Intermittent umbilical cord occlusion in the ovine fetus: effects on blood glucose, insulin, and glucagon and on pancreatic development

OBJECTIVE

To determine whether repetitive umbilical cord occlusion resulting in fetal hypoxemia but not cumulative acidosis also affects fetal glucose levels and the levels of the regulatory hormones insulin and glucagon, by altering glucose delivery and with repetitive insults by inducing fetal glucose production, thus possibly affecting pancreatic development.

METHODS

Fifteen chronically catheterized fetal sheep were studied over 21 days. Umbilical cord occlusions (UCOs) (duration 90 seconds) were performed every 30 minutes for 3-4 hours each day. Fetal arterial blood was sampled at predetermined times on days 1, 9, and 18 for blood gases, pH, glucose, lactate, insulin, and glucagon. When animals were sacrificed, fetal pancreatic tissues were collected for insulin immunostaining.

RESULTS

Blood glucose decreased acutely with each UCO but showed a cumulative increase of approximately 30% over the course of each sampling day. Although plasma insulin levels also increased over the course of sampling on days 9 and 18, plasma glucagon levels remained unchanged throughout the study. The percentage of pancreatic islet cells immunopositive for insulin, which averaged 67%, was also unchanged in experimental compared with control animals.

CONCLUSION

Umbilical cord occlusion during the latter part of pregnancy, which caused severe but limited hypoxemia, also resulted in acute decreases in blood glucose levels because of reduced exogenous glucose delivery and a cumulative increase in glucose in response to repetitive insults, possibly by inducing fetal glucose production, enhancing glucose delivery, or both. However, repetitive UCO as studied had minimal effect on plasma insulin levels and no effect on glucagon levels or on pancreatic immunostaining for insulin, and thus had no evident effect on pancreatic development.

The experimental herbicide CGA 325'615 inhibits synthesis of crystalline cellulose and causes accumulation of non-crystalline beta-1,4-glucan associated with CesA protein

Developing cotton (Gossypium hirsutum) fibers, cultured in vitro with their associated ovules, were used to compare the effects of two herbicides that inhibit cellulose synthesis: 2,6-dichlorobenzonitrile (DCB) and an experimental thiatriazine-based herbicide, CGA 325'615. CGA 325'615 in nanomolar concentrations or DCB in micromolar concentrations causes inhibition of synthesis of crystalline cellulose. Unlike DCB, CGA 325'615 also causes concomitant accumulation of non-crystalline beta-1,4-glucan that can be at least partially solubilized from fiber walls with ammonium oxalate. The unusual solubility of this accumulated glucan may be explained by its strong association with protein. Treatment of the glucan fraction with protease changes its size distribution and leads to precipitation of the glucan. Treatment of the glucan fraction with cellulase digests the glucan and also releases protein that has been characterized as GhCesA-1 and GhCesA-2--proteins that are believed to represent the catalytic subunit of cellulose synthase. The fact that cellulase treatment is required to release this protein indicates an extremely tight association of the glucan with the CesA proteins. In addition, CGA 325'615, but not DCB, also causes accumulation of CesA protein and a membrane-associated cellulase in the membrane fraction of fibers. In addition to the effects of CGA 325'615 on levels of both of these proteins, the level of both also shows coordinate regulation during fiber development, further suggesting they are both important for cellulose synthesis. The accumulation of non-crystalline glucan caused by CGA 325'615 mimics the phenotype of the cellulose-deficient rsw1 mutant of Arabidopsis that also accumulates an apparently similar glucan (T. Arioli, L. Peng, A.S. Betzner, J. Burn, W. Wittke, W. Herth, C. Camilleri, H. Hofte, J. Plazinski, R. Birch et al. [1998] Science 279: 717).

