Carbon recycling with synthetic CO2 fixation pathways

Carbon dioxide (CO2) is the node of alleviating global climate change and supporting living organisms on Earth. Currently, the warming climate and the growing population demand enhanced CO2 fixation for a sustainable future, which stimulates innovations in biotechnology to tackle these challenges. To this endeavor, synthetic biology and metabolic engineering are enabling a promising approach to engineer synthetic carbon fixation in heterotrophic organisms combining the advantages of both autotrophs and heterotrophs. Here, we review the current advances in constructing synthetic CO2 fixation pathways and discuss the underlying design principles with confronting challenges. Moreover, we highlight the application scenarios of these designs at different concentrations of CO2, and how sustainable bioproduction can be improved. We also foresee the future of engineering synthetic carbon fixation pathways for carbon recycling.

[Clinical characteristics of 42 patients with different subspecies of Mycobacterium abscessus complex pulmonary disease]

Objective: To compare clinical features and treatment outcomes of Mycobacterium abscessus (M.abscessus) and Mycobacterium massiliense (M.massiliense) pulmonary disease. Methods: A retrospective analysis was performed for 42 patients diagnosed with M.abscessus complex pulmonary disease for the first time in Guangzhou Chest Hospital from January to September 2021. The age of the 42 patients was 17-73 years, including 15 males and 27 females. According to the targeted next-generation sequencing, the patients were divided into M.abscessus group (28 patients, including 10 males and 18 females) and M. massiliense group (14 patients, including 5 males and 9 females). The clinical characteristics, radiological findings, drug sensitivity and clinical efficacy evaluation at 6 months of the two groups were compared. χ2 test and t-test were used for comparison between two groups. Results: The main symptoms in M. abscessus and M. massiliense groups were cough and sputum production. Radiological findings were significantly more frequent in the M. abscessus group than in the M. massiliense group, tree-in-bud sign [22/28 (78.5%) vs. 5/14], nodular bronchiectasis [27/28 (96.4%) vs. 11/14], and lesions involving more than three lung fields [23/28 (82.1%) vs. 7/14]. Both groups showed high levels of resistance to all antimicrobials. The sensitivity rate of the M. massiliense group to clarithromycin was higher than that of the M. abscessus[13/14 vs. 15/28 (53.5%)], and the success rate of treatment was significantly higher in patients with M. massiliense at the 6-month efficacy evaluation. Conclusions: The radiological findings, drug sensitivity and treatment outcomes differ between M. abscessus and M. massiliense pulmonary disease. Improving the identification of bacterial subspecies in clinical practice can effectively improve the diagnosis and treatment.

Cellular differentiation into hyphae and spores in halophilic archaea

Several groups of bacteria have complex life cycles involving cellular differentiation and multicellular structures. For example, actinobacteria of the genus Streptomyces form multicellular vegetative hyphae, aerial hyphae, and spores. However, similar life cycles have not yet been described for archaea. Here, we show that several haloarchaea of the family Halobacteriaceae display a life cycle resembling that of Streptomyces bacteria. Strain YIM 93972 (isolated from a salt marsh) undergoes cellular differentiation into mycelia and spores. Other closely related strains are also able to form mycelia, and comparative genomic analyses point to gene signatures (apparent gain or loss of certain genes) that are shared by members of this clade within the Halobacteriaceae. Genomic, transcriptomic and proteomic analyses of non-differentiating mutants suggest that a Cdc48-family ATPase might be involved in cellular differentiation in strain YIM 93972. Additionally, a gene encoding a putative oligopeptide transporter from YIM 93972 can restore the ability to form hyphae in a Streptomyces coelicolor mutant that carries a deletion in a homologous gene cluster (bldKA-bldKE), suggesting functional equivalence. We propose strain YIM 93972 as representative of a new species in a new genus within the family Halobacteriaceae, for which the name Actinoarchaeum halophilum gen. nov., sp. nov. is herewith proposed. Our demonstration of a complex life cycle in a group of haloarchaea adds a new dimension to our understanding of the biological diversity and environmental adaptation of archaea.

