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.     

Bleeding from gastrointestinal angioectasias is not related to bleeding disorders - a case control study

Background  

Angioectasias in the gastrointestinal tract can be found in up to 3% of the population. They are typically asymptomatic but may sometimes result in severe bleeding. The reasons for why some patients bleed from their angioectasias are not fully understood but it has been reported that it may be explained by an acquired von Willebrand syndrome (AVWS). This condition has similar laboratory findings to congenital von Willebrand disease with selective loss of large von Willebrand multimers. The aim of this study was to find out if AVWS or any other bleeding disorder was more common in patients with bleeding from angioectasias than in a control group.     

Fecal incontinence after transanal endoscopic microsurgery

Purpose

Transanal endoscopic microsurgery (TEM) procedure could potentially influence the development of fecal incontinence later in life. The aim of our study was to assess long-term functional outcomes after TEM and to determine possible variables related to incontinence.

Methods

Patients, enrolled in a prospectively collected TEM operation database, were interviewed using a postal questionnaire. The questionnaire consisted of EuroQol (EQ)-5D-5L quality of life questionnaire, Wexner fecal incontinence grading scale, and additional questions about other perianal operations and obstetric history for women. We divided patients into two groups: no or minor fecal incontinence (Wexner score of 2 and less) and non-minor incontinence (Wexner score of 3 or more).

Results

One hundred thirty-two patients were included in the study. Patients’ median follow-up time was 96 (12–168) months from their operation. Thirty-eight patients (28.8%) reported Wexner score of 3 or more, and they reported significantly worse quality of life in all tested life spheres. They were older at the time of the operation (63 (18–82) vs. 68 (50–89) years; p?=?0.004), underwent longer operations (50 (10–140) vs. 60 (15–210) min; p?=?0.017), and more often were operated for malignant lesions (17 (18.3%) vs. 14 (36.8%); p?=?0.040). Older age at the time of operation was an independent risk factor in multivariate model (OR 1.057, 95% CI 1.010–1.106; p?=?0.016).

Conclusions

Fecal incontinence after TEM is more common than thought previously, resulting in significantly impaired quality of life. Older age at the time of operation was an independent risk factor for developing significant fecal incontinence.

     

ras and c-myc protein expression in colorectal carcinoma

This study was performed to determine the correlation of tumor ras and c-myc oncogene expression with clinical and prognostic variables in patients prone to develop colorectal cancer. One hundred eighteen patients with colorectal cancer were studied; mean age was 40 years. Fifty-three were young patients (age 40 or less), 49 had ulcerative colitis, and 16 had multiple polyposis coli. Immunoperoxidase stains of paraffin-embedded cancer sections were performed for the c-myc and ras proteins. ras staining was found to correlate with Dukes stage and prognosis. Patients with tumors negative for ras protein stain had an actuarial five-year survival of 61 percent versus 44 percent for those tumors with a positive stain (P less than 0.05). This correlation was not seen with the c-myc stain. Positive ras oncogene stain appears to be a useful indicator of advanced stage and poor prognosis in colorectal cancer occurring in cancer-prone patients.     

Electrophysiological studies on rat dorsal root ganglion neurons after peripheral axotomy: Changes in responses to neuropeptides

The effect of three peptides, galanin, sulfated cholecystokinin octapeptide, and neurotensin (NT), was studied on acutely extirpated rat dorsal root ganglia (DRGs) in vitro with intracellular recording techniques. Both normal and peripherally axotomized DRGs were analyzed, and recordings were made from C-type (small) and A-type (large) neurons. Galanin and sulfated cholecystokinin octapeptide, with one exception, had no effect on normal C- and A-type neurons but caused an inward current in both types of neurons after sciatic nerve cut. In normal rats, NT caused an outward current in C-type neurons and an inward current in A-type neurons. After sciatic nerve cut, NT only caused an inward current in both C- and A-type neurons. These results suggest that (i) normal DRG neurons express receptors on their soma for some but not all peptides studied, (ii) C- and A-type neurons can have different types of receptors, and (iii) peripheral nerve injury can change the receptor phenotype of both C- and A-type neurons and may have differential effects on these neuron types.     

Natriuretic peptides in unstable coronary artery disease.

Patients with unstable coronary artery disease (CAD), i.e., unstable angina or non-ST-elevation myocardial infarction, vary widely in clinical presentation, prognosis and response to treatment. To select appropriate therapy, early risk stratification has become increasingly important. This review focuses on the emerging role of natriuretic peptides in the early assessment of patients with unstable CAD. We conclude that levels of brain natriuretic peptide (BNP) and N-terminal pro-brain natriuretic peptide (NT-proBNP) are strongly associated to mortality and the risk of future congestive heart failure, and carry important prognostic information independent from previously known risk factors in unstable CAD. There are some data indicating that these markers can also be helpful in the selection of appropriate therapy in these patients but further studies are needed. Before a routine use of BNP or NT-proBNP in unstable CAD can be recommended, the cost-effectiveness of adding these new markers to the currently routine markers and their impact on selection of treatment needs further evaluation.