Injectable Tissue-Specific Hydrogel System for Pulp-Dentin Regeneration

The quest for finding a suitable scaffold system that supports cell survival and function and, ultimately, the regeneration of the pulp-dentin complex remains challenging. Herein, we hypothesized that dental pulp stem cells (DPSCs) encapsulated in a collagen-based hydrogel with varying stiffness would regenerate functional dental pulp and dentin when concentrically injected into the tooth slices. Collagen hydrogels with concentrations of 3 mg/mL (Col3) and 10 mg/mL (Col10) were prepared, and their stiffness and microstructure were assessed using a rheometer and scanning electron microscopy, respectively. DPSCs were then encapsulated in the hydrogels, and their viability and differentiation capacity toward endothelial and odontogenic lineages were evaluated using live/dead assay and quantitative real-time polymerase chain reaction. For in vivo experiments, DPSC-encapsulated collagen hydrogels with different stiffness, with or without growth factors, were injected into pulp chambers of dentin tooth slices and implanted subcutaneously in severe combined immunodeficient (SCID) mice. Specifically, vascular endothelial growth factor (VEGF [50 ng/mL]) was loaded into Col3 and bone morphogenetic protein (BMP2 [50 ng/mL]) into Col10. Pulp-dentin regeneration was evaluated by histological and immunofluorescence staining. Data were analyzed using 1-way or 2-way analysis of variance accordingly (α = 0.05). Rheology and microscopy data revealed that Col10 had a stiffness of 8,142 Pa with a more condensed and less porous structure, whereas Col3 had a stiffness of 735 Pa with a loose microstructure. Furthermore, both Col3 and Col10 supported DPSCs' survival. Quantitative polymerase chain reaction showed Col3 promoted significantly higher von Willebrand factor (VWF) and CD31 expression after 7 and 14 d under endothelial differentiation conditions (P < 0.05), whereas Col10 enhanced the expression of dentin sialophosphoprotein (DSPP), alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), and collagen 1 (Col1) after 7, 14, and 21 d of odontogenic differentiation (P < 0.05). Hematoxylin and eosin and immunofluorescence (CD31 and vWF) staining revealed Col10+Col3+DPSCs+GFs enhanced pulp-dentin tissue regeneration. In conclusion, the collagen-based concentric construct modified by growth factors guided the specific lineage differentiation of DPSCs and promoted pulp-dentin tissue regeneration in vivo.

Efficacy of different surgical treatments for management of anal fistula: a network meta-analysis

PURPOSE

Currently, the anal fistula treatment which optimises healing and preserves bowel continence remains unclear. The aim of our study was to compare the relative efficacy of different surgical treatments for AF through a network meta-analysis.

METHODS

Systematic searches of MEDLINE, EMBASE and CENTRAL databases up to October 2022 identified randomised controlled trials (RCTs) comparing surgical treatments for anal fistulae. Fistulae were classified as simple (inter-sphincteric or low trans-sphincteric fistulae crossing less than 30% of the external anal sphincter (EAS)) and complex (high trans-sphincteric fistulae involving more than 30% of the EAS). Treatments evaluated in only one trial were excluded from the primary analyses to minimise bias. The primary outcomes were rates of success in achieving AF healing and bowel incontinence.

RESULTS

Fifty-two RCTs were included. Of the 14 treatments considered, there were no significant differences regarding short-term (6 months or less postoperatively) and long-term (more than 6 months postoperatively) success rates between any of the treatments in patients with both simple and complex anal fistula. Ligation of the inter-sphincteric fistula tract (LIFT) ranked best for minimising bowel incontinence in simple (99.1% of comparisons; 3 trials, n = 70 patients) and complex anal fistula (86.2% of comparisons; 3 trials, n = 102 patients).

CONCLUSIONS

There is insufficient evidence in existing RCTs to recommend one treatment over another regarding their short and long-term efficacy in successfully facilitating healing of both simple and complex anal fistulae. However, LIFT appears to be associated with the least impairment of bowel continence, irrespective of AF classification.

