Complement-derived polypeptide C3adesArg as a mediator of inflammation at the blood-brain barrier in a new experimental cat model

Summary The effect of the complement-derived polypeptide C3adesArg as a mediator of inflammation in the central nervous system was examined. Twenty-five anesthetized cats received 4 mg of this polypeptide by intraventricular injection, 20 cats who served as controls received saline. Cerebrospinal fluid (CSF) was sampled 3 h after intraventricular injection and the brains were removed. For assessment of the permeability of the blood-brain barrier the CSF penetration of four antibiotics, which were given intravenously, was measured. Five control animals were employed for each antibiotic (tobramycin, ampicillin, imipenem, fosfomycin), whereas six C3adesArg-treated animals were used for each antibiotic and seven for tobramycin. Besides CSF levels of glucose, the prostanoids 6-keto-prostaglandin F₁, thromboxane B₂ and prostaglandin E₂ were measured. The morphological examinations in the CSF sediments and histological brain sections in the C3adesArg-treated animals disclosed a distinct inflammation with leptomeningeal and perivascular infiltration of polymorphonuclear granulocytes compared to normal findings in the controls. The CSF/serum ratios of all of the antibiotics were markedly elevated compared to controls, indicating a blood-brain barrier disruption. The levels of all prostanoids were significantly higher in the treatment group than in the control group, whereas the glucose levels were lower. These findings are in accordance with a granulocytic meningitis as seen in some infections at the acute stage. It is concluded that C3adesArg acts as a mediator of inflammation in the central nervous system.     

Radiologic search for embolized leaflets of prosthetic heart valves: A report of two cases

In a radiologic search for embolized leaflets of Edwards-Duromedics bileaflet valves in 2 patients, the embolized fragments were localized in the iliac vessels using computed tomography. Sonography was successful in one case and standard X-ray films of the abdomen were negative in both cases.In vitro investigations with Björk-Shiley and Edwards-Duromedics leaflets suggested that standard X-ray films of the abdomen and pelvis should be considered as the first investigational technique. If negative, computed tomography of the lower abdomen should be done.     

Cardiovascular risk factor prevention in black schoolchildren: two-year results of the "Know Your Body" program

A five-year intervention study of the effectiveness of the "Know Your Body" program in reducing coronary heart disease risk factors among black students in the District of Columbia, who were in grades 4-6 at baseline, was begun in 1983. Nine schools were stratified on socioeconomic status and randomly assigned to control and intervention groups. The "Know Your Body" curriculum focuses on nutrition, fitness, and the prevention of cigarette smoking. At baseline, 1,234 students were eligible for the screening in which the following target risk factors were measured: systolic and diastolic blood pressures, ponderosity index, triceps skinfold thickness, postexercise pulse recovery rate, serum total and high density lipoprotein (HDL) cholesterol, and serum thiocyanate. After two years of intervention, results indicated that the program may have had a favorable impact on the following risk factors: systolic and diastolic pressures, HDL cholesterol, ratio of total to HDL cholesterol, fitness (postexercise pulse recovery rate), and smoking. Significant net changes in the favorable direction also were found for health knowledge and attitude toward smoking. Blood pressure reduction was associated with decreased ponderosity and improved fitness, and increased HDL cholesterol was associated with decreased ponderosity. These results are consistent with other evaluations of the "Know Your Body" program, suggesting that the program may be effective in reducing chronic disease risk in diverse school populations.     

A Comparison of the Cholinergic Activity of Selected H2-Antagonists and Sulfoxide Metabolites

Famotidine and selected H₂-antagonists were evaluated with respect to toxicity and selected pharmacological activities. When administered intraperitoneally to mice at a dose equivalent to 10 times their respective H₂-antagonist ED₅₀ values, no deaths were observed. Similarly, no alteration in brain ACh concentrations or overt pharmacological effects were noted. However, at 400 mg/kg, ranitidine produced 89% lethality, followed by cimetidine (11%) and famotidine. Only cimetidine and famotidine at this dose significantly elevated brain acetylcholine levels. These results do not correlate with the in vitro data, where ORF-17578 and ranitidine were the most potent entities with respect to acetylcholinesterase inhibition (1–2 × 10^–6 M), followed by nizatidine > cimetidine > famotidine. The sulfoxide metabolites of ranitidine and cimetidine were approximately one-tenth as potent as their parent compounds with respect to inhibition of acetylcholinesterase. Direct muscarinic stimulation or potentiation of acetylcholine-induced contraction in ileal tissue was not observed for any of the H₂-antagonists.     

