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Biomedical subjects

B Dimitrov

Publications and source records attributed to B Dimitrov.

At least 55 records · Page 3Linked to original sources
PubMed1982

Brain potentials related to voluntary sustained effort.

The task of the present study was the investigation of the brain potentials while performing a complex motor task, including voluntary sustained contraction (thumb opposition to the index finger). The fast press of a transducer was sustained for periods of 1.5, 5 or 10 seconds, followed by fast release. Potentials related to the start of the contraction were registered (Bereitschaftspotential, N2, etc.) with considerable interindividual variability. The end of the contraction was preceded, too, by a slow potential, similar to Bereitschaftspotential, with prevailing positivity over frontal areas and negativity over postcentral areas; N2 at the release was well expressed, regardless of the polarity of the preceding slow potential. During the sustained contraction a steady positivity was registered. The presence of potentials related to the start as well as to the end of the voluntary effort suggests the existence of two separate commands. The positivity sustained throughout the contraction, strongly expressed frontally and decreasing postcentrally, implies a decisive role for central processes including the organization and preprogramming of the motor task, but not direct reflection of feedback kinaesthetic afferentation.

Action Potentials↗
PubMed1980

[Clinical trial of the Bulgarian preparations, flatugel and almagel-neo in duodenal ulcer].

The therapeutic effect of four new variants of the preparation Almagel was studied in 100 patients with duodenal ulcer (25 patients in each group were examined)---Flatugel, Flatugel A, Almagel-Neo. The pains, with the treatment faded away in 60 to 68% and abated in 25 to 32% of the treated in the separate groups. As compared with the control group, the symptom constipation was influenced in a higher per cent by the new preparations, explained by the twice higher dose of magnesium hydroxide in the new almagel derivatives. Flatugel A and almagel A-neo had the best upon vomiting, due to the anesthesin, contained in them. In half of the patients, the clinical symptoms disappeared during the first week after the initiation of the treatment and after its termination the clinical manifestations remained unaffected in only 8% of the patients. After the 20-day treatment with the new modifications of almagel, the ulcer niche disappeared in 25-29% and its dimensions were reduced in 30-50%. No significant differences were established as regards the effect upon the rest of the clinical symptoms and ulcer niche among the new preparations themselves and each separate preparations as compared with the control group. The new almagel modifications show a tendency of reduction of gastric secretion and acidity 12 hours after the termination of the treatment as compared with the same prior to treatment, but the differences are statistically insignificant. The new variants of almagel have a pleasant taste, they are taken with pleasure and give no toxic and allergic side effects.

Adolescent↗
PubMed1979

[Zollinger-Ellison syndrome].

Three patients with Zollinger-Ellison syndrome are reported. In the first one, on the base of fibroduodenoscopy, an ulceriform cancer was found in the region of Vater's papilla in duodenum, with a penetration to pancreas and the elimination of gastrinoma (duodenectomy with right-side pancreas resection) led to the clinical healing, normalization of stomach secretion and the rest of the laboratory tests. Six years after the operation, the patient had no complaints and is with well preserved capacity for work. A gastrinoma, hazel-nut size, localized in the distal end of Wirsung's canal was concerned in the other two patients, that led to multiple recidivation and complications (hemorrhages and fistulas) of the duodenal peptic ulcer. One of the patients, due to the complications, underwent 7 resections and the other -- 3 but in neither of the two a radical operative intervention was performed (gastrinoma elimination or total gastrectomy) due to which one of them died four years and the other -- 8 years after the first operation and the onset of the clinical manifestations. Only the present radical operation treatment could lead to permanent results.

Adult↗
PubMed1979

[Treatment of duodenal ulcer with Tagamet (cimetidine)].

The results from the treatment of 25 patients with duodenal ulcer with 1 g tagamet daily (3x200 mg after meal and 400 mg in the evening before going to bed) in the course of 20 days, are reported. The subjective complaints of the patients disappeared in 87--100 per cent (in 2/3 of the patients even in the first three days after the initiation of the treatment) and the ulcer in 44 per cent. The immediate results obtained are statistically more significant as compared with the control group (only on diet), but the differences are not significant as regards the groups treated only with oxyferoscorbon and only with Caved-S. Tagamet treatment leads to a decrease of the basic indices of gastric secretion and does not change the content of N-acetylneuroamine acid in the gastric juice. The venous administration of tagamet inhibits the gastric acid production stimulated by pentagastrin. Tagamet treatment does not change the biochemical laboratory indices, the inflammatory and structural changes in the gastric-duodenal mucosa and induces no adverse effects and complications.

Adolescent↗
PubMed1979

[1 case of chronic active hepatitis].

A female patient is described, aged 18, with chronic active hepatitis post viral hepatitis, that led to exitus lethalis within one year and a half. Besides the numberous icteric periods and symptoms for intrahepatal cholestasis, the disease advanced with joint complaints, cardiac pulmonary and adrenal lesions. HBsAg is absent from blood but the latter was found in the nuclei of hapatic cells via electron microscopy. Diffusive hemorrhages were found in both adrenals as well as cortex thinness, reduction of fascicular zone and reduced lipids in cells. The role of the long-term immunosuppressive therapy with prednisolon and immuran is discussed in the origination of liver, adrenal, cardiac and pulmonary lesions (delayed type medicamentosus supersensitivity).