CO2 bubble-assisted in-situ construction of mesoporous Co-doped Cu2(OH)2CO3 nanosheets as advanced electrodes towards fast and highly efficient electrochemical reduction of nitrate to N2 in wastewater

The development of high-efficient and cost-effective electrocatalysts is crucial to remove nitrate pollutant in wastewater. Herein, we design and prepare mesoporous Co-doped Cu₂(OH)₂CO₃ malachite nanosheets as an electrocatalyst toward highly efficient nitrate reduction using a facile CO₂ bubble-assisted coprecipitation synthesis. The electrocatalytic performance is subject to the Co/Cu ratio of this malachite. Remarkably, compared with the pristine monometal Cu or Co-based electrocatalyst, the optimal electrocatalyst, 0.3Co@Cu₂(OH)₂CO₃, displays fast and highly efficient removal capacity of nitrate with an impressive high total nitrogen (TN) removal of 8628.99 mg N g^-1_CoCu (398.79 mg N g_cat^-1 h^-1), N₂ selectivity of 97.11% as well as negligible nitrite product at 100 mg L^-1 NO₃^--N and 2000 mg L^-1 Cl^- neutral electrolyte. Above all, high total nitrogen removal efficiency (81.92%) and chemical oxygen demand (73.74%) in actual wastewater. Its excellent electrocatalytic performance is achieved by regulating the electronic structure and the adsorption/desorption of the intermediate. This study discovers a new type of electrode materials for nitrate removal in wastewater.

Effects of RAD51-stimulatory compound 1 (RS-1) and its vehicle, DMSO, on pig embryo culture

Pigs have become an important model for agricultural and biomedical purposes. The advent of genomic engineering tools, such as the CRISPR/Cas9 system, has facilitated the production of livestock models with desired modifications. However, precise site-specific modifications in pigs through the homology-directed repair (HDR) pathway remains a challenge. In mammalian embryos, the use of small molecules to inhibit non-homologous end joining (NHEJ) or to improve HDR have been tested, but little is known about their toxicity. The compound RS-1 stimulates the activity of the RAD51 protein, which plays a key role in the HDR mechanism, demonstrating enhancement of HDR events in rabbit and bovine zygotes. Thus, in this study, we evaluated the dosage and temporal effects of RS-1 on porcine embryo development and viability. Additionally, we assessed the effects of its vehicle, DMSO, during embryo in vitro culture. Transient exposure to 7.5 μM of RS-1 did not adversely affect early embryo development and was compatible with subsequent development to term. Additionally, low concentrations of its vehicle, DMSO, did not show any toxicity to in vitro produced embryos. The transient use of RS-1 at 7.5 μM during in vitro culture seems to be the best protocol of choice to reduce the potentially toxic effects of RS-1 while attempting to improve HDR in the pig. Direct injection of the CRISPR/Cas9 system, combined with strategies to increase the frequency of targeted modifications via HDR, have become an important tool to simplify and accelerate the production of genetically modified livestock models.

[The clinical characteristics of 89 cases of non-tuberculous mycobacterium pulmonary disease complicated with tracheobronchial lesions]

Objective: To explore the clinical characteristics of non-tuberculous mycobacterium(NTM) pulmonary disease complicated with tracheobronchial lesions. Methods: From January 2014 to December 2018, there were 1 006 patients who were admitted to Guangzhou Chest Hospital for the first time and received examination by bronchoscopy. A total of 89 patients with complete data were selected, including 40 males and 49 females, aged 20 to 85 years, with 46 patients (52%) aged 60 years or older. The clinical symptoms and signs of the patients were analyzed with chest imaging, bronchoscopy and pathological examination results. Comparisons between groups were made by Chi-square test and t test. Results: The number of patients with NTM complicated with tracheobronchial lesions accounted for 8.9%(89/1 006) of those hospitalized with NTM and received bronchoscopy during the same period. Clinical symptoms included cough and sputum (89/89), different degrees of hemoptysis or blood sputum (52/89), and shortness of breath (50/89). Chest CT showed that 72 cases (72/89, 81%) had lung lesions involving more than 3 lung fields, and 83 cases (93%) had bronchiectasis and 63 cases (63/89, 71%) with cavities. Pulmonary atelectasis was shown in 45 cases (45/89, 51%). By bronchoscopy, 39 cases (39/89, 44%) were diagnosed as tuberculous lesions involving bilateral upper bronchi, while lesions of the right lower bronchus was found in 27 cases (27/89, 30%).The percentage of patients with multilobar bronchial involvement was 50.6%(45/89). The morphological characteristics of the bronchial lesions included scar stenosis or atresia in 63 cases (63/89, 71%), hyperemia and edema in 46 cases (46/89, 52%), and multiple types of lesions in 48 cases (48/89, 54%). Conclusions: Patients with NTM lung disease complicated with tracheobronchial inflammatory lesions did not have specific manifestations clinically. Lung lesions are extensive, often accompanied by bronchiectasis and cavity formation. Endoscopic changes were mostly manifested as multilobar tracheobronchial involvement characterized by scar stenosis, congestion and edema, mainly involving bilateral upper bronchi and the right lower bronchus.

