Conditioning of heteronymous H reflex in human temporalis muscle by stimulation of perioral afferents

A heteronymous H reflex in the temporalis muscle can be elicited by selective stimulation of the masseteric nerve. The present study aimed at defining the optimal amplitude of the H reflex to detect inhibitory changes induced by stimulation of the perioral afferents and at providing new information on the control of masticatory muscles. Sixteen healthy volunteers participated in the experiment. A conditioning stimulus (CS) to the perioral skin was applied at various delays before an ipsilateral selective masseteric nerve stimulation (test stimulus: TS) while the subject was clenching the teeth at 25% of the maximal voluntary contraction. Two intensities of CS and TS were employed, high and low. The peak-to-peak amplitude of the H reflex (TS) and the root-mean-square value of the preceding electromyography were measured and the data analyzed by three-way analysis of variance and Tukey's posthoc tests. For both intensities used the heteronymous H reflex in the temporalis muscle was significantly decreased by prior activation of perioral afferents for delays from 5 to 60 ms. With a delay of 5 and 35 ms the preceding EMG level was not changed, while it was reduced at 20 and 60 ms delay. The intensities used to elicit the heteronymous H reflex of the temporalis muscle were appropriate to detect a reduction in motoneuron excitability. The reduction in the H reflex without a change in the preceding EMG at 5 and 35 ms delays could be due to presynaptic inhibition of the masseteric afferents exerted by the ipsilateral perioral afferents.     

Rickettsia-macrophage interactions: host cell responses to Rickettsia akari and Rickettsia typhi

The existence of intracellular rickettsiae requires entry, survival, and replication in the eukaryotic host cells and exit to initiate new infection. While endothelial cells are the preferred target cells for most pathogenic rickettsiae, infection of monocytes/macrophages may also contribute to the establishment of rickettsial infection and resulting pathogenesis. We initiated studies to characterize macrophage-Rickettsia akari and -Rickettsia typhi interactions and to determine how rickettsiae survive within phagocytic cells. Flow cytometry, microscopic analysis, and LDH release demonstrated that R. akari and R. typhi caused negligible cytotoxicity in mouse peritoneal macrophages as well as in macrophage-like cell line, P388D1. Host cells responded to rickettsial infection with increased secretion of proinflammatory cytokines such as interleukin-1beta (IL-1beta) and IL-6. Furthermore, macrophage infection with R. akari and R. typhi resulted in differential synthesis and expression of IL-beta and IL-6, which may correlate with the existence of biological differences among these two closely related bacteria. In contrast, levels of gamma interferon (IFN-gamma), IL-10, and IL-12 in supernatants of infected P388D1 cells and mouse peritoneal macrophages did not change significantly during the course of infection and remained below the enzyme-linked immunosorbent assay cytokine detection limits. In addition, differential expression of cytokines was observed between R. akari- and R. typhi-infected macrophages, which may correlate with the biological differences among these closely related bacteria.     

Immunochemical features of a macromolecule of Treponema denticola

In this study the extraction and the immunochemical features of a lipopolysaccharide-like (LPSL) macromolecule of T. denticola strains 35405, 35404, 33521 and 11 were investigated. The yield of LPSL molecule ranged between 0.5-0.9% of the cell dry weight, it possessed Limulus amebocyte lysate clotting activity, and it contained glucosamine, phosphate, heptose, glucose, small amounts of KDO, myristic and beta hydroxy myristic acid. Sera obtained from healthy individuals (ADA type I) periodontitis, from 3-8 month old infants, or the mouse monoclonal antibody, diluted 1:2, against T. pallidum did not react with the LPSL antigens of T. denticola strains 35405, 35404, 33521, and 11. Sera from patients with ADA type III-IV periodontitis were reactive with two 8-14 kDa bands even at serum dilutions of 1:2000. Sera from patients with ADA type II periodontitis showed good antibody response to the 8-14 kDa band at a dilution of 1:50, but were weekly reactive, or nonreactive at serum dilutions of 1:200. This study indicates that extraction of a lipopolysaccharide-like macromolecule is feasible from the assay spirochetes, and this macromolecule may be used as an antigen for the diagnosis of ADA types II-IV periodontitis.     

Membrane knobs are required for the microcirculatory obstruction induced by Plasmodium falciparum-infected erythrocytes.

We have studied the pathophysiology of the vascular obstruction induced by Plasmodium falciparum-parasitized erythrocytes with the use of an ex vivo microcirculatory preparation perfused with red cells infected with knobless and knobby clones of the FCR-3 strain. We find that parasitized erythrocyte membrane knobs are indispensable for the generation of the circulatory obstruction. Uninfected erythrocytes incubated in culture and erythrocytes infected with early or late forms of the knobless clones or the early forms of the knobby clone all failed to obstruct the microcirculation, although exhibiting various effects on bulk viscosity and peripheral resistance during flow. In contrast, late forms of the knobby clone produced significantly higher peripheral resistance during flow and significant obstruction as detected by changes in time of pressure flow recovery as well as by direct videorecorded microscopic observation. Optical and electron microscopy showed that the adherence of parasitized cells to the endothelium was limited to the venules and involved the knobs in junctions. In addition, we were able to follow the sequence of events during obstruction: initial red-cell adherence to the venular endothelium (sometimes only transitory) followed by progressive recruitment at the venule surface, finally leading to total obstruction that involved parasitized and nonparasitized erythrocytes. Sometimes, retrograde aggregation would extend the obstruction to the capillaries or even precapillary arterioles. These results show that knobs are necessary and sufficient to produce vascular obstruction and that other factors (spleen, immunological, etc.) can only have a modulating role. These results also exclude the possibility that the exclusive adherence to venules is the consequence of "plasma factors" found in the malaric patients.     

