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Biomedical subjects

A Angel

Publications and source records attributed to A Angel.

At least 109 records · Page 6Linked to original sources
PubMed1981

Composition and metabolism of very low density lipoproteins in dog cardiac lymph.

In the present study, very low density lipoprotein (VLDL, d less than 1.006) in cardiac lymph was characterized to determine its role as a metabolic substrate in the interstitial compartment. A major efferent cardiac lymph trunk was cannulated in fasting (18 h) dogs (20-27 kg). Three to five millilitres of lymph were collected over 3-4 h at 4 degrees C. Cardiac lymph VLDL concentration was 1.7 +/- 0.7 mg protein . 100 mL-1 compared with 1.8 +/- 0.8 mg protein . 100 mL-1 in plasma. The VLDL triglyceride concentration in lymph was 1.0 +/- 0.3 mg triglyceride . 100 mL-1 with triglyceride/protein ratio of 0.9 compared with plasma VLDL triglyceride of 5.0 +/- 1.6 mg . 100 mL-1 with a triglyceride/protein ratio of 5.5. Electron microscopy of VLDL revealed globular particles with a mean diameter of 388 A in lymph and 661 A in plasma. Thus, cardiac lymph VLDL are smaller and contain less triglyceride per particle than plasma VLDL. Following i.v. administration of human 125I-labelled low density lipoprotein ([125I]LDL, d 1.025-1.045), cardiac lymph/plasma LDL specific activity ratio was 0.52 +/- 0.15 (n = 3) and 0.55 +/- 0.15 (n = 4)) at 3 and 27 h, respectively. The fact that the specific activity ratio did not reach 1 at plateau suggests continuous addition of unlabelled LDL in the cardiac interstitium, presumably from VLDL precursors. These findings demonstrate that on a protein basis the concentration of VLDL in cardiac lymph equals that of plasma, and also suggests that VLDL degradation and LDL production occur in the cardiac interstitial space.

Animals↗
PubMed1981

Comparison study between acupuncture and pentazocine analgesic and respiratory post-operative effects.

The authors studied the effects of acupuncture and pentazocine on post-operative respiratory function and pain management on patients hysterectomized by means of a subumbilical midline incision. The acupunctural technique consisted of GB-26, St-36, Sp-6 and auricular Shen-Men bilateral electrostimulation for 40 minutes. The analgesic effect of acupuncture was equivalent to that of 30 mg pentazocine, yet the most important effect of acupuncture consisted in a net increase of vital capacity during the period of acupuncture analgesia that lasted for 3-4 hr after stimulation; contrariwise, pentazocine did not cause any vital capacity increment and vital capacity remained at the levels observed prior to narcotic administration.

Acupuncture Therapy↗
PubMed1981

Influence of acupuncture on the postoperative complications following ketamine anesthesia. The importance of manual stimulation of point R and shen menn.

The Authors have investigated the antihallucinogenic and sedative effects of auricular points R and shen menn during surgery under ketamine anesthesia. The results demonstrate that the insertion of the needle in point R is very efficient in reducing hallucinations of ketamine emergence, while the insertion of needle in auricular point shen menn causes only a brief period of sedation in the beginning of the emergence period. The acupunctural technique employed by the Authors has been shown to increase considerably approbation of ketamine anesthesia.

Acupuncture Therapy↗
PubMed1980

Effect of metrazol on the discharge characteristics of muscle spindle afferents from the hind limb of the rat.

The nature of altered fusimotor discharge induced by subconvulsive doses of Metrazol has been investigated in deeply anaesthetized rats. Large amplitude stretching (ramp and hold or sinusoidal) of the appropriate muscle during the course of drug action shows Metrazol to have a predominant gamma d effect on primaries, and an exclusive gamma s effect on secondaries in both plantar and dorsiflexors of ankle and toes. Small amplitude stretches revealed gamma s activity which large amplitude stretching failed to show. Experiments with convulsive doses of Metrazol show that this elevated spindle discharge precedes development of electromyographic activity. It is suggested that fusimotor activity must be considered when analysing the mechanisms of Metrazol-induced seizures in non-paralysed animals.

Animals↗
PubMed1980

Effect of catechol on the discharge of muscle spindle afferents from the hind limb of the rat.

