the present study was to ascertain whether magnolol attenuated cerebral ischaemic injury and free radical formation associated with heatstroke. 2. Urethane-anaesthetized rats were exposed to heat stress (ambient temperature 42 degrees C) to induce heatstroke. Controlled rats were exposed to 24 degrees C. Mean arterial pressure, cerebral perfusion pressure and cerebral blood flow after the onset of heatstroke were all significantly lower than in control rats. However, colonic temperature, intracranial pressure, heart rate, cerebral free radicals, lipid peroxidation and the neuronal damage score were greater after the onset of heatstroke. 3. Magnolol (20 or 40 mg/kg, i.v.) significantly attenuated the heatstroke-induced hyperthermia, arterial hypotension, intracranial hypertension, cerebral ischaemia and neuronal damage and increased free radical formation and lipid peroxidation in the brain. The extracellular concentrations of ischaemic (e.g. glutamate and lactate/pyruvate ratio) and damage (e.g. glycerol) markers in the corpus striatum were increased after the onset of heatstroke. Magnolol significantly attenuated the increase in striatal ischaemia and damage markers associated with heatstroke. 4. Thus, it appears that magnolol has impressive effects against heatstroke reactions.

Consumption of flea faeces and eggs by larvae of the cat flea, Ctenocephalides felis

The effects of the consumption of flea faeces and non-viable eggs on larval development in the cat flea Ctenocephalides felis (Bouché) (Siphonaptera: Pulicidae) were investigated. Only 13.3% of larvae developed into adults when fed a diet of male or female flea faeces alone; however, 90% of larvae developed into adults when fed on flea faeces supplemented with non-viable flea eggs. When fed with non-viable eggs alone, larvae did not develop into adults. Nevertheless, non-viable eggs may provide critical supplemental nutrients, lacking in flea faeces and required for larval development. None of the larvae fed on flea faeces or non-viable eggs alone formed a cocoon. A diet of flea faeces alone significantly extended the second as well as third larval stadia compared to larvae fed on diets containing non-viable eggs. It is suggested that the cannibalism of fertile eggs may limit population growth in the cat flea.

Fluoroalkylated polyethylene glycol as potential surfactant for perfluorocarbon emulsion

So far, perfluorocarbon (PFC) emulsions have been manufactured based mainly on two surfactants, Pluronic F-68 and egg yolk phospholipids (EYP) for clinical use. However, they have been documented to induce inflammatory or allergic responses when PFC emulsions were injected into human bloodstream. The cause of these side effects is associated with the phagocytosis of emulsified PFC microparticles by cells such as macrophages. In order to lessen the side effects, it is logic to develop surfactants, which are more phagocytosis-resistant and biocompatible. In this study, a perfluoroalkylated polyethylene glycol (R(F)-PEG) surfactant was synthesized by reacting perfluorooctanoyl chloride (C7F15COCl) with PEG of molecular weigh 8000. Both R(F)-PEG 8000 and EYP were used to make PFC emulsions separately by an ultrasonic homogenizer. Individual PFC emulsions were then incubated with mouse macrophage J774A.1 cells to examine the degree of phagocytosis. From microscopic observation of cell morphology, our results showed that the process of phagocytosis was retarded to a large extend using the R(F)-PEG surfactant. We also harnessed 19F-NMR to quantitatively detect the amount of PFC emulsions phagocytosed by J774A.1 cells. 19F-NMR result was consistent with the qualitative microscopic observation aforementioned.

The distinct roles that Gln-192 and Glu-217 of factor IX play in selectivity for macromolecular substrates and inhibitors

