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Biomedical subjects

M Ivanov

Publications and source records attributed to M Ivanov.

16 recordsLinked to original sources
PubMed2001

Event-by-event fluctuations of the Kaon-to-Pion ratio in central Pb+Pb collisions at 158 GeV per nucleon.

We present the first measurement of fluctuations from event to event in the production of strange particles in collisions of heavy nuclei. The ratio of charged kaons to charged pions is determined for individual central Pb+Pb collisions. After accounting for the fluctuations due to detector resolution and finite number statistics we derive an upper limit on genuine nonstatistical fluctuations, which could be related to a first- or second-order QCD phase transition. Such fluctuations are shown to be very small.

Journal Article↗
PubMed1996

Planetary protection program for Mars 94/96 mission.

Mars surface in-situ exploration started in 1975 with the American VIKING mission. Two probes landed on the northern hemisphere and provided, for the first time, detailed information on the martian terrain, atmosphere and meteorology. The current goal is to undertake larger surface investigations and many projects are being planned by the major Space Agencies with this objective. Among these projects, the Mars 94/96 mission will make a major contributor toward generating significant information about the martian surface on a large scale. Since the beginning of the Solar System exploration, planets where life could exist have been subject to planetary protection requirements. Those requirements accord with the COSPAR Policy and have two main goals: the protection of the planetary environment from influence or contamination by terrestrial microorganisms, the protection of life science, and particularly of life detection experiments searching extra-terrestrial life, and not life carried by probes and spacecrafts. As the conditions for life and survival for terrestrial microorganisms in the Mars environment became known, COSPAR recommendations were updated. This paper will describe the decontamination requirements which will be applied for the MARS 94/96 mission, the techniques and the procedures which are and will be used to realize and control the decontamination of probes and spacecrafts.

Containment of Biohazards↗
PubMed1996

Selection of sterilization methods for planetary return missions.

Two tasks must be accomplished to provide planetary protection for Mars return missions: (1) sterilization of the scientific module to be landed on Mars and (2) reliable sterilization of all material returned to Earth, while ensuring the scientific integrity of martian samples. This paper examines similarity and differences between these two tasks, and includes a discussion of technological implementation conditions and the nature of terrestrial and hypothesized martian microflora. The feasibility of a number of chemical and physical (ultraviolet and ionizing radiation and heating) methods of sterilization for use on the ground and onboard are discussed and compared. A combination of different methods will probably be selected as the most appropriate for ensuring planetary protection on the return mission.

Containment of Biohazards↗
PubMed1996

Complementary distal arteriovenous fistula and deep vein interposition: a five-year experience with a new technique to improve infrapopliteal prosthetic bypass patency.

PURPOSE: In an attempt to improve graft patency results of prosthetic bypasses to infrapopliteal arteries, we used a new type of adjunctive technique that combines an arteriovenous fistula and vein interposition (AVF/VI). METHODS: Over the past 5 years, 68 such reconstructions were performed in 62 patients with critical ischemia in whom a totally autogenous vein bypass was not feasible. Forty-seven patients (76%) had one or more failed ipsilateral infrainguinal bypasses. The AVF/VI was performed by transposing the central portion of the adjacent deep vein onto the side of the recipient artery. The distal end of a 6-mm polytetrafluoroethylene (PTFE) ringed graft then was anastomosed to the hood of the AVF. The segment of vein interposed between the PTFE graft and the recipient artery widened the anastomosis and improved the compliance mismatch. Simultaneous pressure measurements of the radial artery and the distal portion of the graft were obtained in all cases. RESULTS: Significant pressure gradients ranging from 35 to 70 mm Hg were detected in 26 bypasses (38%), which led to banding of the venous outflow that decreased the gradient to within 20 mm Hg. A gradient < or = 30 mm Hg was found in 28 bypasses (41%), and no banding was required if the absolute intragraft systolic pressure was > or = 100 mm Hg. Only 14 bypasses (21%) had no detectable pressure gradients. Twenty-six bypasses originated from femoral arteries, 34 from iliac arteries, and 8 from patent proximal grafts. The recipient arteries were the anterior tibial artery in 33 cases, posterior tibial in 17, peroneal in 15, dorsalis pedis in 2, and lateral plantar in 1. All patients began a regimen of heparin 6 to 8 hours after surgery and continued to receive chronic anticoagulation. Cumulative, 3-year assisted primary graft patency rates were 78%, 70%, and 62%, respectively. Cumulative 3-year AVF patency rates were 65%, 57%, and 46%, respectively. The 3-year limb salvage rate was approximately 78%. CONCLUSION: Adjunctive AVF/VI significantly improves infrapopliteal PTFE graft patency and limb salvage rates. The combination of a decreased compliance mismatch at the distal anastomosis and the abolishment of a large pressure gradient at the distal anastomosis while maintaining higher graft flow rates may have contributed to the improved results.

