Magnetic Resonance Imaging-based biomechanical simulation of cartilage: A systematic review

MRI-based mathematical and computational modeling studies can contribute to a better understanding of the mechanisms governing cartilage's mechanical performance and cartilage disease. In addition, distinct modeling of cartilage is needed to optimize artificial cartilage production. These studies have opened up the prospect of further deepening our understanding of cartilage function. Furthermore, these studies reveal the initiation of an engineering-level approach to how cartilage disease affects material properties and cartilage function. Aimed at researchers in the field of MRI-based cartilage simulation, research articles pertinent to MRI-based cartilage modeling were identified, reviewed, and summarized systematically. Various MRI applications for cartilage modeling are highlighted, and the limitations of different constitutive models used are addressed. In addition, the clinical application of simulations and studied diseases are discussed. The paper's quality, based on the developed questionnaire, was assessed, and out of 79 reviewed papers, 34 papers were determined as high-quality. Due to the lack of the best constitutive models for various clinical conditions, researchers may consider the effect of constitutive material models on the cartilage disease simulation. In the future, research groups may incorporate various aspects of machine learning into constitutive models and MRI data extraction to further refine the study methodology. Moreover, researchers should strive for further reproducibility and rigorous model validation and verification, such as gait analysis.

General anesthesia in cesarean sections: a prospective review of 465 cesarean sections performed under general anesthesia

BACKGROUND

In many countries, neuraxial blocks comprise the majority of anesthetics given for cesarean section. In Iran, however general anesthesia for cesarean section is prevalent. In our institution, the rate of general anesthesia for cesarean section is 39%, providing an opportunity to collect data regarding airway management in the parturients. We report on the outcomes of a series of patients who received general anesthesia for cesarean section.

METHODS

A prospective observational study was conducted in two university hospitals, with approximately 5,500 deliveries annually. Demographics and airway characteristics were recorded. Eight potential risk factors for difficult intubation (short neck, obesity, facial edema, swollen tongue, receding mandible, and single, missing or protruding maxillary incisors) were analyzed. Then, laryngoscopic view, difficulty at intubation, and major complications were recorded.

RESULTS

Data were obtained from 465 patients. There was a significant correlation between higher Mallampati score and both higher laryngoscopic view graded on the Cormack-Lehane system (P < 0.001) and difficulty at intubation (P-Value = 0.05). Emergency cesarean section was not associated with difficult intubation (P = 0.67). Multivariate analysis showed that receding mandible was the only potential risk factor for difficult tracheal intubation (P < 0.001) and removed short neck or protruding maxillary incisor which initially was powered as a risk factor by univariate analysis. A grade 3 laryngoscopic view was obtained in 15 cases (3.2%). There was no case of grade 4 view. There was only one failed intubation (0.2%), and 9 cases of very difficult intubation (1.9%).

CONCLUSION

General anesthesia for cesarean section is safe with minimal risk.

Applications of chitosan nanoparticles in drug delivery

We have reviewed the binding affinities of several antitumor drugs doxorubicin (Dox), N-(trifluoroacetyl) doxorubicin (FDox), tamoxifen (Tam), 4-hydroxytamoxifen (4-Hydroxytam), and endoxifen (Endox) with chitosan nanoparticles of different sizes (chitosan-15, chitosan-100, and chitosan-200 KD) in order to evaluate the efficacy of chitosan nanocarriers in drug delivery systems. Spectroscopic and molecular modeling studies showed the binding sites and the stability of drug-polymer complexes. Drug-chitosan complexation occurred via hydrophobic and hydrophilic contacts as well as H-bonding network. Chitosan-100 KD was the more effective drug carrier than the chitosan-15 and chitosan-200 KD.

RNA binding to antioxidant flavonoids

Flavonoids are an interesting group of natural polyphenolic compounds that exhibit extensive bioactivities such as scavenging free radical, antitumor and antiproliferative effects. The anticancer and antiviral effects of these natural products are attributed to their potential biomedical applications. While flavonoids complexation with DNA is known, their bindings to RNA are not fully investigated. This study was designed to examine the interactions of three flavonoids; morin (Mor), apigenin (Api) and naringin (Nar) with yeast RNA in aqueous solution at physiological conditions, using constant RNA concentration (6.25 mM) and various pigment/RNA (phosphate) ratios of 1/120 to 1/1. FTIR, UV-visible spectroscopic methods were used to determine the ligand binding modes, the binding constant and the stability of RNA in flavonoid-RNA complexes in aqueous solution. Spectroscopic evidence showed major binding of flavonoids to RNA with overall binding constants of K(morin) = 9.150 x 10(3) M(-1), K(apigenin)=4.967 x 10(4) M(-1), and K(naringin)=1.144 x 10(4) M(-1). The affinity of flavonoid-RNA binding is in the order of apigenin>naringin>morin. No biopolymer secondary structural changes were observed upon flavonoid interaction and RNA remains in the A-family structure in these pigment complexes.

