1H magnetic resonance spectroscopy of chronic cerebral white matter lesions and normal appearing white matter in multiple sclerosis

OBJECTIVES: To test the hypothesis that irrecoverable neurological deficit in multiple sclerosis is associated with axonal loss. METHODS: 1H magnetic resonance spectroscopy (MRS) was carried out in a group of patients with clinically definite multiple sclerosis (n=31). Using this technique, the apparent concentration of NA ([NA] the sum of N-acetyl aspartate (NAA), a neuronal marker, and N-acetylaspartylglutamate has been compared in four groups of patients with multiple sclerosis classified as relapsing-remitting, secondary progressive, primary progressive, benign, and a control group. RESULTS: In the patients with relapsing-remitting disease (n=9) there was a highly significant reduction of apparent NA (median 8.73 mM, range 6.86 mM-10.74 mM, P=0.0008) from an area of high signal compared with the control group (median 11.97 mM, range 10.55 mM-14.5 mM). In the patients with secondary progressive disease (n=10), there was again a highly significant reduction of apparent NA (median 7.82 mM, range 3.5 mM-10.3 mM, P=0.0003) from an area of high signal compared with the control group. In the patients with primary progressive disease (n=6) there was once again a highly significant reduction of apparent NA (median 8.83 mM, range 6.95 mM-9.89 mM, P<0.002) from an area of high signal compared with the control group. In the patients with benign disease, however, there was no significant difference in the apparent NA (median 10.5 mM, range 8.53 mM-12.8 mM, P>0.05) from an area of high signal compared with the control group. In the patients with benign disease (n=5) there was also no significant difference in the apparent NA (median 10.74 mM, range 8.58 mM-13.4 mM, P>0.3) from an area of normal appearing white matter compared with the control group. In the patients with primary progressive disease, however, there was a significant reduction of apparent NA from an area of normal appearing white matter (median 8.78 mM, range 8.7 mM-12.38 mM, P< 0.025) compared with the control group. There was a significant inverse correlation between [NA] from lesions in the patients with multiple sclerosis and disability as measured on the Kurtzke expanded disability scale score (r= -0.364, 0.05>P>0.02). CONCLUSION: These findings support the hypothesis that axonal loss is important in the development of disability in multiple sclerosis. They also provide evidence for axonal loss in normal appearing white matter in patients with primary progressive disease.     

Impaired autoregulation in an experimental model of chronic cerebral hypoperfusion in rats

BACKGROUND AND PURPOSE: To verify the hypothesis that impaired autoregulation may contribute to cerebral swelling or hemorrhage after a sudden recovery of perfusion pressure, we studied the chronic effects of cerebral hypoperfusion on the autoregulatory responses of the pial arterioles in situ. METHODS: Eight to 12 weeks after a carotid-jugular fistula was created in rats, experiments were performed under alpha-chloralose and urethane anesthesia. Regional cerebral blood flow (rCBF) was determined by the hydrogen clearance method, and carotid pressure was measured. Using a closed cranial window, we determined the autoregulatory responses of the arterioles (30 to 50 microns) to both hypertension induced by norepinephrine and sudden fistula closure at various mean arterial pressures (MAPs). RESULTS: rCBF on the fistula side was reduced by 27%. Carotid pressure was significantly lower than normal but was immediately increased by fistula closure. The pial arterioles showed marked elongation and enlargement. During induced hypertension, the arterioles in the fistula group started to dilate at an MAP lower than that of the control group (130 versus 180 mm Hg, respectively). The arterioles constricted when the fistula was occluded at normal MAP. However, when the fistula was occluded at an MAP higher than 130 mm Hg, the vessels dilated. CONCLUSIONS: It was demonstrated that (1) chronic hypoperfusion induced impairment of the upper limit of autoregulation and (2) sudden fistula closure under hypertensive conditions caused vasodilation of the arterioles. These findings suggest that rapid restoration of perfusion pressure is possibly followed by a pressure breakthrough phenomenon in a chronically hypoperfused cerebrovasculature.     

