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J Krivanek

Publications and source records attributed to J Krivanek.

At least 19 recordsLinked to original sources
PubMed2001

Conditioned taste aversion and Ca/calmodulin-dependent kinase II in the parabrachial nucleus of rats.

Bielavska and colleagues (Bielavska, Sacchetti, Baldi, & Tassoni, 1999) have recently shown that KN-62, an inhibitor of calcium/calmodulin-dependent kinase II (CaCMK), induces conditioned taste aversion (CTA) when introduced into the parabrachial nucleus (PBN) of rats. The aim of the present report was to assess whether activity of CaCMK in the PBN is changed during CTA. We induced CTA in one group of rats by pairing saccharin consumption with an ip injection of lithium chloride. Another group of rats received lithium alone (without being paired with saccharin consumption) to test whether lithium has an effect on CaCMK in the PBN, independent of those effects due to training. In animals receiving CTA training, CaCMK activity in extracts of PBN was reduced by approximately 30% at the postacquisition intervals of 12, 24, and 48 h, compared to control animals receiving saccharin with saline injection. By 120 h after CTA training, no effect on CaCMK was present. At those postacquisition intervals showing CaCMK activity effects due to CTA, there were no effects attributable to lithium alone. Lithium alone produced only a short-lasting reduction in CaCMK activity (at 20 min a 30% decrease, at 60 min a 23% decrease; and at 6, 12, and 24 h no decrease). The time course of lithium-induced effects differed markedly from that of CTA training. All changes were Ca2+/- -dependent; we did not observe any changes in Ca-independent activity. CTA effects on CaCMK were selective for PBN, insofar as we did not observe any CTA effects on CaCMK in the visual cortex, a brain region unrelated to taste pathways. Since CTA produces a relatively long-lasting reduction in CaCMK activity (lasting 2 days or more) specifically in the PBN, which is critical a relay for taste information, the reduction of CaCMK activity may enable the consolidation of taste memory in an aversive situation.

Animals↗
PubMed2001

Dowling-Degos disease--a heat aggravated variant.

A 22-year-old woman presented with a 5-year history of a micropapular eruption localized to the flexor aspect of her limbs as well as persistent reticulate pigmentation of her neck and upper chest resembling Darier's disease. The eruption was associated with pruritus that was precipitated by heat and was worse in summer. The axillae, groins and inframammary areas had multiple papules but lacked reticulate pigmentation. Multiple biopsies showed an epidermis with club- and antler-like rete ridges but no acantholysis or dyskeratosis. This distinct clinical presentation may represent an unusual heat aggravated variant of Dowling-Degos disease that clinically shares features with Darier's disease and transient acantholytic dermatosis.

Adult↗
PubMed2001

[Takayasu's disease associated with autoimmune thyroiditis and celiac disease. Clinical course and limitations of treatment].

Takayasu's arteritis is a non-specific form of vasculitis involving the aorta, its main branches and pulmonary arteries. It is a rare disease in our country, contrasting with the high prevalence in Southeast Asia, Africa and South America. We discuss the course of the disease in our patient who was a young women who developed Takayasu's arteritis associated with autoimmune thyroiditis and malabsorption syndrome due to celiac sprue. Long-term immunosuppressive therapy contributed to stabilizing the associated diseases, but did not stop the progression of the vascular lesions. The main adverse outcome in our patient was the development of severe renovascular hypertension. Bilateral renal artery stenosis was treated by angioplasty with stent implantation. Based on literature reports, the association of Takayasu's disease with multiple autoimmune disorders is a rare event. However, it would appear that the arteritis was the limiting disease for prognosis in our patient.

Celiac Disease↗
PubMed2000

Glutamate in the parabrachial nucleus of rats during conditioned taste aversion.

Brain microdialysis combined with HPLC and spectroscopic detection was used to monitor extracellular glutamate in the parabrachial nucleus (PBN) of rats during acquisition of a conditioned taste aversion (CTA). Microdialysis fractions taken every 20 min were used to assess the effects of presentation of the conditioned stimulus alone (CS, consumption of 0.1% saccharin), the unconditioned stimulus alone (US, intraperitoneal injection of 0.15 M LiCl, 2% b.w. induced malaise after water drinking) as well as that of CS-US pairing. After 15 min of saccharin drinking, the glutamate concentration in the eluate (20 microl/20 min) reached 80% above the baseline but returned to the basal value in the next fraction. LiCl alone (applied 1 h after 15 min drinking of water) increased glutamate only following some delay, i.e. in the second and third post-lithium fraction by 90 and 67%, respectively. However, when LiCl was injected 1 h after the onset of saccharin intake, the glutamate concentration rose significantly (by 95%) already in the first post-LiCl fraction and by 120% in the second one. It appears, therefore, that the 'saccharin trace' facilitates the effect of lithium on extracellular concentration of glutamate in PBN during acquisition of CTA.

Animals↗
PubMed1997

Protein kinase C in the parabrachial nucleus of rats during conditioned taste aversion induced by amphetamine.