Previous work had shown that some of the effects of catechol could be via the fusimotor system. In order to determine the extent of fusimotor involvement, recordings have been made from muscle spindle afferents in split dorsal root filaments of anaesthetised rats. Catechol failed to excite de-efferented muscle spindles therefore eliminating many possible non-fusimotor effects. Over 80% of spindle afferents with intact efferents showed increased discharge frequency 1 min after injection, this increase often following a biphasic pattern with a pronounced pre-myoclonic burst and decline followed by a more sustained period of activity during the myoclonic phase. Analysis of spontaneous twitches or twitches evoked by ipsilateral auditory stimulation showed in addition a phasic increase in discharge suggesting alpha-gamma co-activation. Both primary and secondary afferents from many muscle groups around ankle and toes had their discharge frequencies elevated. Elevation of discharge frequencies of secondaries implies increased gamma-s activity confirmed by a decrease in dynamic index. Both gamma-d and gamma-s involvement in catechol action on primaries is suggested by dynamic index measurements. Perhaps a more continuous form of testing such as sinusoidal stretches would reveal any rapid switching between activities in the two systems.

Afferent Pathways↗
PubMed1980

Pressure reversal of the effect of urethane on the evoked somatosensory cortical response in the rat.

1 The cerebral response evoked by stimulation of the forepaw in the rat shows an increase in latency and decrease in the amplitude of its initial components as anaesthetic dose (urethane) is increased. 2 These changes are reversed if the ambient pressure is increased with helium and the electrocorticogram shows an increase in basic frequency. 3 The dose of urethane needed to prevent reflex response to tail stimulation is increased as pressure increases. 4. The implications of these behavioural and somatosensory responsiveness changes as pressure is increased are discussed.

Animals↗
PubMed1979

Synthesis of fatty acids and cholesterol by liver, adipose tissue and intestinal mucosa from obese and control patients.

Biopsies of adipose tissue, liver and small bowel mucosa obtained from grossly obese and control subjects were used to study absolute rates of fatty acid, cholesterol, and other nonsaponifiable lipid synthesis using glucose as substrate and 3H2O as the isotopic marker. Fatty acid synthesis in subcutaneous adipose tissue expressed on a cell basis was greater in obese than control subjects and was stimulated by a high concentration of insulin (1000 micro U/ml), but not by a lower amount (100 micro U/ml). Fatty acid synthesis in omental adipose tissue exceeded by 3-fold that of subcutaneous fat. Fatty acid synthesis in obese liver was twice that of control liver and 20 times greater than obese adipose tissue. In terms of total organ activity fatty acid synthesis in fat tissue equalled or exceeded that of liver in both obese and control subjects. The cholesterol content of obese adipose tissue 1.86 +/- 0.11 mg/g exceeded that of controls 1.47 +/- 0.07 mg/g. All tissues examined synthesized cholesterol and nonsaponifiable lipids, liver greater than adipose tissue greater than small bowel mucosa. Nonsaponifiable lipid synthesis per gram of adipose tissue or liver was similar in obese and control tissue. The synthesis of total nonsaponifiable lipids including sterols, hydrocarbons and squalene was appreciable in adipose tissue and was approximately 15% of that of liver. However, cholesterol synthesis in the liver exporessed in terms of total organ activity was 50 times that in adipose tissue. The study demonstrates by direct comparison that liver is the dominant cholesterogenic organ in man and also shows that adipose tissue is a significant site of formation of fatty acids and nonsaponifiable lipids.

Adipose Tissue↗
PubMed1979

Low density lipoprotein binding, internalization, and degradation in human adipose cells.

