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PubMed1989

The diagnostic significance of reciprocal ST segment depression in acute myocardial infarction.

The relationship between reciprocal ST-segment depression, the result of an early submaximal exercise ECG, and the anatomy of coronary artery disease was explored in 142 patients with acute myocardial infarction. Reciprocal ST-segment depression was observed in 65 per cent of 79 patients with inferior infarction and 57 per cent of 63 with anterior infarction. Thirty-three of the 52 patients with reciprocal ST-segment depression had a significant stenosis of the coronary artery supplying the reciprocal ST-segment territory (63 per cent), and 31 of the 46 patients with a positive exercise test had a significant stenosis of the coronary artery supplying the ischaemic territory (67 per cent). Forty-one of the patients with reciprocal ST-segment depression (79 per cent) and 35 of the patients with positive exercise tests (76 per cent) were found to have multivessel coronary artery disease. The study showed that reciprocal ST-segment depression was associated with stenosis of the coronary artery supplying the territory opposite the infarct in nearly two-thirds of the patients and with multivessel coronary artery disease in almost four-fifths of them. Reciprocal ST-segment depression after infarction was as accurate as a positive submaximal exercise test at predicting the presence of multivessel coronary artery disease.

Coronary Disease↗
PubMedDate not supplied

Segmental pulmonary anatomy in man: a method of study with angiography and single photon emission computed tomography.

To study the appearance of the segmental pulmonary anatomy on single photon emission computed tomography (SPECT), 300 microCi of 99mTc-MAA was injected into one segmental pulmonary artery in patients who had elective cardiac catheterization for coronary artery disease and who had no pulmonary disease. Eighteen patients were enrolled in order to show the appearance of all pulmonary segments (10 in the right lung and 8 in the left lung). Planar and SPECT imaging were performed before and after peripheral intravenous injection of 3 mCi of 99mTc-MAA. Radioactivity in the segment was subtracted from that in the whole lung to show segmental perfusion defects on planar and SPECT whole lung images. Knowledge of the tomographic appearance of the pulmonary segments should make it easier to identify these segments on other imaging modalities that utilize sectional reconstruction, such as computed tomography and magnetic resonance imaging. This knowledge may also increase the specificity of pulmonary SPECT for the diagnosis of pulmonary emboli.

Angiography↗
PubMed1989

[Complications after resection of the apical and posterior lung segments in pulmonary tuberculosis].

The frequency of complications in the early postoperative period after resection of the upper and posterior lung segments was investigated in 153 patients with pulmonary tuberculosis. When the operation was performed on the right lung the complications were twice as frequent as in the patients operated on the left lung (65.1 per cent against 33.3 per cent). The difference was defined by the frequency of atelectases. In the operations on the right lung they amounted to 31.7 per cent and were segmental (atelectasis of the anterior segment) while in the operations on the left lung they amounted to 11 per cent and were mainly total. Segmental atelectases of the 3rd segment in the patients operated on the right lung developed due to the peculiar segmental structure of the operated lobe and specific spatial transfer of the remaining anterior segment after its suture. Pleural complications observed in 22.2 per cent of the operated patients were due to the non-hermetic primary suture in the lung.

Adolescent↗
PubMed1986

DNA sequence of the murine gamma 1 switch segment reveals novel structural elements.

Immunoglobulin heavy chain switch regions are segments of DNA considered to be important in mediating class switching in B lymphocytes. Whereas these segments vary in length among the different murine isotypes, their structural organization schemes are all based on the tandem repetition of unit sequences. We previously showed that the S gamma 1 segment unexpectedly contains sequence elements that differ significantly from its prevalent unit repeat (49mer). Here we extend this preliminary characterization by determining the complete nucleotide sequence of the cloned S gamma 1 segment from BALB/c DNA. We find that S gamma 1 consists of more than 120 tandemly repeated 49mers. In addition, we show that the previously identified non-49mer sequences are part of a direct repeat element about 350 bp in length (DR II), which exists in two copies at the 5' end of S gamma 1. We also show that another unrelated direct repeat element about 500 bp long (DR I) exists near the 5' and 3' ends of S gamma 1. Thus, the structure of the S gamma 1 segment might be may be abbreviated as 5'-DRII-(49mer)15-DRI-DRII-(49mer)n-DRI , where n is between 40 and 160. Our results of Southern hybridization experiments suggest that this basic structural scheme is maintained in eight different Igh haplotypes, although S gamma 1 segments in different Igh haplotypes include different numbers of 49mer elements. Other murine S gamma segments differ in size among various Igh loci, but to a lesser extent than S gamma 1. At the level of tandemly repeated sequences, S gamma 1, S gamma 3, and S gamma 2b represent three distinct, nonoverlapping sets of sequences.