[The role of cardiac catheterization for diagnosis and treatment of pulmonary hypertension]

The role of the cardiac catheterization for diagnosis and treatment of pulmonary hypertension (PH) is very important. When mean pulmonary artery pressure increased more than 25 mmHg, then PH is defined. But this is measured accurately only by the catheterization. And we can discriminate the etiology of PH clearly by pulmonary capillary wedge pressure (Ppcw) or intra-cardiac shunt (L to R) by blood oxygen saturation step-up, and both parameters are obtained by this method. The etiology of PH is diagnosed as left sided heart failure, if Ppcw is increased more than 13 mmHg. PH is produced by congenital heart disease (ASD, VSD, PDA etc.), when the oxygen saturation step-up is recognized. And PH is induced by any pulmonary disease or pulmonary thrombo-embolism or collagen disease or liver cirrhosis or PPH, if Ppcw is normal and no oxygen step-up is recognized.

The effect of intermittent umbilical cord occlusion on insulin-like growth factors and their binding proteins in preterm and near-term ovine fetuses

Intermittent umbilical cord compression with resultant fetal hypoxia can have a negative impact on fetal growth and development. Insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) are the most important regulators of fetal growth. In preterm (107-108 days of gestation) and near-term (128-131 days of gestation) ovine fetuses, we have determined the effect of intermittent umbilical cord occlusion (UCO) over a period of 4 days on the profile and expression of IGFs and IGFBPs. In experimental group animals (preterm n=7; near term n=7) UCOs were carried out by complete inflation of an occluder cuff (duration 90 s) every 30 min for 3-5 h each day, while control fetuses (preterm n=7; near term n=7) received no UCOs. Ewes were euthanized at the end of day 4, and fetal heart, lung, kidney, liver, skeletal muscle and placenta were collected. During UCOs, PO(2! ) fell (by approximately 13 mmHg), pH fell (by approximately 0.05) and PCO(2) increased (by approximately 7 mmHg), and changed to a similar extent in both preterm and near-term groups. In both preterm and near-term groups, there was no difference in fetal body or organ weight between UCO and control fetuses. No significant changes were observed in plasma IGF-I and -II concentrations or IGFBP-1, -2, -3 or -4 levels throughout the 4-day study at either gestational age. In the preterm group UCO fetuses, IGF-II mRNA (1.2-6.0 kb) levels were lower in fetal lung (33%, P<0.05), heart (54%, P<0.01) and skeletal muscle (29%, P<0.05), but there were no differences in IGF-I mRNA levels (7.3 kb); IGFBP-2 mRNA (1.5 kb) levels were lower in the right lobe of the liver (42%, P<0.05) and kidney (22%, P<0.01), but hig! her in the heart (72%, P<0.01), while IGFBP-4 (2.4 kb) levels were lower in skeletal muscle (21%, P<0.01). In the near-term group UCO fetuses, IGFBP-2 mRNA levels were greater in the placenta (39%, P<0.05). Thus, intermittent UCO as studied has a greater effect on the expression of genes encoding certain peptides of the fetal IGF system in selected tissues in preterm fetuses than that in near-term fetuses. Altered IGFBP-2 mRNA levels with reduced IGF-II mRNA levels in selected tissues may mediate changes in growth and/or differentiation that might become apparent if the length of the UCO study were extended.

Activation of the hypothalamic-pituitary-adrenal axis with repetitive umbilical cord occlusion in the preterm ovine fetus

OBJECTIVE

To determine whether repeated hypoxic insults with umbilical cord occlusion over 4 days will lead to activation of the hypothalamic-pituitary-adrenal (HPA) axis altered adrenocortical responsiveness in the preterm ovine fetus.

METHODS

Umbilical cord occlusions of 90 seconds duration were performed every 30 minutes for 3 to 5 hours each day (experimental group n = 7, control group n = 7; at 112-116 days' gestation, term = 147 days). Arterial blood was sampled at predetermined times for blood gases and pH, plasma ACTH, and cortisol. Pituitary proopiomelanocortin (POMC) and glucocorticoid receptor (GR) mRNA also were localized and quantified by in situ hybridization.

