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PubMed1988

The healing of canine vascularized segmental tibial osteotomies. The effect of retained endosteal circulation.

Forty-eight pairs of canine tibial segmental osteotomies, 4 cm in length, were investigated to determine the progress of regeneration. The tibial segment was stripped of all soft tissue in one limb and the vascular pedicle was preserved in the contralateral limb. This allowed the healing of the tibial segments, vascular versus nonvascular, to be compared using sequential blood flow and roentgenographic and angiographic data. The blood flow to the vascular bone segment quadrupled at three weeks and then gradually decreased to 1.5 times baseline at one year. The nonvascular tibial segment showed a linear increase in flow for three months, achieving a level comparable to the contralateral vascular tibia segment. Peak flow in the vascular tibia at three weeks was four times that of the nonvascular tibia. Blood-vessel ingrowth from each osteotomy site progressed at a linear rate but was three times faster in the vascular bone. The deposition of callus and the rate of osteotomy healing were accelerated significantly in the vascular group. At three months 87% of the vascular tibial osteotomies healed versus 43% of the nonvascular osteotomies; these results represent significant advantages in the rate of healing in vascular versus nonvascular segmental tibial osteotomies. Segmental vascular bone grafts that are internally fixed with plate and screws can preserve the vascular structure and its advantages in bone regeneration.

Angiography↗
PubMed1986

[Reduction of myocardial segment shortening during angina-free period in patients with angina pectoris].

In 16 patients with angina pectoris who had no histories of myocardial infarction, myocardial segment shortening was studied during angina-free periods. Myocardial segment length in the anterior wall of the left ventricle was calculated by measuring the spatial length between two points identified as junctions of ramifying branches of the left coronary arteries using biplane coronary cineangiography. Segment shortening was classified according to the severity of coronary arterial stenosis. The patients were categorized according to the severity of coronary arterial stenosis: as 1) the 0% stenosis (normal); 2) the 50% stenosis group; and 3) the 75-90% stenosis group. Total segment shortening in the normal group was the same as that in the 50% stenosis group (10.4 +/- 2.5%). However, in the 75-90% stenosis group, segment shortening was reduced to 7.3 +/- 2.5%. Effective segment shortening during the ejection period was reduced (5.0 +/- 1.8%) in the 75-90% stenosis group, as compared with the normal group (8.4 +/- 2.4%) and the 50% stenosis group (7.2 +/- 3.6%). This study demonstrated that segment shortening was reduced at rest in patients with angina pectoris who had had no previous infarction. A possible mechanism of this reduced segment shortening during angina-free periods may be irreversible myocardial alteration from recurrent ischemic attacks.

Angina Pectoris↗
PubMed1987

[Relationships between segmental left ventricular wall motion abnormalities and pathological findings in patients with dilated cardiomyopathy].

Relationships between segmental left ventricular wall motion abnormalities and myocardial fibrosis at autopsy were examined in 12 patients who died of dilated cardiomyopathy. In each case, wall motion abnormalities were assessed by two-dimensional echocardiograms for 11 segments, and semiquantitatively evaluated as normokinesis (N) to hypokinesis (H), severe hypokinesis (SH) or akinesis (A). From the necropsy specimens, the myocardial fibrosis ratio was histologically quantitated using a point-counting method in each segment corresponding to the echocardiographic segment. Wall motion abnormalities and the fibrosis ratio correlated significantly in a total of 132 segments of the 12 patients, but there were some discordances. The cases were then categorized in uniform and non-uniform groups based on the patterns of myocardial fibrosis. Wall motion abnormalities correlated much better with the fibrosis ratio in a total of 44 segments among four cases with non-uniform fibrosis, whereas no significant correlation was found in a total of 88 segments in eight cases with uniform fibrosis. The latter group had more severe segmental wall motion abnormalities in the interventricular septum than in the left ventricular free wall; and in the apical portion rather than in the basal portion, although no significant difference was observed in the fibrosis ratio among these regions. Patients with non-uniform fibrosis had higher incidences of chest pain and sudden deaths and a significantly larger left ventricular end-diastolic dimension on M-mode echocardiogram as compared to those with uniform fibrosis. Pathologically, in the former group, the heart was heavier, the mean left ventricular fibrosis ratio was significantly higher, and there was a greater incidence of infiltration of the myocardium by mononuclear cells, but there was no difference in the mean left ventricular wall thickness. These results suggest that myocardial fibrosis mainly contributes to the wall motion abnormalities in cases with non-uniform fibrosis which may be caused by chronic myocarditis, but not in cases with uniform fibrosis. In the latter group, other factors such as reduced contractility of the myocardial cells or lack of a compensatory mechanism for wall stress seem to play important roles in causing left ventricular wall motion abnormalities.

