Axonal cytoskeleton changes in experimental optic neuritis

Axonal loss and degeneration in multiple sclerosis (MS) and experimental allergic encephalomyelitis (EAE) have been suggested by brain imaging, pathological and axonal transport studies. Further elucidation of the processes and mechanisms of axonal degeneration in demyelinating diseases is therefore of potential importance in order to alleviate the permanent disabilities of MS patients. However, detailed studies in this area are impeded by the small number of reliable models in which the onset and location of demyelination can be well-controlled. In this study, microinjection of polyclonal rabbit anti-galactocerebroside (anti-Gal C) antibody and guinea pig complement was used to induce local demyelination in the rat optic nerve. We found that treatment with appropriate volumes of the antibody and complement could induce local demyelination with minimal pressure- or trauma-induced damage. Local changes in neurofilaments (NFs) and microtubules (MTs) were examined with both immunohistochemistry (IHC) and electron microscopy (EM). On day 1 after microinjection, we observed moderate NF and MT disassembly in the local demyelinated area, although in most cases, no apparent inflammatory cell infiltration was seen. The NF and MT changes became more apparent on days 3, 5, 7 after microinjection, along with gradually increased inflammatory cell infiltration. These results suggested that acute demyelination itself may induce local cytoskeleton changes in the demyelinated axons, and that the ensuing local inflammation may further enhance the axonal damage. When the lesions were stained with specific antibodies for T lymphocytes, macrophages, and astrocytes, we found that most of the cells were macrophages, suggesting that macrophages may play a greater role in inflammation-related axonal degeneration and axonal loss. These results were confirmed and further characterized on the ultrastructural level.     

Crystallization during volume reduction of solutions with a composition corresponding to that in the collecting duct: the influence of hydroxyapatite seed crystals and urinary macromolecules

To examine the effect of hydroxyapatite (HAP) seed crystals and urinary macromolecules on the crystallization under conditions similar to those in the collecting duct, we evaporated 100 ml samples of salt solutions with an ion composition assumed to correspond to that in the collecting duct without and with HAP seed crystals. The crystallization in seeded solutions was assessed both with and without dialysed urine (dU). After evaporation the number and volume of crystals were recorded in a Coulter Multisizer and the crystal morphology examined with scanning electron microscopy (SEM) and X-ray crystallography. Addition of HAP crystals was apparently followed by an approximately 15–20% increase in heterogeneous nucleation of calcium oxalate (CaOx). In these experiments SEM and X-ray crystallography showed a high percentage of CaOx in the precipitate. In samples reduced to 40–69 ml, addition of dU to the collecting duct solution containing HAP seed resulted in a greater mean (SD) number of crystals; 3895 (1841) in samples with dU and 1785 (583) in samples without. This was mainly explained by an increased mean (SD) number of small crystals. The mean crystal volume was 17.8 (1.1) and 34.3 (9.1) in samples reduced to 40–69 ml with and without dU, respectively. This might reflect the inhibitory effect of dU on the growth and/or aggregation of the CaOx-CaP precipitate or a promoted nucleation resulting in a large number of small crystals. It is concluded that calcium phosphate formed above the collecting duct might induce heterogeneous nucleation of CaOx at lower levels of the renal collecting system, and that urinary macromolecules are powerful modifiers of these processes. Received: 8 July 1998 / Accepted: 12 March 1999     

Human phase I vaccine trials of 3 recombinant asexual stage malaria antigens with Montanide ISA720 adjuvant

Two phase I vaccine trials were conducted to test the immunogenicity and safety of a vaccine containing three recombinant malaria antigens from the asexual stage of Plasmodium falciparum. The three antigens are a fragment of MSP1 (190LCS.T3); MSP2 and a portion of RESA and were formulated in Montanide ISA720 adjuvant. These trials investigated the dose response of each antigen for eliciting both antibody and T-cell responses and the immunogenicity of a mixture of the antigens compared with the antigens injected separately. All three antigens elicited both antibody and T-cell responses. Strong T-cell responses were observed with 190LCS.T3 and RESA with stimulation indices exceeding 100 for peripheral blood leucocytes in some individuals. The antibody responses were generally weak. The human antibody responses observed with MSP2 in Montanide ISA720 were not significantly different from those obtained in an earlier trial which used MSP2 with alum as the adjuvant. No antigenic competition was observed: volunteers receiving a mixture of antigens had similar responses to those receiving the three antigens at separate sites. Tenderness and pain at the injection site were common over the first few days following immunization. In some volunteers, especially those receiving the highest doses tested, there was a delayed reaction at the injection site with pain and swelling occurring approximately 10 days after injection.     