Animals↗
PubMed1988

[Stimulating effect of isolated nerve segments on the regeneration of peripheral nerves].

The present paper concerns observations in two series of experiments in which the effect of isolated nerve segments on nerve regeneration was studied. Bridging of a nerve defect with a tube was used as an experimental model--a model often used in studies on nerve regeneration today. In the first series of experiments performed on rats, 14 mm of the femoral nerve were removed and the gap bridged with the femoral vein. A 2-mm nerve segment was inserted at the center of the vein in one group of the animals. In the second experimental series performed on rabbits, 40-45 mm of the peroneal nerve was resected. Up to three segments were introduced into the lumen of the bridging vein. The experiments demonstrated the promoting effect of nerve segments on nerve regeneration and indicated the probable mode of their action: the nerve segments serve as an additional source of Schwann cells and of neurofibroblasts, contributing substantially to the formation of the guiding structures for the axons. The nerve segments are apparently able to develop a similar nerve structure to that formed by the distal nerve stump. However, this ability also appears to be limited to a distance of 10 mm as is the case with distal nerve stumps. These conclusions do not exclude a possible neurotropic action of the nerve segments.

Animals↗
PubMed1986

An iterative region-growing process for cell image segmentation based on local color similarity and global shape criteria.

An image segmentation process was derived from an image model that assumed that cell images represent objects having characteristic relationships, limited shape properties and definite local color features. These assumptions allowed the design of a region-growing process in which the color features were used to iteratively aggregate image points in alternation with a test of the convexity of the aggregate obtained. The combination of both local and global criteria allowed the self-adaptation of the algorithm to segmentation difficulties and led to a self-assessment of the adequacy of the final segmentation result. The quality of the segmentation was evaluated by visual control of the match between cell images and the corresponding segmentation masks proposed by the algorithm. A comparison between this region-growing process and the conventional gray-level thresholding is illustrated. A field test involving 700 bone marrow cells, randomly selected from May-Grünwald-Giemsa-stained smears, allowed the evaluation of the efficiency, effectiveness and confidence of the algorithm: 96% of the cells were evaluated as correctly segmented by the algorithm's self-assessment of adequacy, with a 98% confidence. The principles of the other major segmentation algorithms are also reviewed.

Biometry↗
PubMed1987

Segment-specific morphogenesis of leech Retzius neurons requires particular peripheral targets.

In most segments of the leech, a pair of Retzius (Rz) cells innervate the body wall musculature and skin; however, in the segments specialized for reproduction (midbody segments 5 and 6), these neurons innervate the reproductive tissue instead. Whereas all Rz cells have the same morphology early in embryogenesis, those in the reproductive segments [Rz(5,6)] become considerably different from their segmental homologs. Unlike standard Rz cells, Rz(5,6) do not have axons in the interganglionic connectives or in the body wall (Glover and Mason, 1986). Rz(5,6) also have significantly smaller somata and fewer branches in the ganglionic neuropil than do standard Rz cells (Jellies et al., 1987). Since these differences between Rz cells do not become apparent until after Rz(5,6) processes appear to contact the reproductive tissue primordia, interactions between Rz(5,6) processes and the reproductive tissue may determine the segmental specializations of these neurons. We have tested this possibility by ablating the reproductive tissue primordia early in embryogenesis and subsequently examining Rz(5,6) morphology. In the absence of reproductive tissue, Rz(5,6) became more like standard Rz cells: they retained axons in the interganglionic connectives, they projected into the body wall, and the density of their arborization within the neuropil increased. These results indicate that the development of some segmental specializations of Rz(5,6) involves an interaction with their unique target tissue.

