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Biomedical subjects

K Kuba

Publications and source records attributed to K Kuba.

At least 91 records · Page 5Linked to original sources
PubMed1983

Origin of calcium ions involved in the generation of a slow afterhyperpolarization in bullfrog sympathetic neurones.

The origin of Ca2+ that activates the Ca2+-dependent K+ conductance which is responsible for the slow afterhyperpolarization (a.h.p.) following an action potential was studied in bullfrog sympathetic ganglia. The decay phase of the a.h.p. was a graded function of the extracellular Ca2+, and showed a voltage sensitivity opposite to that of the Ca2+-dependent K+-current reported previously (Pallotta et al. 1981), indicating that it reflected the time course of an increase in intracellular free Ca2+. An a.h.p. of longer duration was generated in cells which showed more pronounced rhythmic hyperpolarizations induced by intracellular Ca2+ release. The duration of the a.h.p. recorded with electrodes filled with K3-citrate [a.h.p. (citrate)], which favors Ca2+ release, was longer than the a.h.p. recorded with KCl-filled electrodes [a.h.p. (C1)]. D-600 (50-100 microM) drastically reduced the a.h.p. (C1), but had less effect on the a.h.p. (citrate). Caffeine which facilitates Ca2+ release prolonged the a.h.p. (C1), but had less effect on the a.h.p. (citrate). The a.h.p. (citrate) showed a greater sensitivity to a low temperature than the a.h.p. (C1). Mn2+ (1-3 mM) depressed both types of a.h.ps to the same extent. These results suggest that the origin of intracellular Ca2+ for a.h.p. (C1) is mainly Ca2+ influx during an action potential, while that for the a.h.p. (citrate) is both Ca2+ entry and intracellular Ca2+ release, although the effect of Mn2+ is difficult to explain fully.

Action Potentials↗
PubMed1983

The hypolipidemic effect of locust bean gum food products in familial hypercholesterolemic adults and children.

Seventeen adults and 11 children, a group of 18 familial hypercholesterolemic (FHC) and 10 normal subjects, were fed products with and without locust bean gum (LBG) (8 to 30 g/day) to assess the hypolipidemic effect of LBG. Identical food products with and without LBG were consumed by two groups (A and B) of arbitrarily assigned patients using a cross-over design. Plasma cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol, very low-density lipoprotein cholesterol and triglycerides were measured at 2-wk intervals and compared to control feeding periods. In group A, FHC C decreased 10% and LDL-C 11%, normal subjects decreased C 6% and LDL-C 10% (p less than 0.001). In group B, FHC C decreased 17% and LDL-C 19%, normal subjects decreased cholesterol 11%, and LDL-C 6% (p less than 0.001). Cholesterol and LDL-C were lowered in FHC children in both groups. High-density lipoprotein/LDL ratios increased in both groups. The use of food products with LBG in children and adults is a unique approach to treating FHC. LBG food acceptance was good, and there were no significant side effects. LBG in food products appears to be an effective, safe approach to controlling hyperlipidemia.

Adolescent↗
PubMed1983

On the mechanism of calcium actions on the acetylcholine receptor-channel complex at the frog end-plate membrane.

The mechanism of depressant effects of Ca2+ on the acetylcholine (ACh)-activated ion channel conductance was studied in frog muscle fibers. Increasing the extracellular Ca2+ ( (Ca2+)o) suppressed the increase in the end-plate conductance induced by iontophoretic application of ACh and shifted the reversal potential for a neurally-induced end-plate current to a more negative value. The single channel conductance obtained by current fluctuation analysis was reduced at a high (Ca2+)o. The decay phase of a neurally-induced end-plate current was slightly prolonged at a high (Ca2+)o (18 mM), while that of miniature end-plate current and the open time of the end-plate channel measured by noise analysis remained unchanged under the same condition. The Hill coefficient and apparent dissociation constant as measured by quantitative iontophoresis of ACh and comparison of the end-plate response with a theoretical model (DREYER and PEPER, 1975) were not affected by raising (Ca2+)o, while the maximum conductance increase was suppressed. These results suggest that the depressant effect of Ca2+ on the end-plate channel is not due to the effects on surface charges of the membrane, affinity of ACh to the ACh-receptor or binding to intrachannel sites, but presumably arises from the effect on another site involved in the regulation of ion permeation of the receptor-channel complex.

Animals↗
PubMed1983

Lipid concentrations in serum and EDTA-treated plasma from fasting and nonfasting normal persons, with particular regard to high-density lipoprotein cholesterol.

Serum/plasma sample pairs, collected both during (12-h) fasting and nonfasting from 44 healthy subjects, were analyzed for total cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides. Values for total cholesterol and triglycerides averaged 2.1% and 5.2%, respectively, higher for serum than for plasma. Values for HDL cholesterol were not different. Triglyceride concentrations in nonfasting subjects were 40% higher than concentrations during fasting, but total cholesterol and HDL cholesterol were not significantly affected by fasting. These findings suggest that concentrations of HDL cholesterol may be directly compared in clinical and epidemiological settings without regard to whether serum or plasma was sampled or whether the subjects were fasting or nonfasting.

