Scintillation from slow protons: A probe of monopole detection capabilities.
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Journal Article↗
Biomedical subjects
G Liu
Publications and source records attributed to G Liu.
Electrophysiological mapping of the auditory areas in the cerebellum of the cat.
We mapped the topographic distribution of auditory evoked potentials over the posterior cerebellum of the cat. Within the posterior vermis, positive-going evoked potentials were primarily recorded in lobule VI and negative ones in lobule VII. Peak latencies of these evoked potentials were between 8 and 18 ms. The amplitudes of evoked potentials from adjacent surface cortical sites often differed significantly. Thus, besides the segregation of positive and negative polarities in the evoked potentials from lobules VI and VII, the distribution of cerebellar auditory evoked potentials within a given lobule contained high- and low-amplitude sites arranged in a patchy pattern. Within the posterior vermis, the evoked potentials showed significant polarity and amplitude changes as a function of depth during microelectrode penetrations which were vertical to the surface of the cerebellar cortex. Cerebellar auditory evoked potentials were not detected over the paramedian lobules and most of the cerebellar hemispheres. There were no significant changes in the electrical activities as a function of depth in these areas. Auditory responses, however, were observed in the most lateral part of the cerebellar hemispheres.
Animals↗
Investigation of the near-surface electronic structure of Cr(001).
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Journal Article↗
Retrospect and prospect of China's population.
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Age Distribution↗
Increased free cholesterol in plasma low and very low density lipoproteins in non-insulin-dependent diabetes mellitus: its role in the inhibition of cholesteryl ester transfer.
Recombination of low and very low density lipoproteins (VLDL and LDL) from normal subjects with plasma from patients with non-insulin-dependent diabetes mellitus significantly increased the reduced rate of transfer of cholesteryl ester to these lipoproteins, which is characteristic of diabetic plasma, whereas diabetic VLDL and LDL reduced cholesteryl ester transfer rates in normal plasma. VLDL and LDL from diabetic plasma had an increased ratio of free cholesterol to phospholipid compared to normal, and unlike normal VLDL and LDL spontaneously lost free cholesterol to high density lipoprotein. These data suggest that the block to cholesteryl ester transfer to these lipoproteins in non-insulin-dependent diabetes is mediated by their increased free cholesterol content and may be related to the increased risk of these patients for developing atherosclerosis.
Cholesterol↗
The effect of sucrose content in high and low carbohydrate diets on plasma glucose, insulin, and lipid responses in hypertriglyceridemic humans.
To further understand the effect of high carbohydrate (CHO)-low fat diets and the role of variations in dietary sucrose on CHO and lipid metabolism, 10 patients with hypertriglyceridemia were fed 2 isocaloric, typical American diets, containing 40% and 60% CHO, for 15 days in random sequence. Each patient was their own control, and they were divided into 2 groups of 5 patients each. In one group, sucrose was held constant at 13% of total calories (40-13% and 60-13%), whereas the sucrose content was 9% of the total calories on a 40% CHO diet (40-9%), and 15% of total calories on a 60% CHO diet (60-15%) in the other group. Fasting and postprandial blood samples were analyzed for plasma glucose, insulin, cholesterol (Chol), and triglycerides (TG), as well as for Chol and TG in chylomicrons, very low density, low density, and high density lipoproteins (HDL). Fasting plasma TG levels were significantly increased in both groups on the 60% CHO diet, primarily due to increases in very low density-TG concentration. The magnitude of the elevation was attenuated when sucrose content was kept constant. Postprandial TG responses were qualitatively similar. There were no significant changes in plasma Chol concentrations, except for a modest fall in plasma HDL-Chol level after the 60-13% diet period (P less than 0.05). No significant differences were found in fasting plasma glucose or insulin concentration. However, postprandial glucose and insulin responses were increased on both high CHO diets. The results of these studies demonstrate that high CHO-low fat diets, in general, tend to elevate plasma glucose, insulin, and TG concentrations and reduce HDL-Chol concentration in patients with endogenous hypertriglyceridemia. In addition, these data illustrate the important role that small variations in dietary sucrose can play in modulation of CHO and lipid metabolism.
Blood Glucose↗
Insulin-stimulated glucose disposal increases with time in patients with non-insulin-dependent diabetes mellitus.