Animals↗
PubMed1985

Selective reinnervation of intercostal muscles transplanted from different segmental levels to a common site.

We transplanted external intercostal muscles from one of several thoracic (T) levels to the neck of adult rats. The cervical sympathetic trunk, which innervates the superior cervical ganglion, was cut, and its proximal end was apposed to the muscle. Preganglionic axons in the trunk reinnervated muscle fibers in the transplants. We determined the segmental origin of synaptic inputs to transplanted muscles by recording intracellularly from muscle fibers while stimulating individual ventral roots which supply axons to the trunk. In one series of experiments, T2 or T8 muscles were transplanted from the thorax to the neck of the same rat. While T2 and T8 muscles were reinnervated to a similar extent, they differed in the segmental origin of the innervation they received: T2 muscles received more inputs from rostral segments (T1 and T2) than did T8 muscles, and T8 muscles received more inputs from caudal segments (T4 to T6) than did T2 muscles. This difference between reinnervation of T2 and T8 muscles was detected both 2 to 4 weeks and 10 to 14 weeks after surgery. In a separate series, using rats of an inbred strain, T3, T4, or T5 muscles were transplanted from one rat to a separate host. Again, the average segmental origin of inputs to transplants from different levels differed systematically: it was most rostral to T3 muscles, intermediate to T4 muscles, and most caudal to T5 muscles. Finally, T3 and T5 muscles were soaked in a myotoxin, Marcaine, before reimplantation. This treatment kills muscle fibers but not myoblastic satellite cells; therefore, muscle fibers were replaced by regeneration. Marcaine-treated T3 and T5 muscles were successfully reinnervated but did not differ significantly in the segmental origin of their inputs. Our results show that adult mammalian muscles can be selectively reinnervated, and they raise the possibility that the selectivity is based on some positional quality that matches axons and muscles from corresponding segments. However, while differences among muscles survive denervation and transplantation, their expression or accessibility may change during regeneration.

Animals↗
PubMed1985

Comparison of segmental and global ejection fraction in ischaemic heart disease.

In order to evaluate whether segmental ejection fraction (SEF) is a better index of left ventricular (LV) performance than global ejection fraction (EF), 25 patients with significant coronary stenosis and normal EF were studied. SEF was estimated from the LV cineangiogram after dividing the LV into eight segments by means of a long axis and three equally spaced chords perpendicular to it. The area of a given segment was measured in the end-diastole and the end-systole and SEF was calculated by determining the percent decrease in area for each segment. 12 out of the 25 patients presented hypokinesis, akinesis or dyskinesis of at least two segments; the inferior apical and both diaphragmatic segments were the regions most frequently affected. In 7 patients, these abnormalities were compensated by hyperkinesis of two or three other segments, whereas in the remaining 5 patients contraction abnormalities were not accompanied by hyperkinesis in spite of a normal EF. It is concluded that SEF is a more sensitive index of regional LV function than EF in patients with ischaemic heart disease.

Coronary Disease↗
PubMed1979

Development of the segmental innervation of the chick forelimb.