MRI of lightning injury: early white matter changes associated with cerebral dysfunction

A previously healthy male was struck by lightning. He developed neurologic deficits, including mild cerebral brain dysfunction. Magnetic resonance imaging (MRI) showed numerous foci of hyperintensity on long TR images, scattered throughout the supratentorial white matter. To our knowledge, the early MRI findings of lightning injury have not been previously reported.     

Ganglioside changes in brain in chronic relapsing experimental allergic encephalomyelitis induced in the Lewis rat

Chronic relapsing experimental allergic encephalomyelitis (CREAE) was induced in Lewis rats by inoculation with guinea-pig myelin and complete Freund's adjuvant followed by treatment with low-dose cyclosporin A. Rats were sacrificed at different phases of the disease (just before the onset of clinical signs, during the first clinical episode of CREAE and during the first recovery). Gangliosides were extracted from the brain, analysed after purification by HPTLC fractionation and quantified densitometrically. An increase of GM1, the main rat myelin ganglioside, and a decrease of GT1b, suggested to play a role in mediating the interactions between oligodendroglia and axons, were observed during the development of the CREAE. These findings indicating significant ganglioside changes in CREAE give further support to the concept concerning the involvement of gangliosides in autoimmune demyelination.     

Lactate and pyruvate changes in the cerebral gray and white matter during posthypoxic seizures in newborn pigs

Cerebral lactate rises after chemically induced seizures, but it is not known if this occurs with posthypoxic seizures. We examined changes in lactate and pyruvate in gray and white matter in the newborn pig brain after a hypoxic insult known to produce seizures and permanent brain damage. Fourteen halothane-anesthetized piglets aged 24-49 h, were instrumented with a two-channel scalp EEG and microdialysis probes positioned in white and gray matter. Forty-five minutes of hypoxia were induced by reducing the fraction of inspired O2 to the maximum concentration at which EEG amplitude was < 7 microV. Postinsult EEG was classified as electroconvulsive activity (ECA) (n = 4) or burst suppression (n = 2), persistently low amplitude (n = 2), or intermittent spikes on normal background activity (n = 6). Six hours after the insult the brains were perfusion fixed for histologic probe localization. Plasma lactate and brain lactate had different time courses with brain having a persistently elevated lactate/pyruvate (L/P) ratio. The highest L/P ratios in gray and white matter were in the two pigs with persistently low amplitude EEG. There was no association between onset of electroconvulsive activity and an increase in lactate or L/P ratio. Posthypoxic energy metabolism is disturbed in both gray and white matter probably because of mitochondrial dysfunction. Seizure activity does not increase cerebral lactate or L/P ratio above the already raised levels found in posthypoxic encephalopathy. These findings cast further doubt on the hypothesis that such seizures are, in themselves, damaging.     

Brain inflammatory response induced by intracerebroventricular infusion of lipopolysaccharide: an immunohistochemical study

Turkey meningoencephalitis virus (TMEV) causes paralysis and mortality in turkeys. Because the classical diagnostic methods are complicated, we developed the RT-PCR as a new molecular diagnostic method. Since the nucleic acid sequence of TMEV is unknown, the first step in developing the RT-PCR relied on conserved sequences of viruses belonging to the Flaviviridae family, in which TMEV has been classified serologically. Using primers from the NS5 gene, three amplification products of TMEV RNA were obtained (125 bp, 181 bp and 800 bp). Their sequences were homologous to one another and to the NS5 gene of other flaviviruses.     

Expression of neurofibromatosis 2 protein in human brain tumors: an immunohistochemical study