Protein unfolding in drug-RNase complexes

Bovine pancreatic ribonuclease A (RNase A) catalyzes the cleavage of P-O5' bonds in RNA on the 3' side of pyrimidine to form cyclic 2', 5'-phosphates. It has several high affinity binding sites that make it possible target for many organic and inorganic molecules. Ligand binding to RNase A can alter protein secondary structure and its catalytic activity. In this review, the effects of several drugs such as AZT (anti-AIDS), cis-Pt (antitumor), aspirin (anti-inflammatory), and vitamin C (antioxidant) on the stability and conformation of RNase A in vitro are compared. The results of UV-visible, FTIR, and CD spectroscopic analysis of RNase complexes with aspirin, AZT, cis-Pt, and vitamin C at physiological conditions are discussed here. Spectroscopic results showed one major binding for each drug-RNase adduct with KAZT=5.29 (+/-1.6)x10(4) M(-1), Kaspirin=3.57 (+/-1.4)x10(4) M(-1), Kcis-Pt=5.66 (+/-1.9)x10(3) M(-1), and Kascorbate=3.50 (+/-1.5)x10(3) M(-1). Major protein unfolding occurred with reduction of alpha-helix from 29% (free protein) to 20% and increase of beta-sheet from 39% (free protein) to 45% in the aspirin-, ascorbate-, and cis-Pt-RNase complexes, while minor increase of alpha-helix was observed for AZT-RNase adduct.

Influence of uterine exteriorization versus in situ repair on post-Cesarean maternal pain: a randomized trial

BACKGROUND

This study was done to compare post-cesarean delivery pain associated with routine exteriorization of the uterus versus in situ uterine repair in the puerperium.

METHODS

This prospective study included 206 women who underwent cesarean delivery under general anesthesia and who were randomly assigned to two groups based on the site of uterine repair: exteriorized uterine repair (102 women) versus in situ uterine repair (104 women). Exclusion criteria were neuraxial blockade and patient refusal to participate. Visceral and incisional pain was assessed on the first and second postoperative nights using a visual analog score of 0-100 mm.

RESULTS

There were no significant differences between the groups in maternal age, weight, gestational age, race, preoperative hemoglobin or gravidity. All subjects underwent general anesthesia and had a low transverse incision of the uterus. Exteriorization was associated with higher postoperative visceral pain scores: first night 66.7 vs. 43.5 (P<0.001); second night 44.6 vs. 23.9 (P<0.001). The incidence of postoperative fever and wound infection, postoperative hemoglobin and duration of hospital stay were similar between groups.

CONCLUSION

Exteriorization of the uterus for repair of the uterine incision increases the first- and second-night postoperative pain significantly in women undergoing cesarean section.

The effects of drug complexation on the stability and conformation of human serum albumin: protein unfolding

We report different analytical methods used to study the effects of 3\'-azido-3\'-deoxythymidine, aspirin, taxol, cisplatin, atrazine, 2,4-dichlorophenoxyacetic, biogenic polyamines, chlorophyll, chlorophyllin, poly(ethylene glycol), vanadyl cation, vanadate anion, cobalt-hexamine cation, and As2O3, on the stability and secondary structure of human serum albumin (HSA) in aqueous solution, using capillary electrophoresis, Fourier transform infrared, ultraviolet visible, and circular dichroism (CD) spectroscopic methods. The concentrations of HSA used were 4% to 2% or 0.6 to 0.3 mM, while different ligand concentrations were 1 microM to 1 mM. Structural data showed drugs are mostly located along the polypeptide chains with both specific and nonspecific interactions. The stability of drug-protein complexes were in the order K(VO(2+)) 1.2 x 10(8) M(-1) > K(AZT) 1.9 x 10(6) M(-)1 > K(PEG) 4.1 x 10(5) M(-1) > K(atrazine) 3.5 x 10(4) M(-1) > K(chlorophyll) 2.9 x 10(4) M(-1) > K2,4-D 2.5 x 10(4) M-1 > K(spermine) 1.7 x 10(4) M(-1) > K(taxol) 1.43 x 10(4) M(-1) > K(Co(3+)) > 1.1 x 10(4) M(-1) > K(aspirin) 1.04 x 10(4)i(-1) > K(chlorophyllin) 7.0 x 10(3) M(-1) > K(VO(3)(-)) 6.0 x 103 M(-1) > K(spermidine) 5.4 x 10(3) M(-1) > K(putrescine) 3.9 x 10(3) M(-1) > K(As(2)O(3)) 2.2 x 10(3) M(-1)> K(cisplatin) 1.2 x 10(2) M(-1). The protein conformation was altered (infrared and CD results) with major reduction of alpha-helix from 60 to 55% (free HSA) to 49 to 40% and increase of beta-structure from 22 to 15% (free HSA) to 33 to 23% in the drug-protein complexes. The alterations of protein secondary structure are attributed to a partial unfolding of HSA on drug complexation.