In this paper, we report functional characterization of positions 192 and 217 (chymotrypsinogen numbering system) in human factor IX and discuss the distinction and similarity of these two sites among the blood coagulation factors. Recombinant factor IXQ192E (residue glutamine at position 192 replaced by glutamic acid), IXQ192K, IXE217D, and IXE217R proteins exhibited 11%, 46%, 39%, and 2% of the wild-type factor IX's clotting activity, respectively. Binding of these variants to factor VIIIa (FVIIIa) was inefficient compared to that of wild-type factor IX, and the dissociation constants doubled for IXQ192E, 3-fold higher for IXQ192K and 4-fold higher for both IXE217D and IXE217R. In the presence of FVIIIa, all variant factor IX hydrolyzed factor X at the catalytic efficiencies correlating with respective clotting activities. However, FVIIIa greatly enhanced the catalytic efficiency of both IXE217 variants to a greater extent (approximately 7 x 10(4)-fold) as compared to its effect on the wild-type factor IXa and the other two IXQ192 variants [by a factor of (1-2) x 10(4)]. Moreover, while both IXQ192 variants demonstrated small substrate selectivity similar to that of wild-type factor IXa, the selectivity of both IXE217 variants was greatly altered. Mutations at position 192 disturbed the interaction of factor IXa with physiological inhibitors. Although all variants formed an SDS-stable complex with antithrombin III (ATIII) equally well in the presence of heparin and were readily inhibited by ATIII in the absence of heparin, activated IXQ192K exhibited a slower stable complex formation with ATIII without heparin. On the other hand, only IXQ192E showed decreased interaction with TFPI. Our results demonstrate that positions 192 and 217 play different roles unique to factor IX in specifying the interaction of factor IX with substrates and inhibitors.

Postoperative 6-month and 1-year evaluation of health-related quality of life in total hip replacement patients

BACKGROUND AND PURPOSE

During the last decade, health-related quality of life (HRQOL) has been recognized as a principal outcome measure for total hip replacement (THR). However, most THR outcome studies in Taiwan have limited their assessments to the areas of pain relief and physical function. This study examined the effects of THR on quality of life.

METHODS

A longitudinal prospective study design was adopted. A total of 76 THR patients were enrolled. Disease specific (Harris Hip Score) and generic measures (SF-36) were determined before and after surgery. Postoperative evaluations were completed at 6 months and 1 year. Patient characteristics and related medical information were derived from chart data.

RESULTS

Significant improvement was found in HRQOL. This improvement was maintained at both 6-month and 1-year follow-up. Specifically, the mean Harris Hip Score improved from 44.7 to 88.9 at the 6-month postoperative evaluation, and further improved to 91.3 at the 1-year evaluation. In the SF-36, each domain of health status showed a significant improvement at 6-month and 1-year evaluations (p < 0.05 or p < 0.01).

CONCLUSIONS

The results of the Harris Hip Score and the SF-36 showed that THR not only relieved physical pain but also enhanced all aspects of quality of life. In addition to pain relief and improved physical function, improvements in role limitations due to physical or emotional problems were also significant. These findings indicate that a general health survey should be combined with a disease-specific scoring system to assess THR outcome.

Phonological studies of the new gas-induced agitated reactor using computational fluid dynamics

An ozone-induced agitated reactor has been found to be very effective in degrading industrial wastewater. However, the cost of the ozone generation as well as its short residence time in reactors has restricted its application in a commercial scale. An innovated gas-induced draft tube installed inside a conventional agitated reactor was proved to effectively retain the ozone in a reactor. The setup was demonstrated to significantly promote the ozone utilization rate up to 96% from the conventional rate of 60% above the onset speed. This work investigates the mixing mechanism of an innovated gas-induced reactor for the future scale-up design by using the technique of computational fluid dynamics. A three-dimensional flow model was proposed to compute the liquid-gas free surface as well as the flow patterns inside the reactor. The turbulent effects generated by two 45 degrees pitch-blade turbines were considered and the two phases mixing phenomena were also manipulated by the Eulerian-Eulerian techniques. The consistency of the free surface profiles and the fluid flow patterns proved a good agreement between computational results and the experimental observation.

Therapeutic effect of sheng-ji-san on pressure ulcers

In the present study, the effectiveness of sheng-ji-san (SJS) in promoting the healing of pressure ulcers was evaluated. Thirty-two patients with pressure ulcers were divided into two groups. The treated group received routine medical care combined with SJS treatment and the control group received only routine medical care. After three weeks, the treated group showed a significant reduction in both surface area and depth grade, while the control group showed no significant change. The reduction ratio of the surface area of the ulcer and the effectiveness ratio for the treated group were significantly higher than for the control group. Multiple Linear Regression Analysis revealed that only the SJS treatment was significantly associated with the reduction of surface area and that the use of SJS could independently explain the observed high effectiveness ratio and a relatively high Odds Ratio of 9.539. These results indicate that SJS is effective in promoting the healing of pressure ulcers and should be considered as an adjuvant to routine therapy.