Human adipose tissue derives its cholesterol primarily from circulating lipoproteins. To study fat cell-lipoprotein interactions, low density lipoprotein (LDL) uptake and metabolism were examined using isolated human adipocytes. The 125I-labelled LDL (d = 1.025-1.045) was bound and incorporated by human fat cells in a dose-dependent manner with an apparent Km of 6.9 + 0.9 microgram LDL protein/mL and a Vmax of 15-80 microgram LDL protein/mg lipid per 2 h. In time-course studies, LDL uptake was characterized by rapid initial binding followed by a linear accumulation for at least 4 h. The 125I-labelled LDL degradation products (trichloroacetic acid soluble iodopeptides) accumulated in the incubation medium in a progressive manner with time. Azide and F- inhibited LDL internalization and degradation, suggesting that these processes are energy dependent. Binding and cellular internalization of 125I-labelled LDL lacked lipoprotein class specificity in that excess (25-fold) unlabelled very low density lipoprotein (VLDL) (d less than 1.006) and high density lipoprotein (HDL) (d = 1.075-1.21) inhibited binding and internalization of 125I-labelled LDL. On an equivalent protein basis HDL was the most potent. The 125I-labelled LDL binding to an adipocyte plasma membrane preparation was a saturable process and almost completely abolished by a three- to four-fold greater concentration of HDL. The binding, internalization, and degradation of LDL by human adipocytes resembled that reported by other mesenchymal cells and could account for a significant proportion of in vivo LDL catabolism. It is further suggested that adipose tissue is an important site of LDL and HDL interactions.

Adipose Tissue↗
PubMed1979

Inhibition of rat and human adipocyte adenylate cyclase in the antilipolytic action of insulin, clofibrate, and nicotinic acid.

Clofibrate (Atromid-S), nicotinic acid, and insulin are known to be potent hypolipidemic and antilipolytic agents. The present study was undertaken to define the mechanism of action of this latter effect on isolated rat and human fat cells. Sodium clofibrate (0.42 mM), nicotinic acid (0.42 mM), and insulin (100 microU/mL) were shown to inhibit norepinephrine-stimulated lipolysis in rat and human adipose cells and this inhibition was associated with a reduction in intracellular 3',5'-cyclic AMP levels. A similar cyclic AMP lowering effect was demonstrated with insulin in the presence of procaine-HCL, which uncouples the adenylate cyclase system from lipolysis. This insulin effect was attributed to inhibition of adenylate cyclase. A direct and significant inhibition of adenylate cyclase in membrane fractions obtained from isolated human adipocytes was demonstrated for all three antilipolytic agents. The common membrane site of action of these agents whereby adenylate cyclase activity is depressed, thus decreasing cyclic AMP production and free fatty acid (FFA) mobilization from adipose stores, implies a central role for the adenylate cyclase system. These findings are consistent with the view that the hypotriglyceridemic effects of clofibrate, nicotinic acid, and insulin may be partly explained by deprivation of FFA substrate for hepatic very low density lipoprotein synthesis.

Adenylyl Cyclase Inhibitors↗
PubMed1979

Appearance and characterization of lipoprotein X during continuous intralipid infusions in the neonate.

The development of hyperphospholipidemia and hypercholesterolemia was studied in infants that required total parenteral nutrition and given a continuous infusion of Intralipid, (1-4 g/kg body wt per 24 h. Detailed studies were carried out on infusion periods lasting 1-10 d. After 24 h there was a marked increase in plasma free cholesterol (68%) and phospholipid (77%) concentrations. Based on the amount of cholesterol in Intralipid, and the rate of infusion, it was estimated that at least 50% of the plasma cholesterol increment during 64-h infusions was derived from endogenous sources. By contrast, the hyperphospholipidemia could be attributed to the Intralipid as the rise in plasma was calculated to be equivalent to only 16% of the exogenous phospholipid infused. Approximately 10% of the phospholipid in Intralipid was in a triglyceride-free mesophase form with a free cholesterol:phospholipid molar ratio of 0.063. There were no systematic changes in plasma concentrations of cholesterol ester or triglyceride during Intralipid infusions. The increase in free cholesterol and phospholipid was localized in the low density lipoproteins (d = 1.006-1.063 g/ml). The presence of lipoprotein X (Lp-X) in the low density lipoprotein fraction was demonstrated by electrophoresis in agar and by isolation and chemical characterization with hydroxylapatite chromatography. Isoelectric focusing of urea-soluble protein of Lp-X revealed that albumin and apolipoproteins CII and CIII were major components, whereas apolipoprotein E and AI were minor constituents. The abnormal lipoprotein was apparent by 16 h during 64 h of infusion. After 6 d of continuous infusions the free cholesterol in Lp-X was 30+/-10 mg/dl (mean+/-SD), which represents a total Lp-X mass of 90 mg/dl. After cessation of the infusion, Lp-X, as monitored by electrophoresis in agar, disappeared within 72-96 h. Thus, during infusion of Intralipid in infants at rates commonly employed, the capacity of the clearance mechanisms for phospholipid are exceeded, which causes the accumulation of phospholipid and free cholesterol in the form of Lp-X particles. It is suggested that mesophase phospholipids in Intralipid may play a significant role in this process.

