Effect of sulfide on nitrate reduction in mixed methanogenic cultures

The effect of sulfide on nitrate reduction and methanogenesis was investigated in two mixed, mesophilic (35 degrees C) methanogenic cultures: sulfide-free and sulfide-acclimated (67 mg S/L total sulfide). A mixture of dextrin/peptone served as the carbon/electron donor source for the two stock cultures, as well as in all assays reported here. The sulfide-free enriched culture was amended with both nitrate (75-350 mg N/L) and sulfide (10-100 mg S/L). Denitrification was the predominant pathway at all sulfide levels tested and methanogenesis did not recover in any of the sulfide- and nitrate-amended cultures, except in the 10 mg S/L culture. Accumulation of denitrification intermediates such as NO and N(2)O took place, which irreversibly inhibited the methanogens and resulted in the complete cessation of methane production. In contrast, conversion of nitrate to nitrite and then to ammonia via dissimilatory nitrate reduction to ammonia (DNRA) prevented the accumulation of denitrification intermediates and led to the recovery of methanogenesis in the nitrate-amended, sulfide-acclimated, mixed methanogenic culture. The effect of the COD/N value on nitrate reduction was assessed with the sulfide-acclimated, methanogenic culture at COD/N values of 10, 20, and 60. As the COD/N value increased, the fraction of nitrate reduced through DNRA also increased. The results of this study have significant implications relative to the combined anaerobic treatment of carbon-, nitrogen-, and/or sulfur-bearing wastes.     

Using spray-dried and encapsulated Nannochloropsis oculata biomasses in white spread

Journal of Applied Phycology - In this study, dried or encapsulated Nannochloropsis oculata microalgal biomass was used in spread samples (0.00–0.75 g (100 g)?1...     

Health Transformation Project and Defensive Medicine Practice among Neurosurgeons in Turkey

Background

The term “Defensive” medicine was coined in the early 1970′s and has been an important topic of scientific investigation and professional debate ever since.

Objective

The aim of this study was to investigate the characteristics of defensive medicine, its reasons, and the extent to which it is practiced in the Turkish health care system. This is the first national survey to study the practice of defensive medicine among neurosurgeons in Turkey.

Methods

The present cross-sectional study on defensive medicine assessed neurosurgeons registered at the Turkish Neurosurgical Society, who are actively working in various centers and hospitals within the Turkish health care system. A 40-question survey was adapted from existing measures described in the literature and was completed by a total of 404 neurosurgeons, representing 36.7% of the neurosurgeons registered at the Turkish Neurosurgical Society.

Results

Seventy-two percent of the participants in the current study reported practicing defensive medicine. This practice was mainly reported among inexperienced neurosurgeons (74.4%). Most were younger than 40 years of age (75.2%), working in state hospitals/universities (72.7%), and living in the Marmara region (38%). Respondents reported engaging in defensive medicine by avoiding high-risk surgery (62.6%), ordering additional imaging studies (60.9%) and laboratory tests (33.7%), and referring patients to consultants (31.2%). Most participants consider every patient as a potential threat in terms of a medical lawsuit (68.3%) and do not believe the courts can distinguish malpractice from complications (89.6%).

Conclusion

Concerns and perceptions about medical liability lead neurosurgeons to practice defensive medicine. By avoiding high-risk surgery, ordering unnecessary diagnostic tests, and referring the patients to consultants, neurosurgeons try to minimize the risk of malpractice and protect themselves from legal risks, resulting in higher healthcare expenditure and longer treatment periods.     

Anisotropy induced by macroscopic boundaries: surface-normal mapping using diffusion-weighted imaging

In MRI, macroscopic boundaries lead to a diffusion-related increase in signal intensity near them—an effect commonly referred to as edge-enhancement. In diffusion-weighted imaging protocols where the signal attenuation due to diffusion results predominantly from the application of magnetic field gradients, edge-enhancement will depend on the orientation of these diffusion gradients. The resulting diffusion anisotropy can be exploited to map the direction normal to the macroscopic boundary. Simulations suggest that the hypothesized anisotropy may be within observable limits even when the voxel contains no boundary itself—hence, the name remote-anisotropy. Moreover, for certain experimental parameters there may be significant phase cancellations within the voxel that may lead to an edge detraction effect. When this is avoided, the eigenvector corresponding to the smallest eigenvalue of the diffusion tensor obtained from diffusion-tensor imaging can be used to create surface-normal maps conveniently. Experiments performed on simple geometric constructs as well as real tissue demonstrate the feasibility of using the edge-enhancement mechanism to map orientations orthogonal to macroscopic surfaces, which may be used to assess the integrity of tissue and organ boundaries noninvasively.     

