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Biomedical subjects

B Novak

Publications and source records attributed to B Novak.

34 records · Page 2Linked to original sources
PubMed1989

Residues in fish exposed to sublethal doses of endosulfan and fish collected from cotton growing area.

A one step extraction and cleanup procedure for determining endosulfan in fish was investigated. Minced Fish was mixed with trisodium citrate, disodium hydrogen orthophosphate and sodium sulphate into a dry powdery mixture, which was eluted through silicic acid and alumina with a mixture of dichloromethane and hexane. The eluate was concentrated and chromatographed on GLC using an EC detector without further cleanup. Three species of fresh water fish exposed to 0.7-16 micrograms/litre-1 technical grade endosulfan in tanks for various periods of time were found to concentrate both alpha and beta endosulfan and metabolise them to sulfate, diol, ether and lactone. Fish collected from Gwydir River in the cotton growing area in summer (Dec. 1986-Feb. 1987) were found to contain endosulfan residues suggesting endosulfan is quite stable in the environment and can cause residues.

Animals↗
PubMed1989

The first transition point of the mutant cdc2.33 in the fission yeast Schizosaccharomyces pombe.

We show that the first of the two transition points of cdc2.33, a mutant of Schizosaccharomyces pombe, exists in exponential phase cells. Using flow cytometry and a double-block experiment, we have measured the position of this transition point both in the single mutant and in the double mutant cdc2.33 wee1.6. In the single mutant, this point is in early G1. In the double mutant, however, this point is only delayed slightly, if at all, despite much larger delays in the S period and in the transition point of cdc10, another 'start' mutant. There is therefore a significant dissociation in the timing of what are thought to be two start events, and the first one appears not to be subject to a size control and to be associated with the completion of mitosis rather than the G1/S boundary.

Cell Cycle↗
PubMed1987

Periodic cell cycle changes in the rate of CO2 production in the fission yeast Schizosaccharomyces pombe persist after a block to protein synthesis.

CO2 production has been followed by manometry in synchronous and asynchronous control cultures of Schizosaccharomyces pombe prepared by elutriation from the same initial culture. Earlier results showed a periodic change in the rate of production, which took place once per cell cycle. These changes were most clearly shown as oscillations in the difference between values of the second differential (acceleration) for the synchronous and asynchronous cultures. This paper shows that the oscillations continue for at least three cycles in the presence of cycloheximide (with and without chloramphenicol). Protein synthesis is virtually absent and there is no cell division. The control of this metabolic oscillation is therefore not directly dependent on translation. The period of the oscillation under these conditions is about 60% of the normal cycle time.

Carbon Dioxide↗
PubMed1986

Change in the rate of CO2 production in synchronous cultures of the fission yeast Schizosaccharomyces pombe: a periodic cell cycle event that persists after the DNA-division cycle has been blocked.

CO2 production has been followed by manometry in synchronous and asynchronous cultures of Schizosaccharomyces pombe prepared by elutriation from the same initial culture. The rate of production follows a linear pattern in synchronous cultures with a rate change once per cycle at the time of cell division. This pattern is most clearly shown in oscillations of the difference between values of the second differential (acceleration) for the synchronous and asynchronous cultures. The association between the rate change and the time of division is maintained during growth speeded up in rich medium and slowed down in poor medium and at lower temperature. It is also maintained after a shift-up in temperature. Results with wee mutants suggest that the association is with the S period rather than division itself. The rate and acceleration of CO2 production are approximately proportional to cell size (protein content) in asynchronous cultures. When synchronous cultures of the temperature-sensitive mutants cdc2.33 and cdc2.33 wee1.6 are shifted up to the restrictive temperature, the DNA-division cycle is blocked. The oscillatory pattern of CO2 production, however, continues for one to two cycles until the acceleration reaches a constant value, after which the oscillations are undetectable. This point is reached later in the double mutant and there is a phase difference in the oscillations compared to those in the single mutant. With both blocked mutants the 'free-running' oscillations are about 15% shorter than the normal cycle time. There are well-known examples of such oscillations in eggs but they are rare in growing systems.