A number of recent studies have shown that during embryonic development the initial innervation of a target structure may be made up, in part, by axons which do not form part of the mature innervation of that structure. In the present study we have examined the motor innervation of the major muscles of the chick forelimb at different stages of development using HRP-uptake-labelling of motoneurons, electrophysiological recording and measurement of muscle contraction. In the mature White Leghorn chick the major contribution to the motor innervation of the forelimb is from spinal segments 14, 15 and 16. Using the HRP-labelling technique we have shown that at stages 26-29 of development motoneurons in segments 12-17 have axon terminals in the presumptive biceps muscle. Between stages 30 and 35, however, the axon terminals arising from segments 12, 13, 16 and 17 are lost, leaving the mature innervation from segments 14 and 15. We have also observed the loss of innervation of the biceps muscle by segment 16 using electrophysiological recording of compound action potentials in the biceps nerve and by measurement of the local contraction of the biceps muscle in response to stimulation of the segmental nerves. Similar changes in the innervation of the triceps, extensor metacarpi radialis, flexor carpi ulnaris and flexor digitorum profundus muscles have also been observed. These results are discussed in relation to the hypothesis that (i) the motoneuron pools and muscles in the developing spinal cord and forelimb are matched, (ii) that some axons which arrive in a particular muscle during early development are unable to form a stable connexion and (iii) that the inability of an axon terminal to form a stable connexion in a muscle results in the death of the motoneuron. Intracellular recording from muscle cells at stage 35 shows that the synaptic site on each cell is innervated by about three separate axons. Over the next few stages, however, all but one of the innervating axons is lost. From our contraction studies it is clear that the removal of the excess axon terminals after stage 35 is not associated with the establishment of the mature segmental innervation pattern of the muscle.

Action Potentials↗
PubMed1984

Scene-segmentation algorithm development using error measures.

Development of scene-segmentation algorithms has generally been an ad hoc process. This paper presents a systematic technique for developing these algorithms using error-measure minimization. If scene segmentation is regarded as a problem of pixel classification whereby each pixel of a scene is assigned to a particular object class, development of a scene-segmentation algorithm becomes primarily a process of feature selection. In this study, four methods of feature selection were used to develop segmentation techniques for cervical cytology images: (1) random selection, (2) manual selection (best features in the subjective judgment of the investigator), (3) eigenvector selection (ranking features according to the largest contribution to each eigenvector of the feature covariance matrix) and (4) selection using the scene-segmentation error measure A2. Four features were selected by each method from a universe of 35 features consisting of gray level, color, texture and special pixel neighborhood features in 40 cervical cytology images . Evaluation of the results was done with a composite of the scene-segmentation error measure A2, which depends on the percentage of scenes with measurable error, the agreement of pixel class proportions, the agreement of number of objects for each pixel class and the distance of each misclassified pixel to the nearest pixel of the misclassified class. Results indicate that random and eigenvector feature selection were the poorest methods, manual feature selection somewhat better and error-measure feature selection best. The error-measure feature selection method provides a useful, systematic method of developing and evaluating scene-segmentation algorithms.

Computers↗
PubMed1983

Homeotic transformations of the abdominal segments of Drosophila caused by breaking or deleting a central portion of the bithorax complex.

In Drosophila, genes in the centromere-proximal portion of the bithorax complex (BX-C) have been shown to control the development of the metathorax, and parts of the mesothorax and first abdominal segment. Here, we explore the roles of genes positioned more distally by examining the larval and adult phenotypes caused by a breakpoint and deletion in the middle of the complex. We find that both aberrations affect only abdominal segments, transforming the more anterior segments towards the first abdominal segment, and the remaining segments into a graded series of novel segment types which are partially transformed towards more anterior abdominal segments. Moreover, the adult transformations, which we have observed in somatic clones of mutant cells, are in close accord with the transformations observed in mutant first instar larvae, and appear to be expressed in a cell autonomous fashion. We discuss these results in the light of current views of the organization and function of the complex.

Abdomen↗
PubMed1983

Role of the esc+ gene product in ensuring the selective expression of segment-specific homeotic genes in Drosophila.

The product of the extra sex combs+ (esc+) gene is required during embryogenesis for the correct determination of segments in Drosophila. If this product is absent, most segments develop like the normal eighth abdominal segment. Here, I extend previous results (Struhl, 1981a) showing that this phenotype results in large part from indiscriminate expression of the bithorax-complex genes which are normally active only in particular segments of the thorax and abdomen. In addition, I test whether the esc+ gene product is required for the correct expression of other homeotic genes. First, I have examined two genes of the Antennapedia-complex (Sex combs reduced+ and Antennapedia+): I find that both genes are normally required in only some of the body segments, but that in the absence of the esc+ gene product, both appear to function adventitiously in other segments. Second, comparing esc+ and esc- embryos lacking both these genes as well as the bithorax-complex, I find that additional homeotic genes (possibly those normally involved in specifying head segments) appear to be expressed indiscriminately when the esc+ gene product is absent. Finally, I present evidence that the products of the esc+ gene and the Polycomb+ gene (a second gene required for the correct regulation of the bithorax-complex) act independently. On the basis of these results, I propose a tentative outline of the roles and realms of action of all of these genes.