Glycine receptors expression in rat spinal cord and dorsal root ganglion in prostaglandin E2 intrathecal injection models

Background

Glycine receptors (GlyRs) are involved in the development of spinal pain sensitization. The GlyRα3 subunit has recently emerged as a key factor in inflammatory pain pathways in the spinal cord dorsal horn (DH). Our study is to identify the extent of location and cell types expressing different GlyR subunits in spinal cord and dorsal root ganglion (DRGs). To tease out the possible actions of GlyRs on pain transmission, we investigate the effects produced by GlyRs on acute inflammatory pain by behavioral testing using prostaglandin E2 (PGE2) intrathecal injection models. Furthermore, we investigate the changes of GlyR expression in DRGs and spinal cord in rats after the induction of acute inflammatory pain.

Results

Compared to the vehicle administration, the PGE2 intrathecal injection model produced significantly higher hyperalgesia, which started 3 h after PGE2 injection and lasted more than 5 h. PGE2 intrathecal injection significantly decreased GlyRα1 and GlyRα3 protein expressions in the L5 DH at 1 h and lasted to 5 h, and similar results were observed in the L5 DRG at 5 h. Confocal microscopic images showed the co-existence of punctate gephyrin and GlyRα3 immunoreactivity (IR) throughout the gray matter of the spinal cord, mainly in DH laminae I–III neurons and in ventral horn neurons. It also showed the co-existence of punctate gephyrin and GlyRα3 IR in DRG neurons.

Conclusions

In this study, PGE2 intrathecal injection significantly decreased protein expression of gephyrin, GlyRα1 and GlyRα3 in spinal cord DH and DRG. The gephyrin and GlyRα3 were localized on neuron cells both in the DH and DRG.

Electronic supplementary material

The online version of this article (10.1186/s12868-018-0470-8) contains supplementary material, which is available to authorized users.

Development of Antifouling Hyperbranched Polyglycerol Layers on Hydroxyl Poly-p-xylylene Coatings

Antifouling surfaces that are resistant to protein adsorption and cell adhesion are desirable for many biomedical devices, such as diagnostic devices, biosensors, and implants. In this study, we developed an antifouling hyperbranched polyglycerol (hPG) surface on hydroxyl poly-p-xylylene (PPX-OH). PPX-OH was deposited via chemical vapor deposition (CVD), and an hPG film was then developed via the ring-opening reaction of glycidol. The hPG film greatly reduced the adhesion of L929 cells and platelets as well as protein adsorption. The addition of alkenyl groups in the hPG layer allows the conjugation of biomolecules, such as peptides and biotin, and elicits specific biological interactions. Since the CVD deposition of PPX-OH could be applied to most types of materials, our approach makes it possible to decorate an antifouling hPG film on most types of materials. Our method could be applied to biosensors, diagnostics, and biomedical devices in the future.

INVITED REVIEW: Inhibitors of myostatin as methods of enhancing muscle growth and development

With the increasing demand for affordable, high-quality meat, livestock and poultry producers must continually find ways to maximize muscle growth in their animals without compromising palatability of the meat products. Muscle mass relies on myoblast proliferation during prenatal or prehatch stages and fiber hypertrophy through protein synthesis and nuclei donation by satellite cells after birth or hatch. Therefore, understanding the cellular and molecular mechanisms of myogenesis and muscle development is of great interest. Myostatin is a well-known negative regulator of muscle growth and development that inhibits proliferation and differentiation in myogenic cells as well as protein synthesis in existing muscle fibers. In this review, various inhibitors of myostatin activity or signaling are examined that may be used in animal agriculture for enhancing muscle growth. Myostatin inhibitors are relevant as potential therapies for muscle-wasting diseases and muscle weakness in humans and animals. Currently, there are no commercial myostatin inhibitors for agriculture or biomedical purposes because the safest and most effective option has yet to be identified. Further investigation of myostatin inhibitors and administration strategies may revolutionize animal production and the medical field.

Posterior reversible encephalopathy as the first manifestation of Bickerstaff's brainstem encephalitis

Background

Posterior reversible encephalopathy syndrome (PRES) has been associated with Guillain-Barre syndrome in rare cases. Here we report a patient in whom PRES was the presenting manifestation of Bickerstaff’s brainstem encephalitis.