RESULTS

During umbilical cord occlusions fetal arterial oxygen pressure (approximately 17 mmHg) and pH (approximately 0.05) decreased, and carbon dioxide pressure increased (approximately 8 mmHg) as measured on days 1 and 4, but with no cumulative blood gas or pH change over successive occlusions for any of the 4 study days. Plasma ACTH increased, as measured after cord occlusion and over the course of successive cord occlusions on days 1 and 4, and returned to control values by the next day. The cumulative increase in ACTH was much less on day 4 than day 1 (15 +/- 3 compared with 101 +/- 25 pg/mL, P <.05). Plasma cortisol increased, as measured after cord occlusion and over the course of successive cord occlusions on day 4 only (2.7 +/- 0.4 to 4. 7 +/- 0.3 ng/mL, P <.05). POMC mRNA increased 2.5-fold in the pars distalis of the pituitaries from cord occlusion compared to control fetuses, but was unchanged in the pars intermedia. GR mRNA, which was detected in the pars distalis only, was unaltered.

CONCLUSION

Repetitive umbilical cord occlusion in the preterm ovine fetus resulted in the activation of the HPA axis, with increased adrenocortical responsiveness over time, and involved differential regulation of POMC mRNA expression in the pars distalis and pars intermedia of the pituitary, but with no change in GR.

Low-dose cytarabine and aclarubicin in combination with granulocyte colony-stimulating factor (CAG regimen) for previously treated patients with relapsed or primary resistant acute myelogenous leukemia (AML) and previously untreated elderly patients with AML, secondary AML, and refractory anemia with excess blasts in transformation

We used the CAG regimen (low-dose cytarabine [10 mg/m2 per 12 hours, days 1-14], aclarubicin [14 mg/m2 per day, days 1-4], and granulocyte colony-stimulating factor [200 micrograms/m2 per day, days 1-14]) for the treatment of patients with primary resistant acute myelogenous leukemia (AML) and previously untreated elderly patients with AML, secondary AML, and refractory anemia with excess blasts in transformation (RAEB-T) in addition to relapsed AML. Forty-three of 69 (62%) patients achieved complete remission (CR), including 29 of 35 (83%) patients with relapsed AML, 1 of 8 patients with primary resistant AML, 5 of 8 elderly patients with previously untreated AML, and 8 of 18 patients with previously untreated secondary AML or RAEB-T. Ten of 22 (45%) patients > or = 65 years old achieved CR. The patients who achieved CR received at least 1 course of modified CAG therapy as the first consolidation therapy, followed by various second consolidation and intensification therapies. The median disease-free survival and overall survival were 8 and 15 months, respectively, for relapsed AML; 11 and 8 months for the elderly patients; and 8 and 17 months for secondary AML and RAEB-T. Myelosuppression was mild to moderate, and other than fever, severe nonhematologic toxicity was rare. CAG as the induction therapy seems promising for the treatment of various categories of poor-prognosis AML.

Intermittent umbilical cord occlusion in the ovine fetus near term: effects on behavioral state activity

OBJECTIVE

The purpose of this study was to determine the effects on fetal behavioral state activity of intermittent umbilical cord occlusion resulting in repetitive severe short-term hypoxemia.

STUDY DESIGN

Fifteen near-term fetal sheep (experimental group, n = 8; control group, n = 7) were studied during 4 days while behavioral and cardiovascular parameters were monitored. Each day after a 2-hour control period, cord occlusions were performed in the experimental group animals by complete inflation of an occluder cuff (duration, 90 seconds) every 30 minutes for 3 to 5 hours. Results are presented as group mean +/- SEM.

RESULTS

During umbilical cord occlusions fetal arterial PO(2) (change of 12 mm Hg), oxygen saturation (change of 40%), and glucose concentration (change of 0.3 mmol/L) fell and PCO(2) (change of 7 mm Hg) rose, but all returned toward control values after release of occlusion. Fetal behavioral state activity was markedly disrupted by 90 seconds of cord occlusion, with animals showing an abrupt flattening of the electrocorticogram. In >90% of instances the first identifiable state after cord release was the high-voltage non-rapid-eye-movement state. There was no apparent change in this response through the 4 days of the study. For experimental group animals the mean percentages of time spent in low-voltage electrocortical state (from 53 +/- 2 to 36 +/- 2), electro-ocular state (from 45 +/- 3 to 28 +/- 3), and fetal breathing activity (22 +/- 4 to 12 +/- 3) were significantly decreased (P <.001) during occlusion hours with respect to nonocclusion hours.