D-Amphetamine (AM) is a potent inducer of conditioned taste aversion (CTA) the mechanism of which differs from that induced by lithium. The aim of the present communication is to see whether AM-induced CTA will produce shift in the protein kinase (PKC) activity in the parabrachial nucleus (PBN). Activity of PKC was measured in PBN of rats during AM-induced CTA. In the control experiments a single intraperitoneal (i.p.) injection of AM (3 mg/kg) alone (not paired with saccharin drinking) resulted in rise of particulate bound PKC by 77% and a tendency to decrease its activity in cytosol 60 min but not 24 and 48 h after AM administration. The results suggest translocation of the enzyme from cytosol to membrane. Cytosolic PKC increased by 17 and 50%, 24 and 48 h, respectively, after acquisition of CTA (15 min after the retrieval test), when the direct effect of AM on PKC had already disappeared. Particulate PKC did not change at either of the two time intervals. Thus the total PKC activity was increased. Since we have previously observed the same PKC shifts using LiCl or CuSO4 as CTA unconditioned stimuli, we assume that any CTA inducer will elicit the same alteration of PKC in PBN.

Amphetamine↗
PubMed1996

Protein kinase C in the rat cerebral cortex during spreading depression.

Activity and distribution of protein kinase C (PKC) in the rat cerebral cortex was correlated with the development of spreading depression. When the 'waves' of the slow potential shift, induced by topical application of concentrated KCl solutions, were allowed to spread over the cerebral cortex for 10 min, both cytosolic and particulate fractions of the enzyme were increased to 169% and 143%, respectively, of the control values obtained from the contralateral, relatively intact hemicortex. When the enzyme activities were correlated with development of a single slow potential shift, it appeared that in the cortical area fully depolarized (under the maximum of negativity), the respective values were 175% and 157%. One min after recovery of the single wave of spreading depression both cytosolic and particulate fractions continued to rise up to 218% and 239%, respectively. During 5 min of recovery both the cytosolic and particulate fractions fell to 71% and 57%, respectively, of control levels. Even at 10 min the cytosolic enzyme was still decreased to 80%. At 20 min no difference between control and experimental values was found (soluble, 111%; particulate, 96%). The results are discussed in the context of data obtained in a few studies dealing with depolarization-induced changes of PKC in vitro.

Animals↗
PubMed1996

Conditioned taste aversion and protein kinase C in the parabrachial nucleus of rats.

The enzymatic activity of protein kinase C (PKC) was measured in the cytosol and particulate fraction of parabrachial nucleus, the presumed site of conditioned taste aversion (CTA) engrams. At various time intervals after acquisition of the task (pairing saccharin consumption with subsequent LiCl poisoning) the nucleus was dissected from the frozen coronal sections. An increase (+40%) in the cytosol PKC activity was found 48 h after that pairing in comparison with controls (saline injection instead of LiCl). Particulate enzyme activity virtual did not change (-5%). Thus the total PKC activity increased significantly (21%). Qualitatively similar but less markedly expressed PKC shifts (+18% in cytosol) ere found 24 h following CTA. Twelve hours and 5 days after CTA acquisition the activity and distribution of PKC was similar to that seen in normal rats. The control experiments revealed that 6 h after LiCl injection alone (without previous saccharin consumption) translocation of PKC from the cytosol to the membrane fraction (found previously 1 h after LiCl injection alone) still persisted but did not differ from that found 6 h after its pairing with saccharin drinking (CTA). It is concluded that acquisition of conditioned taste aversion may be followed by synthesis of PKC rather than by its translocation or downregulation.

Animals↗
PubMed1994

Intracerebral injection of polymyxin B blocks the acquisition of conditioned taste aversion in rats.

The contribution of protein kinase C (PKC) to the acquisition of conditioned taste aversion (CTA) was tested by injection of three PKC inhibitors--polymyxin B, H7 and staurosporine--into the parabrachial nucleus (PBN). From the tested drugs only polymyxin B (20 mM) prevented CTA acquisition. Application of H7 (10 mM) and staurosporine (100 and 500 microM) into the PBN did not impair CTA learning. The blocking effect of polymyxin B is dose dependent (5 and 10 mM concentration did not disrupt CTA formation) and site specific (application of polymyxin B into the visual cortex did not elicit CTA blockade). The ability of polymyxin B to disrupt CTA learning is not due to irreversible damage of PBN. These results suggest that polymyxin B blocks acquisition of CTA in some nonspecific way not necessarily involving inhibition of PKC. This conclusion is supported by failure of two other more specific PKC inhibitors to affect CTA learning.

Alkaloids↗
PubMed1993

Protein kinase C in nucleus parabrachialis: effect of drugs inducing conditioned taste aversion.