38. Effect of Chlorhexidine Rinsed Blood Contamination on Bond Strength of Brackets Bonded with Self-etch Primer- An in Vitro Study

The present invitro type of study has done to check the effect of blood contamination & chlorhexidine combination on the bond strength of brackets bonded with self-etch primer technique. The study consisted of ninety sound human upper premolars (extracted for orthodontic purpose) fixed in a self-cure acrylic block and segregated into three groups of 30 samples each. 0.022 slot metal MBT brackets (Gemini series-3M unitek) were bonded with self-etch primer using Transbond XT composite, CA, USA and light cure for 40 seconds) on clean buccal surface. Teeth were divided into 3 groups-Group A/Control group, Group B, Group C. A computer was used to record the force applied to debond the bonded bracket in the unit of Newton. The analysis of variance indicated that there were significant differences (F value = 6.891, p value=0.002) in bond strengths between the various groups tested. The highest value of shear bond strength occurred when chlorhexidine (Group C) was used to remove the blood contamination (mean=15.874 MPa). When bonding was done in ideal condition (Group A), shear bond strength obtained was slightly lower (mean=14.497 MPa) as compared to Group C. On the other hand, lowest shear bond strength among all three groups occurred when blood contamination (Group B) was removed with water (mean=11.059 MPa). Analysis of the study showed that shear bond strength of orthodontic brackets to enamel significantly decreased during bonding with self-etch primer in blood contamination condition. Self-etch primer displayed considerably superior performance with the use of chlorhexidine instead of water to wash the blood contamination.

Functional Odontoblastic-Like Cells Derived from Human iPSCs

The induced pluripotent stem cells (iPSCs) have an intrinsic capability for indefinite self-renewal and large-scale expansion and can differentiate into all types of cells. Here, we tested the potential of iPSCs from dental pulp stem cells (DPSCs) to differentiate into functional odontoblasts. DPSCs were reprogrammed into iPSCs via electroporation of reprogramming factors OCT-4, SOX2, KLF4, LIN28, and L-MYC. The iPSCs presented overexpression of the reprogramming genes and high protein expressions of alkaline phosphatase, OCT4, and TRA-1-60 in vitro and generated tissues from 3 germ layers in vivo. Dentin discs with poly-L-lactic acid scaffolds containing iPSCs were implanted subcutaneously into immunodeficient mice. After 28 d from implantation, the iPSCs generated a pulp-like tissue with the presence of tubular dentin in vivo. The differentiation potential after long-term expansion was assessed in vitro. iPSCs and DPSCs of passages 4 and 14 were treated with either odontogenic medium or extract of bioactive cement for 28 d. Regardless of the passage tested, iPSCs expressed putative markers of odontoblastic differentiation and kept the same mineralization potential, while DPSC P14 failed to do the same. Analysis of these data collectively demonstrates that human iPSCs can be a source to derive human odontoblasts for dental pulp research and test bioactivity of materials.

A liquid chromatography tandem mass spectrometry based regulatory compliant method for the determination of tenofovir in human serum

A simple, rapid, and specific assay based on solid phase extraction and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI MS-MS) for the quantitative analysis of Tenofovir in human serum using Tenofovir D6 as internal standard (IS) have been developed. The precursor to product ion transitions of m/z 288.2/176.2 and m/z 293.9/182.3 used to measure the analyte and internal standard (Tenofovir and Tenofovir D6). The method was validated over a concentration range of 5.06-603.72 ng mL(-1). The method was validated over the parameters like selectivity, matrix effect, sensitivity, linearity, precision, accuracy, various stabilities (bench top stability, standard stock solution stability in refrigerator and at room temperature, stock dilution stability, auto sampler stability, freeze thaw stability, long term stability - 65°C±10°C & long term stability - 22°C±5°C, reagent stability, dry extract stability, wet extract stability in refrigerator and at bench top, blood stability), effect of potentially interfering drugs, dilution integrity, recovery and reinjection reproducibility. The mean % recovery of Tenofovir was 98.22% with a precision of 2.42%, The mean % recovery of Tenofovir D6 was 100.96% with a precision of 2.88%. The RSD % of intra-day and inter-day assay was≤15%.