CONCLUSION

Intermittent umbilical cord occlusion with severe but limited hypoxemia and no cumulative acidosis in the near-term ovine fetus disrupts behavioral state activity, with a flattening of the electrocortical activity during occlusions and an overall decrease in the prominence of the low-voltage rapid-eye-movement state. If such insults are frequent and severe enough, they might have an effect on growth and development of the brain during the perinatal period.

Low efficiency of oxygen utilization during exercise in hyperthyroidism

STUDY OBJECTIVE

The mechanism of exercise intolerance in hyperthyroidism has not been fully elucidated. This study was undertaken to determine if hyperthyroidism reduced the efficiency of sub-maximal exercise.

STUDY DESIGN

We measured cardiorespiratory variables up to the anaerobic threshold (AT) during ramp-loading cycle ergometry in 12 patients (New York Heart Association functional class II or III). Studies were performed in the hyperthyroid state and repeated in the euthyroid state after 10 months of medical treatment. In 10-W steps from rest to the AT, we measured oxygen uptake (VO2) as a measure of total body work rate, and pressure rate product (PRP) as a measure of cardiac work rate. Loading watts at AT divided by the increment of Vo2 from rest to the AT (delta Watt/delta VO2) was calculated as an index of work efficiency (where delta means the increment of each value from rest to the AT).

RESULTS

VO2 and PRP at the AT were not significantly different between hyperthyroid and euthyroid states (VO2, 16.6 +/- 3.0 vs 17.5 +/- 2.3 mL/min/kg; PRP, 229 +/- 41 vs 218 +/- 28 x 10(2) mm Hg/min). However, loading watts at the AT were significantly lower in the hyperthyroid than the euthyroid state (28 +/- 22 vs 60 +/- 14 W: p < 0.01). VO2 and PRP while hyperthyroid were significantly higher than when euthyroid at every 10-W step during ramp-loading exercise. Furthermore, delta Watt/delta VO2 was significantly lower in hyperthyroid than euthyroid states (p < 0.001). There was a significant inverse correlation-ship between triiodothyronine and delta Watt/delta Vo2 (r = -0.654, p < 0.001).

CONCLUSION

Hyperthyroidism causes low work efficiency, which may limit exercise tolerance.

Higher plants contain homologs of the bacterial celA genes encoding the catalytic subunit of cellulose synthase

In spite of much effort, no one has succeeded in isolating and characterizing the enzyme(s) responsible for synthesis of cellulose, the major cell wall polymer of plants. We have characterized two cotton (Gossypium hirsutum) cDNA clones and identified one rice (Oryza sativa) cDNA that are homologs of the bacterial celA genes that encode the catalytic subunit of cellulose synthase. Three regions in the deduced amino acid sequences of the plant celA gene products are conserved with respect to the proteins encoded by bacterial celA genes. Within these conserved regions, there are four highly conserved subdomains previously suggested to be critical for catalysis and/or binding of the substrate UDP-glucose (UDP-Glc). An overexpressed DNA segment of the cotton celA1 gene encodes a polypeptide fragment that spans these domains and binds UDP-Glc, while a similar fragment having one of these domains deleted does not. The plant celA genes show little homology at the N- and C-terminal regions and also contain two internal insertions of sequence, one conserved and one hypervariable, that are not found in the bacterial gene sequences. Cotton celA1 and celA2 genes are expressed at high levels during active secondary wall cellulose synthesis in developing cotton fibers. Genomic Southern blot analyses in cotton demonstrate that celA forms a small gene family.