Adult↗
PubMed1987

[Total and segmental left ventricular ejection fraction of acute myocardial infarct patients during serial determination using 2-dimensional echocardiography].

Ultrasonic scanning of the heart was carried out on days 1, 10, 20 and 30 of uncomplicated myocardial infarction (MI) in 46 patients whose total and segmental ejection fraction (EF) (5 segments by a two-chamber projection from the apex) were then calculated. Total left-ventricular EF was moderately reduced on day 1 (48.6 +/- 1.8%) and increased significantly by day 30 (55.4 +/- 2.3%, p less than 0.01). All patients showed impaired segmental contractility in infarcted areas. Segmental EF was essentially reduced in segments 3, 4 and 5 in anterior MI, and in segments 1 and 2 in posterior MI. Recovery was associated with increasing EF in asynergic segments, that nevertheless remained diminished on day 30, as compared to unaffected areas. The rise in left-ventricular total EF is attributed to better contractility of asynergic segments.

Acute Disease↗
PubMed1978

[Reciprocal homology of the preotic mesodermal segments of representatives of different classes of vertebrates].

The data of the literature and those of the author on the origin of preotic mesodermal segments are discussed. Only in Cyclostomata all preotic segments are formed from the wall of archenteron and are larval segments. In all the gnathos tomata, the primary gastral segments are substituted, to different degrees, by postlarval peristonal mesoderm. The preotic mesomeres of Cyclostomata are homologous to II--IV mesomeres of Branchiostoma lanceolata. The anterior cephalic cavity and the premandibular segment of the elasmobranchia are homologous to I and II segments of Branchiostoma lanceolata. The mandibular mesoderm of the elasmobranchia includes the gastral mesoderm (homologous to III and some subsequent segments of Brachiostoma lanceolata) and peristomal mesoderm. The mandibular mesoderm in higher vertebrates has the same composition, but their anterior larval segments disappear and are substituted by gastral part of the mandibular mesoderm.

Amphibians↗
PubMed1987

Holter monitor ST segment evaluation in hospitalized patients with unstable angina.

The correlation of angina attacks with ST segment changes detected during ambulatory Holter monitoring was evaluated in patients with unstable angina. Forty hospitalized patients had one to three 24-hour Holter recordings each. Twenty-three patients had a cardiac catheterization, confirming significant coronary artery disease. The Holter recordings, scanned blindly by computer, were evaluated for ST segment shifts (defined as +/- 1.5 mm from baseline, lasting 60 seconds or longer). Angina attacks were carefully logged. Over the total forty patient experience, only 15 of 74 (20.3%) angina attacks had corresponding ST segment shifts on the Holter recordings. Nine of 34 (26.5%) angina attacks in the 23 patients who had a cardiac catheterization had corresponding ST segment shifts. A total of 159 ST segment shifts were recorded on these forty patients, but only 15 (9.4%) ST shifts corresponded to a time when the patients were actually experiencing angina attacks. The performance of the test procedure was quantified by use of Youden's J statistic. The aggregate J, over all patients, was 0.203 (J = 1.0 is perfect, J = 0.0 is useless). When consideration was restricted to patients with cardiac catheterization, the aggregate experience J was 0.263. Dealing with only the patients who had angina attacks during the monitoring, and computing the J statistic for each individual patient, the resulting mean J statistic was 0.146, with SEM = 0.0731. The Holter monitoring worked reasonably well in only 2 of the 14 patients who gave clear tests of the procedure. In an attempt to improve the performance of the procedure, 21 Holter recordings in eight patients were reread for ST segment shifts of only +/- 1 mm from baseline, lasting 30 seconds or longer. In these eight patients with rescanned Holter recordings, only five of 17 (29.4%) angina attacks resulted in an ST segment shift. In conclusion, ambulatory Holter recordings proved not to be a suitable method of documenting ST segment shifts during angina attacks in this study.