Can screening Chlamydia trachomatis by serological tests predict tubal damage in infertile patients?

Effectiveness of screening Chlamydia trachomatis (CT) antibody to predict tubal damage was assessed in this prospective study which was performed in a teaching hospital between September 2003 and September 2004. The study group consisted of 152 patients who underwent laparoscopy for infertility and the control group consisted of 80 fertile women who gave birth in the same hospital. CT antibody levels were measured by IFA (Indirect Fluorescence Assay for CT). Adhesions were defined by Gomel's classification system. Rate of seropositivity of CT was 34.6% in the study group and 22.5% in the control group (p>0.05). In the study group, the sensitivity, specifity, positive predictive and negative predictive values of CT positivity for tubal damage were 40%, 69.5%, 50% and 60.2% respectively. In the infertile group, the rate of tubal adhesion in the CT positive group was 50% and in the CT negative group it was 39.7% (p>0.05). However, there was a positive correlation between the severity of tubo-peritoneal adhesions and seropositivity for CT. In this study, we found out that tubo-peritoneal adhesions could not be predicted by the presence of CT inserum. There was a positive correlation between high CT seropositivity and high degree of adhesions.     

Atomic force microscope elastography reveals phenotypic differences in alveolar cell stiffness.

To understand the connection between alveolar mechanics and key biochemical events such as surfactant secretion, one first needs to characterize the underlying mechanical properties of the lung parenchyma and its cellular constituents. In this study, the mechanics of three major cell types from the neonatal rat lung were studied; primary alveolar type I (AT1) and type II (AT2) epithelial cells and lung fibroblasts were isolated using enzymatic digestion. Atomic force microscopy indentation was used to map the three-dimensional distribution of apparent depth-dependent pointwise elastic modulus. Histograms of apparent modulus data from all three cell types indicated non-Gaussian distributions that were highly skewed and appeared multimodal for AT2 cells and fibroblasts. Nuclear stiffness in all three cell types was similar (2.5+/-1.0 kPa in AT1 vs. 3.1+/-1.5 kPa in AT2 vs. 3.3+/-0.8 kPa in fibroblasts; n=10 each), whereas cytoplasmic moduli were significantly higher in fibroblasts and AT2 cells (6.0+/-2.3 and 4.7+/-2.9 kPa vs. 2.5+/-1.2 kPa). In both epithelial cell types, actin was arranged in sparse clusters, whereas prominent actin stress fibers were observed in lung fibroblasts. No systematic difference in actin or microtubule organization was noted between AT1 and AT2 cells. Atomic force microscope elastography, combined with live-cell fluorescence imaging, revealed that the stiffer measurements in AT2 cells often colocalized with lamellar bodies. These findings partially explain reported heterogeneity of alveolar cell deformation during in situ lung inflation and provide needed data for better understanding of how mechanical stretch influences surfactant release.     

Transcallosal conduction in paroxysmal kinesigenic dyskinesia

Objectives: Detecting whether a possible disequilibrium between the excitatory and inhibitory interhemispheric interactions in paroxysmal kinesigenic dyskinesia (PKD) exists.

Methods: This study assessed measures of motor threshold, motor evoked potential latency, the cortical silent period, the ipsilateral silent period and the transcallosal conduction time (TCT) in PKD patients. Data were compared between the clinically affected hemisphere (aH) and the fellow hemisphere (fH).

Results: The transcallosal conduction time from the aH to the fH was 11.8?ms (range?=?2.3–20.7) and 13.6?ms (range?=?2.8–67.7) from the fH to the aH. The difference in TCT in the affected side was significant (p?=?.019).

Conclusion: The findings demonstrated that, although inhibitory interneurons act normally and symmetrically between the motor cortices and transcallosal inhibition was normal and symmetrical between both sides, the onset of transcallosal inhibition was asymmetrical. The affected hemisphere’s inhibition toward the unaffected hemisphere is faster compared to the inhibition provided by the fellow hemisphere. These results are consistent with an inhibitory deficit in the level of interhemispheric interactions.

Significance: This study revealed a defect in inhibition of the motor axis could be responsible in the pathological mechanisms of kinesigenic dyskinesia.