Hyperinflation with intrinsic PEEP and respiratory muscle blood flow

Increased end-expiratory lung volume and intrinsic positive end-expiratory pressure (PEEP) are common in obstructive lung disease, especially during exacerbations or exercise. This loads the respiratory muscles and may also stress the circulatory system, causing a reduction or redistribution of cardiac output. We measured the blood flow to respiratory muscles and systemic organs using colored microspheres in 10 spontaneously breathing anesthetized tracheotomized dogs. Flows during baseline breathing (BL) were compared with those during hyperinflation (HI) induced by a mechanical analogue of airway closure and with those during an inspiratory resistive load (IR) that produced an equivalent increase in inspiratory work and time-integrated transdiaphragmatic pressure. Cardiac output was unchanged during IR (3.19 +/- 0.27 l/min at BL, 3.09 +/- 0.34 l/min during IR) but was reduced during HI (2.14 +/- 0.29 l/min; P < 0.01). Among the organs studied, flow was unaltered by IR but decreased to the liver and pancreas and increased to the brain during HI. For the respiratory muscles, flow to the diaphragm increased during IR. However, despite a 1.9-fold increase in inspiratory work per minute and a 2.5-fold increase in integrated transdiaphragmatic pressure during HI, blood flow to the diaphragm was unchanged and flow to the scalenes and sternomastoid fell. The only respiratory muscle to which flow increased during HI was the transversus abdominis, an expiratory muscle. We conclude that the circulatory effects of hyperinflation in this model impair inspiratory muscle perfusion and speculate that this may contribute to respiratory muscle dysfunction in hyperinflated states.

Endomyocardial gene expression during development of pacing tachycardia-induced heart failure in the dog

Selective and specific changes in gene expression characterize the end-stage failing heart. However, the pattern and relation of these changes to evolving systolic and diastolic dysfunction during development of heart failure remains undefined. In the present study, we assessed steady-state levels of mRNAs encoding a group of cardiac proteins during the early development of left ventricular dysfunction in dogs with pacing-induced cardiomyopathy. Corresponding hemodynamic assessments were made in the conscious state in the same animals and at the same time points at baseline, after 1 week of ventricular pacing, and at the onset of clinical heart failure. Systolic dysfunction dominated after 1 week of pacing, whereas diastolic dysfunction was far more pronounced with the onset of heart failure. Atrial natriuretic factor mRNA was undetectable in 7 of 12 hearts at baseline but was expressed in all hearts at 1 week (P < .01 by chi 2 test), and it increased markedly with progression to failure (P = .05). Creatine kinase-B mRNA also rose markedly with heart failure (P < .01). Levels of mRNA encoding beta-myosin heavy chain, mitochondrial creatine kinase, phospholamban, and sarcoplasmic reticulum Ca(2+)-ATPase did not significantly change from baseline, despite development of heart failure. Additional analysis to determine if these mRNA changes were related to the severity of diastolic or systolic dysfunction revealed that phospholamban mRNA decreased in hearts with larger net increases in end-diastolic pressure (+19.2 +/- 1.9 mm Hg) compared with those hearts in which it did not change (+4.0 +/- 4.9, P < .02).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of hyperinflation and CPAP on work of breathing and respiratory failure in dogs

Increased end-expiratory lung volume (EELV) and airway resistance are both characteristic features of obstructive lung disease. Increased EELV alone loads the respiratory muscles and may cause respiratory failure, changes that could be reversed by continuous positive airway pressure (CPAP). To study the effects of elevated EELV on respiration without increased airway resistance, we used a mechanical analogue of airway closure to increase EELV in six spontaneously breathing anesthetized dogs. Hyperinflation of 0.84 +/- 0.11 liter for 30 min decreased minute ventilation from 4.8 +/- 0.37 to 3.5 +/- 0.21 l/min and increased arterial PCO2 from 40.3 +/- 1.5 to 73.2 +/- 8.1 Torr (both P < 0.01). Inspiratory work per breath increased 3-fold, work per liter increased 3.7-fold, and work per minute increased 2.8-fold (all P < 0.01). CPAP at 15 cmH2O restored minute ventilation to 4.3 +/- 0.3 l/min and reduced arterial PCO2 to 54 +/- 6.6 Torr (NS vs. baseline). All measurements of inspiratory work were also restored to baseline, but cardiac output was reduced (baseline 3.09 +/- 0.36, hyperinflation 2.71 +/- 0.36, hyperinflation + CPAP 1.94 +/- 0.29 l/min; P < 0.05, baseline vs. hyperinflation + CPAP). We conclude that increases in EELV mimic important features of airway obstruction, increase inspiratory work, and can cause respiratory failure independent of increased airway resistance. This respiratory failure is reversed by CPAP at the potential expense of hemodynamic compromise.