Diminution of Phagocytosed Perfluorocarbon Emulsions Using Perfluoroalkylated Polyethylene Glycol Surfactant

Perfluorocarbon emulsions have been considered as potential blood substitutes for years due to their high capacity of dissolving respiratory oxygen and carbon dioxide. However, they have been reported to associate with side effects (e.g., flu-like syndrome) after being injected into animal's bloodstream. The cause of these side effects is related to the phagocytosis of perfluorocarbon emulsions by cells (e.g., macrophages). Inspired by the approach of using polyethylene glycol (PEG) to camouflage liposomes, we synthesized a perfluoroalkylated PEG (R(F)-PEG) surfactant to provide steric hindrance for decreasing phagocytosis of perfluorocarbon emulsions. The R(F)-PEG surfactant along with Pluronic F-68 and egg yolk phospholipid mediated perfluorocarbon emulsions were incubated individually with J774A.1 macrophages to examine the degree of phagocytosis. 19F NMR studies were used to quantitatively determine the amount of perfluorocarbon emulsions phagocytosed by macrophages. Results showed that the degree of phagocytosis was diminished to a large extent for perfluorocarbon microparticles emulsified by the R(F)-PEG surfactant.

Folate depletion and elevated plasma homocysteine promote oxidative stress in rat livers

This study was designed to determine whether nutritional folate depletion exerts hepatic oxidative stress in relation to elevated plasma homocysteine. To mimic various extents of folate depletion status in vivo, male Wistar rats were fed an amino acid-defined diet containing either 8 (control), 2, 0.5, or 0 mg folic acid/kg diet. After a 4-wk feeding period, the plasma and hepatic folate concentrations of the rats decreased significantly with each decrement of dietary folate. Folate depletion did not significantly affect two major liver antioxidants: reduced glutathione and alpha-tocopherol. Conversely, folate depletion decreased Cu-Zn superoxide dismutase and glutathione peroxidase activities, but had no effect on catalase activity in liver homogenates. Lipid peroxidation products, as measured by thiobarbituric acid-reactive substances, were significantly higher in livers of folate-depleted rats than in those of the controls. This occurrence of hepatic oxidative stress in folate-depleted rats was confirmed by demonstrating an increased susceptibility of livers of folate-depleted rats to lipid peroxidation induced by additional H2O2 or Fe(2+) treatments compared with the controls. Decreasing dietary folate intake resulted in graded increases in plasma homocysteine concentrations of folate-depleted rats. Elevated plasma homocysteine and decreased plasma and hepatic folate concentrations in folate-depleted rats were all strongly and significantly correlated with increased liver lipid peroxidation (/r/ > or = 0.58, P < 0.0003). These data demonstrate that folate depletion and elevated plasma homocysteine promote oxidative stress in rat livers.

Duck hepatitis B virus expresses a regulatory HBx-like protein from a hidden open reading frame

Duck hepatitis B viruses (DHBV), unlike mammalian hepadnaviruses, are thought to lack X genes, which encode transcription-regulatory proteins believed to contribute to the development of hepatocellular carcinoma. A lack of association of chronic DHBV infection with hepatocellular carcinoma development supports this belief. Here, we demonstrate that DHBV genomes have a hidden open reading frame from which a transcription-regulatory protein, designated DHBx, is expressed both in vitro and in vivo. We show that DHBx enhances neither viral protein expression, intracellular DNA synthesis, nor virion production when assayed in the full-length genome context in LMH cells. However, similar to mammalian hepadnavirus X proteins, DHBx activates cellular and viral promoters via the Raf-mitogen-activated protein kinase signaling pathway and localizes primarily in the cytoplasm. The functional similarities as well as the weak sequence homologies of DHBx and the X proteins of mammalian hepadnaviruses strongly suggest a common ancestry of ortho- and avihepadnavirus X genes. In addition, our data disclose similar intracellular localization and transcription regulatory functions of the corresponding proteins, raise new questions as to their presumed role in hepatocarcinogenesis, and imply unique opportunities for deciphering of their still-enigmatic in vivo functions.

