CTX-M-2 and a new CTX-M-39 enzyme are the major extended-spectrum beta-lactamases in multiple Escherichia coli clones isolated in Tel Aviv, Israel

The rate of occurrence of the extended-spectrum beta-lactamase (ESBL)-producing phenotype among Escherichia coli isolates in Tel Aviv is 12% (22). The aim of this study was to understand the molecular epidemiology of E. coli ESBL producers and to identify the ESBL genes carried by them. We studied 20 single-patient ESBL-producing E. coli clinical isolates. They comprised 11 distinct nonrelated pulsed-field gel electrophoresis (PFGE) genotypes: six isolates belonged to the same PFGE clone, four other clones included two isolates each, and six unrelated clones included only one isolate. All isolates produced various beta-lactamases with pIs ranging from 5.2 to 8.2, varying within similar PFGE clones. The most prevalent ESBL gene was bla(CTX-M); 16 isolates carried bla(CTX-M-2) and three carried a new ESBL gene designated bla(CTX-M-39). Three strains carried bla(SHV) (two bla(SHV-12) and one bla(SHV-5)), and two strains carried inhibitor-resistant ESBL genes, bla(TEM-33) and bla(TEM-30); 18 strains carried bla(TEM-1) and eight strains carried bla(OXA-2). Plasmid mapping and Southern blot analysis with a CTX-M-2 probe demonstrated that bla(CTX-M-2) is plasmid borne. The wide dissemination of ESBLs among E. coli isolates in our institution is partly related to clonal spread, but more notably to various plasmid-associated ESBL genes, occurring in multiple clones, wherein the CTX-M gene family appears almost uniformly. We report here a new CTX-M gene, designated bla(CTX-M-39), which revealed 99% homology with bla(CTX-M-26), with a substitution of arginine for glutamine at position 225.     

Effect of varied gestational stress on acquisition of spatial memory, hippocampal LTP and synaptic proteins in juvenile male rats

Some but not other forms of prenatal stress have been shown to impair spatial memory in adult male offspring. It is not clear if this is because of the intensity of the stress, age of rats, or the way in which learning is assessed. We examined the effect of daily varied prenatal stress consisting of 30 min restraint, saline injections and 15 min forced swim on day 17-21 of gestation on spatial learning, synaptic plasticity and the expression of key proteins of the post synaptic density (PSD) in the hippocampus of males aged 4-5 weeks. Prenatal stress impaired spatial learning in the Morris water maze and induced a significant decrease in long-term potentiation (LTP) in hippocampal slices. There was no change in the paired pulse facilitation ratio but there was a significant reduction in the expression of the NR2B subunit of the glutamate type NMDA receptor and the GluR1 subunit of the AMPA receptor, both of which are important modulators of LTP. These changes were accompanied by a remarkable increase in the scaffolding protein PSD95, which interacts with the intracellular carboxy terminal domains of the NR2 subunits. The high levels of PSD95 may have contributed to the impairment of LTP by disrupting the clustering of NMDA receptors in CA1 synapses. The alteration by prenatal stress in the relative amounts of scaffolding proteins and those which compose glutamate receptors could explain the depression of LTP and impairment in the acquisition of spatial learning.     

Application of the two-layer method on pancreas digestion results in improved islet yield and maintained viability of isolated islets

BACKGROUND: Oxygenation of the pancreas during preservation by the two-layer method (TLM) has shown beneficial effects in islet transplantation. Here, we apply this concept (oxygenation) to the isolation process. METHODS: Rat pancreases were digested using four different methods. Pancreases were digested with preoxygenated perfluorocarbon (PFC) in group 2 and without it in group 1. Additionally, adenosine was included in the collagenase solution in subgroups B but not in subgroups A. Islet yields and viability were compared between groups. RESULTS: Tissue oxygen tension in group 1 was essentially zero during digestion, but rapidly reached around 300 mm Hg and was maintained in group 2. The tissue adenosine triphosphate (ATP) level in rat pancreas just after laparotomy (control) was 4.2+/-0.7 micromol/g dry weight; after digestion, it was 0.12+/-0.03 micromol/g, 0.70+/-0.10 micromol/g, 0.30+/-0.18 micromol/g, and 2.90+/-0.80 micromol/g in groups 1A, 1B, 2A, and 2B, respectively. No significant differences were observed between group 2B and control (P=0.19). Islet yields (IEQ/pancreas) were 1600+/-400, 1400+/-400, 1300+/-400, and 2400+/-100 in groups 1A, 1B, 2A, and 2B, respectively. The islet yield of group 2B was significantly higher than other groups (P<0.05). The cure rate after transplanting 200 islets into athymic nude mice did not differ (80% in all groups). The stimulation indices in the four groups were also the same. CONCLUSIONS: Tissue ATP levels after digestion were well maintained using TLM with adenosine digestion method. Consequently, greater numbers of islets could be retrieved. The new method was at least equivalent to islet function isolated by conventional method. Clinical study is therefore warranted.     

Ocular central nervous system lymphoma mimicking choroidal neovascularization.

Two patients evaluated for metamorphopsia were noted to have inferotemporal retinal pigment epithelium elevations formed by a yellowish lesion. Fluorescein angiography showed granular hyperfluorescence with late leakage, which was interpreted as an occult choroidal neovascularization. One patient underwent photodynamic therapy. In both patients, neither vitreous cells nor neurologic manifestations were evident on presentation. Subsequent neurological signs appeared that prompted performance of brain imaging, which confirmed a space-occupying lesion. In both patients, the tumor was proven on histopathologic examination of brain tissue to be central nervous system lymphoma. Awareness of other possible underlying pathologies is warranted in cases of atypical choroidal neovascularization.     

Light intensity mediated polarotaxis in Pontella karachiensis (Pontellidae, Copepoda)

Polarization sensitivity provides animals with information not available in the intensity or spectral domains. We examined the polarotaxis reactions in the epiplanktonic copepod Pontella karachiensis. Polarotaxis reactions were intensity dependent. At intensities corresponding to ambient daylight, P. karachiensis showed an attraction to a polarized light field; while at low intensities, corresponding to nighttime illumination, it showed negative polarotaxis. P. karachiensis’s eye contained two classes of photoreceptors, each class with microvilli at orthogonal orientation to the other. P. karachiensis’ eye structure can provide information regarding the polarization percentage but is not sufficient to calculate the exact e-vector orientation. The threshold for polarotoxisis response was 20-30%. Animals responded similarly to horizontal and vertical polarization; and also showed negative phototaxis, affected by light polarization. Results suggest that P. karachiensis responds to polarized light analogously to changes in brightness. The dynamic pattern of polarotaxis responses suggests that polarization sensitivity may enable P. karachiensis to detect other planktonic animals.     

Interneuron activity leads to initiation of low‐voltage fast‐onset seizures

Seizures in temporal lobe epilepsy can be classified as hypersynchronous and low‐voltage fast according to their onset patterns. Experimental evidence suggests that low‐voltage fast‐onset seizures mainly result from the synchronous activity of γ‐aminobutyric acid–releasing cells. In this study, we tested this hypothesis using the optogenetic control of parvalbumin‐positive interneurons in the entorhinal cortex, in the in vitro 4‐aminopyridine model. We found that both spontaneous and optogenetically induced seizures had similar low‐voltage fast‐onset patterns. In addition, both types of seizures presented with higher ripple than fast ripple rates. Our data demonstrate the involvement of interneuronal networks in the initiation of low‐voltage fast‐onset seizures. Ann Neurol 2015;77:541–546