Reversed pupillary block.
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Cataract Extraction↗
Biomedical subjects
V Chen
Publications and source records attributed to V Chen.
Presacral extramedullary hematopoiesis in thalassemia intermedia.
Extramedullary hematopoiesis is manifested by several clinical hematologic disorders including beta-thalassemia major and thalassemia intermedia. We report an unusual case of extramedullary hematopoiesis, which presented as a painful presacral mass in a patient with beta-thalassemia intermedia. The diagnosis was confirmed by a needle biopsy guided by computed tomography. The patient responded well to radiation therapy to the sacral region.
Adult↗
Association of umbilical venous with inferior vena cava blood flow velocities.
The fetal cardiac and placental circulations are interconnected through the umbilical venous and arterial vasculature. We hypothesized that alterations in umbilical venous blood flow velocities are present in fetuses with abnormal umbilical arterial circulation, and further, that changes in inferior vena cava blood flow velocities occur with, and might explain, these variations in umbilical venous blood flow velocities. Umbilical venous and inferior vena cava blood flow velocities were examined in 15 normal fetuses and in 59 fetuses with abnormalities that included absent end-diastolic umbilical artery blood flow velocities (N = 21) or abnormal heart rates (N = 27). Inferior vena cava velocities were also analyzed in 11 other fetuses with anomalies or known growth or placental abnormalities who had abnormal umbilical venous blood flow velocities. In normal fetuses, variations in umbilical venous velocities occurred during fetal activity or with fetal breathing; however, no variation in velocity corresponded with heart rate. Eleven of 21 fetuses with absent end-diastolic velocities in the umbilical artery demonstrated decreases in umbilical venous velocities ("venous pulsations") during arterial diastole. Blood flow velocities in the reverse direction, from the right atrium into the inferior vena cava with atrial contraction, were significantly greater in these fetuses than in those without umbilical venous pulsations (27.5 +/- 14.9% and 7.5 +/- 5.7% of total forward flow velocity, respectively; P less than .001). Venous pulsations were also seen in fetuses with abnormally fast or slow heart rates; reverse flow with atrial contraction in the inferior vena cava was likewise greater than normal in these fetuses.(ABSTRACT TRUNCATED AT 250 WORDS)
Arrhythmias, Cardiac↗
Occupation and pancreatic cancer risk in Louisiana.
To study the relation of occupational exposures and pancreatic cancer, we evaluated data from males (198 cases and 209 controls) participating in a hospital-based case-control study conducted in a high-risk area of Louisiana between 1979 and 1983. The questionnaire obtained information on lifetime occupational history, as well as dietary, smoking, and drinking habits and demographic characteristics. After adjustment for smoking and dietary patterns, white collar occupations showed consistent elevations in risk, whereas associations for other occupations were in general unremarkable. Although not significantly elevated, risks for truck drivers (OR = 1.7) and those with long-term employment in machine repair or as mechanics were suggestive (OR = 2.5). No association was found for jobs in oil refining or oil and gas extraction (ORs were 0.5 and 0.4, respectively), although risks were slightly elevated for long-term workers in the chemical processing industry (OR = 1.2). While these associations deserve further study, our findings are consistent with results of other studies which do not suggest that occupational exposures are important determinants of pancreatic cancer.
Adenocarcinoma↗
Metastatic thyroid carcinoma masquerading as lacrimal gland tumor.
A 56-year-old woman presented with orbital signs and symptoms suggestive of lacrimal gland tumor. An excised biopsy specimen was obtained and showed glandular tissue, which could be confused with lacrimal gland acini. Closer microscopic examination and immunohistochemical studies revealed a metastatic tumor of thyroid gland origin. Initially, there was no identifiable nodule in the thyroid, but 3 months later a thyroid nodule was found by ultrasound and radioisotope scan. The histopathologic appearance of the thyroid nodule was similar to that found in the orbit. This case demonstrates the usefulness of immunohistochemistry in establishing a diagnosis when the microscopic appearance is inconclusive.
Adenocarcinoma↗
Preservation of cardiac metabolic capacity after acute catecholamine injury.
