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At least 19 recordsLinked to original sources

Computerized methods of pace-mapping for topical diagnosis of ventricular arrhythmias.

Surgical treatment of ventricular arrhythmias (VAs) is an effective method of solving sudden cardiac death. The important problem of surgical treatment of VAs is the topical diagnosis of the origin of arrhythmia. The precise localization of this area is extremely important for effectiveness of operation. The method of epicardial mapping of the heart during the induced paroxysm of VA is widely used for solving this problem. This problem is difficult when it is impossible to induce tachycardia during the operation. The method of pace-mapping was developed for such cases. This method includes sequential electrical stimulation of ventricles with ECG recording and comparison between intraoperative and preoperative ECG. The goal is the identification of the area of ventricles closed to preoperative ECG with VA. Manual processing of these data is difficult and takes time. The results of such processing have a low precision. That is why we propose using computerized methods. The goal of this investigation is to develop computerized methods of topical ECG diagnosis of VA. We propose a method of computer comparative analysis of ECG morphology for spontaneous and stimulated ECG. The goal is the determination with stimulated ECG the point of ventricles with ECG closest to spontaneous ECG during ventricular tachycardia. Nine patients (15-57 years old) with VA were studied. The main result of this investigation is that computerized pace-mapping method is an effective tool for topical diagnostics of different forms of VAs, which is impossible to induce by electrical programmed stimulation.

Adolescent

Endothelin-sensitive areas in the ventral surface of the rat medulla.

In urethane-anesthetized rats, subregions of the ventral surface of the medulla (VSM) in which endothelin (ET) caused cardiorespiratory effects were mapped by topically applying 1 pmol of ET-1. Two distinct subregions, termed the rostral and caudal ET-sensitive areas, were identified. The rostral area was also sensitive to L-glutamate and glycine. It extended between the caudal end of the trapezoid body and the rootlet of the XIIth nerve partly overlying the pyramidal tract. In this position ET-1 caused the type I response consisting of an initial increase (excitatory component) in arterial pressure (AP), renal sympathetic nerve activity (RSNA), heart rate (HR), phrenic nerve activity (PNA) and the number of bursts of PNA (burst rate) followed by a sustained decrease (inhibitory component) in them. The caudal ET-sensitive area was located near the rootlet of the XIIth nerve. In this position ET-1 caused the type II response consisting of a decrease in PNA and an increase in burst rate. Part of this area responded to nicotine but not to glutamate or glycine. ET-3 (10 pmol) applied to the two ET-sensitive areas produced responses similar to those elicited by ET-1. The dose-response relationship was investigated by delivering ETs to the rostral area. The excitatory component of most of the variables was elicited at a dose of 1 fmol of ET-1 or 1 pmol of ET-3, whereas the inhibitory component was produced at 10 fmol of ET-1 or 10 pmol of ET-3. These results suggest that subregions of the rat's VSM may participate in the central cardiorespiratory control by ET.

Administration, Topical

Immunization against anaplasmosis and babesiosis. Part III. Evaluation of immunization under field conditions in the Cauca River Valley.

Bovine anaplasmosis and babesiosis constitute serious constraints to efficient cattle production in Colombia. Nine commercial ranches located in the Cauca River Valley were used to evaluate the applicability, safety and economics of the newly developed immunization technology to control these diseases under actual field conditions using the minimum infective doses techniques. A total of 432 calves, 6--8 months old, of different breeds were used in this experiment. Calves born and raised in nonendemic areas of Valle, vaccinated against anaplasmosis and babesiosis and then moved to the endemic zone had developed a high degree of resistance. None of them died or required treatment after field challenge. In comparison, non-vaccinated controls suffered severe clinical anaplasmosis and babesiosis. Eighteen percent dies and 85% required chemotherapy to survive. Calves born and raised in the endemic zones of Valle and vaccinated did not suffer clinical disease nor require treatment after field challenge. However, non-vaccinated controls had 2% mortality and 60% of them required treatment to survive under the same field conditions. The weight gains favored vaccinated animals. The results of this study indicate significant reductions in deaths and production losses of cattle and the economic benefits to the livestock producers in controlling tick-borne diseases by vaccination.

Anaplasmosis

Human gene mapping and cancer biology.

The topics covered in this paper include: (i) a somatic cell genetics approach for measuring the individual variability in the susceptibility to DNA damage/repair at the level of specific chromosomal sites; (ii) a rationale for a selective chemotherapy and/or immunotherapy of chromosomally unbalanced tumours; and (iii) studies on complementation for sister chromatid exchange (SCE) in roden-human hybrids. Preliminary studies indicate that the 'radiation co-transfer method' for gene mapping can be simplified and used in screening for differences in individual susceptibility to radiation induced chromosomal damage. The second topic is dealt with only speculatively, with the explicit aim of emphasizing a practical application in clinical medicine which may potentially derive from the admittedly esoteric activity of gene mappers. The third topic summarizes a somatic cell genetic approach to the study of SCE in mammalian cells. The high rate of SCE observed in an established rodent cell line can be fully suppressed after hybridization with SCE-normal human cells. However, this suppression can be fully removed after extensive loss of the human chromosome complement. Correspondingly, the high SCE rate of Bloom syndrome cells is fully corrected after hybridization with a Chinese hamster line, though the chromosomes of the latter parental cells continue to exhibit in the hybrid cells the moderately high rate of SCE which is typical of this animal line. These complementation experiments indicate that more than one lesion can upset the normal chromatid replication of mammalian cells and lead to high SCE. The experimental studies described promise to be of significant help for studies on the biology of SCE in general and offer a suitable way of screening for possible genetical heterogeneity among different Bloom syndrome patients.

Chromatids

A cytoarchitectonic atlas of the mouse hypothalamus.

A description of the organization, areas, and cell groups within the hypothalamus of the mouse is presented in detail. Photomicrographs of cell-stained serial sections through the hypothalamus in frontal, sagittal and horizontal planes are included. The hypothalamus has been divided basically into medial and lateral parts with most well-defined cell groups or nuclei lying within the medial subdivision and surrounded by diffuse collections of cells referred to as areas. The heterogenetiy of cell types within most hypothalamic nuclei and areas has been emphasized with the consequent implications for heterogeneity of neuronal connections and of functions. Recently introduced neuroanatomical techniques permitting increased attention to the cellular level of organization have demonstrated precise connections and functional localization of cells within the hypothalamus. While cytoarchitectonic distinctions imply functional distinctions, morphological and experimental evidence suggest the existence also of systems of cells which transcend conventional cytoarchitectonic boundaries, the cells within each system being interconnected functionally or neuronally.

Animals

The Pariacaca or Tullujuto story: political realism?

The first documented description of acute altitude sickness was published by Father Acosta in 1590. Acosta described this sickness when he traveled through a pass across the Andean divide in central Peru near the mountain Pariacaca. Almost all the maps of modern Peru do not name this mountain. We present evidence that mountaineers who have climbed this mountain know it as Tullujuto. This change in name is the reason why physiologists have found it difficult to locate Acosta's route; consequently the altitude where Acosta experienced this sickness could not be determined until recently. Further, we speculate that political pressures in the late 18th century caused the place name of Pariacaca either to be obliterated or else to be changed to Tullujuto.

Altitude Sickness