Examining damage (inactivation) of antioxidant enzymes in the cells and the pattern of recovery after a single UV exposure might be a useful method for analyzing the mechanisms of chronic UV irradiation, because chronic UV irradiation means repeated single exposures. We irradiated human skin fibroblasts with a single exposure to UVA (1, 6 or 12 J/cm2) and examined the time course of changes in antioxidant enzymes over several days. Only catalase activity was inactivated at the end of the irradiation (66% for 6 J/cm2, 53% for 12 J/cm2), recovering by day 5. Superoxide dismutase (SOD) activity decreased on day 3 (63% for 6 J/cm2, 72% for 12 J/cm2), and recovered on day 5, although it was not changed at the end of exposure. The activities of glutathione peroxidase (GSH-Px) and glutathione reductase (GR) were nearly unchanged by irradiation. If repeated UV exposures occur before the inactivated enzyme activities recover, cellular damage will be significant due to the lowered antioxidant defense system. We examined the rates of synthesis and degradation of catalase in response to UVA irradiation. Both synthesis and degradation rates were changed by irradiation. These data indicate that catalase activity was still low on day 2 due to the existence of inactivated catalase produced at the end of UV irradiation, and catalase activities recovered by day 5 due to a significant increase in the synthesis rate. To elucidate the role of bound NADPH in catalase in response to UV irradiation, we measured the NADPH released from catalase after UVA irradiation using bovine liver catalase. UVA irradiation caused a release of NADPH from catalase (25% for 12 J/cm2), but this was not directly related to the inactivation of catalase.     

Regional cerebral blood flow changes in chronic alcoholic patients induced by naltrexone challenge during detoxification

A follow-up study was performed with the aim to evaluate all individuals surgically treated by the uvulopalatopharyngoplasty (UPPP) or laser uvulopalatoplasty (LUPP) method from a whole county in Sweden, 1-8 years after surgery, by assessing snoring occurrence and daytime sleepiness, as experienced by the patients and their cohabitants. Questionnaires were mailed to all operated people (n = 457) and were returned by 91% (346 men, 69 women) preoperatively diagnosed as habitual snorers (n = 255), cases of obstructive sleep apnea syndrome (n = 110) and unspecified snorers (n = 48). In addition 345 bedpartners participated. For outcome of surgery, no significant differences in diagnoses or sex were found. Improvement in snoring occurrence was reported by 89.6% of the patients, confirmed by 92% of the cohabitants (r = 0.84, p < 0.01). The remaining snoring occurrence was significantly dependent on the surgical method and the time after operation. Excessive daytime sleepiness (EDS) was experienced by 73.3% of the patients compared to 67% reported by the cohabitants. Of 415 patients operated on, 18% were free from snoring and 25% were free from EDS. Individuals with a shorter time since surgery reported less snoring. The UPPP method gave a significantly better result than LUPP for the symptom 'snoring'.     

Neuronal protection by intraischemic brain perfusion: an electron microscopy study in the rat

Organ perfusion with bloodless solutions is an established clinical method for protecting the heart against ischemic damage. In our study, we evaluated the effects of intraischemic bloodless brain perfusion on postischemic ultrastructural neuronal changes in a model of severe incomplete forebrain ischemia produced by hemorrhagic hypotension combined with temporary carotid occlusion in the rat. Four groups of rats were compared. During an ischemic insult of 30 min, the brains of two groups were perfused via both external carotids with either a normosmolar normothermic magnesium-enriched perfusate (MgSO4, 30 mM; NaCl, 37 mM; mannitol, 180 mM; n = 10) or a normothermic normal saline solution (n = 9) at a rate of 6 ml/h. Two other groups (ischemia without perfusion, n = 8; no ischemia and no perfusion, n = 7) served as controls. After 30 min of ischemia, withdrawn blood for hemorrhagic hypotension was reinfused, the carotid arteries reopened, and the brains reperfused for 2 h. After perfusion-fixation, qualitative and quantitative evaluation of postischemic cell changes of hippocampal CA1 neurons was performed by electron microscopy. Brain perfusion with the magnesium-containing solution significantly protected neurons against ischemic cell changes and provided an ultrastructural pattern similar to that seen in the nonischemic control group. In contrast, brain perfusion with normal saline solution did not result in neuronal protection. We conclude that intraischemic intracarotid brain perfusion with magnesium-enriched perfusate protects hippocampal neurons significantly against ischemic cell changes in the early reperfusion period after transient severe forebrain ischemia.     

