The optimal stimulation pattern for skeletal muscle is dependent on muscle length

Stimulation patterns can be optimized by maximizing the force-time integral (FTI) per stimulation pulse of the elicited muscle contraction. Such patterns, providing the desired force output with the minimum number of pulses, may reduce muscle fatigue, which has been shown to correlate to the number of pulses delivered. Applications of electrical stimulation to use muscle as a controllable biological actuator may, therefore, be improved. Although muscle operates over a range of lengths, optimized patterns have been determined only at optimal muscle length. In this study, the patterns with up to four pulses that produced the highest isometric FTI were determined at 10 muscle lengths for 11 rabbit tibialis anterior muscles. The interpulse intervals (IPIs) used ranged from 4 to 54 ms. At high muscle length, the optimal stimulation pattern consisted of an initial short IPI (doublet) followed by longer IPIs, in agreement with previous studies. However, at low length, the third pulse still elicited more than linear summation (triplet); furthermore, the relative enhancement of the FTI per pulse was considerably larger at low length than at high length, suggesting that optimal stimulation patterns are length dependent.     

New method for improving accuracy of 24-hour continuous intragastric pH-metry. Reflections on physiological and pharmacological studies

Continuous 24-hr intragastric pH-metry was prospectively performed in 801 subjects with different clinical conditions using two pH electrodes placed closely adjacent. The aim was to assess the in situ repeatability of the test and to verify whether the removal of artifacts, interference, and noise usually superimposed onto the fundamental signal recorded by the measuring apparatus improves the clinical usefulness of experimental data. The following debugging/filtering procedure was used: first, pH recordings of each channel were amended separately from artifacts, then they underwent 7 min windowed median interference debugging, and finally Wiener noise filtering was applied. Afterwards, the 24-hr mean pH profile was obtained in each subject by averaging the pH tracings of the two channels every minute (1440 data points/24 hr). The efficiency of this procedure was assessed at each step by evaluating the difference among groups using the O'Brien test, a distribution-free nonparametric method well-suited for evaluating differences among groups allocated onto a two-way layout. The differences among groups calculated from raw pH data of the single channels can be very misleading, in that it is possible to find that they are significant on one channel and not significant on the other channel. Conversely, the significance of the differences among groups increases progressively at each step of the above debugging/filtering procedure applied to raw pH profiles of each channel. Seven minutes was shown to be the most suitable time lag for windowed median removal of interference.(ABSTRACT TRUNCATED AT 250 WORDS)     

An overview of rheumatological research in the European Union

We describe a case of a 73-year-old male with a rare T-cell lymphoma that presented deceptively as progressive hepatic failure with fever, weight loss, pancytopenia, mental confusion, splenomegaly, and no lymphadenopathy. An alcoholic history supported the diagnosis of cirrhosis, but a liver biopsy was not performed. A bone marrow biopsy was considered unremarkable. Death occurred after a course of four months. Postmortem examination showed hepatic, splenic, lymph node, and marrow infiltration by characteristically sparse, isolated, bizarre, medium-to-large sized neoplastic cells with extensive hepatic centrilobular necrosis, steatosis, and predominant splenic involvement. Immunohistochemical markers indicated a T-cell lymphoma consistent with either an alpha/beta peripheral T-cell lymphoma or a gamma/delta lymphoma. Definitive immunotyping was not available. However, the pathologic features are most consistent with a gamma/delta T-cell lymphoma. This case is an example of a rare, rapidly progressive lymphoma, which is a recognized clinical entity, easily missed, and treatable. Its diagnostic consideration must be explicitly communicated to pathologists, because the isolated or sparse tumor cells in a lymph node, liver, or bone marrow biopsy may easily be mistaken for variants of megakaryocytes or histiocytes.     

Comparison of 24-h control of gastric acidity by three different dosages of pantoprazole in patients with duodenal ulcer

BACKGROUND: It is now clear that the extent to which gastric acid secretion must be suppressed varies with the clinical condition being treated. AIM: To assess the 24-h control of gastric acidity and the individual response variability of three different doses of pantoprazole. METHODS: Sixty-four duodenal ulcer patients were recruited for this prospective, randomized, multicentre, double-blind, parallel-group study. They were subdivided into three well-matched groups treated with 20 mg o.m., 40 mg o.m. and 40 mg b.d. of pantoprazole, respectively. Endoscopy and intragastric pH monitoring were performed in each patient before and after 14 days of treatment. RESULTS: Fifty-five patients were eligible for final analysis (17 treated with 20 mg o.m., 18 with 40 mg o.m. and 20 with 40 mg b.d. pantoprazole). The ulcer crater healed in 94, 88 and 95% of cases, respectively. The three dosages of pantoprazole produced significant increases in gastric pH compared to basal levels (P < 0.0001). There was also a clear dose-dependent pharmacodynamic effect, which augmented on moving from the lowest dosage of 20 mg o.m. pantoprazole to the highest dosage of 40 mg b.d. (P < 0.01-0.001). The inter-individual response variability within the three treatment groups was more marked with the dose of 20 mg than with the two higher doses of pantoprazole. CONCLUSIONS: All three doses of pantoprazole we tested are highly effective in decreasing gastric acidity and there is a clear dose-dependent pharmacodynamic effect on moving from the lowest to the highest dosage. The greatest inter individual variation in the degree of acid inhibition was seen with pantoprazole 20 mg o.m., while the majority of patients responded adequately to the two higher doses of the drug.     

