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Biomedical subjects

V Popovic

Publications and source records attributed to V Popovic.

At least 73 records · Page 4Linked to original sources
PubMed1991

Long-term outcome following trabeculectomy: II Visual field survival.

The long-term changes of the visual field defects of 54 glaucoma patients operated on with trabeculectomy were reviewed. Five years after operation 28% of the patients had suffered from further loss of visual field despite lowering of the intraocular pressure (IOP). All but three of these patients had their postoperative IOP regulated within statistically normal levels (11-21 mmHg). All patients with continued loss of postoperative field were generated from groups of patients with milder to moderate preoperative field defects (stages 0-III classification of Aulhorn, 1979). No patients suffered from sudden field loss after surgery. The mean of the preoperative IOP and the mean of the percent IOP reduction postoperatively were not significantly different in patients with or without continued postoperative visual field loss. This indicates that other factors than normalization of intraocular pressure play an important role in the group of patients with progression of visual field defects following surgery.

Aged↗
PubMed1990

Cushing's disease cycling over ten years.

Cycles of excessive cortisol secretion have been reported interposed with phases of remission lasting from few days to several months. In this study we report a ten year follow up on a patient who had four episodes of hypercortisolism and Cushing's syndrome associated with hypokalemia and edema and three long lasting spontaneous remissions. This was all caused by corticotroph pituitary adenoma. She demonstrated the longest phase of remission yet recorded in this condition, 4.5 years. The precipitating factors for the recurrence in cyclical Cushing's syndrome are not well defined, but the last recurrence in our patient appeared two months after delivery. We have discussed the continuing uncertainty of the standard dynamic tests in the differential diagnosis of Cushing's syndrome.

Adenoma↗
PubMed1990

Comparison of propofol and thiopental/halothane for short-duration ENT surgical procedures in children.

Experiences with propofol in pediatric anesthesia are limited. We undertook a study to evaluate the quality of induction and recovery from anesthesia with propofol compared to thiopental/halothane. Twenty children received 3 mg.kg-1.min-1 of propofol as a loading dose followed by a maintenance dose of 0.1 mg.kg-1.min-1 (+/- 10%). Twenty children received 5-7 mg/kg of thiopental, and maintenance was provided with halothane (0.5%-1.5%). The interval between the end of the administration of propofol or thiopental/halothane and extubation, as well to discharge to the ward, was significantly shorter with propofol (4.4 versus 13.5 min and 7.22 versus 30.4 min, respectively). Spontaneous movements and pain on injection were seen significantly more frequently with propofol, whereas laryngospasm and hiccup were only observed with thiopental. During the first 6 h after the surgical procedure, analgesics were needed significantly more often in the thiopental group. Nausea and vomiting also were observed more frequently in the thiopental group. In conclusion, propofol used as a single anesthetic is a satisfactory technique for ENT surgery of short duration in children.

Anesthesia, Inhalation↗
PubMed1988

Androgen levels during sequential insulin euglycemic clamp studies in patients with polycystic ovary disease.

It is postulated that insulin may play a role in the regulation of ovarian androgen production. In order to test the possible interrelation between serum insulin levels and androgen production, sequential euglycemic insulin clamp (Mode 9:1 on Biostator, insulin infusion rate: 0.1; 0.2 and 0.4 U/kg b. wt/h, each rate for 90 min, BC = 80 mg/dl) was done in 6 patients with polycystic ovary disease and normal glucose tolerance. Insulin, C-Peptide, testosterone and dehydroepiandrosterone-sulphate were measured in 0, 70, 80, 90, 160, 170, 180, 250, 260 and 270 min. Significant suppression of C-Peptide levels were achieved (0 min vs 270 min = 0.81 + 0.25 vs 0.15 + 0.20 nmol/l; P less than 0.05). Basal insulin as well as the mean plateau for each insulin infusion rate were as follows: 28 + 9; 248 + 119; 427 + 69 and 524 + 77 microU/l. There was significant testosterone increase at the end of insulin infusion (0 vs 270 min = 4.8 + 1.2 vs 8.1 + 1.7 nmol/l; P less than 0.05). There were no significant changes in dehydroepiandrosterone-sulphate levels during clamp studies (0 vs 270 min = 1055 + 133 vs 913 + 114 ng/ml; P greater than 0.05). It is concluded that acute insulin infusion under the condition of sequential euglycemic clamp could increase androgen production in the ovaries of patients with PCO.

Adult↗
PubMed1988

Long-term study of 435 MHz radio-frequency radiation on blood-borne end points in cannulated rats. Part I: Engineering considerations.

To study the effects of exposure to long-term, low-level radio-frequency radiation (RFR) on various physiological systems in a large population of rodents, a complete exposure facility was designed and constructed at the Georgia Institute of Technology. The major components of the facility included a set of circular, stacked, parallel-plate waveguides fed by slotted-cylinder antennas. The waveguides provided a TE10 mode, horizontally polarized field in which the maximal power density occurred midway between the parallel plates. The feed antenna and the parallel-plate waveguides generated a field that radiated outward and was uniform in the azimuthal plane. Thus, animals arrayed along the periphery of the plates were exposed to a uniform 1.0 mW/cm2 field (1.0 microsecond pulse width, 1 kHz pulse repetition rate, 435 MHz carrier). The facility transmitter provided four channels of 435 MHz RFR at 200 W average (continuous wave) or 5 kW peak (pulsed-wave) power; in addition, the transmitter outputs could be combined into a single channel capable of energizing one tier of the stacked parallel-plate waveguide system at 800 W continuous wave or at 16 kW of pulsed waves. To individually house the 200 rodents involved in the study, both biological and engineering criteria were examined and used to design and construct special Plexiglas cages.

