Neuropsychological aspects of vascular dementia

Vascular dementia (VaD) is the second most common cause of dementia in the elderly. Neuropsychologically, VaD has been characterized traditionally as having a "patchy" pattern of cognitive deficits. Newly developed diagnostic criteria for VaD suggest that this "patchy" pattern is associated with one type of VaD-multiple cortical infarctions, and that several additional subtypes of VaD exist, each featuring a characteristic pattern of neuropsychological deficits. Strategic infarct dementias have unique features that reflect the specific brain region affected. Lacunar state and Binswanger's disease produce subcortical dementia with disproportionate executive dysfunction. The profile of neuropsychological disturbances observed in VaD patients provides important insight into the localization and pathophysiology of the underlying cerebrovascular disease.     

Myocardial, neural and vascular aspects of ischemic preconditioning

Ischemic preconditioning can be obtained with brief coronary occlusions. It has been studied in different animal species including dogs, pigs, rabbits and rats. The suggested duration of the occlusions ranges from four periods of 5 min, separated from each other by 5 min of reperfusion, to one period of 2.5 min. In addition to the reduction of the size of a subsequent infarction, preconditioning is responsible for the attenuation of the ischemia-reperfusion injury. The protection has a short duration and does not exceed two hours. Myocardial, neural and endothelial factors are involved in preconditioning. The myocardial component includes an increased release of adenosine with activation of A1 adenosine receptors, the activation of a protein-kinase C and possibly of antioxidant enzymes. The neural component includes a reduction in the release of noradrenaline from the postganglionic sympathetic fibers and a reduced myocardial sensitivity to noradrenaline. The increased myocardial release of adenosine, together with the reduced adrenergic activity, is consistent with the reduction in myocardial metabolism which has been observed after preconditioning. The coronary vascular endothelium is concerned in an increased release of nitric oxide which seems to be responsible for a prevention of reperfusion arrhythmias. In addition to the protective effect exerted on the myocardium, ischemic preconditioning seems to be responsible for a change in the coronary responsiveness to short periods of occlusion followed by release. This change in responsiveness is mainly represented by a greater velocity of the increase in flow occurring in the coronary reactive hyperemia.     

Intervention and clinical aspects combined with endovascular irradiation of intimal hyperplasia of the vascular system

After implantation of stents in femoropopliteal arteries we found restenosis or occlusions by intimal hyperplasia in up to 40% especially in the hunter's channel. Repeated balloon angioplasty and prophylactic endovascular radiotherapy with a surface dose of 12 Gy in the vessel wall using an iridium 192 source in the same investigational session is a new technique to reduce or eliminate further recurrence. All 18 patients had developed recurrent stenoses or occlusions 6-8 months after original stent implantations. The patients have not redeveloped recurrent obstructions after this treatment, which up to date showed no short term or long term complications. We conclude that the encouraging results of this pilot study justify further randomized trials.     

The biochemical and clinical aspects of the participation of granulocytes and their proteinases in a vascular wall lesion

Some components of plasma and granulocyte proteolytic system, granulocyte activation degree were evaluated in 15 patients with nonspecific aortic arteritis (NAA) and 12 hereditary hypercholesterolemia (HHC) patients. Catepsin G activity in blood plasma of NAA and HHC patients was higher than in donors 8-9 and 6-fold, respectively (p < 0.001). Granulocyte collagenase activity, spontaneous NBT test values in them were higher than in donors 6 and 4-fold (p < 0.02 and p < 0.01, respectively), 2-fold (p < 0.005 and p < 0.001, respectively). The data obtained confirm the suggestion on the presence of an inflammatory component not only in pathogenesis of NAA, but also in HHC causation.     

Histopathological aspects of dural arteriovenous fistulas in the transverse-sigmoid sinus region in nine patients

OBJECTIVE: In recent years, dural arteriovenous fistulas (DAVFs) have been primarily thought to be acquired lesions, formed after sinus thrombosis. The pathogenesis of DAVF, however, is still controversial. We have studied histopathological aspects of DAVFs in resected specimens obtained from nine patients, to obtain clues to the pathogenesis of DAVFs. METHODS: Histological comparison was made among nine DAVF cases and five control cases without venous sinus disease. In addition, the relationship between the clinical course and histological aspects was investigated. RESULTS: The essential abnormality found was a connection between the dural arteries and the dural veins within the venous sinus wall, through small vessels averaging approximately 30 microns in diameter. By using several staining methods, we confirmed that the vessels were part of the venous system; we named these dilated venules "crack-like vessels." CONCLUSIONS: The development of abnormal communications between dural arteries and dural veins (crack-like vessels) is regarded as the essential part of the pathogenesis of DAVFs, and sinus thrombus is not thought to be an essential lesion of DAVFs. It might be postulated that sinus hypertension caused by stenocclusive disease of the venous sinuses triggers the development of fistulous connections between arteries and veins in the dural wall, which may result in increasingly dilated venules and the formation of DAVFs.     

Sequence analysis of the coding region of human methionine synthase: relevance to hyperhomocysteinaemia in neural-tube defects and vascular disease

Elevated homocysteine (Hcy) levels are observed in two apparently unrelated diseases: neural-tube defects (NTD) and premature vascular disease. Defective human methionine synthase (MS) could result in elevated Hcy levels. We sequenced the coding region of MS in 8 hyperhomocysteinaemic patients (4 NTD patients and 4 patients with pregnancies complicated by spiral arterial disease, SAD). We identified only one mutation resulting in an amino acid substitution: an A-->G transition at bp 2756, converting an aspartic acid (D919) into a glycine (G). We screened genomic DNA for the presence of this mutation in 56 NTD patients, 69 mothers of children with NTD, 108 SAD patients and 364 controls. There was no increased prevalence of the GG and AG genotypes in NTD patients, their mothers or SAD patients. The D919G mutation does not seem to be a risk factor for NTD or vascular disease. We then examined the mean Hcy levels for each MS genotype. There was no correlation between GG- or AG-genotype and Hcy levels. The D919G mutation is thus a fairly prevalent, and probably benign polymorphism. This study, though limited, provides no evidence for a major involvement of MS in the aetiology of homocysteine-related diseases such as NTD or vascular disease.     

