Exploring the Development of Ground-State Destabilization and Transition-State Stabilization in Two Directed Evolution Paths of Kemp Eliminases

Computer-aided enzyme design presents a major challenge since in most cases it has not resulted in an impressive catalytic power. The reasons for the problems with computational design include the use of nonquantitative approaches, but they may also reflect other difficulties that are not completely obvious. Thus, it is very useful to try to learn from the trend in directed evolution experiments. Here we explore the nature of the refinement of Kemp eliminases by directed evolution, trying to gain an understanding of related requirements from computational design. The observed trend in the directed evolution refinement of KE07 and HG3 are reproduced, showing that in the case of KE07 the directed evolution leads to ground-state destabilization, whereas in the case of HG3 the directed evolution leads to transition-state stabilization. The nature of the different paths of the directed evolution is examined and discussed. The present study seems to indicate that computer-aided enzyme design may require more than calculations of the effect of single mutations and should be extended to calculations of the effect of simultaneous multiple mutations (that make a few residues preorganized effectively). However, the analysis of two known evolution paths can still be accomplished using the relevant sequences and structures. Thus, by comparing two directed evolution paths of Kemp eliminases we reached the important conclusion that the more effective path leads to transition-state stabilization.

The Efficacy of Shielding Systems for Reducing Operator Exposure during Neurointerventional Procedures: A Real-World Prospective Study

BACKGROUND AND PURPOSE

Neurointerventional surgery may expose patients and physician operators to substantial amounts of ionizing radiation. Although strategies for reducing patient exposure have been explored in the medical literature, there has been relatively little published in regards to decreasing operator exposure. The purpose of this study was to evaluate the efficacy of shielding systems in reducing physician exposure in a modern neurointerventional practice.

MATERIALS AND METHODS

Informed consent was obtained from operators for this Health Insurance Portability and Accountability Act-compliant, institutional review board-approved study. Operator radiation exposure was prospectively measured during 60 consecutive neurointerventional procedures from October to November 2013 using a 3-part lead shielding system. Exposure was then evaluated without lead shielding in a second 60-procedure block from April to May 2014. A radiation protection drape was randomly selected for use in half of the cases in each block. Two-way analysis of covariance was performed to test the effect of shielding systems on operator exposure while controlling for other covariates, including procedure dose-area product.

RESULTS

Mean operator procedure dose was 20.6 μSv for the entire cohort and 17.7 μSv when using some type of shielding. Operator exposure significantly correlated with procedure dose-area product, but not with other covariates. After we adjusted for procedure dose-area product, the use of lead shielding or a radiation protection drape significantly reduced operator exposure by 45% (F = 12.54, P < .0001) and 29% (F = 7.02, P = .009), respectively. The difference in protection afforded by these systems was not statistically significant (P = .46), and their adjunctive use did not provide additional protection.

CONCLUSIONS

Extensive lead shielding should be used as much as possible in neurointerventional surgery to reduce operator radiation exposure to acceptable levels. A radiation protection drape is a reasonable alternative when standard lead shielding is unavailable or impractical to use without neglecting strategies to minimize the dose.

Sclerosing mesenteric panniculitis in a young patient : common cause of diagnostic dilemma and treatment refractoriness

BACKGROUND

Sclerosing mesenteric panniculitis (SMP) is an idiopathic chronic fibroinflammatory disorder of the intra-abdominal fat.

CASE PRESENTATION

Herin, we report a case of SMP, involving the omentum, mesentery and peri-colic fat in a 18 year old male, who presented with significant and recurrent abdominal distension for 4.5 years. Computed tomogram revealed ascites, with nodular and irregular omental thickening and foci of calcification. Non-specific radiological and histological features made an accurate diagnosis extremely difficult. After a thorough work up and exclusion of other differentials, diagnosis of a nodular SMP (Weber Christian disease) was given. After showing resistance to chemotherapeutic agents, slow response was noted with cyclophosphamide, followed by rapid symptomatic improvement with mesenterectomy.

