Liquefaction of human vitreous in model aphakic eyes by 300-nm UV photolysis: monitoring liquefaction by fluorescence

After the lens is removed in cataract surgery, the vitreous presumably receives all of the ambient 300-nm light that has filtered through the cornea. Using this model for aphakic eyes, we progressively irradiated intact vitreous samples of a 49-year-old human with 300-nm light and monitored changes in absorption, fluorescence, and circular dichroism (CD) properties. CD and fluorescence measurements of unirradiated vitreous samples showed a) a strong tryptophan fluorescence band of non-collagenous protein at 336 nm and a very weak band around 430 nm due to N-formylkynurenine (N-FK), a photoproduct of tryptophan, and b) a strong, negative CD band below 250 nm representing a composite spectrum of hyaluronic acid, collagen, and non-collagenous protein. Upon irradiation, the tryptophan emission band at 336 nm progressively decreased with time and the band maximum was concomitantly red-shifted; the N-FK fluorescence band at 430 nm, on the other hand, continually increased with the time of irradiation. A significant increase in the fluidity (liquefaction) of the vitreous gel also was noted upon irradiation, a change that was monitored successfully by measuring the progressive decrease in the polarization value of tryptophan fluorescence. The extent of liquefaction, measured spectroscopically, was found to be 40% upon irradiation for 10 hr. In addition, CD measurements indicated a partial loss in the secondary structure of the non-collagenous protein.

Serum-induced collagen gel contraction

PURPOSE

To understand the molecular events underlying disease-related vitreous gel contraction, the effect of serum components on collagen was investigated.

METHODS

Bovine vitreous or dermal collagen was incubated with a mixture of transglutaminase (TG; factor XIIIa) and fibronectin (FN), and the biochemical changes of collagen were monitored by gel electrophoresis. In addition, serum-induced changes in the volume of the collagen gel were monitored.

RESULTS

Gel electrophoresis revealed a new high-molecular-weight band (M(r) 240,000) presumably due to intermolecular cross-links of collagen peptides and FN. The serum components also were shown to cause a significant decrease in the volume of the collagen gel. CONCLUSION. Collagen gel contraction could be attributed to the collagen-FN-collagen cross-links catalyzed by TG.

Ascorbic acid therapy in a thermal burn model of corneal ulceration in rabbits

We studied the effect of topical and systemic ascorbic acid on a rabbit model of corneal ulceration produced by thermal burn. Central stromal ulceration occurred in 77% to 100% of eyes in all treatment groups. The rate of ulceration was accelerated in animals treated with systemic ascorbic acid. Ulceration began after 5.80 +/- 2.14 days in control eyes and 2.75 +/- 1.26 days in the eyes of rabbits treated with both topical and systemic ascorbic acid (P less than .02). Subconjunctival ascorbic acid alone did not affect the rate of ulceration (average onset, 6 +/- 1 days). Once ulceration occurred in animals treated with both topical and systemic ascorbic acid, the incidence of perforation and descemetocele formation was increased and that of healing was decreased. The time required for healing was not significantly altered by treatment (9.50 +/- 2.28 days for control eyes vs 5.75 +/- 2.78 days for treated eyes) (P greater than .05).

Hydrodynamic Synchronization of Spontaneously Beating Filaments

Using a geometric feedback model of the flagellar axoneme accounting for dynein motor kinetics, we study elastohydrodynamic phase synchronization in a pair of spontaneously beating filaments with waveforms ranging from sperm to cilia and Chlamydomonas. Our computations reveal that both in-phase and antiphase synchrony can emerge for asymmetric beats while symmetric waveforms go in phase, and elucidate the mechanism for phase slips due to biochemical noise. Model predictions agree with recent experiments and illuminate the crucial roles of hydrodynamics and mechanochemical feedback in synchronization.

