Polyclonal bacteremia due to gram-negative rods.

The frequency of, risk factors for, and outcome of polyclonal gram-negative bacteremia are still unknown. We investigated them in a prospective cohort study of patients for whom a blood culture yielded >/=1 species of gram-negative aerobic rod. For each patient, pulsed field gel electrophoresis (PFGE) was performed on 4 colonies of each morphologic type. Episodes of bacteremia were considered polyclonal if caused by >1 PFGE type of the same species. Ten (6.5%) of 153 investigated patients had polyclonal bacteremia. Bacteremia due to nonfermenting rods was the single significant risk factor for polyclonal bacteremia. Complications were equally frequent in all patient groups. However, patients with polyclonal bacteremia received more extensive antibiotic therapy than did patients with monoclonal bacteremia. Nearly 20% of episodes of bacteremia due to nonfermenting rods were polyclonal, but it remains unclear why nonfermenting rods were more likely to cause polyclonal bacteremia than were other gram-negative rods.

Morphology, axonal projection pattern, and responses to optic nerve stimulation of thalamic neurons in the salamander Plethodon jordani.

In the salamander Plethodon jordani, the morphology and axonal projections of thalamic (TH) neurons and their responses to electrical optic nerve stimulation were determined by intracellular recording and biocytin labeling under in vitro, whole-brain conditions. Based on their axonal projections, labeled neurons (n = 76) were divided into the following groups: TH1 neurons, with mostly ipsilateral projections to the striatum; TH2 neurons, with ipsilateral or bilateral projections to the medial amygdala and nucleus accumbens; TH3 neurons, with bilateral projections to the medial and dorsal pallium; TH4 neurons, with mostly ipsilateral projections to the striatum and ipsilateral projections to the tectum opticum, tegmentum, and rostral medulla oblongata; and TH5 neurons, with ipsilateral projections to the tegmentum, medulla oblongata, and rostral spinal cord without (TH5.1) or with (TH5.2) additional projections to the optic tectum. TH1-TH4 neurons are found in the dorsal thalamus and around the sulcus medialis, and TH5 neurons are found in the ventral thalamus. Labeled neurons with ascending projections, i.e., the more dorsally situated TH1-TH4 neurons, are mostly inhibited by electrical stimulation of the optic nerve and have significantly longer latencies (mean +/- S.D., 42.1 +/- 11.6 msec) than neurons with exclusively descending projections, i.e., the ventrally located TH5 neurons (8.5 +/- 6.1 msec), which receive the bulk of retinal afferents and show excitation at electrical optic nerve stimulation. Neurons recorded without labeling in the dorsal thalamus likewise exhibit mostly inhibition and have significantly longer latencies (35.7 +/- 18.9 msec) than those recorded in the ventral thalamus (10.9 +/- 7.7 msec), which mostly show excitation. None of the neurons recorded in the dorsal thalamus followed repetitive stimulation of the optic nerve. Thus, neurons situated in the dorsal thalamus and projecting to pallial or subpallial telencephalic targets are unlikely to receive monosynaptic or oligosynaptic, excitatory retinal input. Accordingly, no retino-thalamo-telencephalic pathway homologous to that found in amniotes appears to exist in salamanders.

Morphology, axonal projection pattern, and response types of tectal neurons in plethodontid salamanders. II: intracellular recording and labeling experiments.

In the plethodontid salamanders Plethodon jordani and P. glutinosus, the morphology and axonal projections of 140 tectal neurons and their responses to electrical optic nerve stimulation were determined by intracellular recording and biocytin labeling. Six types of neurons are distinguished morphologically. TO1 neurons have wide dendritic trees that arborize mainly in tectal layers 1 and 3; they project bilaterally to the tegmentum and contralaterally to the medulla oblongata. TO2 neurons have very wide dendritic trees that arborize mainly in layers 2 and 3; axons project bilaterally or unilaterally to the pretectum and thalamus and ipsilaterally to the medulla oblongata. TO3 neurons have very wide and flat dendritic trees confined to layers 3-5; some have the same axonal projection as TO2 neurons, whereas others have descending axons that reach only the level of the cerebellum. TO4 neurons have narrower dendritic trees that arborize in layers 2 and 3; they project to the ipsilateral pretectum, thalamus, and medulla oblongata. TO5 neurons have dendritic trees that arborize in layers 1 and 2 or 1-3 and project bilaterally or unilaterally to the pretectum and thalamus. TO-IN are interneurons, with a number of subtypes with respect to variations in dendritic arborization pattern. TO1-TO5 neurons generally have short latencies of 2-16 ms (average = 8.4 ms) at electrical optic nerve stimulation; first responses are always excitatory, often followed by inhibition. They are likely to be mono- or oligosynaptically driven by retinal afferents. TO-IN interneurons have long latencies of 20-80 ms (average = 38.6 ms) and appear to receive no direct retinal input. With their specific dendritic arborization, consequent dominant retinal input, specific axonal projections, the different types of tectal projection neurons constitute separate ascending and descending visual pathways. Hypotheses are presented regarding the nature of the information processed by these pathways.