Existence of a nitric oxide synthase/nitric oxide system in fish testis and its role in modulation of androgenesis

Fish testis is equipped with different isoforms of nitric oxide synthase (NOSs) and is capable of producing nitric oxide (NO). Cellular sources of NO in the catfish testis are germ cells, Leydig cells, and macrophages. Production of testicular NO is under endocrine inhibitory control. Expression of NOSs exhibits seasonality and that depends on the reproductive status of fish. Leydig cells are highly sensitive to chemical as well as biological NO. NO inhibits testosterone production by the testis in vivo as well as by the isolated Leydig cells in vitro.

Development and characterization of microsatellite markers from tropical forage Stylosanthes species and analysis of genetic variability and cross-species transferability

A limited number of functional molecular markers has slowed the desired genetic improvement of Stylosanthes species. Hence, in an attempt to develop simple sequence repeat (SSR) markers, genomic libraries from Stylosanthes seabrana B.L. Maass & 't Mannetje (2n=2x=20) using 5' anchored degenerate microsatellite primers were constructed. Of the 76 new microsatellites, 21 functional primer pairs were designed. Because of the small number of primer pairs designed, 428 expressed sequence tag (EST) sequences from seven Stylosanthes species were also examined for SSR detection. Approximately 10% of sequences delivered functional primer pairs, and after redundancy elimination, 57 microsatellite repeats were selected. Tetranucleotides followed by trinucleotides were the major repeated sequences in Stylosanthes ESTs. In total, a robust set of 21 genomic-SSR (gSSR) and 20 EST-SSR (eSSR) markers were developed. These markers were analyzed for intraspecific diversity within 20 S. seabrana accessions and for their cross-species transferability. Mean expected (He) and observed (Ho) heterozygosity values with gSSR markers were 0.64 and 0.372, respectively, whereas with eSSR markers these were 0.297 and 0.214, respectively. Dendrograms having moderate bootstrap value (23%-94%) were able to distinguish all accessions of S. seabrana with gSSR markers, whereas eSSR markers showed 100% similarities between few accessions. The set of 21 gSSRs, from S. seabrana, and 20 eSSRs, from selected Stylosanthes species, with their high cross-species transferability (45% with gSSRs, 86% with eSSRs) will facilitate genetic improvement of Stylosanthes species globally.

Superior sagittal sinus thrombosis secondary to hyperthyroidism

Superior sagittal sinus thrombosis (SSST) is associated with a variety of hypercoaguable states. Although coagulation disturbances are reported in hyperthyroidism, a direct link between hyperthyroidism and cerebral venous thrombosis is not established. We report a 39-year-old man who developed increased intracranial pressure, seizures, and rapid atrial fibrillation. Neuroimaging showed SSST, and laboratory studies were consistent with hyperthyroidism. No other causes of a hypercoaguable state were identified. Prompt treatment of his hyperthyroidism led to recanalization of the superior sagittal sinus and a full neurological recovery. Given the known effects of hyperthyroidism on factor VIII activity, we hypothesize that hyperthyroidism is an independent risk factor for SSST. A high index of suspicion for SSST is warranted in patients with hyperthyroidism and neurological symptoms. Furthermore, thyroid dysfunction should be excluded in patients with unexplained SSST.

Isolation and characterization of microsomal omega-6-desaturase gene (fad2-1) from soybean

A genomic DNA sequence (fad2-1) encoding seed specific microsomal 0-6 desaturase was isolated from soybean (Glycine max. L cv. Pusa-9702). A positive genomic clone of 1852 nucleotides containing a single uninterrupted 3' end exonic region with an ORF of 1140 bp encoding a peptide of 379 amino acids, a complete 3' UTR of 206 bp and 86 bp of 5' UTR interrupted by a single intron of 420 bp was obtained on screening the sub-genomic library of soybean. Southern blots revealed at least two copies of the gene per haploid genome. Analysis of the translated product showed the presence of three histidine boxes, with the general sequence HXXXH and five probable transmembrane segments reported to be involved in substrate specificity.