Animal Husbandry↗
PubMed1988

Long-term study of 435 MHz radio-frequency radiation on blood-borne end points in cannulated rats. Part II: methods, results, and summary.

This study investigated the effects of long-term, low-level exposure to radio-frequency radiation (RFR) on various physiological systems in a large rodent population. Two hundred adult male white rats with chronically implanted aortic cannulas were randomly divided into two groups. Animals in the first group were exposed to the low-level RFR environment for approximately 22 hours daily, seven days a week, for six months. Depending on animal orientation within the home cage (all animals singly caged) the estimated whole-body specific absorption rate (SAR) ranged from 0.04 to 0.4 W/kg. The estimated mean whole-body SAR ranged from 0.3 W/kg (medium-sized rats) to 0.35 W/kg (large-sized rats). A second, sham-exposure group was maintained under identical conditions, but were not radiated. Microsamples of blood were withdrawn on a cyclic schedule from the unanesthetized and unrestrained rats. The blood samples were assayed for plasma adrenocorticotropin (ACTH), plasma corticosterone, plasma prolactin, plasma catecholamines (norepinephrine, epinephrine, and dopamine), hematological end points (hematocrit ratio, complete red blood cell count, complete white blood cell count, and a differential count of neutrophils, eosinophils, and monocytes), and cardiovascular end points (heart rate and mean arterial blood pressure). Analysis of the results showed no significant RFR-induced differences in these end points when the RFR-exposed group was compared to the sham-exposed group. Chronic exposure to the low-level, pulsed field resulted in no adverse effects on animal health, as measured by the spectrum of blood-borne end points.

Adrenocorticotropic Hormone↗
PubMed1988

Two cases of primary bilateral malignant melanoma of the choroid.

The first two Swedish cases of primary bilateral malignant melanoma of the choroid are presented. In one case bilateral histological confirmation was obtained as both eyes were enucleated. In the other case one eye was enucleated and the other irradiated with an episcleral ruthenium plaque. Sweden has a population of 8.38 millions, so that bilateral choroidal melanomas may be less rare than previously thought.

Aged↗
PubMed1988

Adaptation to restraint in the rat.

Use of telemetry in physiological research is still in early stages. Cardiovascular studies planned for gravitational work during the next few years on primates or squirrel monkeys depend on restraint devices. Two rat cardiovascular experiments (US Space Lab SLS I and SLS II) use unrestrained rats for resting cardiovascular measurements (chronic intravascular cannulas and implanted blood flow probes), but employ semi-restrained animals for microcirculatory investigations. Prior to weightlessness, these instrumented rats will be exposed a number of times to semi-restraint. In order to ascertain if there is adaptation to restraint (decreased toward normal of plasma stress hormones), the rats were exposed 18 times to restraint chambers, but the level of stress hormones stayed elevated.

Adaptation, Physiological↗
PubMed1985

Survival of hypothermic dogs after 2-h circulatory arrest.

Adult mongrel dogs were rapidly cooled to a body temperature of 4-5 degrees C with a combination of internal (core) cooling and external surface cooling. All dogs survived profound cooling and 2-h circulatory arrest when profound hemodilution and drainage of the left ventricle were used during cooling and when preferential microwave chest rewarming and hypervolemia were employed during rewarming. After recovery no permanent neurological damage was observed. The histology of the brain and heart of animals killed 6 mo after the cooling indicated normal tissue. When during rewarming the selective microwave chest heating was not used, fewer dogs survived the 2-h circulatory arrest.

Animals↗
PubMed1982

Circadian rhythm and 5-fluorouracil toxicity in C3H mice.

In order to study the effect of daily (circadian) rhythm on toxicity of an anticancer drug, 5-fluorouracil, adult female C3H mice were used in this work. A dose of 200 mg/kg of 5-FU was administered intraperitoneally to the animals. Body weights and animal mortality were observed daily during the following 21 days after administration of the drug. The most severe toxic effect of 5-FU, with 100% mortality, was observed when the drug was administered at 4 am, whereas at 12 am 5-FU was least toxic. Since C3H mice are nocturnal animals, they are at the peak activity in the early morning hours of the day. Thus, it seems that an increased 5-FU toxicity in C3H mice coincides with an increased metabolic rate and other physiological processes of these nocturnal animals.

Animals↗
PubMed1978

Treatment of experimental cerebral infarction in rats with levodopa or with glycerol.

Administration of large amounts of levodopa did not improve survival rates of rats after acute cerebral infarction induced by injection of carbon microspheres. However, when 10% glycerol was used, the number of rats that survived after cerebral infarction was significantly greater than in the control or in the levodopa-treated rats. Combination of levodopa and glycerol therapy also significantly improved the survival rate of beneficial effect. Pathological findings (gross or microscopic) indicate striking changes in brain tissue after embolization. Development of brain edema of the infarcted left hemisphere corresponded to the type of treatment and to the length of animal survival. Brain-tissue histology indicates that glycerol-treated animals developed less severe edema and had less tissue disruption than control animals. The results suggest that treatment of edema should be one of the primary steps in therapy after acute cerebral infarction.

Animals↗