Extracellular polymers of ozonized waste activated sludge

Effect of ozonation on characteristics of waste activated sludge was investigated in the current study. Concentrations of cell-bound extracellular polymers (washed ECPs) did not change much upon ozonation, whereas the sum of cell-bound and soluble extracellular polymers (unwashed ECPs) increased with increasing ozone dose. Washed ECPs in original sludge as divided by molecular weight distribution was 39% < 1,000 Da (low MW), 30% from 1,000 to 10,000 Da (medium MW), and 31% > 10,000 Da (high MW). It was observed that the low-MW fraction decreased, and the high-MW fraction increased in ozonized sludge. The unwashed ECPs were characterized as 44% in low MW, 30% in medium MW, and 26% in high MW. Both low-MW and medium-MW fractions of unwashed ECPs decreased while high-MW fraction increased in ozonized sludge. The dewaterability of ozonized sludge, assessed by capillary suction time (CST) and specific resistance to filtration (SRF), deteriorated with ozone dose. The optimal dose of cationic polyelectrolyte increased with increasing ozone dose. The production rate and the accumulated amount of methane gas of ozonized sludge were also higher.

Tunnel study of on-road vehicle emissions and the photochemical potential in Taiwan

Motor vehicle emission factors of carbon monoxide (CO) and non-methane volatile organic compounds (NMVOCs) were calculated inside the Chung-Cheng Tunnel of Kaohsiung in Taiwan. The results were compared with those model predictions from the Mobile Taiwan 2.0 model. Individual concentrations of 21 species of NMVOCs were also determined. Photochemical potential of NMVOCs was evaluated by using the maximum incremental reactivity (MIR). Field data showed that the integrated emission factors of CO and NMVOCs for actual fleet were 6.3 and 1.5 g/veh km, respectively. The error range of these factors may be up to 45%. The predicted values by the Mobile Taiwan 2.0 model closely matched the observed data. Concentrations of isopentane, 2-methylpentane, toluene and m,p-xylene were the dominant species of NMVOCs. The ratio of maximum incremental reactivity to NMVOCs concentration was 3.9, similar to those of the studies in the US Fort McHenry and Tuscarora Tunnel.

Identification of a new CA dinucleotide repeat in the human factor VIII gene

We describe the identification of a new CA dinucleotide repeat marker for the diagnosis of haemophilia A carriers. The marker (CA-6) is present in intron 6 as a single copy 5 kb upstream of exon 7. Of 195 and 118 X chromosomes from normal individuals and haemophilia A patients, respectively, we observed three alleles of CA-6 with 12-14 repetitions [(CA)(12-14)]. The frequencies were 0.5% and 0% for (CA)(12), 99% and 95.8% for (CA)(13), and 0.5% and 4.2% for (CA)(14) in normals and patients respectively. We conclude that the low polymorphism of the CA-6 marker renders it less useful for the diagnosis of Chinese haemophilia A carriers.

Hierarchical order of critical residues on the immunity-determining region of the Im7 protein which confer specific immunity to its cognate colicin

The directed mutagenesis study of the Im7 protein of colicin E7 revealed that three residues, D31, D35, and E39, located in the loop 1 and helix 2 regions of the protein were critical for initiating the complex formation with its cognate colicin E7. Interestingly, the importance of these three critical residues in conferring specific immunity to its own colicin was exhibited in a hierarchical order, respectively. Moreover, we found that existence of the three critical residues was common among the DNase-type Im proteins. Most likely the three residues of the DNase-type immunity proteins are critical for initiating the unique protein-protein interactions with their cognate colicin. In addition, replacement of the helix 2 of Im7 by the corresponding region of Im8 produced a phenotype of the mutant protein very similar to that of Im8. This result suggests that the DNase-type Im proteins indeed share a "homologous-structural framework" and evolution of the Im proteins may be engendered by minor amino acid changes in this specific immunity-determining region without causing structural alteration of the proteins.