Aged↗
PubMed1996

The natural history of the external carotid artery after carotid endarterectomy: implications for management.

PURPOSE: Most surgeons perform some type of endarterectomy of the external carotid artery (ECA) routinely during standard carotid endarterectomy (CEA). This approach has been shown to result in a small percentage of ECA occlusions, the clinical significance of which remains poorly understood. We have modified our approach to the management of the ECA during standard CEA by averting any attempt at external CEA. To evaluate the natural history of the untreated ECA after CEA, we reviewed the preoperative, postoperative, and follow-up duplex scans obtained from 232 CEAs over the past 4 years. METHODS: Preoperative and postoperative carotid artery duplex examinations with specific evaluation of the extent of ECA stenosis were available for review on 114 CEAs performed between January 1991 and July 1994. All CEAs were performed for internal carotid artery stenosis greater than 75% as determined by duplex scanning, which was confirmed by either contrast arteriography or magnetic resonance angiography. RESULTS: Seventy-three (64.0%) procedures were performed for symptomatic lesions, whereas 41 (36.0%) were performed for asymptomatic stenosis. There were no perioperative strokes or transient ischemic attacks in this group, and there was one postoperative death (0.9%). Short- and intermediate-term follow-up demonstrated insignificant changes in ECA diameter after operation, with no cases of ECA occlusion and only five cases progressing to greater than 75% on the 1-year follow up duplex examination. CONCLUSION: We conclude from these data that averting external CEA during standard CEA does not result in significant progression of ECA stenosis or occlusion.

Aged↗
PubMed1990

Late EEG after-effects in humans following hyperventilation. I. A comparison between intero- and exteroceptive influences.

Using a modification of the computer period analysis of the EEG (Aladjov and Daskalova 1987) we studied the late after-effects (until the 30th min) in human EEG (monopolar leads at F1, C3, P3 and 01) following two kinds of influences: a) short interoceptive one: 3 min hyperventilation (HV) and b) a series of 5 trains of visual light flashes (VS), presented in 5-7 min intervals. The changes in the ongoing EEG in the 2nd min after each VS and in intervals of 5 min after HV were compared with the values before the stimulation. VS did not elicit long-lasting EEG after-effects, which characterized the single interoceptive influence (HV) and consisted mainly of beta-2 (24-36 Hz) EEG activity increase in all studied cortical regions (Nikolov and Kisselkova 1988). Moreover, the exteroceptive stimulation (VS) had no essential influence on the late EEG after-effects after HV, when both kinds of stimulation were applied in the same experiment.

Adult↗
PubMed1990

Late EEG after-effects in humans following hyperventilation. II. A comparison between subjects with different level of adaptation to hypoxia.

The late EEG after-effects following application of a short-lasting ventilatory interoceptive influence (3 min hyperventilation-HV) were studied in humans with three degrees of adaptation: students (ST) with a lower degree of training, professional alpine climbers with a high level of training (AL1) and the same subjects (AL2) in a middle position of adaptation i.e. 6 months after an expedition. ST developed late EEG after-effects, consisting mainly in an increase of the beta-2 EEG activity; AL1 showed very slight changes, while in AL2 the EEG after-effects were intermediate. It is suggested, that a lower level of adaptation facilitates the triggering through HV of processes in the cortical EEG which accompany an improvement of the brain tone.

Adaptation, Physiological↗
PubMed1979

[New sorbents for industrial gas marks with a visual reading of their depletion].

The current status of problems, referrable to the use of industrial gas masks, is reviewed, with special reference to the type of sorbent to be used, the pathways of gas mask modernization in respect of the sorbents used, and the modern trends in adsorption cartridge manufacturing; decrease of weight, alleviated construction, adjustment to serve definite toxico-chemical agent, use of ion-exchange resins and hemosorbents. Aspects are discussed for producing sorbents, permitting visual registration of filter mass exhaustion, i.e. sorbents wtih alternating color in the process of sorption, with the purpose of increasing gas mask security and efficiency. The physico-chemical parameters of reference hemosorbent samples with alternating color in the process of sorption were compared with those of widely used sorbents - active carbon (specially processed and crude) and ion-exchange resins: relative dynamics, aktivity protection time, weight, mass activity, etc. Inferences are drawn from which one may see, that these new hemosorbents are highly perspektive, and their industrial acceptance is justifiable.

Adsorption↗
PubMedDate not supplied

[Obesity, hypertension and the lumbar syndrome in workers at the Neoplanta Meat Plant in Novi Sad].

