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Background Genetic predisposition to coronavirus disease 2019 (COVID-19) may contribute to its morbidity and mortality. Because cytokines play an important role in multiple phases of infection, we examined whether commonly occurring, functional polymorphisms in macrophage migration inhibitory factor (MIF) are associated with COVID-19 infection or disease severity. Aim To determine associations of common functional polymorphisms in MIF with symptomatic COVID-19 or its severity. Methods This retrospective case–control study utilized 1171 patients with COVID-19 from three tertiary medical centers in the USA, Hungary and Spain, together with a group of 637 pre-pandemic, healthy control subjects. Functional MIF promoter alleles (-794 CATT5-8, rs5844572), serum MIF and soluble MIF receptor levels, and available clinical characteristics were measured and correlated with COVID-19 diagnosis and hospitalization. Experimental mice genetically engineered to express human high- or low-expression MIF alleles were studied for response to coronavirus infection. Results In patients with COVID-19, there was a lower frequency of the high-expression MIF CATT7 allele when compared to healthy controls [11% vs. 19%, odds ratio (OR) 0.54 [0.41–0.72], P  < 0.0001]. Among inpatients with COVID-19 (n  = 805), there was a higher frequency of the MIF CATT7 allele compared to outpatients (n  = 187) (12% vs. 5%, OR 2.87 [1.42–5.78], P  = 0.002). Inpatients presented with higher serum MIF levels when compared to outpatients or uninfected healthy controls (87 ng/ml vs. 35 ng/ml vs. 29 ng/ml, P  < 0.001, respectively). Among inpatients, circulating MIF concentrations correlated with admission ferritin (r  = 0.19, P  = 0.01) and maximum CRP (r  = 0.16, P  = 0.03) levels. Mice with a human high-expression MIF allele showed more severe disease than those with a low-expression MIF allele. Conclusions In this multinational retrospective study of 1171 subjects with COVID-19, the commonly occurring -794 CATT7 MIF allele is associated with reduced susceptibility to symptomatic SARS-CoV-2 infection but increased disease progression as assessed by hospitalization. These findings affirm the importance of the high-expression CATT7 MIF allele, which occurs in 19% of the population, in different stages of COVID-19 infection. [ABSTRACT FROM AUTHOR]

Aim: The hypothesis that colonization with cagA[sup +] Helicobacter pylori strains protects against the development of gastroesophageal reflux disease (GERD) and its complications is tested. Methods: Patients with reflux esophagitis and Barrett’s esophagus were studied. Antral biopsy specimens were obtained for detection of H. pylori. A serum sample was obtained for determination of IgG antibodies to H. pylori and to the CagA protein. Results: 736 patients were studied. 118 patients had reflux esophagitis, 36 had Barrett’s esophagus, 108 had hiatal hernia without signs of inflammation (the reflux group), and 20 patients had esophageal or stomach cancer. The remaining 454 patients had no signs of GERD. The 262 patients with reflux disease had a significantly lower prevalence of H. pylori (34.9%) than the 454 controls (54.6%; p < 0.001). Among 310 H. pylori-positive patients from whom serum was available, colonization with cagA[sup +] strains was detected in 59% in the control group versus 35% in the reflux group (p < 0.001). Conclusion: Patients with reflux esophagitis and Barrett’s esophagus have a significantly lower prevalence of H. pylori colonization than controls, in particular of the cagA[sup +] type. These data suggest that colonization with cagA[sup +] H. pylori strains may be protective against the development of GERDCopyright © 2000 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The structure of the compound eyes of adult Cicindela tranquebarica Herbst was examined by use of light, scanning, and transmission electron microscopy. Each ommatidium of these photopic eyes is eucone and has a 'subcorneal layer' situated between the corneal lens and crystalline cone. A distal rhabdomere consisting only of microvilli from retinula cell seven, a more proximal, rectangular, fused rhabdom formed from six retinula cells, and a basal, eighth retinula cell with a spherical rhabdomere comprise the light sensitive portions of the ommatidium. The 'subcorneal layer' consists of lamellae of endocuticular microfibrils and, in surface view, shows 11 concave polygons. Proximal extensions of the crystalline thread form inter-retinular fibres containing microtubules between retinula cells 1/2, 3/4, 5/6, and 7/1. The primary pigment cells are devoid of pigment granules, but are rich in rough endoplasmic reticulum. Proximal to each retinula cell nucleus are two basal bodies, one perpendicular to the other. The more proximal basal body extends two fibrillar feet proximally which fuse to form a horizontally-banded ciliary rootlet extending the length of the retinula peripheral to the rhabdom. Each ommatidium is surrounded by 16 secondary pigment cells. Interfacetal mechanoreceptors between some adjacent lenses each have a single bipolar neuron, with a dendritic sheath, tubular body, cilium, outer and inner sheath cells, and an axon surrounded by a neurilemma sheath cell. [ABSTRACT FROM AUTHOR]

The frequency response function of phototransduction was studied in the locust compound eye at three levels of dim light adaptation. The eyes were stimulated with light from a green light emitting diode (LED) and the resulting changes in membrane potential were measured with intracellular electrodes. Absolute sensitivities and light adaptation levels were established by counting the arrivals of single photons in dark adapted eyes. Frequency response functions for phototransduction could be well fitted by a model developed earlier for fly compound eyes, which includes underdamped second order poles and a pure time delay. However, the locust data requires longer time constants for the poles and a longer delay than were used to fit the fly data, reflecting the slower response characteristics of the locust. Changing the level of light adaptation at dim levels caused changes in both the sensitivity and the dynamic properties of the photoreceptors. Sensitivity was reduced and significant decreases were seen in the delay and several time constants. The behavior also became much more damped, with one of the second order poles decomposing into first order poles. [ABSTRACT FROM AUTHOR]

The dynamic properties of sensory transduction in an insect mechanoreceptor, the femoral tactile spine of the cockroach, Periplaneta americana, have been studied by measurement of the frequency response function between randomly varying movement of the tactile spine and afferent action potentials from the sensory neuron which innervates it. The frequency response function of the mechanoreceptor has been characterized over a frequency range which is more than ten times larger than has previously been used for this preparation. Also the effects of varying the amplitude of the stimulating signal have been studied by the use of a range of input signal strengths from about 0.5 to 10 μm R.M.S. displacement. The measured frequency response functions can all be well fitted by a theoretical relationship which is a fractional exponent of complex frequency, provided that the time delay caused by conduction of the action potentials from the sensory dendrite to the recording electrodes is taken into account. Under small signal conditions the exponent of complex frequency is close to 0.5 but with larger displacements its value decreases to about half this value. The overall sensitivity of the receptor, as measured by the gain of the frequency response function at a natural frequency of 1 radian/s, is not significantly altered by changes in the input movement amplitude, so that the receptor behaves linearly in this respect. However, the mean rate of action potential occurrence is not linearly related to input movement amplitude. These results are discussed in terms of current theories of sensory transduction and the possible role of tubular bodies in the dynamic behaviour of insect cuticular mechanoreceptors. [ABSTRACT FROM AUTHOR]

We have recently examined the electrophysiology and ultrastructure of approximately 100 tactile spines from the metathoracic legs of adult cockroaches. In only one animal the single sensory neuron that innervates the spine was replaced with a pair of apparently identical neurons which we believe were both functional. As far as we are aware this is the first reported study of unprovoked duplication in a peripherally-located insect sensory neuron. [ABSTRACT FROM AUTHOR]