Molecular and electrophysiological characterizations of fGluR3 alpha, an ionotropic glutamate receptor subunit of a teleost fish

Here we report the cloning and functional analysis of a cDNA encoding a functional glutamate receptor subunit of Oreochromis sp., a freshwater teleost fish. The deduced amino acid sequence of this cDNA clone, fGluR3 alpha, displays the highest sequence identity to that of the mammalian GluR3 subunit. Results of quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) analysis indicated that the expression level of fGluR3 alpha in the cerebellum was much less than that in the telencephalon and optical lobe. Similar to its mammalian counterpart, variants of fGluR3 alpha were created by alternative splicing and RNA editing at the R/G site. The channel properties of homomeric fGluR3 alpha expressed in Xenopus oocytes were similar to those of the mammalian alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-preferring receptors. The rank order of agonist potency of the expressed fGluR3 alpha is AMPA > or = glutamate > or = quisqualate > domoate > or = kainate. This is the first functional glutamate receptor of teleost fish being demonstrated to be sensitive to AMPA. Furthermore, this study suggested a strong functional conservation of AMPA-preferring receptors in vertebrates.

Distant metastasis of gastric cancer is associated with elevated expression of the antimetastatic nm23 gene

To understand the clinical significance of nm23 gene expression in gastric cancer patients, the Nm23-H1 protein level of fresh resected specimens from a total of 37 gastric cancer patients was measured by Western blot analysis. The elevated nm23 expression group (Nm23-H1 protein level in tumor tissue greater than the 75th percentile value of patients) was significantly associated with the histologically differentiated type (P = 0.036). This group had a higher incidence of distant (hematogeneous) metastasis (P = 0.0023) and a lower 2-year disease-free survival rate (P = 0.033) than the non-elevated group. The result was not consistent with the previous assumption that nm23 is an antimetastatic gene for gastric cancer.

Mouse and human neuronal pentraxin 1 (NPTX1): conservation, genomic structure, and chromosomal localization

We have previously identified novel members of the pentraxin family (neuronal pentraxin 1 and 2) that are expressed in the nervous system. Neuronal pentraxin 1 (NP1) was identified as a rat protein that may mediate the uptake of synaptic material and the presynaptic snake venom toxin, taipoxin. NP2 was identified as a separate gene discovered by screening for a human homolog for NP1. Here, we report human cDNA and mouse genomic DNA sequences for NP1 (gene symbol NPTX1). Human NP1 and mouse NP1 show 95 and 99% amino acid identity, respectively, with rat NP1 and conserve all potential glycosylation sites. Like rat NP1, human NP1 message is large (6.5 kb) and is exclusively localized to the nervous system. The mouse NP1 gene is 13 kb in length and contains four introns that break the coding sequence of NP1 in the same positions as the introns of the human NP2 gene. The human and mouse NP1 genes are localized to chromosome 17q25.1-q25.2 and chromosome 11e2-e1.3, respectively. These data demonstrate the existence of a separate family of pentraxin proteins that are expressed in the human brain and other tissues and that may play important roles in the uptake of extracellular material.

Isokinetic strength of the quadriceps and hamstrings and functional ability of anterior cruciate deficient knees in recreational athletes

OBJECTIVE

To test the hypothesis that increasing the hamstrings and quadriceps (H:Q) isokinetic strength ratio will, in the short term, improve the functional ability of an anterior cruciate ligament (ACL) deficient knee.

METHODS

The isokinetic muscular characteristics at a speed of 60 degrees s-1 and 180 degrees s-1 of 46 recreational athletes with an arthroscopically confirmed ACL tear were determined using the Cybex II+ isokinetic dynamometer. The variables tested included peak torque, endurance ratio, total work output, and explosive power. Functional ability was scored with the Cincinnati rating system, measuring the severity of pain and swelling, the degree of giving way, and the overall ability to walk, run, ascent and descent stairs, jump and twist.

RESULTS

Among all muscular characteristics, the H:Q ratio at 180 degrees s-1 at 30 degrees of knee flexion was shown to have the highest correlation to the functional score (r = 0.6249, P < 0.001). All variables involving hamstring strength were shown to be significantly correlated to the functional ability score (P < 0.01), while none of the variables involving quadriceps strength showed significant correlation with the functional ability of the injured knee.