Apolipoproteins↗
PubMed1979

Thrombosis and free fatty acids in patients subjected to total hip arthroplasty.

The plasma concentrations of free fatty acids were estimated at intervals before, during and after total hip arthroplasty in seven patients. Each patient underwent examination for deep vein thrombosis with iodine-125 leg scanning, impedance plethysmography and contrast venography. Substantially higher concentrations of free fatty acids were found in the plasma of patients shown to have thrombosis than in those without thrombosis.

Aged↗
PubMed1979

Pancuronium bromide precurarisation. II An evaluation of clinical aspects in patients of female sex.

The authors have studied the effects of precurarisation by means of pancuronium on 120 female patients by using three multiple doses of pancuronium bromide. The authors have demonstrated that the dose of pancuronium, capable of abolishing almost completely fasciculations and postoperative succinylcholine myalgias, corresponds to 0.009 mg/kg. This dose has proved to be most efficient in causing a considerable increase in subjective precurarisation symptoms (Heavy eye-lids, blurred vision etc.). Such symptoms have never caused even the least discomfort to the patients. The authors have finally demonstrated that the doses of pancuronium employed cause a decrease in V.C. within limits that do not, however, compromise ventilation.

Adult↗
PubMed1978

Pathophysiologic changes in obesity.

Obesity is the common expression of several diverse interacting genetic, familial and environmental factors. In addition to having hypertrophic fat cells because of inordinate triglyceride accumulation, many patients with childhood-onset obesity and those who are massively obese regardless of age at onset have an excessive number of adipocytes. Several endocrinologic and metabolic abnormalities are associated with obesity. Triglyceride formation in and lipid mobilization from hypertrophic adipocytes are exaggerated. The increased availability of free fatty acids to the liver contributes to the excessive synthesis of triglycerides and very-low-density lipoproteins; thus, hypertriglyceridemia is frequently associated with obesity. Hepatic synthesis and biliary excretion of cholesterol are also increased. Most of the excess cholesterol is stored in fat cells. The plasma concentrations of high-density lipoproteins are decreased. Hyperinsulinemia, which is characteristically found in the obese, leads to a decreased number of insulin receptors in target cells. The relative insulin insensitivity of the obese frequently results in glucose intolerance. The endocrinologic and metabolic abnormalities are correctable by an appropriate program of meal planning and physical activity.

Adipose Tissue↗
PubMed1978

Medical complications of obesity.

Obesity leads to several complications that affect many body systems. This paper focuses mainly on the cardiovascular complications, which include coronary heart disease, cerebrovascular disease and stroke, and congestive heart failure; the last may be secondary not only to advanced coronary atherosclerosis, but also to other pathogenetic factors. The increased frequency of coronary heart disease in the obese is largely attributable to the commonly associated hypertension, diabetes mellitus and lipoprotein abnormalities, rather than the adiposity. The lipoprotein disorders that have a role in atherogenesis are decreased plasma concentrations of high-density lipoproteins and elevated plasma concentrations of low-density lipoproteins. Abnormalities in cholesterol metabolism are responsible for the increased frequency of cholelithiasis in obese persons. The factors that mediate the development of cardiovascular and gallbladder complications are correctable by an appropriate program of meal planning and physical activity.

Adult↗
PubMed1978

A pharmacological investigation of the electrically evoked convulsive activity induced by administration of catechol in the anaesthetized rat.

1 The response evoked by electrical stimulation at the wrist has been recorded from muscles of the forelimb of anaesthetized rats induced to convulse by administration of catechol.2 This response can be divided into three temporally distinct components, the characteristics of which have been described.3 The probability of occurrence of the two early components of the response has been measured before and after administration of various drugs. The results show that the first component is not affected by cholinoceptor or adrenoceptor blocking drugs or anticholinesterase agents. The probability of occurrence of the second component is significantly reduced by cholinoceptor blocking drugs and increased by physostigmine.4 The implications of these results in explaining the convulsant actions of catechol are discussed.

Animals↗