Adult↗
PubMed1986

Venous segmentation of the human spleen. A corrosion cast study.

Partial splenectomy is possible because of vascular segmentation of this organ. Although interest has focused upon arterial supply, this study shows similar venous segmentation. Emerging splenic veins in excess of 1.7 mm at the hilum of ten unembalmed spleens were injected with different colors of modified Batson's compound, and corrosion casts were made. In four additional spleens, alternate veins and arteries were injected. Ten spleens had two primary segments (lobes); four had three lobes. Half of these lobes were further subdivided into two segments. Lobes and segments extended through the full thickness of the spleen. Relatively avascular interlobar planes were always approximately perpendicular to the longitudinal axis of the spleen, whereas intersegmental planes were more variable. Both interlobar and intersegmental planes frequently corresponded to marginal notches. When arteries and veins were both injected, similar segmentation was noted. Venous drainage did not overlap arterial segments, indicating that veins are intrasegmental. These results indicate that the surgical unit of the spleen can be based upon surgically accessible vessels at the hilum of the spleen. Identification of segmental vessels could permit salvage of a larger amount of splenic tissue than would be possible if only lobar vessels were identified.

Adult↗
PubMed1986

Pioneer growth cone morphologies reveal proximal increases in substrate affinity within leg segments of grasshopper embryos.

We have compared the morphologies of approximately 5000 antibody-labeled afferent pioneer growth cones fixed at various stages of growth along their characteristic path over the epithelium in the legs of grasshopper embryos, and have used growth cone morphology as an indicator of differences in the affinity of the epithelial substrate for pioneer growth cones in vivo. Growth cone morphologies differ markedly between different locations in limb buds, and also in the same location in limbs at different stages of differentiation. Growth cones characteristically extend branches and lamellae circumferentially along segment boundaries, and filopodia and lamellae are retained (or extended) longer there. Where they contact a relatively well-differentiated segment boundary, the growth cones also abruptly reorient circumferentially. In the proximal regions of limb segments, growth cones consistently have a high degree of branching and lamellae; previously formed axons also extend secondary branches and spread there as development progresses. Low incidence of these morphologies is observed at all stages in the distal regions of limb segments. Thus, neuronal morphologies correlate both spatially and temporally with the differentiation of limb segmentation. These results suggest the following: Detailed growth cone morphology is a reliable indicator of differences in extrinsic guidance cues. The affinity of the epithelial substrate for afferent pioneer growth cones increases proximally within segments, with a peak at the segment boundary. (This affinity could be based on surface density of adhesion molecules or on nonadhesive molecules that actively regulate growth cone extension.) Increasing epithelial affinity within segments appears to act as a proximal guidance cue for afferent pioneer growth cones. Pioneer growth cones are observed to navigate proximally in circumstances where proximally located guidepost cells differentiate too late to guide them.

Animals↗
PubMedDate not supplied

Error measures for objective assessment of scene segmentation algorithms.

Scene segmentation is an important element in pattern recognition problems. Previous efforts to evaluate and compare scene segmentation procedures have been largely subjective. Quantitative error measures would facilitate objective comparison of scene segmentation algorithms. A theoretical discussion leading to a new generalized quantitative error measure, G2, based on comparison of both pixel class proportions and spatial distributions of "true" and test segmentations, is presented. This error measure was tested on 14 manual segmentations and 40 gynecologic cytology specimens segmented with five different scene segmentation techniques. Results indicate that G2 seems to have the desirable properties of correlation with human observation, categorization of error allowing for weighting, invariance with picture size and ease of computation necessary for a useful scene segmentation error measure.

Autoanalysis↗
PubMed1979

Segmental innervation of the chick forelimb following embryonic manipulation.

