Micro-Imaging by Interference Microscopy: A Case Study of Orientation-Dependent Guest Diffusion in MFI-Type Zeolite Host Crystals

Because of the small particle size, orientation-dependent diffusion measurements in microporous materials remains a challenging task. We highlight here the potential of micro-imaging by interference microscopy in a case study with MFI-type crystals in which, although with different accuracies, transient concentration profiles in all three directions can be observed. The measurements, which were performed with “rounded-boat” shaped crystals, reproduce the evolution patterns of the guest profiles recorded in previous studies with the more common “coffin-shaped” MFI crystals. The uptake and release patterns through the four principal faces (which in the coffin-shaped crystals extend in the longitudinal direction) are essentially coincident and there is no perceptible mass transfer in the direction of the long axis. The surface resistances of the four crystal faces through which mass transfer occurs are relatively small and have only a minor effect on the mass transfer rate. As a result of the pore structure, diffusion in the crystallographic c direction (which corresponds to the direction of the long axis) is expected to be much slower than in the transverse directions. This could explain the very low rate of mass transfer observed in the direction of the long axis, but it is also possible that the small end faces of the crystal may have high surface resistance. It is not possible to distinguish unequivocally between these two possibilities. All guest molecules studied (methyl-butane, benzene and 4-methyl-2-pentyne) show the same orientation dependence of mass transfer. The long 4-methyl-2-pentyne molecules would be expected to propagate at very different rates through the straight and sinusoidal channels. The coinciding patterns for uptake through the mutually perpendicular crystal faces therefore provide clear evidence that both the coffin shaped crystals and the rounded-boat-shaped crystals considered in this study, must be intergrowths rather than pure single crystals.     

Five-year Longitudinal Study of Signs and Symptoms of Mandibular Dysfunction in Adolescents

A longitudinal study covering five years of clinical signs and subjective symptoms of mandibular dysfunction was performed in 119 adolescents, 15 years old at the first examination and 20 years old at the follow-up. Sixty-two percent had clinical signs of mandibular dysfunction, but the signs were in most cases mild, while moderate and severe signs were found in 17%. No change in clinical signs between the two examinations were noted in nearly half of the individuals, and improvement and impairment had occurred at an almost equal rate.

At the follow-up, 31% of the participants reported that they sometimes had TMJ sound, tiredness in the jaws, or difficulties in mouth opening, and another 8% suffered from one or more of these symptoms frequently. The frequency of subjective symptoms as well as reports of bruxism had increased statistically significantly compared with five years previously.

A statistically significant correlation was found between the subjective symptoms and the clinical dysfunction index used. No single subjective or clinical variable or combination of variables seemed to have any significant influence on the positive or negative changes of the clinical dysfunction index between the two examinations. The explanation suggested is that the development of clinical signs of mandibular dysfunction is very complex, including numerous variables, some of which were not recorded in the present investigation.     

Psychosocial Factors Associated with Resilience in a National Community-Based Cohort of Australian Gay Men Living with HIV

HIV-positive gay men may experience multiple sources of adversity and stress, related both to their HIV diagnosis and sexual identity. Most of these men, however, do not experience mental health problems. Little is known about factors that help them achieve resilience in the face of life challenges. This study examined psychosocial factors associated with resilience in a national community-based sample of 357 Australian HIV-positive gay men. Resilience was measured using the Connor–Davidson Resilience Scale. Higher levels of resilience were linked with experiencing low or no internalized HIV-related stigma, having no previous history of mental health problems, and a number of socioeconomic indicators. In addition to providing a more complete picture of the mental health of HIV-positive gay men, findings from this study can be used to inform strength-based approaches to mental health prevention and support.     

Recalcitrant granulomatous periorificial dermatitis with good response to low‐dose oral isotretinoin

Granulomatous periorificial dermatitis is a clinical variant of periorificial dermatitis. We present the case of an 18‐year‐old girl with several reddish papular lesions in the perioral, perinasal, and periorbital regions unresponsive to conventional therapy. After 6 months of therapy with low‐dose oral isotretinoin, the lesions fully remitted.     

Increasing mitochondrial ATP synthesis with butyrate normalizes ADP and contractile function in metabolic heart disease

Metabolic heart disease (MHD), which is strongly associated with heart failure with preserved ejection fraction, is characterized by reduced mitochondrial energy production and contractile performance. In this study, we tested the hypothesis that an acute increase in ATP synthesis, via short chain fatty acid (butyrate) perfusion, restores contractile function in MHD. Isolated hearts of mice with MHD due to consumption of a high fat high sucrose (HFHS) diet or on a control diet (CD) for 4 months were studied using ³¹P NMR spectroscopy to measure high energy phosphates and ATP synthesis rates during increased work demand. At baseline, HFHS hearts had increased ADP and decreased free energy of ATP hydrolysis (ΔG _{~ ATP}), although contractile function was similar between the two groups. At high work demand, the ATP synthesis rate in HFHS hearts was reduced by over 50%. Unlike CD hearts, HFHS hearts did not increase contractile function at high work demand, indicating a lack of contractile reserve. However, acutely supplementing HFHS hearts with 4mM butyrate normalized ATP synthesis, ADP, ΔG _{~ ATP} and contractile reserve. Thus, acute reversal of depressed mitochondrial ATP production improves contractile dysfunction in MHD. These findings suggest that energy starvation may be a reversible cause of myocardial dysfunction in MHD, and opens new therapeutic opportunities.