Animals↗
PubMed1978

[Several important questions concerning the segmental structure of dog liver].

Anatomical structure of the dog liver has been studied in 82 isolated preparations. Besides the external surface of the organ, the study has been carried on in preparations of intraorganic branches of the portal vein, hepatic veins. Roentgenography of the portal vein and the hepatic artery has been performed. According to the external composition and intraorganic branching of the portal vein and the hepatic artery, two separate lobes--right and left--can be determined in the dog liver. The right lobe consists of two segments, the left one has five segments. Their classification is presented. From the left hepatic lobe, blood outflows along the hepatic veins which open into the posterior vena cava by their common orifice. The right portions of the fifth segment, segments 6, 7 are drained by veins having their own orifices. The hepatic artery has 3--4 branches: the left carrying blood to 1, 2, 3 segments, middle supplying with blood 4, 5 segments and gall bladder, one--two right branches going to 6, 7 segments.

Animals↗
PubMed1994

The spinal segmental and preganglionic projections from the brainstem in relation to the chicken cloaca.

Descending projections from the brainstem to the sympathetic and parasympathetic regions of the chicken spinal cord were investigated by means of the WGA-HRP method. The segmental and preganglionic injections of WGA-HRP were made into spinal segments 20-23 and 30-33 which were sympathetically and parasympathetically related to the cloaca, respectively. After injections of a large amount of WGA-HRP into each level of segments 20-23 and 30-33, the labeled SP-neurons (segmental projection neurons) were distributed mainly in the ventral half of the medulla in both cases. The distribution of these labeled neurons extended mainly to the central (20-23 segmental injections) and the lateral (30-33 segmental injections) tegmental regions of the pons. In the mesencephalon, some SP-neurons were found in the dorsomedial reticular formation and the dorsal midline area, in addition to the Ru in both cases. By iontophoretic microinjections of WGA-HRP into the preganglionic regions of these segments, the labeled preganglionic projection neurons (PP-neurons) were found in the ventromedial part of the medulla. Both distributions of the labeled PP-neurons projecting to the sympathetic and parasympathetic regions were similar in the medulla. In the pons, although the sympathetic PP-neurons were found in the ventromedial pontine tegmentum, most of the parasympathetic PP-neurons were found in the dorsolateral tegmentum, e.g., the LoC-SC region. In the mesencephalon, a few sympathetic PP-neurons were found in the midline area ventromedial to the EW, but no parasympathetic PP-neurons were observed in the mesencephalon.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Hypothalamic projections to the spinal segments and preganglionic regions by means of choleratoxin subunit B conjugated HRP in the chicken.

Hypothalamo-spinal projections were studied using the method of retrograde axonal transport of choleratoxin subunit B conjugated to horseradish peroxidase (CTb-HRP) in chickens. CTb-HRP was injected into the segmental and preganglionic regions of spinal segments 23-24 and segments 31-32 which are sympathetically and parasympathetically connected with the cloaca, respectively. Many labeled SP-neurons (segmental projection neurons) were found in the paraventricular nucleus (PVN), except in its lateral protrusion. The distribution of these labeled neurons continued to the more caudal areas such as the vicinity of the nucleus periventricularis hypothalami (PHN), areas medial to the stratum cellulare externum (SCE), the nucleus interstitialis (IS), and the posterior hypothalamic areas. Some labeled SP-neurons were also found in the lateral hypothalamic area. These labeled SP-neurons were distributed in almost the same areas in both cases of injection into segments 23-24 and 31-32. However, the number of labeled neurons was somewhat different rostrocaudally according to the spinal levels injected. In contrast, after microinjections into the spinal preganglionic regions, a small number of PP-neurons (preganglionic projection neurons) were found only in the ventral part of the PVN. These PP-neurons showed the rostrocaudally discernible segregation; PP-neurons in the rostral PVN and those in the caudal PVN were predominantly labeled by microinjections into segments 23-24 and segments 31-32, respectively. The present study suggests that the rostral PVN is more sympathetic and the caudal PVN is more parasympathetic in chickens.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1976

Electorcardiographic ST-segment analysis in the characterization of myocardial ischemia and infarction.