Synergism between CACGTG (G-box) and CACCTG cis-elements is required for activation of the bean seed storage protein beta-phaseolin gene

Expression of bean seed storage protein phaseolin is under strict developmental control. Four distinct nuclear proteins recognize in vitro the proximal beta-phaseolin promoter (-295/+45) which confers spatial and temporal regulation of the native gene. Functional significance of these protein-binding sites was evaluated by substitution mutation of the motifs in the promoter, which was fused to GUS reporter gene, and subsequent transient gene expression assay using protoplasts from developing bean cotyledons. DNA-binding protein CAN binds three CANNTG motifs, CACGTG (-248/-243), CACCTG (-163/-158), and CATATG (-100/-95). Substitution mutation of the CACGTG motif, which is commonly known as G-box, reduced the -295 promoter activity by 75%, indicating that the G-box is a major positive cis-element. Mutation analyses also demonstrated that the CACCTG and CATATG motifs act as positive and negative cis-elements, respectively. Substitution mutation of all three CANNTG motifs essentially eliminated the -295 promoter activity. A construct containing the G-box and CACCTG motif resulted in a transcriptional level that is much greater than the sum of the transcriptional levels from the individual cis-elements, demonstrating that the G-box and CACCTG act synergistically. Substitution mutations of two AT-rich sequences, to which a nuclear protein AG-1 binds, showed that these sites function as major negative (-376/-367, -356/-347) or positive (-191/-182) cis-elements, and that the effect of the two AG-1 binding sites was counteractive in the -391 promoter. These results indicate that the three CANNTG motifs and two AG-1-binding sites play critical roles in transcription of the beta-phaseolin gene in cotyledons.

5' distal and proximal cis-acting regulator elements are required for developmental control of a rice seed storage protein glutelin gene

Using a homologous transgenic rice system it is demonstrated that 5' distal and proximal cis-acting transcriptional regulatory elements are required for developmental control of a rice seed storage protein glutelin gene. Analyses of gene expression of nine progressively truncated 5' promoter sequences in developing endosperm indicated the existence of at least one major positive element located from the -5.1 to -1.8 kb region. The functional importance of proximal elements in the context of 1.8 kb promoter was demonstrated by single substitution mutations in the TATA box (-28/-23), AACA motif (-73/-61), and protein-binding boxes I (-103/-86), II (-124/-110), III (-175/-158) and IV (-200/-217). A simultaneous mutation of five protein-binding sites (-410/-86) essentially eliminated the activity of the 1.8 kb promoter. Although temporal control of the Gt1 gene during endosperm development was retained in plants of constructs from -5.1 kb to -155 bp, spatial control of the glutelin gene was altered when the 5.1 kb promoter was deleted to -507 bp or -154 bp as the reporter gene activities of these constructs were detected in phloem of leaves, and in stems, sheaths and roots of plants.

[The acute and chronic effects of bunazosin on exercise capacity estimated by the anaerobic threshold in patients with chronic congestive heart failure]

To study the effect of bunazosin on exercise capacity in patients with congestive heart failure (NYHA II-III), anaerobic thresholds (AT, VO2, ml/min/kg) were measured before (control) and after initial 1 = 2mg administration of bunazosin (acute phase; N = 14) and after two weeks of bunazosin therapy (3mg/day, 1mg t. i. d., chronic phase; N = 6). AT were determined by Wasserman's V-slope method during ergometer exercise test with a ramp loading (10 watt/min). AT increased significantly from control during both acute (14.2 +/- 2.7 to 16.9 +/- 3.6 ml/min/kg p < 0.005) and chronic (13.6 +/- 2.5 to 16.7 +/- 1.0 p < 0.05) phase. Additionally, work (watt) attained at AT increased significantly from control during both acute (33.6 +/- 19.2 to 52.6 +/- 30.2 p < 0.005) and chronic (35.8 +/- 25 to 49.3 +/- 15 p < 0.05) phase. Pressure-rate-products (PRP, x 10(2) mmHg/min) at AT increased significantly from control during the acute phase (119 +/- 35 to 240 +/- 50 p < 0.005) alone. In the chronic phase, PRP decreased significantly at the work level equal to AT during control (from 207 +/- 41 to 187 +/- 39 p < 0.05). These data suggest that bunazosin has favorable acute and chronic effects on exercise capacity in patients with congestive heart failure.

