Control of Retinal Sensitivity : I. Light and Dark Adaptation of Vertebrate Rods and Cones

Rods and cones in Necturus respond with graded hyperpolarization to test flashes spanning about 3.5 log units of intensity. Steady background levels hyperpolarize the rods, and the rod responses become progressively smaller as background level is increased. In cones, higher background levels reduce the effectiveness of test flashes, so higher ranges of test intensities are required to elicit the full range of graded responses. When backgrounds are terminated, cones return rapidly, but rods return slowly to the dark potential level. The effects of backgrounds on both rods and cones can be observed at intensities that cause negligible bleaching as determined by retinal densitometry. During dark adaptation, changes are observed in the rods and cones that are similar to those produced by backgrounds. Receptor sensitivities, derived from these results, show that rods saturate, cones obey Weber's law, and sensitization during dark adaptation follows a two-phase time-course.     

Membrane potential of the corpus cardiacum neurosecretory cells of the blowfly, Calliphora erythrocephala

The corpus cardiacum neurosecretory cells (c.n.c.) of Calliphora are unipolar cells with slender projections (axonal length: 50 to 110 μ; diameter: 0·25 to 1·75 μ).The cell body, where production of neurosecretory material occurs, is electrically inexcitable (resting potential about 36 mV, inside negative), whereas the axon—responsible for controlled neurohormone release—is excitable. Spike potentials with a duration of 3 to 7 msec occur in volleys the number and duration of which are supposed to determine the amount of secretion released. Electrical activity may be stimulated via the brain. Resting and action potentials are compared with recordings from other cell types of the blowfly.     

The role of African buffalos (<Emphasis Type="Italic">syncerus caffer</Emphasis>) in the maintenance of foot-and-mouth disease in Uganda

Background

To study the role of African buffalos (Syncerus caffer) in the maintenance of foot-and-mouth disease in Uganda, serum samples were collected from 207 African buffalos, 21 impalas (Aepyceros melampus), 1 giraffe (Giraffa camelopardalis), 1 common eland (Taurotragus oryx), 7 hartebeests (Alcelaphus buselaphus) and 5 waterbucks (Kobus ellipsiprymnus) from four major National Parks in Uganda between 2005 and 2008. Serum samples were screened to detect antibodies against foot-and-mouth disease virus (FMDV) non-structural proteins (NSP) using the Ceditest^® FMDV NS ELISA. Solid Phase Blocking ELISAs (SPBE) were used to determine the serotype-specificity of antibodies against the seven serotypes of FMDV among the positive samples. Virus isolation and sequencing were undertaken to identify circulating viruses and determine relatedness between them.

Results

Among the buffalo samples tested, 85% (95% CI = 80-90%) were positive for antibodies against FMDV non-structural proteins while one hartebeest sample out of seven (14.3%; 95% CI = -11.6-40.2%) was the only positive from 35 other wildlife samples from a variety of different species. In the buffalo, high serotype-specific antibody titres (≥ 80) were found against serotypes O (7/27 samples), SAT 1 (23/29 samples), SAT 2 (18/32 samples) and SAT 3 (16/30 samples). Among the samples titrated for antibodies against the four serotypes O, SAT 1, SAT 2 and SAT 3, 17/22 (77%; CI = 59.4-94.6%) had high titres against at least two serotypes.FMDV isolates of serotypes SAT 1 (1 sample) and SAT 2 (2 samples) were obtained from buffalo probang samples collected in Queen Elizabeth National Park (QENP) in 2007. Sequence analysis and comparison of VP1 coding sequences showed that the SAT 1 isolate belonged to topotype IV while the SAT 2 isolates belonged to different lineages within the East African topotype X.

Conclusions

Consistent detection of high antibody titres in buffalos supports the view that African buffalos play an important role in the maintenance of FMDV infection within National Parks in Uganda. Both SAT 1 and SAT 2 viruses were isolated, and serological data indicate that it is also likely that FMDV serotypes O and SAT 3 may be present in the buffalo population. Detailed studies should be undertaken to define further the role of wildlife in the epidemiology of FMDV in East Africa.

     

Secretory hyperactivity and mitochondrial changes in neurosecretory cells of an insect

Summary The neurosecretory cells of the corpus cardiacum of the desert locust Schistocerca gregaria secrete their hormonal products by exocytosis. The insecticide lindane is known to cause release of hyperglycaemic and adipokinetic neurohormones. Electron microscopy of lindane-poisoned corpora cardiaca reveals many exocytotic omega figures. Mitochondria are affected either directly by the poison or by the consequences of secretory hyperactivity. They occur in increased number, divide, acquire dense mitochondrial granules larger than in the controls, and sometimes line up along plasma membranes, mitochondria in two neighbouring cells forming pairs in juxtaposition. Between two such mitochondria the plasma membranes form a junction-like structure. It is suggested that these effects reflect an excessive calcium entry caused by lindane.This work was supported by a Wellcome-Carlsberg Travelling Research Fellowship awarded to T.N. and by a Commonwealth Scholarship for Postgraduate Research awarded to M.S.     

Efficacy of injections with Disci/Rhus toxicodendron compositum for chronic low back pain--a randomized placebo-controlled trial

Background

The effectiveness of injection therapy for low-back pain is still debatable. We compared the efficacy of local injections of the homeopathic preparation Disci/Rhus toxicodendron compositum (verum) with placebo injections and with no treatment in patients with chronic low back pain.