CONCLUSION

SMP is an uncommon benign mesenteric/ omental inflammation, and is a diagnosis of exclusion. As treatment refractoriness is common, management should be individualized and continued for along period. Surgical omentectomy may be helpful.

Double-Blind Crossover Study to Compare Pain Experience During Inferior Alveolar Nerve Block Administration Using Buffered Two Percent Lidocaine in Children

PURPOSE

Buffering of anesthetic solutions has been suggested to reduce pain on injection and onset of anesthesia. The purpose of this study was to assess the reduction in pain on injection during inferior alveolar nerve block administration in children.

METHODS

A double blind crossover study was designed where 30 six- to 12-year-old patients received two sessions of inferior alveolar nerve block scheduled one week apart. Two percent lidocaine with 1:200,000 epinephrine was given during one appointment, and a buffered solution was given during the other. Pain on injection was assessed using the sound, eye, and motor (SEM) scale, and the time to onset was assessed after gingival probing. The Heft-Parker visual analogue scale (HP-VAS) was self recorded by the patient after administration of local anesthesia.

RESULTS

When tested using Mann-Whitney analysis, no significant differences were found between the SEM scores (P=0.71) and HP-VAS scores (P=0.93) for the two solutions used. Student's t test was used to assess the difference in the onset of anesthesia, which was also found to be statistically insignificant (P=0.824).

CONCLUSION

Buffered lidocaine did not reduce the pain on injection or time to onset of anesthesia for inferior alveolar nerve block in children.

An in-vitro evaluation of the effect of 980 nm diode laser irradiation on intra-canal dentin surface and dentinal tubule openings after biomechanical preparation: Scanning electron microscopic study

Context:

Very recently, diode laser has been used for disinfecting the root canals in endodontic treatment and increasing its success rate and longevity utilizing the thermal effect of laser on surrounding tissues.

Aims:

The aim of this study is to evaluate the effect of 980 nm laser irradiation on intra-canal dentin surface – scanning electron microscopic (SEM) - in-vitro study.

Methods:

A total of 40 single-rooted freshly extracted permanent teeth were collected. Teeth were sectioned at the cemento-enamel junction using diamond disc. Root canals of all samples were prepared using hand ProTaper, which were randomly assigned into two groups (n = 20 each). Group 1: Receiving no treatment after biomechanical preparation; Group 2: 980 nm diode laser-treated root canals. Teeth were prepared for SEM analysis to check the size of intra-canal dentinal tubule openings.

Statistical Analysis Used:

Data were analyzed using SPSS V.16 software and compared using Levene's and independent t-test.

Results:

On statistical analysis, width of intracanal dentinal tubule openings in Group 1 (control) was significantly higher than those observed in Group 2 (diode laser-treated) (P < 0.001).

Conclusion:

This study showed that the application of 980 nm diode laser on intra-radicular dentin resulted in ultrastructural alterations resulting in melting of dentin.

A comparative evaluation of dermatoglyphics in different classes of malocclusion

Aim

To study associations of dermatoglyphic features with malocclusion in Indian children.

Materials and methods

A total of 237 children aged 12–16 years, who attended our outpatient clinic in a government medical college, were selected. Finger and palm prints were collected, and fingertip pattern frequencies, total ridge counts (TRCs), and atd angles (formed by the triradii below the first and last digits and that in the hypothenar region of the palm) were calculated. These parameters were analyzed with their Angle’s class of malocclusion using appropriate statistical tests. Dermatoglyphic parameters were examined and asymmetry analysis was conducted in subjects with different occlusion patterns.

Results

Although no fingerprint pattern was found to be specific for a particular class of occlusion, increased tendencies toward high frequencies of whorls in subjects with class II malocclusion and plain arches in those with class III malocclusion were observed. Significant differences in atd angle and TRC were observed among malocclusion types (p = 0.0001). Asymmetry scores did not differ significantly.