India--workshops on "HIV/AIDS: the law and ethics"

The Lawyers Collective HIV/AIDS Unit is a non-governmental organization providing legal aid, advice, and support to people with HIV/AIDS in India. This article summarizes a series of workshops on "HIV/AIDS: The Law and Ethics" organized by the Unit to empower people with HIV/AIDS and educate the Indian judiciary.

Phylogenetic relationships and genetic polymorphisms in wild Indian mice

Randomly amplified polymorphic DNA (RAPD) analysis was used to examine the extent of variability in 11 Indian wild derived commensal house mice (Mus musculus) populations and compared with inbred strains of musculus and domesticus subspecies as well as commonly used laboratory inbred strains C57BL/6J and DBA/2J. Arbitrary designed 10 mer oligonucleotide primers with 60-70% (G+C) content were used to amplify DNA template. Out of 52 primers screened initially on the laboratory strains, 20 were selected for analysis on the basis of amplification product in the size range of 200-1400 bp. Among 353 total polymorphic bands, 220 bands (64%) were found to be polymorphic in Indian wild mice, 85 bands (25%) in wild derived inbred strains and 37 bands (11%) in laboratory mice strains. The amplification patterns produced by primers were statistically analysed by Jaccard's similarity coefficient the value of which ranged from 0.56 to 0.80. High level of genetic diversity was seen in the Indian wild mice populations as compared to the controls. The UPGMA phenogram grouped mice population into two major clusters except Bikaner [BIK], Bilaspur [BIL] and Ranikhet [RK] populations which were placed outside the close-knit clusters. Inspite of low values of bootstrap estimates obtained by Wagner and Dollo parsimony analysis, the results were comparable with UPGMA phenogram when constitution of the populations in the major cluster was considered. Indian mice populations appeared to be diverse from laboratory inbred mice strains.

Nonrandomized comparison of local urokinase thrombolysis versus systemic heparin anticoagulation for superior sagittal sinus thrombosis

BACKGROUND AND PURPOSE

We sought to compare the safety and efficacy of direct urokinase thrombolysis with systemic heparin anticoagulation for superior sagittal sinus thrombosis (SSST).

METHODS

At University at Buffalo (NY) and University of Texas (Dallas, Houston), we reviewed 40 consecutive patients with SSST, treated with local urokinase (thrombolysis group) or systemic heparin anticoagulation (heparin group). The thrombolysis group (n=20) received local urokinase into the SSS followed by systemic heparin anticoagulation. The heparin group (n=20) received systemic heparin anticoagulation only. Neurological dysfunction was rated as follows: 0, normal; 1, mild (but able to ambulate and communicate); 2, moderate (unable to ambulate, normal mentation); and 3, severe (unable to ambulate, altered mentation).

RESULTS

Age (P=0.49), sex (P=0.20), baseline venous infarction (P=0.73), and predisposing illnesses (P=0.52) were similar between the thrombolysis and heparin groups. Pretreatment neurological function was worse in the thrombolysis group (normal, n=5; mild, n=8; moderate, n=4; severe, n=3) than in the heparin group (normal, n=8; mild, n=8; moderate, n=3; severe, n=1) (P=NS). Discharge neurological function was better in the thrombolysis group (normal, n=16; mild, n=3; moderate, n=1; severe, n=0) than in the heparin group (normal, n=9; mild, n=6; moderate, n=5; severe, n=0) (P=0.019, Mann-Whitney U test). Hemorrhagic complications were 10% (n=2) in the thrombolysis group (subdural hematoma, retroperitoneal hemorrhage) and none in the heparin group (P=0.49). Three of the heparin group patients developed complications of the underlying disease (status epilepticus, hydrocephalus, refractory papilledema). No deaths occurred. Length of hospital stay was similar between the groups (P=0.79).

CONCLUSIONS

Local thrombolysis with urokinase is fairly well tolerated and may be more effective than systemic heparin anticoagulation alone in treating SSST. A randomized, prospective study comparing these 2 treatments for SSST is warranted.