Accelerated purine nucleotide degradation by anaerobic but not by aerobic ergometer muscle exercise

The exact conditions under which exercise causes purine nucleotide degradation are not well understood. We determined plasma hypoxanthine and uric acid levels serially in eight individuals during ergometer muscle exercise. When the load was increased gradually by 15 W/min, plasma hypoxanthine was elevated only after the status exceeded the anaerobic threshold (AT), as determined by analysis of expired gas. Nonstrenuous ergometer exercise, which kept the status continuously below the AT, induced neither blood lactic acid nor plasma hypoxanthine elevation. These results suggest that the AT is also the threshold for the acceleration of purine nucleotide degradation. Muscle exercise to a degree that does not exceed the AT does not cause major purine nucleotide degradation, and, therefore, is expected to be beneficial for patients with gout and/or hyperuricemia.

Transposition of the maize activator element in transgenic rice plants

Transposition of the maize Activator (Ac) element was observed in transgenic rice. After protoplast transformation, Ac excision from an interrupted hygromycin phosphotransferase gene was monitored by appearance of the hygromycin-resistant colonies. The frequency of Ac excision, based on the biological assay was up to 19%. Southern hybridization analysis indicated that at least one copy per genome of the hygromycin-resistance gene was reconstituted after Ac excision and that the transposed Ac element was reintegrated into the rice genome. Analysis of DNA sequences at 14 empty donor sites indicated that the Ac element was excised in rice in a similar manner as maize. The excision of an Ac mutant in which a 1.3 kbp Tn903 fragment was inserted at a unique BamHI site so as to disrupt binding of the putative transposase was not detected by DNA analysis. These results demonstrated that the maize Ac element might be used as an effective heterologous transposon for mutagenesis and gene tagging in rice, an important food crops.

Chloroplast DNA evolution in potato (Solanum tuberosum L.)

A deletion specific to chloroplast (ct) DNA of potato (Solanum tuberosum ssp. tuberosum) was determined by comparative sequence analysis. The deletion was 241 bp in size, and was not flanked by direct repeats. Five small, open reading frames were found in the corresponding regions of ctDNAs from wild potato (S. tuberosum ssp. andigena) and tomato (Lycopersicon esculentum). Comparison of the sequences of 1.35-kbp HaeIII ctDNA fragments from potato, tomato, and tobacco (Nicotiana tabacum) revealed the following: the locations of the 5' ends of both rubisco large subunit (rbcL) and ATPase beta subunit (atpβ) mRNAs were probably the same as those of spinach (Spinacia oleracea); the promoter regions of the two genes were highly conserved among the four species; and the 5' untranslated regions diverged at high rates. A phylogenetic tree for the three potato cultivars, one tomato cultivar, and one tobacco cultivar has been constructed by the maximum parsimony method from DNA sequence data, demonstrating that the rate of nucleotide substitution in potato ctDNA is much slower than that in tomato ctDNA. This fact might be due to the differences in the method of propagation between the two crops.