Case presentation

A 75-year-old woman presented with acute onset of hypertension, headache, blurred vision, and left eyelid drooping. Magnetic resonance imaging of the brain showed characteristic PRES lesions involving the parietal and occipital lobes bilaterally. On the 6th day after symptom onset, the patient developed complete ptosis and external ophthalmoplegia of both eyes, progressive ataxia, and bilateral lower limb weakness. Cerebrospinal fluid analyses revealed albuminocytological dissociation (protein: 66.6 mg/dL, WBC: 0/μl), and nerve conduction studies showed demyelinating sensorimotor polyneuropathy. The patient developed somnolence and a left extensor plantar response on the 8th day. A diagnosis of Bickerstaff’s brainstem encephalitis was made. Treatment with plasmapheresis led to a rapid improvement of clinical symptoms. To date, only five similar cases have been reported, but this is the only case in which PRES developed prior to treatment.

Conclusions

PRES can be a comorbid condition with Bickerstaff’s brainstem encephalitis, either preceding or following treatment; caution should be used in patients with either syndrome who exhibit atypical presentations.

Information Disclosure, Social Responsibility, Trust, and Attitude Affect Loyalty to Housing Agents

We applied a linear structural equation model to explore the impact of information disclosure, social responsibility, trust, and attitude on consumers' loyalty to housing agents. Participants were 466 consumers and potential consumers of housing agency industry services, who completed a survey assessing the variables of interest. Results showed that information disclosure had a direct and significant impact on trust, and an indirect impact on trust through the mediator of corporate social responsibility (CSR), and that trust had an indirect and significant impact on loyalty through the mediator of attitude. The structural relationships among information disclosure, CSR, trust, and attitude should be acknowledged when discussing consumers' loyalty to housing agents.

Efficacy of continuous theta burst stimulation of the primary motor cortex in reducing migraine frequency: A preliminary open-label study

BACKGROUND

Theta burst stimulation is a type of pattern-specific repetitive transcranial magnetic stimulation that requires less stimulation time and lower intensity to induce long-lasting effects comparable to those of other repetitive transcranial magnetic stimulation protocols. This pilot study investigated whether continuous theta burst stimulation (cTBS) on the primary motor cortex reduced headache frequency in patients with migraine.

METHODS

Nine patients with migraine were recruited into our study. All patients received 20 cTBS sessions (bursts of 3 50-Hz TMS pulses at 200-ms intervals for 40 seconds), administered every weekday for 4 consecutive weeks. All patients kept headache diaries for 4 weeks before stimulation (baseline; T1), during stimulation (T2), and 4 weeks after stimulation (T3). The primary outcome measures were the changes of total headache and migraine days from baseline (Wilcoxon signed-rank test; T2 and T3 vs. T1).

RESULTS

The number of total headache days was reduced at T2 and T3 compared with T1 [9.4 ± 6.2 days (p = 0.024) and 8.7 ± 10.1 days (p = 0.012) vs. 13.4 ± 10.1 days]. The number of migraine days was also reduced at T2 and T3 compared with T1 [2.9 ± 2.7 days (p = 0.021) and 1.0 ± 1.6 days (p = 0.008) vs. 8.6 ± 8.7 days].

CONCLUSION

Our results indicate that cTBS on the primary motor cortex might reduce the number of total headache and migraine days in patients with migraine. However, large-scale randomized controlled trials are necessary to further validate the findings.

Mild heat stress enhances differentiation and proliferation of Japanese quail myoblasts and enhances slow muscle fiber characteristics

The objective of this study was to investigate the effect of mild heat stress on muscle fiber hyperplastic and hypertrophic growth in quail primary myogenic cells to better understand the mechanisms leading to increased skeletal muscle development in avian embryos incubated at a higher temperature. Compared to control cultures maintained at 37°C, incubation at 39°C enhanced myotube length (P < 0.01) and diameter (P < 0.001) at 3 days after differentiation (D3). This enlargement of the myotubes incubated at 39°C can be explained by differences in the fusion index (56.7 vs. 46.2%, P < 0.05) and nuclei number per myotube (18.1 vs. 10.8, P < 0.001) compared to the control cells at D3. Additionally, a higher density of myotubes at D3 in cultures exposed to a higher temperature were related to higher levels of Pax-7 (P < 0.05) compared to the control cells incubated continuously at 37°C. These results indicated a higher proliferative capacity in cells exposed to mild heat stress compared to the control cells. On the other hand, mild heat stress enhanced protein levels of slow myosin heavy chain isoform (P < 0.01) and cytochrome c oxidase subunit IV (P < 0.01) compared to the control cells at D3. These discrepancies in protein expression indicated maintenance of slow muscle fiber type characteristics in myotubes incubated at 39°C. Our results suggest that mild heat stress plays a significant role in myogenic mechanisms related to muscle mass and development.