Does spaced education improve clinical knowledge among Family Medicine residents? A cluster randomized controlled trial

Advances in Health Sciences Education - Spaced education is a learning strategy to improve knowledge acquisition and retention. To date, no robust evidence exists to support the utility of spaced...     

Effectiveness of a Universally Offered Chlamydia and Gonorrhea Screening Intervention in the Pediatric Emergency Department

PurposeAdolescents represent more than half of the newly diagnosed sexually transmitted infections in the U.S. annually. Emergency departments (EDs) may serve as an effective, nontraditional setting to screen for chlamydia/gonorrhea (CT/GC). The objective was to evaluate the effectiveness of a universally offered CT/GC screening program in two pediatric ED settings.MethodsThis was a prospective, delayed start pragmatic study conducted over 18 months in two EDs within the same academic institution among ED adolescents aged 14–21 years with any chief complaint. Using a tablet device, adolescents were confidentially informed of CT/GC screening recommendations and were offered screening. If patients agreed to CT/GC testing, a clinical decision support tool was triggered to inform the provider and order testing. The main and key secondary outcomes were the proportion of CT/GC testing and positive CT/GC test results in each respective ED.ResultsBoth EDs experienced modest but statistically significant increases in CT/GC testing post- versus pre-intervention (main: 11.5% vs. 7.9%; confidence interval [CI]: 2.9–4.2; p < .0001 and satellite: 3.8% vs. 2.6%; 95% CI: .7–1.7; p < .0001). Among those tested, the positivity rate at the main ED did not significantly change post- versus pre-intervention (24.1% vs. 23.2%; 95% CI: ?1.9 to 3.8; p = .71) but significantly decreased at the satellite ED (7.6% vs. 14.8%; 95% CI: ?12.2 to ?2.2; p = .01).ConclusionsA universally offered screening intervention increased the proportion of adolescents who were tested at both EDs and the detection rates for CT/GC at the main ED, but patient acceptance of screening was low.     

Changes in glucose level affect rod function more than cone function in the isolated, perfused cat eye.

The glucose concentration (gl) in mammalian serum incorporates a normal range of variation of several millimoles. We studied the effects of such variations on light-evoked electrical signals in the in vitro arterially perfused cat eye, avoiding extraocular regulatory mechanisms that might confound data interpretation. Changes in gl from the nominal control value of 5 mmol/l were maintained for 5-40 min. Stimuli of near rod threshold intensity were presented in full dark adaptation, and stimuli of higher intensity were presented in the presence of a white background for cone responses. We recorded the dc-electroretinogram (ERG), the scotopic threshold response (STR), the optic nerve response (ONR), and the transretinal slow P-III and transepithelial retinal pigment epithelium c-wave from the subretinal space. The ocular standing potential changed by up to +/- 2 mV in parallel with an increase and decrease in gl, independent of the adaptation condition. Our results show that the rod-ERG, STR, and rod-driven optic nerve response (ONR) have a marked sensitivity to small changes in gl (+/- 1 to 3 mmol/l). The field potentials increased and decreased in parallel with changes in gl. The cone ERG and cone ONR, in contrast, failed to respond consistently to increases in gl and revealed decreases in amplitudes only with an extreme decrease in gl. Decrease in gl, down to 2 mmol/l and less, is known to induce drastic behavioral and electrophysiologic phenomena in the central nervous system. Our results imply that the "normal" glucose level, at least in the cat, could be marginal for rod-mediated retinal function. The results also suggest a marked difference in metabolic mechanisms for cone versus rod photoreceptors.     

男、女用避孕套临床可接受性的比较

目的:比较男、女用避孕套的临床可接受性。方法:以40名健康育龄期妇女自愿者为研究对象,采用交叉设计,每人使用男女用避孕套各5个,每使用完一种后填写评价性调查表;使用完两种后,填写总结性调查表,对两种避孕套进行比较。结果:在避孕套的取出/取下、性生活中阴茎的插入、以及性生活中是否感觉不舒服(疼痛、烧灼感)等方面,对两种避孕套的评价基本相同。男用避孕套的主要优点是易学、易用,而女用避孕套可使性生活更有兴趣和感到更安全。总的说来,女性对使用两种避孕套的态度没有明显差异,而男性则比较喜欢使用男用避孕套。结论:通过适当的推广和改进,在我国会有一定比例的育龄妇女接受并使用女用避孕套。