A method for the dissection of the nucleus parabrachialis (NPB) from the coronal sections of frozen rat brain is described. The protein kinase C (PKC) activity was determined in the cytosol and particulate fractions of the pooled samples of the nucleus. The effect of the i.p. administration of the conditioned taste aversion-inducing agents LiCl and CuSO4 on PKC in the NPB and visual cortex (VC) was tested. 1 h after the LiCl injection, the portion of the membrane-bound PKC was increased by 23% (P < 0.01) above the level found after the saline injection. CuSO4 produced a 19% increase. Since the PKC activity in the cytosol declined, it is likely that the translocation of the enzyme took place. No changes in the PKC distribution in the VC samples could be detected. The results support the idea that the PKC translocation is not directly induced by the tested substances but that it rather reflects changes in the activity of the visceral system.

Animals↗
PubMed1991

ATP-citrate lyase is another enzyme the histidine phosphorylation of which is inhibited by vanadate.

We have recently shown that phosphorylation of histidine residue of the alpha-subunit of the succinyl-CoA synthetase is inhibited by both vanadate and vanadyl. To assess the university of this inhibition, we have estimated the effect of vanadate on the phosphorylation of another enzyme ATP-citrate lyase, prepared from rat liver. This enzyme contains histidine as the only amino acid with an acid-labile (P-N) phosphate bond. The 67% inhibition of endogenous phosphorylation by 1 mM vanadate disappeared after cleavage of the acidic P-N bond of histidine with acidic sample solution. The remaining 33 per cent radioactivity was due to labelling of the acid-stable phosphoamino acids (P-serine and P-threonine), the phosphorylation of which was not affected by vanadate. The dose response curve for vanadate inhibition closely resembles that shown previously for inhibition of phosphorylation of histidine in the succinyl-CoA synthetase. The results suggest that the action of vanadate on histidinyl phosphorylation is a more general effect (like its influence on phosphorylation of the protein-bound tyrosine).

ATP Citrate (pro-S)-Lyase↗
PubMed1989

Development of Na, K-ATPase in neocortical grafts.

Pieces of cerebral cortex from 14-day rat embryos were transplanted into freshly prepared cavities in the cerebral cortex of adult rats. At various time intervals after implantation. Na,K-ATPase, Mg-ATPase as well as the ratio of two molecular forms of Na,K-ATPase were determined in the grafts and compared with the values obtained from intact cortex at various stages of postnatal development. Up to the 57th postimplantation day (PID), Na.K-ATPase develops very slowly, reaching on PID 57, i.e. on postconceptional day (PCD) 71, only 40% of the enzyme activity of intact brain cortex (PND 49, PCD 71). At PID 90 (PCD 104) Na,K-ATPase activity attained that of the intact adult tissue (PND 82, PCD 104). Mg-ATPase activity in the grafts developed similarly to that of intact brain but was much higher in the early postimplantation phase. The maximum ratio of the two molecular forms of Na,K-ATPase [alfa(+)/alfa] was shifted toward later developmental periods in the grafts as compared with the intact cerebral cortex.

Animals↗
PubMed1989

Inhibition of phosphorylation of the mitochondrial 34 kDa protein. A unique effect of vanadium ions?

We have shown previously that vanadate stimulates overall endogenous phosphorylation of proteins in subcellular particulate fractions. In brain mitochondria there is a single peptide band of Mr (approx.) 34 kDa, phosphorylation of which is inhibited rather than stimulated by both vanadate and vanadyl ions. Here, further characterization of this unique effect of vanadium ions is reported. Phosphorylation of the 34 kDa protein proceeds in the Triton X-100 extracts of mitochondria. The P-labeled 34 kDa band was recovered from TCA sediments of endogenously phosphorylated mitochondria. Acid lability of the phosphate linkage suggests a bond of P-N type. Phosphorylation of the 34 kDa protein is highly sensitive to Mg2+, while Mn2+ is a less potent activator. The results provide further evidence for existence of a protein occurring exclusively in mitochondria, the phosphorylation of which is selectively modified by both vanadate anion and vanadyl cation in a way differing from those hitherto described.

Animals↗
PubMed1985

Halo eczema around melanocytic nevi.

Nine patients developed multiple areas of eczema surrounding centrally located pigmented nevi. There was no significant history of atopy or evidence of external contact factors to account for the reaction. The eczema did not appear to influence the central melanocytic nevi, which persisted after resolution of the inflammation. The pathogenesis of this striking phenomenon remains unclear but differs from that associated with classical halo nevi.

Adult↗
PubMed1979

Life stresses and depression in the menopause.

Research on the climacteric has largely concentrated on relationships between ovarian insufficiency, oestrogen deficiency, and climacteric symptoms. Little attention has been paid to those who have no symptoms. It is proposed, in addition to these relationships, that the life events of this period are significantly involved; and that resultant stress may contribute to oestrogen deficiency as opposed to physiologically normal postmenopausal oestrogen levels. In this preliminary study, two groups of women under conditions of relatively low stress and high stress were tested over a period of 15 mth. They were rated on the Hamilton Rating Scale for depression and anxiety and results were compared with the corresponding total urinary oestrogen output. The results, which suggest a significant relationship between stress related to depression and oestrogen levels in the menopause, are discussed and compared with differing life circumstances of the subjects.

Anxiety↗