INTRODUCTION: Obesity is more and more considered a serious medical problem associated with hyperlipoproteinemia, diabetes, cardiovascular disease, locomotor system diseases not only in the workers with hypertension and increased body fat, but also in the workers with lumbar syndrome. The objective of this study was to examine obesity and trends in frequency of lumbar syndrome and hypertension in workers employed in the meat industry, starting from the premise that obese workers are more prone to developing lumbar syndrome, hypertension or both diseases jointly. MATERIAL AND METHODS: The following data: sex, age, years of employment in meat industry, body mass and height were filled out in the epidemiological questionnaire. The sample represented 36% of the statistical mass--475 examined subjects, 285 men and 190 women. The workers were divided by BMI values into the following groups: normal weight, overweight, significantly obese and extremely obese. Frequency of lumbar syndrome and hypertension among obese and normal weight workers were tested, p < 0.05. RESULTS: The obtained results showed that 34.31% of the examined workers were with normal weight, 43.58% overweight, 20.84% significantly obese and 1.26% extremely obese. Tested occurrence of lumbar syndrome among normal and overweight workers, value chi 2 = 2.80, showed no significant difference, while there was difference in hypertension chi 2 = 11.7 and in both diseases jointly chi 2 = 12.25. However, significant frequency of lumbar syndrome, chi 2 = 5.26, hypertension, chi 2 = 39.72 and both diseases jointly chi 2 = 37.25 was found among normal weight and obese workers. DISCUSSION: It should be pointed out that increase in body mass leads to significant increase in both diseases jointly, not just hypertension. The absence of significant difference of lumbar syndrome, chi 2 = 2.80, is to be associated with the shorter length of service. On determining the share of lumbar syndrome in absenteeism the relation of obesity and imbalanced nutritional patterns has to be taken into consideration. CONCLUSION: With the increase of body mass, frequency of occurrence of hypertension and lumbar syndrome accompanied with hypertension increases too.

Female↗
PubMedDate not supplied

[Cardiovascular disease risk factors in product quality control workers at the AD Neoplant facility in Novi Sad].

INTRODUCTION: Monitoring the health status of the employed in the meat industry "Neoplanta", a high prevalence of cardiovascular risk factors was observed. It was also observed that workers employed in the meat industry have specific dietary habits as a result of working practice. Their hypercaloric diet is with high dietary animal fat and protein intake. This particularly refers to the group of workers in charge of the quality control of meat products who, besides regular hot meal and frequent business lunches, consume certain quantities of these products on a daily basis. A common characteristic shared by members of this group is that they very seldom or never have preventive medical examination. OBJECTIVE: The objective of this paper was to determine cardiovascular risk factors in this group of workers and to evaluate educational program effects on the prevalence of risk factors. MATERIAL AND METHODS: Cardiovascular risk factors were examined in 39 workers (28 men and 11 women) involved in the daily control of meat products and performing executive jobs of different complexity levels in the meat industry "Neoplanta". Cardiovascular risks and lipid status were examined before and after a nine-month-long educational program. Occurrence of increased risks and lipid status elements were tested, p < 0.05. RESULTS: According to obtained results hypercholesterolemia is present in 94.87%, obesity in 82.05%, positive family cardiovascular anamnesis in 74.48%, physical inactivity in 69.33%, continuous alcohol consumption in 69.23%, excessive consumption of black coffee in 61.54%, hypertension in 51.28%, "stress alleviation" with food in 46.15%, hypertriglyceridemia in 46.15% and cigarette smoking in 46.15% of examinees. Cigarette smoking, chi 2 = 1.85, alcohol consumption, chi 2 = 0.26, black coffee drinking, chi 2 = 0.22, preparation of the meals on the fat, chi 2 = 0.10 has remained unchanged after educational program. The number of patients "alleviating" stress with food, chi 2 = 5.26 and physically inactive patients, chi 2 = 1.06 has significantly increased. Body mass, chi 2 = 0.06 and hypertension, chi 2 = 1.42, has not reduced, hyperholesterolemia has remained unchanged, chi 2 = 2.22, LDL-cholesterol has decreased insignificantly, chi 2 = 0.60, while HDL-cholesterol has decreased significantly, chi 2 = 4.27. Atherosclerosis index has increased significantly, chi 2 = 4.47. Thus, poor effects of the educational program can be attributed to unchanged lifestyle habits of the examined workers. CONCLUSION: It can be concluded that cardiovascular risk factors as well as lipid status elements have not decreased in this group of workers after educational program and therefore continuous medical educational program is suggested with purpose to increase the motivation of workers.

Adult↗