Abnormal viscoelastic behaviour of passive ankle joint movement in diabetic patients: an early or a late complication?

AIMS/HYPOTHESIS

The goal of the present study was to compare the range of motion and both the viscous and elastic components of passive ankle joint movement in short- and long-term diabetic patients with that of a control population.

METHODS

Thirty-four diabetic patients and 16 control subjects entered into the study. Patients with a history of over 15 years of diabetes were considered as a long-term diabetic group. In order to quantify the passive ankle joint movement, a device was designed to measure the dorsi- and plantar-flexion angle and the net moment at the ankle. Elastic behaviour was examined as the separate slope of regression lines (stiffness) of plantar and dorsal components in the loading moment-angle curve. It was also examined as the slope of the regression line in the final 10% of each component. Hysteresis, a characteristic of viscoelastic materials that indicates loss of energy during unloading, was corrected for range of motion and used to examine viscous behaviour of the ankle joint.

RESULTS

Total and plantar ranges of motion were significantly lower in long-term diabetic patients than in short-term diabetic and control groups (p < 0.05). Plantar-flexion stiffness was significantly lower in short-term diabetic patients than in control subjects and long-term diabetic groups (p < 0.05). Corrected hysteresis was significantly higher in long-term diabetic than in short-term diabetic and control (p < 0.05) groups in the dorsal range of motion.

CONCLUSIONS/INTERPRETATION

This study shows that both decreased plantar and total ankle joint ranges of motion, and increased viscous component of passive ankle joint movement are among the late complications of diabetes.

Thymol and carvacrol binding to DNA: model for DRUG-DNA interaction

Thymol and carvacrol can bind to major and minor grooves of B-DNA. The aim of this study was to examine the interaction of calf thymus DNA with thymol and carvacrol in aqueous solution and physiological pH with thymol/DNA and carvacrol/DNA (phosphate) molar ratios of 1/20, 1/10, 1/5, and 1/1. Fourier transform infrared and UV-visible difference spectroscopy were used to determine the thymol and carvacrol binding mode, binding constant, sequence selectivity, DNA secondary structure, and structural variations of thymol/DNA and carvacrol/DNA complexes in aqueous solution. Spectroscopic evidence showed that the thymol and carvacrol interaction occurred mainly through H-bonding of the thymol and carvacrol OH group to the guanine N7, cytosine N3, and backbone phosphate group with overall binding constant of K(thymol-DNA) = 2.43 x 10(3) M(-1), K(carvacrol-DNA) = 1.55 x 10(3) M(-1). In thymol and carvacrol-DNA complexes, DNA remains in the B-family structure.

Thallium-DNA complexes in aqueous solution. Major or minor groove binding

Thallium (Tl) binds to the major and minor grooves of B-DNA in the solid state (Howerton et al., Biochemistry 40, 10023-10031, 2001). The aim of this study was to examine the binding of Tl(I) cation with calf-thymus DNA in aqueous solution at physiological pH, using constant concentration of DNA (12.5 mM) and various concentrations of metal ions (0.5 to 20 mM). UV-visible and FTIR spectroscopic methods were used to determine the cation binding site, the binding constant and DNA structural variations in aqueous solution. Direct Tl bindings to guanine and thymine were evident by major spectral changes of DNA bases with overall binding constant of K = 1.40 x 10(4) M(-1) and little perturbations of the backbone phosphate group. Both major and minor groove bindings were observed with no alteration of the B-DNA conformation. At low metal concentration (0.5 mM), the number of cations bound were 10 per 1000 nucleotides, while at higher cation concentration (10 mM), this increased to 30 cations per 1000 nucleotides.