Consideration of the evolution of the Saccharomyces cerevisiae MEL gene family on the basis of the nucleotide sequences of the genes and their flanking regions

Analysis of the DNA sequences of new members of the Saccharomyces cerevisiae MEL1-MEL10 gene family showed high homology between the members. The MEL gene family, α-galactosidase-coding sequences, have diverged into two groups; one consisting of MEL1 and MEL2 and the other of MEL3-MEL10. In two S. cerevisiae strains containing five or seven MEL genes each, all the genes are nearly identical, suggesting very rapid distribution of the gene to separate chromosomes. The sequence homology and the abrupt change to sequence heterogeneity at the centromere-proximal 3′ end of the MEL genes suggest that the distribution of the genes to new chromosomal locations has occurred partly by reciprocal recombination at solo delta sequences. We identified a new open reading frame sufficient to code for a 554 amino acid long protein of unknown function. The new open reading frame (Accession number Z37509) is located in the 3′ non-coding region of MEL3-MEL10 genes in opposite orientation to the MEL genes (Accession numbers Z37508, Z37510, Z37511). Northern analysis of total RNA showed no hybridization to a homologous probe, suggesting that the gene is not expressed efficiently if at all.     

Revealing Nanomechanical Domains and Their Transient Behavior in Mixed-Halide Perovskite Films

Halide perovskites are a versatile class of semiconductors employed for high performance emerging optoelectronic devices, including flexoelectric systems, yet the influence of their ionic nature on their mechanical behavior is still to be understood. Here, a combination of atomic-force, optical, and compositional X-ray microscopy techniques is employed to shed light on the mechanical properties of halide perovskite films at the nanoscale. Mechanical domains within and between morphological grains, enclosed by mechanical boundaries of higher Young's Modulus (YM) than the bulk parent material, are revealed. These mechanical boundaries are associated with the presence of bromide-rich clusters as visualized by nano-X-ray fluorescence mapping. Stiffer regions are specifically selectively modified upon light soaking the sample, resulting in an overall homogenization of the mechanical properties toward the bulk YM. This behavior is attributed to light-induced ion migration processes that homogenize the local chemical distribution, which is accompanied by photobrightening of the photoluminescence within the same region. This work highlights critical links between mechanical, chemical, and optoelectronic characteristics in this family of perovskites, and demonstrates the potential of combinational imaging studies to understand and design halide perovskite films for emerging applications such as photoflexoelectricity.     

Antimicrobial silicone rubbers based on photocatalytically active additives

The modification of plastics to generate germ-reducing surface materials is a promising strategy to decrease nosocomial infections in hygiene-sensitive areas. In this paper, photocatalytically active nanoparticles were incorporated as additives, not as a coating, into silicone rubber matrix material to produce elastic antibacterial bulk materials. Samples with 5 wt% and 10 wt% of two different types of TiO₂ and ZnO were prepared and investigated. The thermal analysis of the developed materials showed a complete vulcanization of the developed materials and slight modifications of mechanical properties were found. Investigations of the surface of the materials indicated no changes in the wettability of the surfaces or in their fourier transform infrared spectrometer (FT-IR) spectra, suggesting no degradation of the developed material. The photocatalytic activity on the surface of the test samples was investigated by microbial tests with Escherichia coli, Pseudomonas fluorescens, and Staphylococcus aureus bacteria. Depending on the additive type and the test germs, the samples showed different intensities of a germ-reducing effect (up to >99,999%).     

Take Five, a nutrition education intervention to increase fruit and vegetable intakes: impact on consumer choice and nutrient intakes

Employing clonal cell lines derived from rat embryonic hippocampal cells, we detected neuropeptide Y (NPY) mRNA in three progenitor subcloned cell lines. These cell lines upon differentiation express markers indicative of commitment to either neuronal (H19-7; NF +, GFAP -), glial (H19-5; GFAP +, NF -), or bipotential (H583-5; NF +, GFAP + ) lineages. Induction of differentiation was associated with the persistence of the NPY mRNA, however, in the differentiated H19-7 cells a 20-fold increase in NPY mRNA levels was observed (P<0.05). NPY immunoreactivity was observed only in cells with a differentiated neuronal phenotype. The cellular radioimmunoassayable NPY peptide levels increased twelve-fold without a change in extracellular NPY peptide levels by multi-factorially induced neuronal or glial cell differentiation. The differentiated H19-5 cells expressed lower levels of NPY that could not be immunocytochemically detected. The peripheral sympathetic PC-12 neuronal cells examined in the undifferentiated and nerve growth factor-driven differentiated states expressed NPY only upon differentiation. We conclude that NPY is expressed by the cultured undifferentiated and differentiated rat hippocampal clonal cell lines, while the peripheral sympathetic PC-12 neuronal cell line only expresses the NPY gene upon differentiation. These immortalized embryonic neural cell line(s) will provide a hippocampal cell line(s) to conduct future in-vitro investigations targeted at determining the cellular and molecular mechanisms governing NPY gene expression.