Dose-dependent regulation of cell proliferation and collagen degradation by estradiol on ligamentum flavum

Background

Estradiol plays an important role in the regulation of collagen metabolism. Deficiency of estradiol has been reported to be associated with the degeneration of many connective tissues. However, the association of estradiol and hypertrophy of the ligamentum flavum was seldom explored. Therefore, we studied the effects of estradiol on cultured cells from the ligamentum flavum.

Methods

Primary cultures of human ligamentum flavum cells obtained from surgical specimens of 14 patients undergoing spinal surgery were used to investigate the effect of estradiol on cell proliferation and the expression of collagen, elastin, and matrix metalloproteinases. Downstream pathways of estrogen receptor underlying the regulation of metalloproteinases were also investigated.

Results

In our study, we revealed the existence of estrogen receptors on both female and male ligamentum flavum cells with a gender difference. 17β-estradiol increased early (24 hours) proliferation of ligamentum flavum cells in a dose dependent manner and the effect could not be seen when the cell density increased. Estradiol with a concentration of 10^-9 M decreased collagen levels and increased the expression of MMP-13. Adding an antagonist of PI3K downstream pathway could reverse the expression of MMP-13 caused by estradiol.

Conclusions

The results implied estradiol regulated the expression of MMP-13 via PI3K pathway and contributed to the homeostasis of extracellular matrix in the ligamentum flavum.

Safety of high doses of urokinase and reteplase for acute ischemic stroke

BACKGROUND AND PURPOSE

ET is considered in selected patients with AIS with persistent arterial occlusion after receiving IVT. Limited data exist on the safety of IA high doses of UK and RT for ET. We investigated any correlation between IA doses of UK or RT and safety outcomes in patients who underwent ET.

MATERIALS AND METHODS

We identified all patients from our stroke registry who received UK or RT for ET from 1998 to 2008. Demographics, baseline National Institutes of Health Stroke Scale scores, recanalization rates, rates of attempted MT, mortality, SICH, and discharge modified Rankin Scale scores were collected.

RESULTS

Of 197 patients; 72 received UK and 125 received RT. More than 90% of patients in both groups had received prior IVT. The median IA dose of UK was 200,000 U (range, 25,000-1,500,000 U) and of RT was 2 mg (range, 1-8 mg). Concurrent MT was attempted in 59.7% of UK-treated patients and 72.0% of RT-treated patients, with SICH rates of 4.2% and 8.0%, respectively. Logistic regression adjusting for prior IVT and MT revealed no correlation between SICH and doses of UK (OR, 1.00; 95% CI, 0.99-1.00; P = .94) or RT (OR, 0.803; 95% CI, 0.48-1.33; P = .39). There was no correlation between mortality and doses of UK (OR, 1.00; 95% CI, 0.99-1.00; P = .51) or RT (OR, 1.048; 95% CI, 0.77-1.42; P = .75).

CONCLUSIONS

High IA doses of UK and RT may be safe when given with or without MT in patients with AIS despite receiving a full dose of intravenous recombinant tissue plasminogen activator. These results need prospective validation.

Requirement of inducible nitric-oxide synthase in lipopolysaccharide-mediated Src induction and macrophage migration

Previously, we have demonstrated the induction of Src in lipopolysaccharide (LPS)-stimulated macrophages. In this study, we observed that pharmacological blockade or knockout of inducible nitric-oxide synthase (iNOS) reduced LPS-mediated Src induction and macrophage migration. Either SNAP (a NO donor) or 8-Br-cGMP (a cGMP analogue) could rescue these defects in iNOS-null macrophages, which indicated the participation of NO/cGMP in LPS-elicited Src expression and mobilization. In addition, Src family kinase (SFK)-specific inhibitor, PP2, inhibited SNAP- and 8-Br-cGMP-evoked motility implicating the involvement of SFKs downstream of NO/cGMP. Analysis of the expression of SFKs indicated LPS dramatically induced Src, which could be attributable to the increased level of the src transcript. Attenuation of Src by src-specific siRNA reduced LPS- and SNAP-evoked mobilization in Raw264.7 macrophages, and reintroduction of avian Src could rescue their motility. Furthermore, LPS-mediated Src induction led to increased FAK Pi-Tyr-397 and Pi-Tyr-861, which was also iNOS-dependent. With these findings, we concluded that iNOS was important for LPS-mediated macrophage locomotion and Src was a critical player in this process.