Localization of SNARE proteins and secretory organelle proteins in astrocytes in vitro and in situ

Astrocytes are capable of regulated release of messenger molecules. Astrocytes cultured from new born rodent brain express a variety of classical presynaptic proteins. We investigated the question whether the capability to express synaptic proteins in culture was a feature only of immature astrocytes, and whether these proteins were also expressed by astrocytes in situ. Experiments were performed with transgenic mice expressing the enhanced green fluorescent protein under the control of the human glial fibrillary acidic protein promoter. Using double fluorescence and astrocytes cultured from 1 to 16 day-old animals we show that the astrocytic expression of synaptic proteins in culture is invariant of the age of donor animals. Culturing can induce the astrocytic expression of specific synaptic proteins such as SV2, synaptophysin and SNAP-25. Astrocytes in brain sections of 1-16 day-old animals revealed a punctuate immunofluorescence for secretory carrier membrane protein (SCAMP), SNAP-23, synaptobrevin II, and cellubrevin, to a minor extent for SNAP-25 and synaptophysin, and none for SV2. Our results demonstrate that cultured astrocytes express synaptic proteins not present in situ. Nevertheless, astrocytic organelles in situ are equipped with molecules that could be involved in regulated exocytosis of messenger substances.     

The Modality Specificity of the Slow Negative Wave

Event-related potentials were recorded in a simple reaction time task using a 3-sec interval between S₁ and S₂. The sensory modalities of S₁ and S₂ were varied across 4 conditions to yield all possible combinations of tones and flashes. A negative component which peaked between 600 and 800 msec after S₁ was specific in scalp distribution to the modality of S₁ but not S₂. It was concluded that this negative component is a response to S₁ and not related to processes associated with anticipation of S₂. A slow negative shift which peaked at S₂ was largest at the vertex in all conditions, suggesting its motor origin. A trend for the latter activity to be more negative in posterior recordings when S₂ was visual than auditory leaves open the possibility that the terminal CNV is a combination of motor activities and anticipation of the sensory modality of S₂.     

A simple organ culture method for differentiation of melanocytes in mouse embryonic skin using “origami” membrane filter

Summary A simple organ culture method for culturing embryonic skin was developed. A piece of skin with a part of the neural tube from mouse embryo (11 to 12 d) was placed on a 25 mm d membrane filter. The filter was folded to wrap the explant and inserted into glass tubing. The explant and filter in the glass tubing were placed in a rotating tissue culture tube containing 5 ml culture medium (Ham's F12 supplemented with 15 to 20% fetal bovine serum) and filled with a mixture of 95% air:5% CO₂. In explants cultured for 6 d fully differentiated melanocytes were observed in the epidermis.     

A green to red photoconvertible protein as an analyzing tool for early vertebrate development.

Lineage labeling is one of the most important techniques in developmental biology. Most recently, a set of photoactivatable fluorescent proteins originating from marine cnidarians became available. Here, we introduce the application of the green to red photoconvertible protein EosFP as a novel technique to analyze early vertebrate development. Both injection of EosFP mRNA and purified, recombinant EosFP followed by a light-driven green to red conversion allow lineage labeling in virtually any temporal and spatial dimension during embryonic development for at least 2 weeks. Specific staining of cells from nonsurface layers is greatly facilitated by light-driven conversion of EosFP compared with traditional methods. Therefore, green to red photoactivatable proteins promise to be a powerful tool with the potential to satisfy the increasing demand for methods enabling detailed phenotypical analyses after manipulations of morphogenetic events, gene expression, or signal transduction.     