Calculation of the first excited (1)S(e) state of the He atom using supersymmetric quantum mechanics and extension to the nth excitation

Usually the renormalized Numerov (RN) algorithm is used to solve the set of coupled differential equations of the few-body system, mainly for the ground state. The straightforward approach of this algorithm faces some serious problems of convergence to calculate the excited states. Here we present an alternative method using the supersymmetric quantum mechanics formalism to a multidimensional bound-state problem. The problem of convergence is avoided in this approach by searching for the ground state of the partner potential. Application of this formalism to the first excited (1)S(e) state of the He atom gives excellent results; it is much better than the conventional RN algorithm and the hyperspherical adiabatic approximation. We also indicate how the method can be generalized to the nth excited state.

Preference for biological motion is reduced in ASD: implications for clinical trials and the search for biomarkers

BACKGROUND

The neurocognitive mechanisms underlying autism spectrum disorder (ASD) remain unclear. Progress has been largely hampered by small sample sizes, variable age ranges and resulting inconsistent findings. There is a pressing need for large definitive studies to delineate the nature and extent of key case/control differences to direct research towards fruitful areas for future investigation. Here we focus on perception of biological motion, a promising index of social brain function which may be altered in ASD. In a large sample ranging from childhood to adulthood, we assess whether biological motion preference differs in ASD compared to neurotypical participants (NT), how differences are modulated by age and sex and whether they are associated with dimensional variation in concurrent or later symptomatology.

METHODS

Eye-tracking data were collected from 486 6-to-30-year-old autistic (N = 282) and non-autistic control (N = 204) participants whilst they viewed 28 trials pairing biological (BM) and control (non-biological, CTRL) motion. Preference for the biological motion stimulus was calculated as (1) proportion looking time difference (BM-CTRL) and (2) peak look duration difference (BM-CTRL).

RESULTS

The ASD group showed a present but weaker preference for biological motion than the NT group. The nature of the control stimulus modulated preference for biological motion in both groups. Biological motion preference did not vary with age, gender, or concurrent or prospective social communicative skill within the ASD group, although a lack of clear preference for either stimulus was associated with higher social-communicative symptoms at baseline.

LIMITATIONS

The paired visual preference we used may underestimate preference for a stimulus in younger and lower IQ individuals. Our ASD group had a lower average IQ by approximately seven points. 18% of our sample was not analysed for various technical and behavioural reasons.

CONCLUSIONS

Biological motion preference elicits small-to-medium-sized case-control effects, but individual differences do not strongly relate to core social autism associated symptomatology. We interpret this as an autistic difference (as opposed to a deficit) likely manifest in social brain regions. The extent to which this is an innate difference present from birth and central to the autistic phenotype, or the consequence of a life lived with ASD, is unclear.

Fluid circulation driven by collectively organized metachronal waves in swimming T. aceti nematodes

Recent experiments have shown that the nematode T. aceti can assemble into collectively undulating groups at the edge of fluid drops. This coordinated state consists of metachronal waves and drives fluid circulation inside the drop. We find that the circulation velocity is about 2 mm/s and nearly half the speed of the metachronal wave. We develop a quasi-two-dimensional hydrodynamics model using the Stokes flow approximation. The periodic motion of the nematodes constitute our moving boundary condition that drives the flow. Our model suggests that large-amplitude excursions of the nematode tails produce the fluid circulation. We discuss the constraints on containers that would enhance fluid motion, which could be used in the future design of on demand flow generating systems.

Interplay of phosphorus doses, cyanobacterial inoculation, and elevated carbon dioxide on yield and phosphorus dynamics in cowpea

Phosphorus (P) demand is likely to increase especially in legumes to harness greater benefits of nitrogen fixation under elevated CO₂ condition. In the following study, seed yield and seed P uptake in cowpea increased by 26.8% and 20.9%, respectively, under elevated CO₂ level. With an increase in phosphorus dose up to 12 mg kg^-1, seed yield enhanced from 2.6 to 5.4 g plant^-1. P application and cyanobacterial inoculation increased the microbial activity of soil, leading to increased availability of P. Under elevated CO₂ condition, microbial activity, measured as dehydrogenase, acid phosphatase, and alkaline phosphatase activities showed stimulation. Soil available P also increased under elevated CO₂ condition and was stimulated by both P application and cyanobacterial inoculation. Higher P uptake in elevated CO₂ condition led to lower values of inorganic P in soil. Stepwise regression analysis showed that aboveground P uptake, soil available P, and alkaline phosphatase activity of soil influenced the yield while available P, and organic and inorganic P influenced the aboveground P uptake of the crop. This study revealed that under elevated CO₂ condition, P application and cyanobacterial inoculation facilitated P uptake and yield, mediated through enhanced availability of nutrients, in cowpea crop.