Methodology/Principal Findings

In a randomized controlled partly double blind multicenter trial patients with chronic low back pain from 9 German outpatient clinics were enrolled and randomly allocated in a 1∶1∶1 ratio to receive subcutaneous injections (verum or placebo) into painful sites on the lower back over 12 treatment sessions within eight weeks, or no treatment (rescue pain medication with paracetamol or NSAIDs). All trial personnel and participants were masked to treatment allocation. The primary outcome measure was the average pain intensity over the last seven days on a visual analogue scale (0–100 mm, 0 = no pain, 100 = worst imaginable pain) after eight weeks. Follow-up was 26 weeks. Primary analysis was by intention to treat. Between August 2007 and June 2008, 150 patients were randomly allocated to three groups (51 verum, 48 placebo and 51 no treatment). The mean baseline-adjusted low back pain intensity at week eight was: verum group 37.0 mm (97.5% CI 25.3;48.8), no treatment group 53.0 (41.8;64.2), and placebo group 41.8 (30.1;53.6). The verum was significantly superior to no treatment (P = 0.001), but not to placebo (P = 0.350). No significant side effects were reported.

Conclusions/Significance

The homeopathic preparation was not superior to placebo. Compared to no treatment injections resulted in significant and clinical relevant chronic back pain relief.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00567736","term_id":"NCT00567736"}}NCT00567736     

Comparative Effectiveness of Homoeopathic vs. Conventional Therapy in Usual Care of Atopic Eczema in Children: Long-Term Medical and Economic Outcomes

Background

One in five children visiting a homeopathic physician suffers from atopic eczema.

Objectives

We aimed to examine the long-term effectiveness, safety and costs of homoeopathic vs. conventional treatment in usual medical care of children with atopic eczema.

Methods

In this prospective multi-centre comparative observational non-randomized rater-blinded study, 135 children (48 homoeopathy, 87 conventional) with mild to moderate atopic eczema were included by their respective physicians. Depending on the specialisation of the physician, the primary treatment was either standard conventional treatment or individualized homeopathy as delivered in routine medical care. The main outcome was the SCORAD (SCORing Atopic Dermatitis) at 36 months by a blinded rater. Further outcomes included quality of life, conventional medicine consumption, safety and disease related costs at six, 12 and 36 months after baseline. A multilevel ANCOVA was used, with physician as random effect and the following fixed effects: age, gender, baseline value, severity score, social class and parents’ expectation.

Results

The adjusted mean SCORAD showed no significant differences between the groups at 36 months (13.7 95% CI [7.9–19.5] vs. 14.9 [10.4–19.4], p = 0.741). The SCORAD response rates at 36 months were similar in both groups (33% response: homoeopathic 63.9% vs. conventional 64.5%, p = 0.94; 50% response: 52.0% vs. 52.3%, p = 0.974). Total costs were higher in the homoeopathic versus the conventional group (months 31–36 200.54 Euro [132.33–268.76] vs. 68.86 Euro [9.13–128.58], p = 0.005).

Conclusions

Taking patient preferences into account, while being unable to rule out residual confounding, in this long-term observational study, the effects of homoeopathic treatment were not superior to conventional treatment for children with mild to moderate atopic eczema, but involved higher costs.     

Alcohol consumption, genetic variants in alcohol deydrogenases, and risk of cardiovascular diseases: a prospective study and meta-analysis

Objective

First, to investigate and compare associations between alcohol consumption and variants in alcohol dehydrogenase (ADH) genes with incidence of cardiovascular diseases (CVD) in a large German cohort. Second, to quantitatively summarize available evidence of prospective studies on polymorphisms in ADH1B and ADH1C and CVD-risk.

Methods

We conducted a case-cohort study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam cohort including a randomly drawn subcohort (n = 2175) and incident cases of myocardial infarction (MI; n = 230) or stroke (n = 208). Mean follow-up time was 8.2±2.2 years. The association between alcohol consumption, ADH1B or ADH1C genotypes, and CVD-risk was assessed using Cox proportional hazards regression. Additionally, we report results on associations of variants in ADH1B and ADH1C with ischemic heart disease and stroke in the context of a meta-analysis of previously published prospective studies published up to November 2011.

Results

Compared to individuals who drank >0 to 6 g alcohol/d, we observed a reduced risk of MI among females consuming >12 g alcohol/d (HR = 0.31; 95% CI: 0.10–0.97) and among males consuming >24 to 60 g/d (HR = 0.57; 95% CI: 0.33–0.98) or >60 g alcohol/d (HR = 0.30; 95% CI: 0.12–0.78). Stroke risk was not significantly related to alcohol consumption >6 g/d, but we observed an increased risk of stroke in men reporting no alcohol consumption. Individuals with the slow-coding ADH1B*1/1 genotype reported higher median alcohol consumption. Yet, polymorphisms in ADH1B or ADH1C were not significantly associated with risk of CVD in our data and after pooling results of eligible prospective studies [ADH1B*1/1: RR = 1.35 (95% CI: 0.98–1.88; p for heterogeneity: 0.364); ADH1C*2/2: RR = 1.07 (95% CI: 0.90–1.27; p for heterogeneity: 0.098)].

Conclusion

The well described association between alcohol consumption and CVD-risk is not reflected by ADH polymorphisms, which modify the rate of ethanol oxidation.     

High-resolution analysis of the spatio-temporal activity patterns in rat olfactory bulb evoked by enantiomer odors

Understanding how mammals process olfactory stimuli has motivated the development of tools and techniques which permit the simultaneous study of finely structured spatial and temporal patterns of neural activity. A technique is described that uses an array of 32 penetrating microelectrodes implanted bilaterally into the dorsal aspect of rat olfactory bulb to investigate the responses of mitral and tufted neurons to stimulation with simple enantiomer odor pairs at a number of concentrations. It is shown that stable, simultaneous recordings from up to 49 single- and multi-units can be performed for periods of up to 14 h. We show that such odors evoke unique spatial and fast-temporal activity patterns which may subserve odor discrimination. This technique is extensible to other systems neuroscience investigations of olfactory sensory processing.