Cytogenetic and comparative genomic hybridization findings in four cases of breast cancer after neoadjuvant chemotherapy

To assess a potential common pattern of genetic alterations in chemotherapy-resistant tumors we analyzed four tumors from breast cancer patients (patients 1-4) after neoadjuvant chemotherapy, by comparative genome hybridization (CGH) and conventional chromosome banding analysis. All patients showed structural aberrations involving chromosomes 1, 5, 11, 16, and 17. In CGH analysis, the patients showed typical imbalances for ductal breast cancer: gains of 1q (3 patients), 5q (2 patients), 8q (3 patients), and X (4 patients) and losses of 1p33 approximately p36 (3 patients), 16q (3 patients), 17p (3 patients), 19 (4 patients), and 22q (4 patients). Other recurrent imbalances of atypical pattern for ductal breast cancer were gain of 4q21 approximately q32 (2 patients), 20q21 approximately q22 (2 patients), and 21 (2 patients) and loss of 20p (3 patients). Three patients showed involvement of several regions bearing genes of drug resistance (MDR1 [HUGO symbol: ABCB1], BCRP [HUGO symbol: ABCG2], MRP1 [HUGO symbol: ABCC1], RFC1); the fourth patient displayed an amplification in the region of MYC (alias c-myc), thus providing--at the level of the light microscope--an explanatory background for the ability of their tumors to survive anthracycline-, taxane- and cyclophosphamide-based chemotherapy. Conventional cytogenetic analysis and CGH displayed highly coincidental findings in the tumors of four patients after neoadjuvant chemotherapy for breast cancer.     

Habituation and adaptation of the vestibuloocular reflex: a model of differential control by the vestibulocerebellum

Summary We habituated the dominant time constant of the horizontal vestibuloocular reflex (VOR) of rhesus and cynomolgus monkeys by repeated testing with steps of velocity about a vertical axis and adapted the gain of the VOR by altering visual input with magnifying and reducing lenses. After baseline values were established, the nodulus and ventral uvula of the vestibulocerebellum were ablated in two monkeys, and the effects of nodulouvulectomy and flocculectomy on VOR gain adaptation and habituation were compared. The VOR time constant decreased with repeated testing, rapidly at first and more slowly thereafter. The gain of the VOR was unaffected. Massed trials were more effective than distributed trials in producing habituation. Regardless of the schedule of testing, the VOR time constant never fell below the time constant of the semicircular canals (5 s). This finding indicates that only the slow component of the vestibular response, the component produced by velocity storage, was habituated. In agreement with this, the time constant of optokinetic after-nystagmus (OKAN) was habituated concurrently with the VOR. Average values for VOR habituation were obtained on a per session basis for six animals. The VOR gain was adapted by natural head movements in partially habituated monkeys while they wore ×2.2 magnifying or ×0.5 reducing lenses. Adaptation occurred rapidly and reached about ±30%, similar to values obtained using forced rotation. VOR gain adaptation did not cause additional habituation of the time constant. When the VOR gain was reduced in animals with a long VOR time constant, there were overshoots in eye velocity that peaked at about 6–8 s after the onset or end of constant-velocity rotation. These overshoots occurred at times when the velocity storage integrator would have been maximally activated by semicircular canal input. Since the activity generated in the canals is not altered by visual adaptation, this finding indicates that the gain element that controls rapid changes in eye velocity in the VOR is separate from that which couples afferent input to velocity storage. Nodulouvulectomy caused a prompt and permanent loss of habituation, returning VOR time constants to initial values. VOR gain adaptation, which is lost after flocculectomy, was unaffected by nodulouvulectomy. Flocculectomy did not alter habituation of the VOR or of OKAN. Using a simplified model of the VOR, the decrease in the duration of vestibular nystagmus due to habituation was related to a decrement in the dominant time constant of the velocity storage integrator (1/h ₀). Nodulouvulectomy, which reversed habituation, would be effected by decreasing h ₀, thereby increasing the VOR time constant. Small values of h ₀ would cause velocity storage to approach an ideal integrative process, leading the system to become unstable. By controlling the VOR time constant through habituation, the nodulus and uvula can stabilize the slow component of the VOR. VOR gain adaptation was related to a modification of the direct vestibular path gain g ₁, without altering the coupling to velocity storage g ₀ or its time constant (1/h ₀). The mismatched direct- and indirect-pathway gains simulated the overshoots in the dynamic response to a step in velocity, that were observed experimentally. We conclude that independent distributed elements in the VOR modify its dynamic response, under control of separate parts of the vestibulocerebellum.