Persistent lower abdominal pain induced by long peritoneal shunt catheter

Persistent abdominal pain directly induced by a peritoneal catheter of a ventriculoperitoneal shunt, which is associated with no other complications such as bowel perforation, pseudocyst or infection, has not been previously reported. A 65-year-old woman with hydrocephalus developed persistent lower abdominal pain radiating to the perineal area after shunt insertion. Radiography suggested that the distal end of a peritoneal catheter was located in a cul-de-sac of the pelvis. Otherwise, all studies were negative for shunt infection, fluid collection, or other abdominal and pelvic events. The patient's pain resolved completely after surgery in which the peritoneal catheter was shortened. In the presence of unexplained, persistent lower abdominal pain after shunt placement, the need to shorten the peritoneal catheter should be considered.

The role of amino acids T148 and R281 in human dihydrolipoamide dehydrogenase

Human dihydrolipoamide dehydrogenase (hE3) is a common component of alpha-ketoacid dehydrogenase complexes. Mutations of this homodimeric protein cause E3 deficiency and are always fatal. To investigate its reaction mechanism, we first performed multiple sequence alignment with other 17 eukaryotic E3s. According to hE3 structure and the result of multiple sequence alignment, two amino acids, T148 and R281, were subjected to mutagenesis and four hE3 mutants, T148G, T148S, R281N, and R281K, were expressed and assayed. The specific activities of T148G, T148S, R281N, and R281K are 76.34%, 88.62%, 12.50%, and 11.93% to that of wild-type E3, respectively. The FAD content analysis indicated that the FAD content of these mutant E3s were about 71.0%, 92%, 96%, and 93% that of wild-type E3, respectively. The molecular weight analysis showed that these three mutant proteins form the dimer. Kinetic data demonstrated that the K(cat) of forward reaction of all mutants, except T148 mutants, were decreased dramatically. The results of kinetic study suggest that T148 is not important to E3 catalytic function and R281 play a role in the catalytic function of the E3.

The role of N286 and D320 in the reaction mechanism of human dihydrolipoamide dehydrogenase (E3) center domain

According to the multiple alignment of various dihydrolipoamide dehydrogenases (E3s) sequences, three human mutant E3s of the conserved residues in the center domain, N286D, N286Q, and D320N were created, over-expressed and purified. We characterized these mutants to investigate the reaction mechanism of human dihydrolipoamide dehydrogenases. The specific activities of N286D, N286Q, and D320N are 30.84%, 24.57% and 48.60% to that of the wild-type E3 respectively. The FAD content analysis indicated that these mutant E3s about 96.0%, 99.4% and 82.7% of FAD content compared to that of wild-type E3 respectively. The molecular weight analysis showed that these three mutant proteins form the dimer. Kinetic's data demonstrated that the K(cat) of both forward and reverse reactions of these mutant proteins were decreased. These results suggest that N286 and D320 play a role in the catalytic function of the E3.

Gelatin-tricalcium phosphate membranes immobilized with NGF, BDNF, or IGF-1 for peripheral nerve repair: An in vitro and in vivo study

In the present study, NGF, BNDF from the neurotrophin family and IGF-1 were covalently immobilized on gelatin-tricalcium phosphate (GTG) membrane using carbodiimide. We investigated the effects of these growth factors released from the GTG composites on cultured PC12 cells and sciatic nerve regeneration across a 10-mm-long gap in rats. In PC12 cell culture, the total protein content and MTT assay indicated more cell attachment on the composites modified with growth factors. The IGF-1 group showed a higher survival promotion effect on PC12 cells than did BDNF and NGF groups. On the other hand, NGF released from the composite showed the highest level of neuritogenesis for PC12 cells in neurite outgrowth assay. In the animal study, the GTG conduits modified with various growth factors were well tolerated by the host tissue. In the regenerated nerves, the number of the axons per unit area of the BDNF group was significantly higher than that of NGF and GTG groups but similar to that of IGF-1 group. However, the average axon size was the largest in NGF group. This result was in concordance with the neurite outgrowth assay in which NGF showed the highest neuritogenic potential. In the assessment of motor and sensory recovery after nerve repair, conduits modified with various neurotrophic factors showed a more favorable outcome in compound muscle action potential. The BDNF group had a better gastrocnemic muscle weight ratio than blank GTG repair. Nevertheless, the different effects of GTG conduits modified with various neurotrophic factors on functional recovery cannot be simply illustrated in the sciatic function index.