High concentrations of adrenergic agonists are known to cause significant structural damage to the heart, accompanied by depressed cardiac performance. These studies were undertaken to further elucidate mechanisms that contribute to this process. Rabbits were infused with either norepinephrine (NE, 3 micrograms.min-1.kg-1 iv) for 90 min or with an equivalent volume of normal saline (controls). The heart was immediately extracted and studied as an isolated working heart preparation perfused with erythrocyte-enhanced buffer. Stroke work, coronary flow, and O2 metabolism were determined, and substrate oxidation was measured by [14C]glucose or palmitate. Stroke work performed by hearts exposed to NE was only 31% of controls (2.6 +/- 0.4 vs. 8.4 +/- 0.9 g.cm-1.g-1). This was matched by reductions in coronary flow and O2 metabolism. Glucose oxidation was reduced from 54.6 +/- 3.9 to 16.0 +/- 5.3 nmol.min-1.g-1, and palmitate oxidation from 49.8 +/- 5.3 to 21.0 +/- 4.1 nmol.min-1.g-1 in the NE group. However, ATP, creatine phosphate, glycogen, and triacylglycerol concentrations were identical with the control group. O2 delivery per unit substrate oxidation was not lower in the NE group, and O2 extraction did not differ significantly. These findings indicate that the markedly lower contractile performance of the hearts exposed to NE cannot be attributed to a deficiency of metabolic capacity or limitation of O2 or substrate availability because of vasospasm. In view of the brief time (90 min), it is unlikely that leukocyte accumulation was a major factor. The observations are consistent with NE-derived oxidant injury, possibly causing disordered excitation-contraction coupling.
Animals↗
Myocardial hibernation in the ischemic neonatal heart.
We explored the effects of sustained low-flow ischemia on function and metabolism in isolated neonatal hearts. The hearts were extracted from 21 piglets (1-12 days old) and set up as modified Langendorff preparations beating isometrically. They were perfused with red blood cell-enhanced buffer at controlled rates of coronary flow. Mechanical measurements, O2 usage, and substrate oxidation were determined simultaneously at 30-minute intervals for 2 hours. In control hearts, coronary flow was maintained at 1.8 ml/min/g. There was no significant change in mechanical function, diastolic compliance, or O2 or substrate metabolism after 2 hours. In the ischemia group, coronary flow was reduced to 0.2 ml/min/g and sustained for 2 hours. With the onset of ischemia, mechanical function promptly fell to 20% of control. Although O2 delivery was reduced to 11%, O2 extraction doubled so that myocardial O2 consumption was 22% of control, matching mechanical function. Glucose oxidation fell from 37 to 12 nmol/min/g, and lactate release appeared. These measures and ventricular compliance remained constant for the full 2 hours. Concentrations of glycogen and creatine phosphate did not differ from the control group; ATP was 76% of controls. These studies indicate that when myocardial O2 supply is limited, mechanical function rapidly diminishes, largely preserving critical energy stores and preventing irreversible myocellular injury. Although the signal remains to be determined, the strategy is similar to that employed by hibernating species to survive extended periods of O2 deprivation.
Adenosine Triphosphate↗
Effect of hyperoxia (PaO2 50-90 mmHg) on fetal breathing movements in the unanaesthetized fetal sheep.
Hypoxia inhibits fetal breathing movements but after birth it stimulates breathing. These differences have long been thought to involve central nervous inhibitory mechanisms. Such mechanisms might exert a tonic inhibition of fetal breathing movements at normal fetal PaO2 and the rise in PaO2 at birth might lift this inhibitory effect. To test this hypothesis 7 fetal sheep were chronically instrumented at 125-130 days for recording electrocortical activity (ECoG), and the electromyograph (EMG) activity of the diaphragm and neck muscles. Catheters were placed in a fetal carotid and a brachial artery and in the fetal trachea. For an extracorporeal membrane oxygenation system a 12 F gauge silastic catheter was placed in the right atrium for draining fetal blood and a 9.6 F gauge catheter was placed in a carotid artery to return oxygenated blood. Three days after operation the fetuses were connected to the extracorporeal membrane oxygenation system and fetal PaO2 was raised to 65.2 +/- 4.4 mmHg (SEM) for 6 to 19 h without changing pH or PaCO2. Neither the incidence of high voltage ECoG (48.5 +/- SEM 2.0% vs 52.8 +/- 3.3%) nor of fetal breathing movements (37.3 +/- 2.6% vs 23.8 +/- 5.9%) changed during the periods of hyperoxia. Since fetal breathing movements did not become continuous, we conclude that the lower PaO2 in the fetus compared to the neonate does not exert a tonic inhibitory influence on fetal breathing movements.
Animals↗
Mass screening for cervical cancer in Taiwan from 1974 to 1984.
The cervical cancer screening program in Taiwan was carried out in two phases. This study focused on the first 10-year screening program. Univariate descriptive analysis with chi-square test and multivariate analysis with logistic regression were applied to find the significant risk factors related to cervical cancer in Taiwan. Comparison of Phase I and II screening revealed a cohort effect. The high examination rate in women aged 30 to 39 years in Phase I resulted in a drop in the suspicious rate in the 35 to 44 year age group in Phase II, and a decreasing trend of age-specific death rates from both cervical and uterine cancer in the 40 to 49 year age group based on all of the female population in Taiwan. In Phase II, an increasing trend in ratio of carcinoma in situ to invasive carcinoma was also found. These findings suggest that the 10-year screening program in Taiwan conducted by the Cancer Society of the Republic of China has been effective. How to increase the examination rate is the key issue in the control of cervical cancer in Taiwan.