Adolescent↗
PubMed1979

[Treatment of peptic ulcer with Biogastrone (carbenoxolone)].

The results are reported from the treatment of 30 patients with gastric and 13 with diodenal ulcers with biogastrone in the course of 20 days (300 mg were given the first week, where on -- 150 mg daily). A more favourable effect upon the clinical symptoms and ulcer were observed in the patients with gastric ulcer (the symptoms disappeared in 87 per cent whereas the ulcer -- in 32 per cent) as compared with the duodenal ulcer (the symptoms disappeared in 46 per cent, whereas -- the ulcer in none). Biogastrone treatment influences the pain in a higher per cent as compared with Caved-S and oxyferroscorbon (p greater then 0.05), whereas regards the rest of the clinical symptoms -- no statistically significant difference was established. As compared with the treatment with oxyferroscorbon, Caved-A and cimetidin, biogastrone has a slower effect on the subjective complaints and the ulcer niche. After biogastrone treatment, the indices of gastric secretion and acidity decrease and the sialic acid in gastric juice is increased only in the gastric ulcer, but does not change considerably in the duodenal ulcer. The rest of the laboratory indices do not change with biogastrone treatment. In two of the patients, in the course of biogastrone treatment, light edema appeared on the face and the arterial blood pressure was elevated in other two, disappearing after the treatment without any additional treatment. Biogastrone treatment is indicated mainly in cases with gastric ulcer, with decreased sialic acid in gastric juice.

Carbenoxolone↗
PubMed1978

Influences between the contingent negative variation and the preceding readiness potential.

Contingent negative variation (CNV) is a slow negative shift in the potential, developing in the period of association between the warning and the imperative stimulus. The readiness potential (RP) resembles the CNV in morphology and amplitude and appears before the performance of a voluntary action. When RP precedes the appearance of the warning stimulus, CNV amplitude reaches considerably lower values. This phenomenon could be explained with the assumptions about a common neuronal pool of McAdam (1971) and with the "ceiling" hypothesis of Hamilton et al. (1973). The aim of the present study is to examine the effect of time intervals with different duration between RP and CNV. A decrease in the amplitude of CNV following RP has been found, without statistically significant differences depending on the interval between them. A more significant influence is observed on CNV morphology: in addition to a decrease in the amplitude, there is also a transition from type B to type A CNV when it is preceded by RP. Under conditions of a more complicated task involving combination with CNV, the RP itself shows lower values compared with the case of independent generation. This gives grounds for the conclusion that the complexity and the complex requirements of the task determine the value of the negatively directed slow-potential changes.

Adult↗
PubMedDate not supplied

Brain macropotentials associated with distinct phases of voluntary sustained isometric contraction in man.

Brain potentials recorded from the scalp during voluntary sustained isometric contraction have been consistently found to accompany both the beginning and the termination of the contraction. This study attempts to evaluate the dependence of the potentials related to the voluntary termination of a sustained effort on the physical parameters of the motor task and also to further investigate the relationship between potentials related to the initiation and to the termination of action. Brain potentials from healthy male volunteers performing hand-grip squeeze were time-locked to (1) beginning of contraction; (2) execution of an additional effort; and (3) the moment of voluntary relaxation, and then averaged. The waveshape and amplitude of the entire potential curve preceding and following the decision to act were evaluated with best-fit mathematical approximation procedures. Few correlations between the various descriptive parameters of the three types of potentials were found. The brain potentials accompanying beginning of the contraction from state of rest differed significantly from those accompanying execution of an additional effort and both potentials preceding initiation of voluntary effort differed from potentials preceding decision to terminate the action. It is hypothesised that brain macropotentials are linked to separate underlying commands for initiation and termination of voluntary action.

Adult↗
PubMedDate not supplied

Modulation of somatosensory evoked potentials during coordination between posture and movement.

Somatosensory evoked potentials (SEPs) elicited during execution of voluntary movements undergo modification in their amplitude ('gating'). We have studies SEP changes during a motor task that includes anticipatory postural adjustment and focal movement. Upright standing subjects were performing fast forward elevation of one arm. The electrical stimulus was presented over the ipsilateral posterior tibial nerve within two different time frames: (1) preceding the EMG activity of femoral biceps muscle, known to be first in occurrence in such task; (2) during this EMG activity, yet before the EMG occurrence in anterior deltoid muscle-prime mover for the forward arm elevation. The following significant changes in SEPs preceding focal movements as compared with control SEPs during quiet stance were found: The early component P42-N50 showed a marked decrease, regardless of its time relation to the anticipatory activity in the leg. Component N50-P60 increased in amplitude, more so when elicited within an earlier time frame. Thus, diminution of amplitude as an expression of gating, was found to exist already before the occurrence of anticipatory postural adjustment activity and to persist during the ensuing focal movement.

Acoustic Stimulation↗