A number of studies have shown that the segmental innervation of some muscles in the developing limb undergoes some modification during the earliest stages of ontogeny. These observations can be interpreted in support of the hypothesis that the motor axons and muscles are matched during this period of development. As a further test of this suggestion we have made a quantitative examination of the motor innervation of the chick forelimb under conditions of controlled abnormal development. Embryos were surgically manipulated at stages before the motor axons invade the limb. The operations were controlled such that forelimbs were induced with segments deleted or reduplicated or simply that a segment of the spinal cord had been deleted. In preparations with abnormal limbs the motor innervation of the muscles present was the same as for those muscles in the normal limb. Where a spinal segment had been deleted the limbs developed normally and their innervation was completed by the remaining brachial segments. These results suggest that any particular matching property of a developing muscle does not develop as a consequence of its position in the limb relative to those segments of the limb proximal to it. Furthermore, that some muscles which are normally innervated by two spinal segments can be completely innervated by one of those spinal segments, in the absence of the other, suggests that any matching between growing axons and developing muscle cells is hierarchical rather than strictly all-or-nothing.

Animals↗
PubMed1981

Embryonic development of identified neurons: segment-specific differences in the H cell homologues.

Although all of the segmental ganglia of the grasshopper come from identical sets of embryonic precursor cells, there are striking differences in the number and properties of the neurons in the mature ganglia. In every segment, midline precursor 3 (MP3) divides once and gives rise to two progeny. We describe the fate of the two MP3 progeny in different segments. The morphology, physiology, and survival of the MP3 progeny depend upon their segmental position in the embryo. In the meso- and metathoracic segments (T2 and T3), one of the two progeny of MP3 transforms into the H cell. In many of the abdominal segments, beginning with the fourth (A4), both MP3 progeny die. A gradient of transformation and cell death is seen in the intervening first three abdominal segments (A1 to A3). From A1 to A3, the MP3 progeny acquire fewer of the morphological phenotypes of the H cell. This is paralleled by the partial acquisition of the physiological phenotypes of the H cell. Thus, cells that are the progeny of the same precursor cell in different segments can either live or die and, if they survive, can develop different morphological and physiological properties.

Animals↗
PubMed1993

Preserved endothelial function in the spastic segment of the human epicardial coronary artery in patients with variant angina--role of substance P in evaluating endothelial function.

This study aimed to determine whether or not endothelium-dependent vasodilation is preserved in spastic segments of human epicardial coronary arteries. Segmental responses of coronary arteries to substance P were examined in 30 patients with variant angina and in 10 patients with atypical chest pain using a quantitative angiographic technique. Coronary diameter at the basal state was matched between spastic and non-spastic segments in patients with variant angina, normal coronary arteries and with atypical chest pain (2.3 +/- 0.2 mm, 2.3 +/- 0.4 mm, 2.4 +/- 0.3 mm, respectively). In segments where vasospasm was induced by ergonovine and/or acetylcholine, changes in diameter in response to substance P did not differ from those in non-spastic segments; maximal dilation averaged 27.1 +/- 9.5% in the spastic segments and 24.4 +/- 9.6% in the non-spastic segments (expressed as a percent increase over the value before drug administration). It would appear that the potential of the endothelium to release endothelium-dependent relaxant factor (EDRF) and the vasodilator response to EDRF are preserved, even in spastic segments.

Acetylcholine↗
PubMed1979

Photoreceptor outer segment development: light and dark regulate the rate of membrane addition and loss.

The rate of membrane addition during outer segment development and the onset of membrane loss through shedding was evaluated for Xenopus laevis embryos reared at 23 degrees C in constant light (LL), constant darkness (DD), and cyclic light (12 hr L/12 hr D; LD). Embryos were placed under these lighting conditions 1 day following fertilization at open neural plate stages and were sampled each day for 9 days. Rod and cone outer segments were present in each treatment group on day 3 of development. At the end of 10 days of development, rod outer segment volumes were 708 +/- 195, 380 +/- 40, and 297 +/- 33 micrometer3 (mean +/- S.D.) for LL, LD, and DD treatment groups, respectively, whereas mean cone outer segment volumes were 57 +/- 8, 48 +/- 8, and 35 +/- 9 micrometer3 for these same treatment groups. The loss of outer segment material through shedding was assessed by monitoring the phagosome content of the pigment epithelium. Phagosomes were present in the pigment epithelium in DD embryos as early as 6 days of development, were present at day 5 only after the onset of the light cycle in LD embryos, and were rarely observed in LL embryos. The rate of outer segment membrane elaboration in rods (determined with 3H-leucine autoradiography) was virtually identical in LL and LD (100 and 98 micrometer3/day) but was greatly reduced in DD (70 micrometer3/day). These findings indicate that the relatively rapid rate of rod outer segment volume accumulation in LL embryos is due to a reduction in membrane loss through shedding and not to a higher rate of membrane addition as compared to animals reared in LD. In contrast, the reduced rate of rod outer segment development in DD embryos is the result of both a slower rate of membrane elaboration accompanied by the early onset and enhanced rate of membrane loss through shedding in darkness.