CONCLUSIONS

The H:Q ratio is strongly correlated to the functional ability of ACL deficient knees in Chinese recreational athletes. It could be used as an additional measure to guide in the decision making process in the management of ACL deficient knees.

A mutation that allows endosperm development without fertilization

The mechanisms that initiate reproductive development after fertilization are not understood. Reproduction in higher plants is unique because it is initiated by two fertilization events in the haploid female gametophyte. One sperm nucleus fertilizes the egg to form the embryo. A second sperm nucleus fertilizes the central cell to form the endosperm, a unique tissue that supports the growth of the embryo. Fertilization also activates maternal tissue differentiation, the ovule integuments form the seed coat, and the ovary forms the fruit. To investigate mechanisms that initiate reproductive development, a female-gametophytic mutation termed fie (fertilization-independent endosperm) has been isolated in Arabidopsis. The fie mutation specifically affects the central cell, allowing for replication of the central cell nucleus and endosperm development without fertilization. The fie mutation does not appear to affect the egg cell, suggesting that the processes that control the initiation of embryogenesis and endosperm development are different. FIE/fie seed coat and fruit undergo fertilization-independent differentiation, which shows that the fie female gametophyte is the source of signals that activates sporophytic fruit and seed coat development. The mutant fie allele is not transmitted by the female gametophyte. Inheritance of the mutant fie allele by the female gametophyte results in embryo abortion, even when the pollen bears the wild-type FIE allele. Thus, FIE carries out a novel, essential function for female reproductive development.

Human neuronal pentraxin II (NPTX2): conservation, genomic structure, and chromosomal localization

We have previously identified a novel rat neuronal member of the pentraxin family (neuronal pentraxin) that may mediate the uptake of synaptic material and the presynaptic snake venom toxin, taipoxin. Here we report human cDNA and genomic sequences of a second neuronal pentraxin. This pentraxin, which we propose to name neuronal pentraxin II (NPII; gene symbol NPTX2), shows 54% amino acid identity to rat neuronal pentraxin (NPI) with 69% identity over the carboxyl-terminal half of NPI and is 88% identical to a newly identified sperm acrosomal pentraxin p50/apexin. Northern blot analysis reveals that NPII message is present in brain, testis, pancreas, liver, heart, and skeletal muscle, so, unlike NPI, NPII is not exclusively localized to neurons. Like NPI, NPII has potential N-linked glycosylation sites. The human NPII gene is 11 kb in length, contains four introns, and is localized to chromosome 7q21.3-q22.1. These data demonstrate the existence of a family of pentraxin proteins that are expressed in the brain and other tissues and that may play important roles in the uptake of extracellular material.

Studies of cloning, chromosomal mapping, and embryonic expression of the mouse Rab geranylgeranyl transferase beta subunit

The mouse Rab geranylgeranyl transferase beta subunit has been cloned from a mouse E8.5 embryonic cDNA library. Sequence comparison reveals 97.4% sequence identity at the amino acid level to the rat clone isolated from an adult rat brain cDNA library. This gene, given a gene symbol of Rabggtb, is mapped in the distal region of mouse chromosome 3. It is ubiquitously expressed in adult animals but displays an interesting pattern of expression during a specific time of embryonic development. The expression of this gene can be detected in the whole embryos during early embryonic stages and is specifically concentrated in the developing brain, heart, and liver between gestation stages of E11.5 and E13.5. In addition, the expression of this gene is induced by retinoic acid in a mouse embryonal carcinoma cell line, P19.

Congenital biliary tract dilatation in infancy and childhood--74 cases experience

This report presented a twelve-year experience from 1981 to 1992. Seventy-four cases of congenital biliary tract dilatation were at diagnosed an age of 6 days to 16 years. Twenty-two cases were infants. There were 54 females and 20 males. The ratio of female to male was 2.7:1. The classic triad of abdominal pain, jaundice and a palpable mass was seen in eleven cases (14.9%). Most children suffered from abdominal pain (50/74), vomiting (45/74), anorexia (42/74) and jaundice (34/74). Prolonged jaundice was the main symptom in infancy (15/22). A long common pancreatico-biliary channel was seen in six cases (6/47); the bile amylase level was elevated in five cases (5/20), one patient had a complex union with obstructive jaundice. All these cases were diagnosed by preoperative sonography accurately (100%). According to the Todani's classification, type Ia was the most common (40/74), followed by type IV-A (25/74) and type Ic (8/74). Cholelithiasis (13/74), perforation (9/74), and atresia/stenosis of distal choledochus (8/74) were the most common associated conditions. Cyst excision with biliary tract reconstruction was performed in all cases. Reoperation was needed in ten cases. Two cases died postoperatively due to sepsis and cholangitis induced hepatic failure.