Diazepam induced early oxidative changes at the subcellular level in rat brain

Binding of calcium to calmodulin (CAM) induces specific structural rearrangements in the whole protein molecule. Ca2+ organizes and stabilizes the four-domains structure of calmodulin in a helical, active conformation that can bind to its target proteins; the central helix remaining flexible is an essential condition for their bio-recognition. The conformation of calmodulin, and its efficacy to interact with target proteins, is profoundly altered when bound to metal ions other than calcium. As recently reported, the local structural changes of CaM, which occur upon aluminium binding, lead to the impairment of protein flexibility and to the loss of its ability to interact with several other proteins, which may decrease or inhibit the regulatory character of calmodulin. In this study we followed conformational changes occurring in the calmodulin molecule after aluminium binding using highly specific monoclonal antibodies (mAbs) able to differentiate between the conformational states of calmodulin, as well as mAbs which recognize aluminium free or bound to proteins. Under the same experimental conditions, mAb CAM-1, a Ca2+ conformation sensitive antibody raised against calmodulin, fails to recognize the calmodulin-aluminium complex, despite the presence of Ca2+, while the anti-Al antibodies show a maximal binding pattern towards their antigen. These data suggest that Al3+ ions bind to calmodulin in the presence of Ca2+ ions, leading to an inactive, reversible conformation, instead of its physiological active form. Alteration of the conformation of calmodulin imposed by Al binding may have possible implications in the neurotoxicity mechanism related to Alzheimer's disease.     

Metastatic adenocarcinoma to the brain: an immunohistochemical approach

The diagnosis of metastatic adenocarcinoma to the brain of unknown primary is problematic, and the role of immunohistochemistry in identifying a source has not been fully characterized. Sixty-eight metastatic adenocarcinomas of the brain with known primaries were immunostained with antibodies to cytokeratin 7 (CK7), cytokeratin 20 (CK20), CAM 5.2, wide-spectrum keratin (WSK), gross cystic disease fluid protein-15 (GCDFP-15), glial fibrillary acidic protein (GFAP), estrogen receptor (ER), and progesterone receptor (PR). True positive staining was defined as CK7 in lung or breast; CK20 in gastrointestinal; and GCDFP-15, ER, and PR in breast carcinomas. CK7 immunoreactivity was present in all 27 lung carcinomas and 14 of 15 breast carcinomas with a sensitivity of 98% and specificity of 78%. CK20 stained 15 of 16 GI carcinomas with a sensitivity and specificity of 94%. None of the cytokeratins stained surrounding brain tissue. GCDFP-15, ER, and PR had sensitivities of 33%, 33%, and 87%, with specificities of 92%, 84%, and 28%, respectively. PR often stained nuclei of normal brain tissue and was accentuated in areas of necrosis or cautery artifact. CK7 and CK20 are highly sensitive and specific in patients with metastatic adenocarcinoma to the brain of unknown primary. GCDFP-15 and ER are relatively specific, but insensitive markers, and PR is nonspecific and difficult to interpret.     

Effect of propentofylline on hippocampal brain energy state and amyloid precursor protein concentration in a rat model of cerebral hypoperfusion

An animal model of graded cerebral hypoperfusion achieved by way of 2- and 4-brain vessel occlusion (vo) was used to test the effect of chronic propentofylline (PPF) administration on hippocampal energy state and amyloid precursor protein (APP) concentration. For this purpose, forty adult rats were subjected to stepwise and permanent 2 vo and 4 vo and PPF in a dose of 25 mg/day per kilogram body weight was continuously administered intraperitoneally for 1 week or 3 weeks, respectively. During the final steady-state experiment arterial blood parameters and blood gases (mean arterial blood pressure, PO2, pCO2, pH, hematocrit, hemoglobin, body temperature) were measured. Brain tissue concentrations of adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine were measured in rat hippocampus by high-pressure liquid chromatography (HPLC) analysis; APP concentration was determined using Western blot techniques. In adult rat brain, long-term PPF treatment induced a striking increase in hippocampal ATP concentration which was paralleled by an enhancement of the ATP/ADP-ratio. Specifically, after 2 vo with 1 week of PPF treatment the ATP concentration in hippocampus was enhanced by 18% when compared with 2 vo without PPF treatment, whereas after 3 weeks PPF administration with 4 vo the concentration of ATP was enhanced by 31%. Furthermore, PPF reduced the tissue concentration of adenosine from 17.75 +/- 2.79 to 8.83 +/- 3.68 pmol/mg wet weight during 4 vo if compared with animals without PPF. In addition, the APP concentration was enhanced by 35% after 1 week PPF administration when compared with non PPF treated animals. In summary, the results demonstrated that chronic administration of PPF induced an enhancement in ATP concentration in adult rat hippocampus under conditions of long-term brain vessel occlusion. Interestingly, 1 week PPF seems to have a stimulating effect on APP which may act neuroprotectively. Thus, PPF may protect hippocampal neurons from chronic ischemic damage. In conclusion, PPF may have some beneficial effects and could be used in the treatment of patients with chronic cerebrovascular disorders or neurodegenerative diseases such as vascular dementia.     