Conclusion

Dermatoglyphic analysis can be used as an indicator of malocclusion at an early age, thereby aiding the development of treatments aiming to establish favorable occlusion. Inheritance and twin studies, as well as those conducted in different ethnic groups, are required to examine these relationships further.

Deciphering the Origin of Stereoinduction in Cooperative Asymmetric Catalysis Involving Pd(II) and a Chiral Brønsted Acid

The density functional (M06) computations on a cooperative multicatalytic reaction involving palladium acetate and a chiral Brønsted acid in the conversion of an indenyl cyclobutanol to spirocyclic indene bearing a quaternary carbon ring junction are reported. A chiral Pd-bis-phosphate is identified as the active catalyst in the enantioselective ring expansion as compared to alternative possibilities wherein the chiral phosphate/phosphoric acid is in the outer sphere of palladium. The enantiocontrolling transition state exhibited more effective C-H···π interactions, lower distortion of the catalyst, and an orthogonal orientation of the bulky phosphate ligands.

Rational design of catalysts for asymmetric diamination reaction using transition state modeling

DFT calculations have been used to design chiral phosphoramidite ligands for the asymmetric diamination of vicinal diamines. The substituents at both the 3,3′ positions of the binol framework and the amido nitrogen play a vital role in the stereochemical outcome.

Attitudes and Awareness Regarding Hepatitis B and Hepatitis C Amongst Health-care Workers of a Tertiary Hospital in India

Background:

Hepatitis is an inflammatory disease of the liver. In sever cases, it may lead to permanent liver damage including liver cirrhosis or hepato-cellular carcinoma and may ultimately lead to death. Health-care workers (HCWs), due to their regular contact with patients are at a high-risk of acquiring this disease.

Aim:

The aim of this study was to assess the knowledge and attitude toward hepatitis B and C infection among the health-care interns and correlate the level of awareness to the attitude they behold toward the disease.

Subjects and Methods:

A closed ended questionnaire consisting of questions to evaluate the knowledge regarding hepatitis B and C infection and attitude of the (HCWs/interns) was duly filled by 255 participants including, 100 dental, 100 medical, and 55 nursing interns. Statistical analysis was carried out using the Chi-square test, ANOVA test, post-hoc test and Pearson's correlation.

Results:

Although most of the interns were aware of the existence of hepatitis B and C infection, the level of awareness regarding the modes of transmission and vaccination was found to be dissatisfactory. Awareness level regarding the infection among nursing interns was statistically significantly lower than the dental and medical interns. A direct positive correlation as found between awareness score and behavior score, which reveals that interns with better awareness level had better attitudes toward the infection and prevention of its transmission.

Conclusion:

There is an urgent need to increase the level and quality of training among HCWs to prevent the spread of hepatitis B virus and hepatitis C virus.

Developmental malformation of primary and permanent dentition: a rare sequel of trauma

Dentofacial injuries that occur prior to the eruption of primary teeth can result in developmental disturbances not only in the primary but also in permanent dentition. Here we report a rare case of long term sequelae of trauma in a female child of 4 to 5 months of age which resulted in dilaceration and impaction of maxillary primary central incisors and subsequent enamel hypoplasia of the permanent maxillary central incisors.

Generalised stunting of roots in an epileptic child: is long-term phenytoin therapy the cause?

Long-term phenytoin therapy is known to cause disturbance in calcium and bone homeostasis. Dental tissues being calcified tissues can also be affected by this derangement of mineral metabolism, especially during developmental phases. This report describes a case of an epileptic child who presented with short roots, enlarged pulp chambers, blunt apices and delayed eruption of permanent dentition, which might be attributed to long-term phenytoin therapy. The purpose of this case report is to increase awareness among the clinicians about its possible dental implications and emphasise upon the need of regular dental check-ups in epileptic children.