Carbon Dioxide↗
PubMed1981

Hereditary hemorrhagic telangiectasia with oral manifestations. Report of periodontal treatment in two cases.

The periodontal conditions of two patients with hereditary hemorrhagic telangiectasia were successfully treated by a two-phase plan. The first phase of treatment eliminated inflammation from local etiologic factors by removing plaque and plaque-retaining factors. The second phase eliminated the residual anatomic defects of periodontal disease. Gingival bleeding has been indicated as a symptomatic factor of hereditary hemorrhagic telangiectasia, but such bleeding is more likely the result of periodontal inflammation.

Dental Scaling↗
PubMed1978

HeLa DNA polymerase alpha activity in vitro: specific stimulation by a non-enzymic protein factor.

A non-enzymic protein factor that increases the in vitro rate of synthesis by HeLa DNA polymerase alpha 15- to 30-fold with denatured DNA as template has been partially purified from the cytoplasmic fraction of HeLa cells. The stimulatory effect is highly specific for HeLa DNA polymerase alpha and for DNA templates that contain extensive regions of single-strandedness. Synthesis with denatured DNA as template presumably proceeds from 3'-hydroxyl termini formed at loop-back regions since the synthesized DNA product and template are covalently linked. The stimulatory protein factor chromatographs as a basic protein, has an approximate molecular weight of 30,000 daltons and binds with moderate affinity to denatured DNA cellulose, being eluted by o.4M NaCl. The purified factor lacks detectable DNA polymerase, exo- and endodeoxyribonuclease and RNA polymerase activities. It also does not promote helix-coil transitions with poly[d(A-T)] and Clostridium perfringens DNA.

DNA Polymerase II↗
PubMed1977

Optokinetic training and vestribular habituation.

The present study deals with the interaction of the visual and vestibular system with special reference to habituation. The results indicate that vestibular responses are modified by repeated uni- and bidirectional optokinetic stimulation. This transfer mechanism is more evident in test subjects after wide angle (foveo-peripheral) than after narrow angle (foveal) optokinetic stimulation. The modification of vestibular responses by means of repetitive optokinetic stimuli is characterized by an enhancement on the one side and a decline of the responses on the other, depending entirely on the nature of the optokinetic stimulus (uni- or bidirectional, foveal or foveo-peripheral). There is some evidence to suggest that these phenonomena are habituation transfer mechanisms. They seem to subserve the improvement of the gain of the vestibulo-ocular reflex. They help the vestibular system to improve the assessment of self-rotation within the environment and to impede the development of visual-vestibular conflicts.

Adolescent↗
PubMed1977

[Dumping syndrome after selective vagotomy and pyloroplasty].

We have analysed the late complications (3--6 years after the operation) in 48 patients we treated by selective vagotomy and pyloroplasty because of duodenal ulcer. Authors have encountered six patients with so severe postoperative dumping syndrome that revison surgery has been performed. By reoperation there was no evidence of peptic disease but gastroduodenitis. After additional antrectomy dumping symptoms disappeared in all but one patient and radiologically the rate of test meal emptying of the stomach was reduced.

Dumping Syndrome↗
PubMedDate not supplied

Profunda femoris revascularization in limb salvage.

A retrospective study of 282 profunda femoris artery reconstructions between 1971 and 1981 with follow-up at least two years in 212 (75.1%) is presented. Arteriographic evaluation was performed in 92 cases. Stages III and IV were the indication for revascularization in 86% of cases. An inflow correction was necessary in 60.3% of profunda reconstructions. Factors that bear on the success or failure of profundaplasty were evaluated. These were aorto-iliac inflow, the extent of disease in the profunda femoris artery, the run-off in the distal popliteal-tibial system and the extent of the ischemic lesion. Of the failures most were due to established gangrene, obstructions throughout the whole length of the profunda or patients with a poor popliteal-tibial run-off system. The cumulative limb salvage at two years was 86.8% in limbs subjected to inflow correction procedure and profundaplasty but only in 56.5% of repair of the profunda alone. In the majority of the below-knee amputations after profundaplasty, repair of the profunda was used to lower the level of amputation from above knee to below the knee. Profundaplasty is worth considering even in those patients who cannot be offered other revascularization surgery.

Adult↗