Pathogenetic aspects of the L-arginine-NO metabolic pathway in arteriosclerosis and possible therapeutic aspects

A yearly pattern in the occurrence of uterine cervical cancer (UCC), obtained from cytological examinations reported as type V (cases concluding a malignant alteration), has been previously shown for data obtained in the Monterrey Metropolitan Area (state of Nuevo Leon, Mexico) for a span of 10 years (1978-1987), with a peak of relative incidence in the month of February being high stable for consecutive years. With the aim of extending and validating those results, we analyzed the monthly totals of positive detected cases of UCC in the states of Nuevo Leon, Chihuahua, Coahuila, and Tamaulipas (covering most of Northern Mexico) during the same period. To eliminate bias due to the seasonal variation in the number of screening smears, data were first expressed in relation to the number of cytological examinations done the same month. The least-squares fit of a 1-year cosine curve to the data of relative incidence in the four states reveals a statistically significant yearly pattern (p = .008), with a maximum of relative incidence in February almost double that during the rest of the year. Results indicate that the relative incidence of UCC is higher than the yearly average during the winter, with secondary peaks in May and October. In view of the nonsinusoidal waveform in the incidence of UCC, we undertook a multiple-component analysis, allowing several cosine functions to be simultaneously fitted to the data. Results indicate that the yearly pattern in the relative incidence of UCC can be represented by a model that includes two components with periods of 12 and 4 months (p = .004). The same model can be documented as statistically significant independently for each of the four states. These results, summarizing over 2200 positive cases of UCC detected in more than 1,100,000 screening smears, are in full agreement with those found previously for part of the state of Nuevo Leon and reveal a highly stable and predictable yearly pattern of variation in the relative incidence of UCC in Northern Mexico.     

Patient education by the surgeon. Judicial aspects, ethical aspects, deontologic aspects

AIM OF THE STUDY: The surgeon must inform his patient about eventual risks before any investigation with diagnosis purpose and before any therapeutic intervention. According to the decree of the first Civil chamber of the "Court of Cassation", the surgeon must be able to prove that this information has been given as required by the article 1315 of the civil code. This decree has created in France an important change in the relationship between surgeon and patient. The French Academy of Surgery has organized a special session to study this problem in terms of legal, ethical and deontological aspects. CONCLUSIONS OF THE ACADEMY: The Academy confirms the necessity to give information to the patients and suggests that the modalities of the information be prepared by the medical societies, the "Conseil National de l'Ordre des Médecins", eventually by ethical committees and legal organizations concerned with medical questions, in view of a common use in all French juridictions. According to the Academy, it is necessary to determine the limits of the information to be given to the patient concerning the most common risks and those with the most serious consequences, in order not to disturb him psychologically. The Academy wishes that necessary and sufficient means be indicated in order for the surgeon to be able to prove that the information has really been given.     

Re-evaluating the role of vascular changes in the differential diagnosis of Alzheimer's disease and vascular dementia

Alzheimer's disease (AD) and vascular dementia (VaD) are the two most common causes of dementia, and much effort has been devoted to their differential diagnosis. However, current epidemiological, clinical and neuropathological evidence points to a substantial overlap between AD and VaD and suggests that vascular pathology, the traditional cornerstone of the differential diagnosis between the two entities, may not represent as clear a line of demarcation as originally believed. It may be time to reevaluate the dichotomy between AD and VaD.     

General aspects of the thermomechanical

This article represents a survey on the thermomechanical treatment (TMT) of two-phase intermetallic TiAl compounds. Nearly all of the important parameters, such as temperature, cooling rate, forging ratio, and direction, of the TMT steps were examined. The aim of this investigation was to understand the effects of the different parameters and thus to provide the knowledge of how to achieve all desired types of microstructures depending on the application purpose. Along the way, it was necessary to overcome the brittleness of TiAl compounds in order to permit further working and deformation processes, such as near net shape forming and sheet rolling. We obtained the best ductility with homogeneous equiaxed microstructures with true plastic X tensile strains at room temperature of more than 6 pct for Ti-48Al-2Cr (atomic percent). In the case of equiaxed microstructures, the Hall-Petch relationship could be confirmed for both the yield and the fracture stress. Therefore, the microstructures causing highest strength and high ductility and the way to achieve these properties were elaborated and are discussed in detail here. J. SEEGER, formerly with the Technical University of J. SEEGER, formerly with the Technical University of     

The genetic polymorphism of the fourth component of human complement: methodological aspects and a presentation of linkage and association data relevant to its localization in the HLA region

The C4 polymorphism in man has been studied by immunofixation electrophoresis, crossed immunoelectrophoresis, and functional detection after agarose gel electrophoresis. It has so far not been possible to reveal this polymorphism by isoelectric focusing and functional detection of C4 bands. Three common alleles and one less frequently occuring allele have been identified. In a small population sample studied by all the different techniques and verified by family segregation, the following gene frequencies have been found: C4F: 0.46, C4S: 0.32, C4F1: 0.20, and C4M: 0.02. By linkage and association studies in a family material it has been shown that a structural C4 locus is situated in the HLA region of chromosome 6 very close to the HLA-B and Bf loci.