[A study on tooth preparation by means of the newly developed parallelometer and its educational effect, with primary regard to convergence angles of abutment tooth]

Proper tooth preparation is one of the fundamental requirements in crown & bridge prosthodontics. However, it is difficult for students in particular to prepare adequate convergence angles of abutment tooth in the limited environment of patient's mouth. Therefore, the parallelometer was developed to improve the preparations as a supplementary device which informs the person by a signal of alarming simultaneously when a bur is not properly installed to convergence angles of abutment tooth. Sixty subjects were selected from students of Kanagawa Dental College and they were divided into two groups (A and B) to prepare abutment tooth of lower right 1st molar for full cast crown on typodont mounted into the manikin. A preliminary training was performed for once without the parallelometer for group A and with it for group B prior to a comparative experiment. The following results were obtained with primary regard to convergence angles of abutment tooth. 1. Related to each of four convergence angles, group B is superior to group A in all mean values with a statistical significance (P less than 0.01). 2. Related to a total of four convergence angles by the maximum number of subjects, group B is also superior to group A in a mean value by about ten degrees. 3. A newly developed parallelometer proved to be an efficient supplementary device for training of students to master a technique of preparation for adequate abutment tooth.

Reduction in pulmonary varix size after mitral valve replacement

A 48-year-old female was admitted to our hospital for examination of an abnormal shadow in the right lung field. She had a systolic murmur (4/6) over the apex and the chest radiograph revealed cardiac enlargement with three round opacities in the right lung field. Cardiac catheterization showed marked mitral regurgitation and large pulmonary varices. Pulmonary varix caused by mitral regurgitation was diagnosed. The size of the pulmonary varix was reduced with improvement of pulmonary artery wedge pressure one month after mitral valve replacement. We conclude that pulmonary varices can decrease in size secondary to lowering of left atrial pressure within one month after operation.

Abnormal breathing patterns in patients with mitral stenosis: a possible compensatory role

The breathing patterns of 37 patients with mitral stenosis were investigated in standing position by Konno-Mead analysis. Hemodynamic parameters were measured by cardiac catheterization, pulmonary function variables by pulmonary function testings and distribution of pulmonary perfusion by Tc-99m-MAA scintigraphy. Seventeen patients displayed rib cage dominant breathing patterns, and 6 patients displayed paradoxical breathing patterns, whereas 14 patients displayed normal breathing patterns. None of these patients exhibited an abdomen dominant breathing pattern. The patients with abnormal breathing patterns (rib cage dominant or paradoxical) displayed significantly higher values of pulmonary arterial pressure (p less than 0.01), capillary wedge pressure (p less than 0.01), total pulmonary vascular resistance (p less than 0.01) and mitral valve gradient (p less than 0.05) as well as smaller mitral valve area (p less than 0.05) and lower values of both in PaO2 (p less than 0.05) and diffusing capacity (p less than 0.05) than patients with normal breathing patterns. Abnormal distribution of pulmonary perfusion with hyperperfusion in the upper zone of the lung were found to be associated with the abnormal breathing patterns. Since rib cage dominant and paradoxical breathing patterns are known to increase ventilation in the upper zone of the lung, these abnormal breathing patterns may represent a compensatory mechanism serving to match ventilation and perfusion.

[Utility of digital perfusion images of the lung in mitral stenosis: the pathophysiological significance of the distribution of pulmonary perfusion]

The relationship between pulmonary hemodynamics (cardiac index; CI and the mean pulmonary artery wedge pressure; mPw) and the redistribution of pulmonary perfusion were studied in 300 patients with mitral stenosis using computerized Tc99m-MAA perfusion images (digital perfusion images: DPI), which consisted of isocount areas. Various types of DPI were obtained and were classified in six grades according to patterns of 100-70% of the isocount area in the right anterior DPI, i.e. grade-0 (normal), grade-1 (increased perfusion in the upper zone), grade-2 (uniform distribution), grade-3 (disappearance of the basal hyperperfusion area), grade-4 (apical hyperperfusion area) and grade-5 (decrease of perfusion at the lower zone). The mPw was thought to be one of the factors determining distribution. Thus, it was not adequate to estimate the mPw from DPI. In patients with the mPw less than 20 mmHg, an increase in perfusion at the upper zone and disappearance of the basal hyperperfusion might be noted, however, the mPw more than 20 mmHg was necessary to cause an apical hyperperfusion area. The predictive values of grades 0 and 1 for the mPw less than 20 mmHg were 70% (54/77) and those of grades 4 and 5 for the mPw less than 20 mmHg and the mPw less than 25 mmHg were 86% (110/128) and 56% (71/128), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)