Adult↗
Biochemical characteristics of mammalian myocardia.
Selected biochemical parameters of the ventricular myocardium were compared among several orders of adult mammals with established differences in resting heart rate (cattle, 51 beats/min; swine, 68; canine, 107; rabbit, 256; guinea-pig, 273; rat, 355; mouse, 475). It was hypothesized that the biochemical character of mammalian myocardia is associated with the chronic functional demand on the muscle. Therefore, differences observed in the myocardial biochemical potential among the species could reflect differences in resting heart rate. Myocardia from smaller mammals with higher resting heart rate had significantly (P less than 0.05) higher maximal activities of citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, lactate dehydrogenase (muscle/total), hexokinase and oxidation rates of glucose and palmitate than did larger mammals with lower resting heart rate. Maximal activities of phosphorylase and phosphofructokinase were more uniform across the animals. Correlation coefficients determined among average values of measured biochemical parameters and resting heart rate indicated that resting heart rate was closely associated with: citrate synthase (r = 0.86), 3-hydroxyacyl-CoA dehydrogenase (r = 0.93), ratio muscle/total lactate dehydrogenase (r = 0.89), hexokinase (r = 0.89), glucose oxidation (r = 0.88), and palmitate oxidation (r = 0.93). Significant correlations were observed among all of these parameters with the exception of citrate synthase vs. 3-hydroxyacyl-CoA dehydrogenase, and glucose oxidation vs. muscle/total lactate dehydrogenase. It was concluded that the oxidative capacity of mammalian myocardia was closely associated with resting heart rate, whereas the glycolytic potential of the myocardia was more uniform among the species.
Animals↗
Postmortem metabolic indices of antemortem adrenergic stimulation.
Tissue lactate concentration has been reported to be a useful postmortem indicator of antemortem awareness of mortal danger. The purpose of this study was to determine further whether selected tissue metabolites could be used as postmortem markers of antemortem adrenergic stress. Sprague-Dawley albino rats were anesthetized with pentobarbital and then injected with 2.0 mg kg-1 i.p. epinephrine hydrochloride to induce experimentally a severe sympathetic response that may be associated with the awareness of mortal danger; 20 min after the injection of epinephrine, when the metabolic response was at its peak, the animals were killed by exsanguination. Samples of the following tissues were removed immediately prior to death (0 h) and 48 h postmortem: soleus, plantaris, kidney medulla, kidney cortex, liver, and heart. These samples were analyzed for glycogen, lactate, ATP, creatine phosphate, pH, and total protein concentration. Significant differences in lactate concentration were observed in all tissues except soleus at 0 h in the epinephrine-injected animals. Specific tissues also had significant reductions in glycogen, ATP, and creatine phosphate concentrations at 0 h. At 48 h postmortem, however, only the liver and soleus lactate concentrations were significantly different from the 48-h control samples. It is unlikely that these small differences found in some tissues at 48 h postmortem would be detected in an uncontrolled accident situation. We concluded from these findings that these selected tissue metabolites are not useful as long-term postmortem indicators of antemortem adrenergically induced hypermetabolism.
Adenosine Triphosphate↗
Ventricular function and fatty acid metabolism in neonatal piglet heart.
Studies in which subcellular systems were used suggest that neonatal myocardium has a sharply limited capacity to metabolize fatty acids. The relationship of these findings to the intact heart was tested on piglets, 8 h to 12 days of age. Left ventricular (LV) performance, O2 consumption (MVO2), and fatty acid (FA) uptake and oxidation were measured. Hearts were perfused at 70 cmH2O pressure with buffer containing 2% bovine serum albumin, insulin (100 microU/ml), 5 mM glucose, and 1.5 mM lactate. 14C-labeled palmitate was added (net FA, 0.5 mM). Washed erythrocytes were used to assure adequate O2 delivery. LV end-diastolic pressure (EDP) was controlled with a fluid-filled balloon. FA oxidation was estimated by measuring 14CO2 production. Hearts less than 24 h (group I, n = 6), those approximately 3 days (group II, n = 5), and those 6-12 days of age (group III, n = 10) were compared. Measurements at a low EDP (2-4 cmH2O) and at a higher EDP (7-9 cmH2O) were compared. At the low EDP, rates of FA oxidation for groups I-III averaged 30.0 +/- 3.0, 31.4 +/- 2.9, and 50.2 +/- 2.6 nmol.min-1.g-1, respectively. These values increased to 43.8 +/- 3.7, 42.6 +/- 2.5, and 63.8 +/- 4.0 nmol.min-1.g-1, respectively, at the higher EDP level (P less than 0.01 for each group). Thus within a few hours of birth, pig hearts are able to oxidize long-chain FA, and the rate of oxidation is linked to mechanical function. However, both the oxidation rate and the percentage of MVO2 accounted for by FA oxidation are greater in older hearts.