Cocaine- and amphetamine-regulated transcript peptide immunohistochemical localization in the rat brain

The clinical features of Crohn's disease manifest during adolescence are varied as in adults. The potential complication of growth impairment and concomitant delay in pubertal development is unique to this population. Cytokines released from the inflamed bowel and chronic nutritional insufficiency are the major factors in the pathophysiology of growth inhibition. Hence reduction of intestinal inflammation and consistent provision of adequate nutrition are of paramount importance in management. Drug treatment mirrors that of adults; few specifically paediatric clinical trials have been conducted. Enteral nutrition is an important therapeutic alternative for young patients. There is evidence that it constitutes both a primary therapy of inflammation and a means of providing the calories needed for growth. In the setting of extensive disease, dependency on corticosteroids should be minimized through judicious administration of immunosuppressive drugs. For an adolescent with localized stenotic disease, optimal management includes a timely referral for intestinal resection as a means of providing an asymptomatic interval during which growth and pubertal development can normalize.     

Acute changes in wavelength of the process of auricular activation induced by stretching. Experimental study

OBJECTIVE: An evaluation is made of the acute modifications in the wavelength of the atrial excitation process induced by atrial stretching. MATERIAL AND METHODS: In 10 isolated Langendorff-perfused rabbit hearts and using a multiple electrode the wavelength of the atrial activation process (functional refractory period x conduction velocity) was determined in the right atrium. An analysis was also made of the inducibility of rapid repetitive atrial responses after 20 episodes of atrial burst pacing. Measurements were made under control conditions, after inducing two degrees of atrial wall stretch (D1 and D2), and following the suppression of atrial dilatation. RESULTS: Under control conditions the wavelength was 72.6 +/- 7.7 mm (250 ms cycle) and 54.0 +/- 5.1 mm (100 ms cycle). In D1 (mean longitudinal increase in atrial wall length = 24 +/- 3%) the wavelength shortened, with values of 59.8 +/- 6.6 mm (250 ms cycle; p < 0.01) and 44.9 +/- 5.1 mm (100 ms cycle; p < 0.01). In D2 (mean longitudinal increase in atrial wall length = 41 +/- 4%) the wavelength also shortened significantly, with values of 41.6 +/- 2.5 mm (250 ms cycle; p < 0.01 vs control) and 29.6 +/- 2.1 mm (100 ms cycle; p < 0.01 vs control). After suppressing atrial dilatation the wavelength was 65.7 +/- 8.0 mm (250 ms cycle, NS vs control) and 47.9 +/- 5.5 mm (100 ms cycle; NS vs control). The inducibility of rapid repetitive atrial responses increased during dilatation (22 episodes with over 30 consecutive repetitive responses in D1 [p < 0.01], 50 episodes in D2 [p < 0.001] vs 5 episodes under control conditions), and diminished after suppressing atrial dilatation (0 episodes with over 30 consecutive repetitive responses; p < 0.05). CONCLUSIONS: In the experimental model used, acute atrial dilatation produced a shortening in refractoriness and a decrease in conduction velocity. Both effects shortened the wavelength of the atrial activation process, facilitating the induction of atrial arrhythmias. The effects observed reverted upon suppressing atrial dilatation.     