Image segmentation of a color-blindness plate

One way of testing color vision is with a color-blindness plate (CBP) consisting of a set of brilliant colored dots to form a pattern (a figure) and a set of other colored dots to form a background. Classification of such a type of color image into a pattern and a background with a traditional technique is difficult. Based on a self-organizing feature map and a labeling process as well as spatial distance computation, an effective approach to the segmentation of a CBP image is presented. We describe the principle of a CBP segmentation and then introduce the CBP. The proposed approach is described, and its experimental results are presented. We conclude that the method can segment the CBP image into a pattern and a background successfully.

Tyrosine residue 719 of the c-kit receptor is essential for binding of the P85 subunit of phosphatidylinositol (PI) 3-kinase and for c-kit-associated PI 3-kinase activity in COS-1 cells

The receptor tyrosine kinase c-kit is thought to mediate its diverse effects on different cell lineages by association and activation of distinct second messenger systems. One of the immediate events after binding of the kit ligand to the receptor is its association with the 85-kDa subunit (p85) of the phosphatidylinositol (PI) 3-kinase and the activation of the enzyme. In the present study, we examined the association and activation of PI 3-kinase with mutant forms of the c-kit receptor transiently expressed in COS-1 cells. To define the binding site of p85 we substituted the putative tyrosine phosphorylation sites in the kinase insert region of the c-kit receptor by phenylalanine (YF702, YF719, YF728, and YF745, respectively). The results indicate that, upon stimulation of cells with kit ligand, 1) the wild-type c-kit protein was readily autophosphorylated and autophosphorylation was not diminished significantly with any of the mutant proteins; 2) p85 and PI 3-kinase activity associated with wild-type c-Kit protein as well as with the mutant proteins YF702, YF728, and YF745. Ligand-induced association of p85 and PI 3-kinase activity were abolished with the YF719 c-Kit protein, and this was not due to different levels of expression of p85 or c-kit; and 3) c-kit receptor-bound p85 was not phosphorylated on tyrosine residues. These results indicate that tyrosine 719 within the 719YMDM motif in the kinase insert plays an important role in binding of p85 and that its phosphorylation is a prerequisite for binding of p85 and the subsequent activation of PI 3-kinase.

The ligand of the c-kit receptor promotes oocyte growth

Both genetic and descriptive studies have implicated the c-kit receptor and its ligand, KL, in the process of oocyte growth in the postnatal mouse ovary. In order to test the hypothesis that KL is an oocyte growth factor, we used an oocyte culture system to study its effects in vitro. Initial experiments established that both ovarian c-kit and KL are biologically active. An immune complex kinase assay demonstrated that ovarian c-kit, found primarily on oocytes, has autophosphorylation activity, and a bone marrow-derived mast cell coculture assay indicated that granulosa cells produce functional KL. The addition of 10 ng/ml KL to growing follicles cultured in collagen gels resulted in a 67% increase in the rate of oocyte growth, and a doubling of the rate was achieved at around 50 ng/ml. ACK2, a monoclonal antibody against c-kit, severely inhibited the growth of late fetal and neonatal oocytes in coculture with ovarian cells and had less effect on growing oocytes cultured in follicles from 10- to 11-day-old mice. Genistein, an inhibitor of tyrosine kinases, including c-kit, blocked oocyte growth and disrupted follicle morphology. In initial studies on the regulation of KL production in granulosa cells, we found that both dibutyryl cyclic AMP and growing oocytes were able to induce increased KL mRNA accumulation in granulosa cell monolayers as assessed by Northern analysis. These studies demonstrate that c-kit and KL are required for maintenance of oocyte growth in vitro.