Algorithms↗
Ectopic glial cells in rat cerebella following neonatal administration of methylazoxymethanol acetate.
Immunological and ultrastructural studies of adult cerebella following neonatal injection of methylazoxymethanol acetate revealed ectopic glial cells in the molecular layer and at the pial surface. This finding strengthens the view that the external granular layer might give rise to Bergmann glia.
Animals↗
Acute respiratory failure following pharmacologically induced hyperventilation: an experimental animal study.
The pulmonary effects of hyperventilation following infusion of sodium salicylate into the cisterna magna was studied in 16 spontaneously breathing adult sheep. We found a fall in PaO2, a decrease in the static compliance of the respiratory system, abnormal chest roentgenographic films, and grossly abnormal lungs following 3.5 to 13 h of hyperventilation. A control group of 15 sheep (10 sheep similarly injected with sodium salicylate, but then sedated and paralyzed and ventilated at normal tidal volume and respiratory rate on a mechanical ventilator, and 5 sheep infused with saline alone and breathing spontaneously) showed no pulmonary or arterial blood gas abnormalities. We conclude that prolonged hyperventilation under the conditions of this experiment precipitated events that resulted in acute lung injury.
Animals↗
Stretch activated ion channels in ventricular myocytes.
Patch-clamp recordings from ventricular myocytes of neonatal rats identified ionic channels that open in response to membrane stretch caused by negative pressures (1 to 6 cm Hg) in the electrode. The stretch response, consisting of markedly increased channel opening frequency, was maintained, with some variability, during long (greater than 40 seconds) stretch applications. The channels have a conductance averaging 120pS in isotonic KCl, have a mean reversal potential 31 mV depolarized from resting membrane potential, and do not require external Ca++ for activation. The channels appear to be relatively non-selective for cations. Since they are gated by physiological levels of tension, stretch-activated channels may represent a cellular control system wherein beat-to-beat tension and/or osmotic balance modulate a portion of membrane conductance.
Animals↗
Biochemical characteristics of mammalian diaphragms.
Selected biochemical characteristics of diaphragm muscle were compared among several orders of adult mammals (cattle, swine, rabbit, guinea pig, rat, and mouse) with known differences in resting breathing frequencies (f, range = 15-138). Diaphragms from smaller animals had significantly higher citrate synthase (CS) and phosphofructokinase (PFK) activities and substrate oxidation rates than larger animals. Ranges of activities for CS and PFK were 93-27 and 58-39 mumol.g-1.min-1, respectively; and 34-5 and 19-2 nmol.g-1.min-1 for [U-14C]glucose (GLU) and [1-14C]palmitate (PAL) oxidation, respectively. The percent of native fast myosin (FM) isoforms was significantly different among groups. Mouse diaphragm had the highest % FM (88.6%), whereas the lowest values (7.5%) were observed in cattle diaphragm. Myosin ATPase (M-ATPase, pH 9.8) activity was significantly lower in cattle (0.06 mumol.mg protein-1.min-1) and swine (0.38 mumol.mg protein-1.min-1) diaphragm than in other mammals (range of 1.14-0.67 mumol.mg protein-1.min-1). Correlation coefficients determined among means of measured biochemical parameters and established values of f indicated that CS activity and substrate oxidation rates were significantly correlated with f (r = 0.92, 0.92, 0.86 for CS, GLU, PAL, respectively) and the % FM increased with f. M-ATPase (pH 9.8) was significantly correlated with % FM (r = 0.85), whereas PFK and M-ATPase activities were not closely associated with f. It was concluded that f in mammals is significantly correlated with the biochemical parameters of aerobic capacity and is associated with the percent of FM isoforms in the diaphragm.
Animals↗
Acute angle closure glaucoma precipitated by orbital pseudotumour.
A 62-year-old woman presented with acute angle closure glaucoma. After a poor response to conventional treatment the presenting signs were re-evaluated and a diagnosis of pseudotumour of the orbit was made. Treatment with oral steroids resolved both the glaucoma and the orbital pseudotumour. The presumed pathogenesis and literature are reviewed.
Cimetidine↗
Nd: YAG laser treatment of anterior chamber implantation cysts.
The development of an epithelial implantation cyst is a severe complication of anterior segment surgery and trauma. Two patients with anterior chamber implantation cysts were treated with Nd: YAG laser. One required surgical correction as the cyst reformed after each of 6 laser treatment sessions. In the other patient, the cyst reformed once, and has not recurred for 18 months since the second laser treatment. Collapse of anterior chamber implantation cysts can be achieved with Nd: YAG laser, though multiple treatment sessions may be required due to the cyst's tendency to reform.
Aged↗