The relative effects of time versus ambient glucose concentration on insulin-stimulated glucose uptake was estimated by performing 5-h insulin clamp studies in patients with NIDDM. Each experimental subject was studied three times, at steady-state plasma insulin levels approximately 2000 microU/ml, but at different steady-state plasma glucose concentrations (studies A, B, and C). Study A consisted of a 5-h clamp, with plasma glucose level maintained at the basal level of fasting hyperglycemia; study B differed in that the basal level of fasting hyperglycemia was reduced during the first hour to approximately 80 mg/dl, and maintained there for the next 4 h; and study C was carried out by clamping the patient at the basal glucose level for 2 h, lowering the glucose concentration to approximately 80 mg/dl during the third hour, and then clamping at this level for the last 2 h. The glucose metabolic clearance rate (MCR) was calculated from 60 to 120 min and from 240 to 300 min during each study, and the results indicated that values for glucose MCR were time dependent, being significantly greater (20-60%) in the fifth than in the second hour in two (studies A and B) of the three studies. In contrast, glucose MCR was independent of plasma glucose concentration, and relatively constant in each subject, as long as it was measured during the same time period. The time-dependent increase in glucose MCR was associated with an approximate 30% increase in steady-state plasma insulin concentrations when comparing the second and fifth hours.(ABSTRACT TRUNCATED AT 250 WORDS)
Blood Glucose↗
Insulin secretion and action in noninsulin-dependent diabetes mellitus. Is insulin resistance secondary to hypoinsulinemia?
The insulin-stimulated glucose metabolic clearance rate, assessed by the insulin clamp technique, was compared in 40 normal subjects and 40 age- and weight-matched patients with noninsulin-dependent diabetes mellitus. These studies were conducted at steady-state plasma insulin levels of approximately 100 microU/ml, and the mean (+/- standard error of the mean) glucose metabolic clearance rate of patients with noninsulin-dependent diabetes mellitus was 81 +/- 9 ml/m2 per minute, as compared with a value of 235 +/- 14 ml/m2 per minute for normal subjects. This difference was highly statistically significant (p less than 0.001) and documents the extreme resistance to insulin-stimulated glucose utilization seen in noninsulin-dependent diabetes mellitus. Patients with noninsulin-dependent diabetes mellitus were also shown to have a lower than normal plasma insulin response to an oral glucose challenge. In contrast, ambient plasma insulin concentrations of normal subjects and patients with noninsulin-dependent diabetes mellitus were found to be quite comparable when measured throughout the day in response to the ingestion of conventional mixed meals. Consequently, absolute hypoinsulinemia is not characteristic of patients with noninsulin-dependent diabetes mellitus under conditions of daily living. Finally, the ability of intensive insulin treatment to improve insulin resistance was studied after one and six weeks of therapy. These results indicated that successful control of hyperglycemia led to a significant improvement in insulin action as early as one week after the initiation of insulin therapy, with no further changes noted after prolonged insulin administration. The degree to which insulin action approached normal values was greater when studies were carried out at circulating insulin levels of approximately 2,000 microU/ml as compared with insulin levels of approximately 100 microU/ml, but in both instances insulin-treated diabetic patients remained insulin-resistant as compared with normal subjects. These results have corroborated the fact that abnormalities of both insulin action and secretion can be documented in patients with noninsulin-dependent diabetes mellitus. However, patients with noninsulin-dependent diabetes mellitus were not found to be absolutely hypoinsulinemic in their daily existence, and control of their hyperglycemia with exogenous insulin did not restore insulin-stimulated glucose utilization to normal. Consequently, these data are not consistent with the view that the insulin resistance in noninsulin-dependent diabetes mellitus is entirely a secondary consequence of the hypoinsulinemia presumed to be present in these patients.
Adult↗
Does day-long absolute hypoinsulinemia characterize the patient with non-insulin-dependent diabetes mellitus?
Plasma glucose and insulin responses to a standard oral glucose tolerance test (75 g of glucose) and to mixed meals were compared in 15 normal subjects and 15 patients with non-insulin-dependent diabetes mellitus (NIDDM). Fasting plasma glucose levels were above 140 mg/dL in all patients with NIDDM, and the two groups were weight matched. Plasma glucose levels were significantly higher in patients with NIDDM throughout the glucose tolerance test, and this was associated with a marked reduction in plasma insulin response. Plasma glucose levels were also higher in patients with NIDDM when measured hourly from 8 AM to 5 PM (mixed meals were consumed at 8 AM and 12 PM), but the plasma insulin concentration of the two groups were similar. Thus, the day-long circulating insulin levels of patients with NIDDM are not reduced. Consequently, these patients cannot be considered to be absolutely insulin deficient.
Adult↗
Introduction of exogenous DNA into cotton embryos.
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Cloning, Molecular↗
Projections from the cochlear nucleus to the cerebellum.
The connections between the brainstem auditory system and the cerebellar auditory area in the posterior vermis (VI, VII, and VIIIA) were studied using the horseradish peroxidase technique. Injections also were made in the cerebellar hemispheres, the paramedian and the vestibulocerebellum (VIIIB, IX). Labeled cells were found in the cochlear nuclei bilaterally, but not in the superior olivary complex or the inferior colliculus. As the injection sites moved more laterally from the vermis area to the paramedian and the cerebellar hemispheres, the number of labeled cochlear nucleus neurons decreased progressively. This observation suggests that the terminals of the cochlear-nucleus-cerebellum projection tend to concentrate in the vermis auditory area. In the cochlear nucleus, labeled cells did not appear to belong to a single, homogenous cell type, nor did the cells group into a single area in the cochlear nucleus. The total number of labeled neurons in one cochlear nucleus did not exceed 200 in our largest injection.