Automatic Border Detection to Assess Right Ventricular Function Following Surgical Treatment of Thromboembolic Pulmonary Hypertension

Automatic border detection (ABD) has been developed as a potentially useful means for evaluating ventricular function on line in an automatic fashion. Its success with tracking left ventricular function is established, but little is known about its ability to assess right ventricular (RV) function. Accordingly, 20 patients with severe pulmonary hypertension due to chronic thromboembolic disease underwent standard two-dimensional echocardiography and imaging with ABD before and after pulmonary thromboendarterectomy to correct pulmonary hypertension. ABD-derived results were compared to manually planimetered RV areas calculated from the apical four-chamber view. Doppler tricuspid regurgitant velocity fell significantly with surgery from 4.4 ± 0.6 to 2.9 ± 0.7 m / sec (P < 0.001). The mean values for RV areas derived by manual planimetry and ABD were similar, as was fractional area shortening, which improved significantly with surgery (manual 0.24 ± 0.01 preoperative vs 0.31 ± 0.11 postoperative, P < 0.05; and ABD 0.19 ± 0.05 preoperative vs 0.32 ± 0.15 postoperative, P < 0.001). There was, however, very little correlation between the individual values for ABD versus manually derived RV areas and fractional area shortening, with the best correlation being the RV end-diastolic areas after surgery (y = 0.684x + 7.9, r = 0.564, P = 0.01). These results demonstrate that both manually planimetered RV areas and those determined by ABD can adequately follow changes in ventricular function over time. However, variability within each technique may prevent direct comparison of the absolute values of the two techniques.     

In vitro and in vivo uptake of nickel sulfides by rat lymphocytes

The uptake, the biological transformation and the interaction with cellular constituents of Ni₃S₂ and NiS have been studied in vitro and in vivo on rat lymphocytes. NiS crystals are phagocytized in vitro and no structural degradation is observed within the first 3 days of exposure. Energy dispersive spectrometry (EDS) reveals a slight dissolution characterized by the loss of sulfur. Ni₃S₂ is degraded in the extracellular space to minute particles (50–100 nm) covering the cell membrane. Smaller intracellular particles (10–30 nm) are found selectively bound to mitochondria, endoplasmic reticulum, Golgi vesicles, nuclear membranes, and the euchromatinic part of nuclei. EDS analyses reveal that the particles bound to cell membranes and euchromatin no longer contain sulfur but phosphorus and nickel as inorganic compounds. This observation suggests the formation of a Ni/P complex with the phosphate groups either of membranous phospholipids or of nuclear RNA or DNA. A similar uptake and transformation process of Ni₃S₂ is observed on lymphocytes after in vivo incubation. This leads us to consider lymphocytes as target cells, as compared with other cell types where the Ni₃S₂ uptake occurs only partially. The present findings show a difference of uptake and biological transformation between Ni₃S₂ and NiS. The identical results obtained after in vitro and in vivo bioassays enhance the in vitro experiments, at least for this cell type.     

Effect of chronic clonidine treatment on the turnover of noradrenaline and dopamine in various regions of the rat brain

Summary The turnover of noradrenaline (NA) and dopamine (DA) was estimated in various rat brain regions by measuring the depletion of the amines after inhibition of their biosynthesis by -methyltyrosine. Acute treatment with clonidine (0.1 mg/kg) reduced NA turnover in the brain stem, hypothalamus and rest of the brain but had no effect on DA turnover in the corpus striatum and rest of the brain. After chronic clonidine treatment (0.1 mg/kg, twice daily for 15 days), NA turnover was not affected by an additional injection of clonidine in the brain stem or in the hypothalamus but was still markedly reduced in the rest of the brain. In addition, DA turnover was reduced in the corpus striatum and rest of the brain, an effect which was also observed after a single injection of a high dose of clonidine (1 mg/kg). These findings suggest that a chronic administration of clonidine may cause regionally differential changes in the sensitivity of central NA receptors.