Neuronal contact guidance in magnetically aligned fibrin gels: effect of variation in gel mechano-structural properties

Neurite outgrowth from chick dorsal root ganglia entrapped in isotropic and magnetically aligned fibrin gels was studied, and the dependence on the diameter of the fibrin fibrils was characterized. The fibrin fibril diameter was varied, as inferred from turbidity measurements, by using different Ca2+ concentrations in the fibrin-forming solution, but this variation was accomplished without affecting the degree of magnetic-induced alignment, as directly visualized in fluorescently spiked gels. Magnetically aligned fibrin gels possessing different fibril diameters but similar alignment resulted in drastic changes in the contact guidance response of neurites, with no response in gels formed in 1.2 mM Ca2+ (having smaller fibril diameter, ca. 150 nm), but a strong response in gels formed in 12 and 30 mM Ca2+ (having larger fibril diameter, ca. 510 nm) with an attendant two-fold increase in neurite length. These changes are attributed to variation of the mechano-structural properties of the network of aligned fibrils as the fibril diameter is varied.

Early computed tomography hypodensity predicts hemorrhage after intravenous tissue plasminogen activator in acute ischemic stroke

Parenchymal hypodensity is a proposed risk factor for hemorrhage after recombinant tissue plasminogen activator (TPA) thrombolysis for ischemic stroke. In Buffalo, NY, and Houston, TX, the authors reviewed 70 patients who were treated with intravenous TPA for acute middle cerebral artery (MCA) stroke. Two observers blinded to clinical outcome analyzed initial noncontrast head computed tomography (CT) scans. Basal ganglia CT hypodensity was quantitated in Hounsfield units (HUs). Contralateral-ipsilateral difference in density was calculated using the asymptomatic side as a control. Ictus time to TPA averaged 2.5 hours. Six patients developed symptomatic intraparenchymal hematomas (2 fatal). The hemorrhage group had more severe basal ganglia hypodensity (mean 7.5 +/- 1.4, range 6-10 HU) than the nonhemorrhage group (2.2 +/- 1.4, range 0-9 HU) (P < .0001). The hemorrhage group had hypodensity of > 5 HU; the nonhemorrhage group had hypodensity of < or = 4 HU, except 1 patient with hypodensity of 9 HU. In predicting hemorrhage, the positive predictive value of hypodensity > 5 HU was 86%; the negative predictive value was 100%. Prethrombolysis NIH Stroke Scale (NIHSS) deficit (P = .0007) and blood glucose (P = .005) were also higher in the hemorrhage group. Age, gender, smoking, hypertension, and ictus time to TPA infusion did not differ between the 2 groups. Logistic regression indicated that basal ganglia hypodensity was the best single predictor of hemorrhage. Hypodensity and NIHSS score together predicted all cases of hemorrhage. The authors conclude that basal ganglia hypodensity quantified by CT may be a useful method of risk stratification to select acute MCA stroke patients for thrombolytic therapy.

Fatigue in multiple sclerosis and its relationship to depression and neurologic disability

We studied multiple sclerosis fatigue (MSF) and its relationship to depression and disability. Seventy-one patients [50 relapsing-remitting, 21 secondary progressive] were grouped by Fatigue Severity Scale (FSS) into MS-fatigue (MSF) (FSS>/=5; n=46) or MS-nonfatigue (MSNF) (FSS</=4; n=20). Forty-one patients were grouped into MS-depression (MSD) (n=15) or MS-nondepression (MSND) (n=26) by interview. Higher expanded disability status scale (EDSS) scores were noted in MSF than MSNF patients (P=0.0003); EDSS scores correlated with FSS scores (rho=0.43, P=0.003). However, fatigue was present in 58% (n=29) of relapsing-remitting patients and in 52% (n=26) of patients with mild physical disability (EDSS<3.5). Hamilton/Beck depression severity scores were higher in MSF than MSNF patients and correlated with FSS scores (P<0.05). MSD had higher FSS scores than MSND patients (P=0.008). After controlling for EDSS, depression severity continued to correlate with FSS scores (rho=0.37, P=0.02). After controlling for depression, FSS scores no longer correlated with EDSS scores (rho=0.27, P=0.09). Thus, MSF is independent of physical disability, but is associated with depression, suggesting that common mechanisms play a role in MSF and MSD including psychological factors or brain lesions in specific neuroanatomic pathways. Further study is warranted to determine if antidepressant medications improve fatigue in MS.