The ST segments of the electrocardiogram (ECG) become elevated within 20 to 30 seconds after the onset of acute coronary occlusion and, when persistent, such changes offer a possible indirect marker of the extent and severity of myocardial ischemic injury and of eventual cell death. When ST-segment elevation on the epicardial ECG is measured 15 minutes after an acute coronary occlusion in the dog, a general correlation exists with biochemical changes, regional myocardial blood flow, and myocardial electrolyte alterations measured at 15 minutes, although when an effort is made to correlate the degree of such alterations with the magnitude of the ST-segment change there is considerable scatter. On the other hand, when the ST-segment elevation at 15 minutes is correlated with myocardial blood flow, histologic changes, and creating phosphokinase (CPK) depletion 24 hours later, the correlation is good. Possible mechanisms underlying ST-segment elevation are discussed, and data are reviewed which indicate that the epicardial ECG my be relatively insentive to subendocardial injury; in the experimental setting this problem may be partially corrected by the use of intramyocardial ECG leads. The extension of direct epicardial ECG maps to precordial ST-segment mapping poses additional problems that include reduced sensitively, problems due to reciprocal changes in the ECG at the body surface, surface contact of the electrodes, pericarditis, and individual variability in the rate of spontaneous regression of ST-segment changes. Such mapping appears reliable only for infarctions of the anterior and lacteral wall. Further research is necessary on analysis of the QRS complex, and use of vector leads. Despite these problems experimental and clinical studies indicate that precordial electrocardiographic analysis may be useful for detecting acute changes in the severity of ischemic injury over relatively short periods of time (2 to 4 hours). This indirect measure clearly will require correlation with specific markers of ischemic damage, but with further improvements it seems likely that analysis of serial ECG changes will evolve into a valuable and reliable nonivasive clinical tool for characterizing myocardial ischemia and infarction.

Adenosine Triphosphate↗
PubMed1993

Mapping of the high molecular weight kininogen binding site of prekallikrein. Evidence for a discontinuous epitope formed by distinct segments of the prekallikrein heavy chain.

Prekallikrein, a glycoprotein involved in contact phase activation, circulates in plasma in the form of a binary complex with high molecular weight kininogen (H-kininogen). The binding to H-kininogen is mediated by the prekallikrein heavy chain consisting of four repetitive domains, A1-A4. To define more precisely the region(s) involved in kininogen binding, we have employed an affinity cross-linking strategy with a synthetic peptide of 31 residues which mimics the prekallikrein binding site of H-kininogen. Cross-linking of the radiolabeled peptide to (pre)kallikrein revealed a binding segment in the NH2-terminal portion of the prekallikrein heavy chain; another binding segment was located in the COOH-terminal part of the heavy chain. The latter binding segment is harbored by a previously identified fragment of the kallikrein heavy chain involved in H-kininogen binding (Page, J.D., and Colman, R.W. (1991) J. Biol. Chem. 266, 8143-8148). Chemical cleavage of the heavy chain cross-linked with the radiolabeled peptide mapped the NH2-terminal binding segment to 60 residues (positions 53-112) of A1. Synthesis of a peptide (positions 56-86) and development of specific antibodies to this peptide narrowed down the kininogen binding segment to 31 residues of the center portion of A1. This NH2-terminal segment is equivalent to a kininogen binding site previously identified in factor XI (Baglia, F.A., Jameson, B.A., and Walsh, P.N. (1992) J. Biol. Chem. 267, 4247-4252). We conclude that prekallikrein exposes at least two segments on its heavy chain portion which form a continuous surface thereby facilitating the intimate binding of the zymogen to its nonenzymatic cofactor, H-kininogen.

Amino Acid Sequence↗