Long-term follow-up of giant serpentine MCA aneurysm treated with EC-IC bypass and proximal occlusion

Giant serpentine aneurysms are a rare but important subset of giant aneurysms, with unique management considerations. We present long-term follow-up clinical and imaging features of a giant serpentine middle cerebral artery lesion treated with extracranial-intracranial bypass and proximal occlusion more than a decade earlier. Calcification of the obliterated aneurysm sac and durability of this management strategy are demonstrated.

Anin vivo study of tricalcium phosphate and glutaraldehyde crosslinking gelatin conduits in peripheral nerve repair

In order to modulate the mechanical properties of gelatin, we previously developed a biodegradable composite composed by tricalcium phosphate and glutaraldehyde crosslinking gelatin (GTG) feasible for surgical manipulation. In this study, we evaluated the in vivo applications of GTG conduit for peripheral nerve repair. The effect of sciatic nerve reconstruction was compared between resorbable permeable GTG conduits and durable impermeable silicone tubes. Traditional methods of assessing nerve recovery following peripheral nerve repair including histomorphometric and electrophysiologic features were conducted in our study. In addition, autotomy score and sciatic function index (SFI) in walking tract analysis were used as additional parameters for assessing the return of nerve function. Twenty-four weeks after sciatic nerve repair, the GTG conduits were harvested. Microscopically, regeneration of nerves was observed in the cross-section at the mid portion of all implanted GTG conduits. The cross-sectional area of regenerated nerve of the GTG group was significant larger than that of the silicone group. In the compound muscle action potentials (CMAP), the mean recovery index of CMAP amplitude was 0.24 +/- 0.02 for the silicone group, 0.41 +/- 0.07 for the GTG group. The mean SFI increased with time in the GTG group during the evaluation period until 24 weeks. Walking tract analysis showed a higher SFI score in the GTG group at both 12 and 24 weeks. The difference reached a significant level at 24 weeks. Thus, the histomorphometric, electrophysiologic, and functional assessments demonstrate that GTG can be a candidate for peripheral nerve repair.

Release characteristics and bioactivity of gelatin-tricalcium phosphate membranes covalently immobilized with nerve growth factors

The gelatin-tricalcium phosphate membranes were cross-linking with low concentration glutaraldehyde solution (GTG). This material has good mechanical property, biocompatibility, and is feasible for surgical manipulation. For axonal regeneration, nerve growth factors (NGF) were immobilized onto the composite (GTG) with carbodiimide. The purpose of this study was to evaluate the release characteristics and bioactivity of NGF after covalent immobilization onto the GTG membranes (GEN). NGF immobilized onto and released from the composite was quantified using ELISA method. PC 12 cells were cultured on the GTG and GEN composites. Cell survival, cytotoxicity, and cellular activity were evaluated by total protein content, LDH activity, and MTT assay respectively. Neurite outgrowth assay was used to evaluate the biological activity of NGF released from GEN composite. From ELISA measurement, the releasing curve for NGF showing two distinctive parts with different slopes indicated that NGF were released from the composite in diffusion-controlled mechanism and degradation-controlled mechanism respectively. While culturing with PC 12 cells, LDH leakage results implied that whether GTG composite cross-linked with NGF or not showed little cytotoxicity. The total protein content and cellular activity of PC 12 cells were lower on GTG and GEN membranes than control group. However, 56%+/-3.98 of PC 12 cells showed significant neurite outgrowth on GEN membranes which was statistically higher than GTG without NGF immobilization. In addition, sustained release of bioactive NGF for two months had been demonstrated by neurite outgrowth assay. From these experiments, it can be concluded that the technique used in the present study is capable of immobilizing NGF onto GTG membranes covalently and remaining the bioactivity of NGF. Therefore, GEN composite can be materials for sustained release of bioactive NGF and a candidate for future therapeutic application in nerve repair.