Animals↗
PubMed1976

Total synthesis of the structural gene for the precursor of a tyrosine suppressor transfer RNA from Escherichia coli. 8. Enzymatic joining of the chemically synthesized segments to form DNA duplexes corresponding to nucleotide sequences 23-60 and 23-66.

Polynucleotide ligase-catalyzed joining of the eight chemically synthesized deoxyribopolynucleotide segments (Fig. 1) comprising the nucleotide sequence 23-66 of the DNA corresponding to the Escherichia coli tyrosine tRNA precursor has been systematically investigated. Joining was studied using all possible combinations of 3, 4, and 5 and larger numbers of segments at a time. The extent of joining varied widely (0 to about 90%) in three component systems. The "self-structure" of some of the components evidently inhibited the joining. Addition of a fourth segment in general enhanced the extent of joining and optimal yields were obtained in systems containing six or more segments. A comparison of the T4-induced ligase and the E. coli polynucleotide ligase for joining of the chemically synthesized segments showed the E. coli enzyme to be inferior to the T4-induced ligase. Satisfactory syntheses of the duplexes [IIa] and [IIb] comprising, respectively, eight and seven segments were achieved in single steps. Of the two terminal segments carrying 5'-OH groups in the duplexes, only one (segment 7) was used in the prephosphorylated form. The duplexes were isolated pure and characterized by enzymatic degradations and by electrophoresis.

Base Sequence↗
PubMed1995

Segmental pedicle screw fixation in the treatment of thoracic idiopathic scoliosis.

STUDY DESIGN: This retrospective clinical study compared the results of correction of idiopathic thoracic scoliosis using Cotrel-Dubousset segmental pedicle screw fixation with those of hooks and screws inserted in a hook pattern. OBJECTIVES: The study's objective was to evaluate the efficacy and safety of segmental pedicle screw fixation in the management of idiopathic thoracic scoliosis. SUMMARY OF BACKGROUND DATA: Seventy-eight idiopathic thoracic scoliosis patients were treated with Cotrel-Dubousset instrumentation from 1987 to 1991. Thirty-one were treated with hooks; 23 were treated with pedicle screws inserted in a hook pattern; and 24 were treated with segmental pedicle screws. METHODS: After a minimum follow-up of 2 years (range, 25-52 months), the results of frontal, sagittal, and rotational correction of each group were compared and statistically analyzed using analysis of variance. RESULTS: Major curve correction was 55% with hooks, 66% with hook pattern screws, and 72% with segmental screws, with loss of correction of 6%, 2%, and 1%, respectively. Compensatory curve correction was 57% with hooks, 67% with hook pattern screws, and 70% with segmental pedicle screws. In patients with hypokyphosis, all showed significant improvement with best restoration in segmental screws. Rotational correction of the apical vertebra measured by the Perdriolle method was 19% with hooks, 26% with hook pattern screws, and 59% with segmental screws. Thirteen screws (3%) were malpositioned, but they did not cause neurologic impairment or adversely affect the results of treatment. CONCLUSIONS: Segmental pedicle screw fixation is a safe and effective method for correcting the triplanar deformity of the idiopathic thoracic scoliosis.

Adult↗
PubMed1995

Measurements of dendritic path lengths provide evidence that ethanol-induced lengthening of terminal dendritic segments may result from dendritic regression.