[Histological classification of uveal melanoma]. / Histologiczna klasyfikacja czerniaków naczyniówki.

Cytological classification of choroidal malignant melanomas recommended by WHO and based on the Callender classification (spindle A and B, mixed and epithelioid) is presented. Prognosis according to the histological types is discussed.

[Use of neodymium-YAG laser in cataract extraction]. / Zastosowanie lasera neodymowego YAG w chirurgii zacmy.

Observations of 45 procedures in 35 patients before and after cataract surgery suggest, that the application of Nd-YAG laser is an effective and safe method of treatment. The most frequent procedures were posterior capsulotomy, iridotomy, vitreotomy, membranotomy, anterior and posterior synechotomy and decission of secondary cataract. Possible complications include intraocular pressure elevations, damage of artificial lenses and hemorrhages from iris vessels.

Cytoarchitecture of the tectum mesencephali in salamanders: a Golgi and HRP study.

The tectum mesencephali of salamanders shows a morphology that has long been considered primitive when compared with that of frogs. The alternative hypothesis is that the salamander brain is secondarily simplified. In order to test these two hypotheses, the cytoarchitecture of the tectum and the projections of tectal neurons were studied in 11 species of salamanders. Application of the Golgi method reveals three major morphological types. Type 1 has a very wide dendritic arborization mostly confined to the deep fiber layers, and somata are always located within the most superficial part of the periventricular gray matter. Type 2 possesses a wide to medium-size dendritic arborization. In subtype 2a the somata are located in the uppermost part of the gray, and dendrites always reach the uppermost layer of retinal afferents; in subtype 2b the somata are found in deeper parts of the gray, and dendrites arborize in the deeper layers of retinal afferents; and in subtype 2c the somata are also located in deeper parts, but the wide dendritic arborization is confined to deep fiber layers. Type 3 shows the narrowest dendritic arbors that always reach the upper two tectal fiber layers. The somata are found at any depth of the gray matter. HRP experiments reveal a correlation between morphological differences and the projections of tectal neurons. Type 1- and type 2c-like cells constitute the uncrossed tecto-bulbo-spinal tract, whereas type 1- and type 2a-like cells and migrated large spindle-shaped cells (Salamandra) constitute the crossed tecto-bulbo-spinal tract. Type 3-like neurons project to thalamic, pretectal, and isthmic termination sites. The HRP experiments also demonstrate the existence of two classes of mesencephalic trigeminal cells. A comparison shows that salamanders and frogs possess very similar functional and morphological types of tectal cells. However, tectal cells of salamanders show a "juvenile" morphology, and the number of migrated cells is about 10 times higher in frogs compared to salamanders. Both phenomena are seen as the result of secondary simplification of brain structures in the context of paedomorphosis.

Low oxygen prevents epithelial overgrowth of corneas in long-term organ culture.

Forth human corneo-scleral rings and 40 whole corneas with scleral rim were preserved in organ culture for up to six weeks in either normal (20%) or low (6%) oxygen concentration in the gas phase of the culture. Decreasing the oxygen prevented epithelial invasion of the inner side of the cornea without adversely affecting the condition of the endothelium. It is suggested that lower oxygen level might improve corneal preservation in organ culture.

[Fibrin glue improves wound healing of non-perforating keratotomy]. / Fibrinklebung verbessert die Wundheilung nichtperforierender Keratotomie.

Wound healing in non-perforating keratotomy with and without application of fibrin glue was studied in 28 rabbits. The following advantages were observed after filling the wound space with fibrin glue (Tissucol): (1) fibrin glue prevented epithelial invasion of the wound space; (2) fibrin stimulated fibroblastic activity and served as a matrix for fibroblasts and keratocytes; (3) fibrin accelerated wound healing and strengthened the scar formed.