Biocompatibility of NGF-grafted GTG membranes for peripheral nerve repair using cultured Schwann cells

We previously developed a biodegradable composite with potentially good biocompatibility composed by tricalcium phosphate and gluataraldehyde cross-linking gelatin (GTG) with good mechanical property feasible for surgical manipulation. The purpose of this study was to evaluate the feasibility of immobilizing nerve growth factor (NGF) onto the composite (GTG) with carbodiimide (GEN composite). Cultured Schwann cells were seeded onto the GTG and GEN composites. For comparison, GTG membrane soaked in NGF solution without carbodiimide (GN composite) as cross-linking agent was also used to culture Schwann cells. Cell morphology was observed by a scanning electron microscope. Cell survival, cytotoxicity and cellular metabolism on the NGF-grafted GTG membrane were assessed quantitatively in terms of cell protein content, leakage of cytosolic lactate dehydrogenase (LDH) activity and by the well-established MTT assay, respectively. The result of LDH study did not show significant difference among GTG, NGF-modified GTG and control group. This indicated that GTG composite, whether cross-linking with NGF or not, has little cytotoxic effect. Comparing the protein content and MTT assay among GEN, GN composite and control group, the data confirmed more attachment of Schwann cells on GEN composite. Although GTG cross-linking with NGF did not promote Schwann cell proliferation, the techniques we used in this study provided a method to fabricate a novel biomaterial incorporation of Schwann cells and covalently immobilized NGF.

Novel CLCN1 mutations in Taiwanese patients with myotonia congenita

We have performed genetic screening on the skeletal muscle chloride channel gene (CLCN1) in Taiwanese population. A total of four patients with myotonia congenita (MC) together with 106 normal individuals were examined. All 23 exons of the CLCN1 gene were analysed by direct sequencing of PCR products to detect the nucleotide changes. Five mutations and three polymorphisms were identified in this study. Among these, three missense mutations (S471F, P575S, D644G) and one polymorphism (T736I) are novel and could be unique to the Taiwanese. In addition, a previously documented recessive G482R mutation was identified in a heterozygous patient and his nonsymptomatic father, indicating that this mutation might indeed function recessively or dominantly with incomplete penetrance. In conclusion, this is the first report of MC in Taiwan with proven CLCN1 gene mutations and showing high molecular heterogeneity in Taiwanese MC patients.

[Studies on the active constituents of sichuan liang shan rhododendron L. I. Determination of two flavonoids in leaves, extracts and jinjuan liquors]

A reversed-phase HPLC method for the separation and determination of the two flavonoids: quercetin and kaempferol is described. The column was 25 cm x 4.6 mm i.d., packed with Zorbax SB-C18(5 microns). The mobile phase was a mixture of MeOH-H2O (60:40, V/V). The flow rate was 0.7 mL/min. UV detection was performed at 360 nm. External standard was used and the calibration curves showed good linearity over the range of 6.0-100 mg/L, r = 0.9995-0.9998, and detection limits were 3.3-6.2 mg/L. The recoveries were 96.0% and 97.3% for quercetin and kaempferol respectively. The relative standard deviations of the method were 2.1%-4.5%. The method is simple, fast, sensitive and accurate and can be applied to the analysis of quercetin and kaempferol. It provides a scientific basis for industrial production and quality control of Jinjuan liquor preparations for clinical uses.

[Determination of tetramethylpyrazine in animal serum and cerebrospinal fluid by high performance liquid chromatography]

A reversed-phase high performance liquid chromatographic (RP-HPLC) method for the determination of the tetramethylpyrazine(TMP) in Chuanxiong extract, the animal(mouse) serum and cerebrospinal fluid has been developed. The TMP was separated on an ODS column Zorbax SB-C18(4.6 mm i.d. x 250 mm, 5 microns) at room temperature and detected by using UV detector at 270 nm. The mobile phase was methanol-water (50:50, V/V) containing 0.2 mmol/L of NH4H2PO4 flowing at a rate of 0.8 mL/min and 20 microL samples were injected. The detection limit of TMP was 1 mg/L and the calibration curve is linear between 5 and 500 mg/L with a correlation coefficient (r) of 0.999. The recovery of TMP ranged 98%-103%. The extract of Chuanxiong and pretreated serum and cerebrospinal fluid sample are stable for a week at room temperature.

Metabolism of 2,4,5,2',5'-pentachlorobiphenyl in the rat. Qualitative and quantitative aspects

The metabolism of 2,4,5,2',5'-pentachloro [14C] biphenyl (5-CB) was studied in the male rat. Following iv administration of 5-CB (0.6 mg/kg), 84% of the total dose was excreted within 7 days and 89% of the radioactivity excreted was in the form of 5-CB metabolites. Mass spectral and proton nuclear magnetic resonance analysis or chemical methods in conjunction with mass spectral analysis were used to identify the metabolites. The major metabolite was identified as 3'-hydroxy 5-CB. One minor metabolite was identified as the 3',4'-dihydrodiol of 5-CB and a second minor metabolite was tentatively identified as 3',4'-dihydroxy-5-CB. The relative amounts of 5-CB and its metabolites excreted in the urine and feces were also determined.