The present study proposed to determine the significance of previously reported ethanol-induced dendritic lengthening in mature cerebellar Purkinje neurons (PN). An analysis of dendritic path lengths (PL) was used to make this determination. A PL is the curvilinear length from the origin of the dendritic root segment to the free tip of a dendritic terminal. It was hypothesized that treatment-induced dendritic lengthening resulted from dendritic growth, and that growth should produce an upward shift in the value of the median PL. The PL and the segment length (SL) for each dendritic terminal were measured in PN of 24 month old male F344 rats, previously fed a liquid diet containing 35% ethanol-derived calories for 48 weeks, to test that hypothesis. Because there are large numbers of terminal dendrites in PN networks a shift in the value of their median PL is a sensitive measure of change in these networks. It was found that almost 30% of the ethanol-exposed cell sample had median PL that were shorter than expected and that the median SL in these same neurons tended to be longer than expected. At the end of the ethanol treatment, half of these rats were weaned from the ethanol diet for a subsequent 8 weeks to test for reversibility of these changes. Following the period of abstinence from dietary ethanol, the significant ethanol-related differences previously found in dendritic lengths were no longer present. A consideration of two models of dendritic regression suggested that elongation of surviving terminal dendritic segments in the ethanol-exposed neurons occurred through deletion of other terminal segments at their vertices (branch points). It was shown that deletions of entire terminal dendritic segments at their vertices would produce increases in the lengths of associated terminal segments in the absence of real growth. Deletions of dendritic segments would also entail loss of PL unique to the deleted segments, thereby causing a shift in the value of the median PL of affected networks.

Animals↗
PubMed1993

[Analysis of usefulness for quantitative methods determining segmental mobility in assessing contrast ventriculography of the left ventricle].

The aim of this study was to compare two different quantitative methods used to determine left ventricular regional wall motions. Circumferential and radial methods were used to distinguish between normo- and hypokinesia of the 5 segments proposed by AHA for RAO position. One hundred ventriculograms were analyzed. Fifty cases with normal wall motion and ejection fraction greater than 55% were chosen as a base to enumerate normokinetic values of regional contractility. The other fifty cases represented hypokinesia of different segments. Respective values for the radial method were 61.42 vs 38.10 for antero-basal segment, 73.8 vs 58.5 for antero-lateral segment, 67.74 vs 42.5 for apical segment, 69.88 vs 47.70 for postero-lateral segment and 41.72 vs 33.4 for postero-lateral segment. The values obtained with the circumferential method were 12.27 vs 10.21, 20.06 vs 16.21, 22.19 vs 18.78, 17.08 vs 11.39 and 8.50 vs 8.15, respectively. These results suggest that the radical method allows to better differentiate between hypo- and normokinesia. Postero-basal segment proved to be most difficult to assess. Both methods fail to make a clear distinction in these cases.

Evaluation Studies as Topic↗
PubMed1993

[Electrocardiographic ST-segment deviation in acute inferoposterior myocardial infarction caused by obstruction of the left circumflex coronary artery].

Electrocardiographic ST-segment deviation was evaluated as a method for identifying the occlusive site of the coronary artery in acute inferoposterior myocardial infarction. ST-segment elevation in 2 or more of the inferior leads (II, III, aVF) occurred in 11 of 22 patients (50%) with left circumflex coronary artery occlusion, and in 24 of 27 patients (88.9%) with right coronary artery occlusion. The ST-segment elevation in the inferior leads was 3.8 +/- 2.6 mm (mean +/- SD) in left circumflex coronary artery occlusion and 8.5 +/- 4.9 mm in right coronary artery occlusion (p < 0.01). Two millimeters or greater ST-segment elevation in any 2 or more of the inferior leads was observed in 81.5% of the patients with right coronary artery occlusion, but in only 13.6% of the patients with left circumflex coronary artery occlusion (p < 0.01). ST-segment elevation in the inferior leads was found in 8 of 10 patients (80%) with distal left circumflex coronary artery (segment 13) occlusion, but in only 2 of 9 patients (22.2%) with proximal left circumflex coronary artery (segment 11) occlusion (p < 0.05). These findings suggest that identification of the site of coronary artery occlusion, left circumflex coronary artery or right coronary artery, in patients with acute inferoposterior myocardial infarction can be indicated by the location, summation and intensity of the ST-segment elevation in the inferior leads.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