Glycosaminoglycan conformations and changes on periodate oxidation

The progressive periodate oxidation of glycosaminoglycans (GAG), including hyaluronate (HA), chondroitins (CH) (chondroitin, chondroitin 4- and 6-sulfate), dermatan sulfate (DS), and keratan sulfate (KS), were monitored by CD and high performance liquid chromatography (HPLC) using a size-exclusion column. The rate of oxidation also was measured and calculated using first- and second-order kinetics, and the data appear to fit better with first-order kinetics. In both HA and CH, the n - pi amide band at 208 nm decreases in intensity upon oxidation, but in HA it becomes positive after 16 h of periodate treatment. In CH, the band disappears, and the pi - pi amide band below 200 nm becomes optically active. Concomitantly, a second negative band near 290 nm appears for these two oxidized GAG. Oxidation causes a slight change in the CD of DS. It ordinarily displays a very weak n - pi band at 210 nm, but instead shows an intense pi - pi amide band near 190 nm. CD of KS remains unaffected by periodate. Kinetic studies, however, show a higher oxidation rate for DS than HA and CH. With the exception of KS, all other oxidized polymers shown an apparent decrease in molecular weight (higher peak retention time) in HPLC analysis. Both CD and HPLC results have been attributed to a major conformational change of HA and CH, and a minor one for DS. The ease and extent of periodate oxidation as well as the changes in molecular properties following periodate treatment are critically dependent on the configuration of the individual GAG rather than the oxidation rate. There is a distinct difference in the conformational change between HA and CH, as manifested by their dichroic behavior, that was attributed to the equatorial disposition of C-4 hydroxyl group in HA and axial disposition CH.

Non-adenomatous non-epithelial carcinoma (hemangiopericytoma) of prostate treated with conservative surgery followed by adjuvant chemoradiation

Hemangiopericytoma is a malignant vascular tumour of soft tissue. Microscopically, the tumour shows tightly packed cellular areas surrounding thin-walled branching blood vessels. Traditionally these tumours are treated using wide surgical excision. Only a very few cases of hemangiopericytoma of the prostate have been described worldwide. The feasibility of managing such a case with a combination of conservative surgery and adjuvant anti-malignancy treatment is unexplored. Here, we report a case of hemangiopericytoma of the prostate treated with local excision, with preservation of prostate, followed by adjuvant radiotherapy (40 Gy in 20 fractions to pelvis followed by 24 Gy in 12 fractions as boost to prostate) and chemotherapy (doxorubicin and iphosphamide). Post-treatment computed tomography scan after 4 weeks showed regression of pelvic lymph nodes and a normal-appearing prostate. Levels of serum prostate-specific and carcinogenic embryonic antigen were normal throughout the period of treatment. To date, followup has been uneventful, except for occasional bouts of diarrhea.We conclude that conservative surgery followed by adjuvant radiation and chemotherapy, with subsequent close follow-up, may adequately control localized disease in selected cases of hemangiopericytoma of the prostate. The role of conservative surgery in tumours located at other sites has yet to be defined.

Collective Motion and Pattern Formation in Phase-Synchronizing Active Fluids

Many active particles, such as swimming micro-organisms or motor proteins, do work on their environment by going though a periodic sequence of shapes. Interactions between particles can lead to synchronization of their duty cycles. Here, we study the collective dynamics of a suspension of active particles coupled through hydrodynamics. We find that at high enough density the system transitions to a state of collective motion by a mechanism that is distinct from other instabilities in active matter systems. Second, we demonstrate that the emergent nonequilibrium states feature stationary chimera patterns in which synchronized and phase-isotropic regions coexist. Third, we show that in confinement, oscillatory flows and robust unidirectional pumping states exist, and can be selected by choice of alignment boundary conditions. These results point toward a new route to collective motion and pattern formation and could guide the design of new active materials.