Astroglial changes in the cerebral cortex of AIDS brains: a morphometric and immunohistochemical investigation

Sutureless phacoemulsification with implantation of a 7-mm PMMA intraocular lens was performed through a modified scleral tunnel in 100 consecutive patients. This was done to minimize postoperative astigmatism while retaining the advantages of implanting intraocular lenses with large optics. Visual and keratometric results and complications are reported after completion of a follow-up period of 6 months for the first 30 patients. Average uncorrected visual acuity improved from 0.13 preoperatively to 0.30 as early as 1 week postoperatively. Average best-corrected visual acuity improved from 0.23 before surgery to 0.51 as early as 1 week after surgery. No significant changes in visual acuity were recorded thereafter. The absolute value of keratometric astigmatism was not increased significantly at any postoperative examination time. The induced cylinder (Jaffe and Clayman) shifted from -1.27 D x 166 degrees at 1 week to 1.18 D x 91 degrees at 1 month postoperatively without further relevant changes thereafter. Endothelial cell loss did not differ from that reported by other authors after conventional cataract surgery. Corneal thickness was not increased significantly at any postoperative examination time. Implantation of intraocular lenses with large optics through a scleral tunnel allows quick visual rehabilitation as well as early stability of refraction.     

A study of the contribution of changes in the cerebral blood volume to the haemodynamic response to anoxia in rat brain

A susceptibility contrast agent which does not pass into the extra-cellular space was used to study the effect of changes in the relative cerebral blood volume (CBV) on the haemodynamic response to anoxia, for both normal and ischaemic brain tissue, in a rat model of acute focal ischaemia. In non-ischaemic tissue a strong CBV component was observed in the haemodynamic response, both during and after anoxia. During anoxia the change in the CBV of the non-ischaemic tissue was estimated to be 40% in the caudate putamen and 70% in the frontal-parietal cortex. For severely ischaemic tissue (ischaemic caudate putamen) there was no change in the CBV during anoxia while in areas of moderate ischaemia (ischaemic frontal parietal cortex) a change of 20% was observed. The effect of the contrast agent on spin-echo images was consistent with a small reduction in the microvascular blood volume of the ischaemic tissue.     

Transient lectin binding by white matter tract border zone microglia in the foetal rabbit brain

Axonal growth cones of developing white matter tracts are guided through the cerebrum by interactions with cell surface and extracellular matrix molecules expressed by glial cells that mediate cell adhesion and contact-dependent inhibition. Specific carbohydrates are considered essential for the proper functioning of these molecular complexes. We studied developmental aspects of complex carbohydrate expression by white matter glia in the foetal rabbit brain using the tomato lectin Lycopersicon esculentum, which has affinity for components of the extracellular matrix proteins and cell surface proteins (N-acetylglucosamine) and activated lysosomal membrane glycoproteins (N-acetyllactosamine). Concentrations of the lectin-positive glia were transiently found immediately adjacent to developing white matter tracts of the foetal rabbit brain from 22 to 32 days' gestation. The number of positive cells markedly diminished by the fourth post-natal day and in the adult brain. The lectin-positive glia did not react with antibody to glial fibrillary acidic protein. However, they did express the macrophage surface antigen, Mac-1, indicating that the lectin binding reflected the presence of microglial activated lysosomal membranes. These data suggest that, in addition to their role as central nervous system scavengers, microglia are involved in a specifically timed function in the neurodevelopmental programme of white matter tract formation.     

A light and electron microscopic study of HLA-DR positive cells in the human cerebral cortex and subcortical white matter

Specimens of histologically normal human cerebral cortex and subcortical white matter were obtained during neurosurgical operations and studied by electron microscopy and immunocytochemistry using an antibody against HLA-DR. Greater numbers of labelled cells were present in the white matter than in the overlying cortex. The labelled cells consisted of ramified microglia and perivascular cells. Microglia were often found just outside the walls of small blood vessels, but perivascular cells were actually enclosed by two leaflets of basement membrane in the walls of capillaries, arterioles and venules up to 100 microns in luminal diameter. Labelled microglial processes were often seen enclosing neuronal processes in the cortex and myelinated and unmyelinated axons in the white matter. The enclosed processes appeared healthy, and without features of degenerating neurons. These observations are consistent with a previous suggestion that microglia continually modify the processes of central nervous system neurons by a process of phagocytosis. An intact blood-brain barrier is likely to be of great importance in preventing antigen presentation of the processed neuronal, and perhaps even oligodendrocytic, antigenic peptide fragments to circulating lymphocytes.