Animals↗
Nucleoside salvage pathway for NAD biosynthesis in Salmonella typhimurium.
A previously undescribed nucleoside salvage pathway for NAD biosynthesis is defined in Salmonella typhimurium. Since neither nicotinamide nor nicotinic acid is an intermediate in this pathway, this second pyridine nucleotide salvage pathway is distinct from the classical Preiss-Handler pathway. The evidence indicates that the pathway is from nicotinamide ribonucleoside to nicotinamide mononucleotide (NMN) and then to nicotinic acid mononucleotide, followed by nicotinic acid adenine dinucleotide and NAD. The utilization of exogenous NMN for NAD biosynthesis has been reexamined, and in vivo evidence is provided that the intact NMN molecule traverses the membrane.
NAD↗
Cancer and specific red cell adherence test.
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Humans↗
Purification of trypsin by affinity chromatography with sulphamethoxazolum ligand.
Pharmaceuticals have already been studied comprehensively both in their physico-chemical properties and their biological effect. Most of these compounds are chemically synthesized and less susceptible to degradation by micro-organism or suffering from solvent effect compared with the bio-active substances. Affinity chromatographic columns composed of pharmaceutical compounds as the ligand should have advantages such as long life, low cost and low toxicity. This paper describes the preparation of sulphamethoxazolum immobilized on silica as the column packing and the study of its interactions with proteins and enzymes. It was found that this material showed an affinity specific to trypsin with a dissociation constant of around 10(-6) M. The enzymatic activity of commercial trypsin can be increased by a factor of ten after purification with such a column.
Adsorption↗
Integrin alpha(v)beta(3) is involved in stimulated migration of vascular adventitial fibroblasts by basic fibroblast growth factor but not platelet-derived growth factor.
We examined the effects of basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF) on the migration of vascular adventitial fibroblasts (VAFs) isolated from rat aortic adventitiae. Both bFGF and PDGF significantly stimulated VAF migration in vitro. An antibody to rat beta(3) integrin reduced bFGF-stimulated migration in a dose dependent manner. Moreover, VAF migration was inhibited in the presence of cyclic RGD (cRGD) peptide. However, PDGF-directed migration was blocked only by equivalent cRGD peptide but not by antibody to beta(3) integrin. These data suggest that alpha(v)beta(3) integrin mediates VAF migration stimulated by bFGF and that chemoattractant directed migration may be through distinct integrins.
Animals↗
CT appearance of ectopic pancreas: a case report.
The appearance of ectopic pancreas on computed tomography (CT) is described in a 47-year-old man with bowel obstruction. The enhancement pattern of ectopic pancreas after intravenous iodine contrast administration is the same as that of leiomyoma or carcinoid. This CT finding has not been reported previously to our knowledge.
Choristoma↗
Flexing and folding double helical DNA.
DNA base sequence, once thought to be interesting only as a carrier of the genetic blueprint, is now recognized as playing a structural role in modulating the biological activity of genes. Primary sequences of nucleic acid bases describe real three-dimensional structures with properties reflecting those structures. Moreover, the structures are base sequence dependent with individual residues adopting characteristic spatial forms. As a consequence, the double helix can fold into tertiary arrangements, although the deformation is much more gradual and spread over a larger molecular scale than in proteins. As part of an effort to understand how local structural irregularities are translated at the macromolecular level in DNA and recognized by proteins, a series of calculations probing the structure and properties of the double helix have been performed. By combining several computational techniques, complementary information as well as a series of built-in checks and balances for assessing the significance of the findings are obtained. The known sequence dependent bending, twisting, and translation of simple dimeric fragments have been incorporated into computer models of long open DNAs of varying length and chemical composition as well as in closed double helical circles and loops. The extent to which the double helix can be forced to bend and twist is monitored with newly parameterized base sequence dependent elastic energy potentials based on the observed configurations of adjacent base pairs in the B-DNA crystallographic literature.
Base Composition↗
Galactose metabolism and ovarian toxicity.
Galactose is an energy-providing nutrient and also a necessary basic substrate for the biosynthesis of many macromolecules in the body. Metabolic pathways for galactose are important not only for the provision of these pathways but also for the prevention of galactose and galactose metabolite accumulation. Problems with galactose metabolism can cause a variety of clinical manifestations in animals and humans. It has been found that the mammalian ovary is particularly susceptible to damage from the accumulation of galactose and galactose metabolites. The galactose metabolites Gal-1-P, galactitol, and UDPgal are all considered to be important in this toxicity and proposed mechanisms include interference with ovarian apoptosis and gonadotrophin signaling. This review addresses the most recent scientific findings regarding the possible mechanisms of galactose-induced ovarian toxicity and also the possible protective role of hormonal and antioxidant therapy. In addition, the available epidemiologic and scientific evidence linking galactose intake with risk of ovarian cancer is discussed.
Animals↗