Guided neurite elongation and schwann cell invasion into magnetically aligned collagen in simulated peripheral nerve regeneration

High-strength magnetic fields were used to align collagen gel formed into 4-mm-diameter rods during the self-assembly of type I collagen monomers into fibrils. We developed an in vitro assay to study neurite elongation into the magnetically aligned collagen gel rods from dorsal root ganglia (DRG) explants placed onto one end of the rods. The depth of neurite elongation from chick embryo DRG neurons into these rods was found to be substantially greater than that observed in controls and increased with an increase in magnetic field strength, as did the collagen gel rod birefringence, indicative of collagen fibril alignment along the rod axis. Moreover, the axial bias of neurite elongation became more pronounced with an increase in magnetic field strength, presumably due to a contact guidance response of growth cones at the neurite tips. Coinvasion of Schwann cells from neonatal rat DRG was also studied in these assays using double immunolabeling. In the absence of serum, Schwann cells were highly associated with, and often trailed, elongating neurites. In the presence of serum, Schwann cells showed significantly higher rates of invasion and formed axially aligned chords reminiscent of bands of Büngner. These results may translate into an improved method of entubulation repair of transected peripheral nerves by directing and stimulating axonal growth through a tube filled with magnetically aligned collagen gel.

Magnetically aligned collagen gel filling a collagen nerve guide improves peripheral nerve regeneration

Bioresorbable collagen nerve guides filled with either magnetically aligned type I collagen gel or control collagen gel were implanted into 4- or 6-mm surgical gaps created in the sciatic nerve of mice and explanted 30 and 60 days postoperation (dpo) for histological and immunohistochemical evaluation. The hypothesis was that contact guidance of regenerating axons and/or invading nonneuronal cells to the longitudinally aligned collagen fibrils would improve nerve regeneration. The criterion for regeneration was observation of regenerating myelinated fibers distal to the nerve guide. Consistent with previous studies showing poor regeneration in 6-mm gaps at 60 dpo with entubulation repair, only one of six mice exhibited regeneration with control collagen gel. In contrast, four of four mice exhibited regeneration with magnetically aligned collagen gel, including the appearance of nerve fascicle formation. The numbers of myelinated fibers were less than the uninjured nerve in all groups, however, which may have been due to rapid resorption of the nerve guides. An attempt to increase the stability of the collagen gel, and thereby the directional information presented by the aligned collagen fibrils, by crosslinking the collagen with ribose before implantation proved detrimental for regeneration.

Magnetic-induced alignment of collagen fibrils in tissue equivalents

The use of reconstituted type I collagen gel as a scaffold for engineered soft tissues is a highly attractive prospect, given that collagen is the principal component of the extracellular matrix (ECM) in vivo, providing a mechanically suitable and information-rich scaffold for cell-ECM interactions. It has the advantage that cells can be directly entrapped within the comprising collagen fibrils as they grow into an entangled network from a cell containing solution of monomeric type I collagen. These tissue equivalents have the further advantage that the collagen fibrils can be aligned by applying a magnetic field during fibrillogenesis. Then, through a process termed "contact guidance," the cells align with the fibrils by directing their motility. Such alignment is characteristic of many tissues, and may provide microstructural and mechanical cues for regulation of cell phenotype and function, as well as influence the gross mechanical properties of the tissues. Recent research in our laboratory has used magnetic-induced alignment in the fabrication of tissue-equivalents, notably circumferential alignment in tubes, and longitudinal alignment in rods (patent pending). The former is aimed at reproducing the architecture of the arterial media; the latter is aimed at providing a bridge that promotes directed axonal growth between severed nerve ends. These tissue engineering applications exploit the finding of Torbet and Ronziere (1) in their cell-free studies that forming fibrils tend to align in the plane normal to the direction of the field (because of the negative diamagnetic anisotropy of collagen) and parallel to the mold surfaces (because of an uncharacterized interfacial effect).