Adult↗
PubMed1983

Contents of free histidine and histamine in fish meals and in the model compounds and their toxicities to induce gizzard erosion.

Whole meal produced from fresh sardine had a high content of histidine, while that from rancid fish had a high content of histamine. The toxicity to induce gizzard erosion, which appeared after heating, was stronger in the former whole meal than in the latter. Thus, the content of histidine, not that of histamine, was well correlate to the degree of toxicity of the heated fish meal. Changes in the contents of histidine and histamine were also studied in model compounds during heating.

Animal Feed↗
PubMed1982

Lightly hydrogenated soy oil versus other vegetable oils as a lipid-lowering dietary constituent.

Fully refined, bleached, deodorized corn oil and soy oil, and lightly hydrogenated, winterized soy oil were compared for effectiveness in lowering plasma cholesterol. Twenty-four, healthy, young college students were the subjects for the 10-wk studies. At the 300 cal level, the corn oil and unhydrogenated soy oil diets contained approximately 53 g of polyunsaturated and 26 g of saturated fat. The hydrogenated soy oil diet contained 42 and 25 g, respectively. All diets contained approximately 700 mg of cholesterol. Corn oil and unhydrogenated soy oil were equally effective in lowering both total and low density lipoprotein cholesterol. Lightly hydrogenated soy oil was also quite effective, but less so that the more unsaturated oils. Triglycerides were also lowered, but very low density and high density lipoprotein cholesterol concentrations, as well as total high density lipoproteins, were scarcely affected. All of the polyunsaturated fat diets produced small but statistically significant reductions in the cholesterol to protein ratio of all three lipoproteins.

Adult↗
PubMed1982

Cholesterol excretion studies in familial hypercholesterolemic children and their normolipidemic siblings.

Twenty children ages 3 to 17 yr, eight with normal lipids and 12 with familial hypercholesterolemia were studied on a metabolic unit for 14 days to evaluate fecal bile acid and fecal neutral sterol excretion. The diet contained a moderately low cholesterol content, 180 to 200 mg/day. Stools were collected in three separate, 3-day pools. Fecal bile acids and fecal neutral sterols were measured using two stool markers and thin-layer, and gas-liquid chromatography techniques. Fecal neutral sterol and fecal bile acid excretion were the same for normal and familial hypercholesterolemic children on a mg/kg basis. Fecal neutral sterols in familial hypercholesterolemic children decreased with age, p less than 0.001; fecal bile acid excretion also appeared to decrease with age, but less significantly, p less than 0.07. Although the familial hypercholesterolemic children have significantly increased plasma and potentially elevated tissue or total body cholesterol, the excretion of fecal bile acids and fecal neutral sterols did not differ between familial hypercholesterolemic and normal children.

Adolescent↗
PubMed1981

Multilaboratory evaluation of an ultrafiltration procedure for high density lipoprotein cholesterol quantification in turbid heparin-manganese supernates.

High density lipoprotein (HDL) can be quantitated by measurement of cholesterol in supernates after precipitation of low and very low density lipoprotein (LDL and VLDL) with heparin and Mn(2+). Supernatant turbidity, often observed with hypertriglyceridemic specimens, indicates incomplete sedimentation of LDL/VLDL and precludes accurate quantitation of HDL. Ten Lipid Research Clinic Laboratories compared an ultrafiltration technique for clearing turbid heparin-Mn(2+) supernates to current methods involving repeat precipitation of either the original specimen after dilution or the d > 1.006 g/ml fraction after removal of VLDL from the initial specimen by ultracentrifugation. Results for ultrafiltration of 429 turbid supernates averaged only slightly higher (1.0-1.1 mg/dl) than results by the dilution or ultracentrifugation methods on the same specimens, but this difference was found to be significant (P < 0.005). The agreement of the ultrafiltration method with the other two methods is indicated by the following linear regression equations: a), ultrafiltration = (0.964 x ultracentrifugation) + 2.4 mg/dl, and correlation coefficient = 0.926; and b), ultrafiltration = (0.936 x dilution) + 3.3 mg/dl, and correlation coefficient = 0.933. We conclude that ultrafiltration of turbid heparin-Mn(2+) supernates is a convenient alternative to precipitation after either dilution or removal of VLDL.-Warnick, G. R., J. J. Albers, P. Bachorik, J. Turner, C. Garcia, C. Breckinridge, K. Kuba, S. McNeely, G. Hillerman, P. King, R. Muesing, B. Most, and K. Lippel. Multi-laboratory evaluation of an ultrafiltration procedure for high density lipoprotein cholesterol quantification in turbid heparin-manganese supernates.

Chemical Phenomena↗
PubMed1980

Calcium localization in the sympathetic ganglion of the bullfrog and effects of caffeine.

The localization of Ca2+ in the bullfrog sympathetic ganglion was studied using electron microscopy with Oschman and Wall's technique. When the ganglion was incubated and processed in an extremely high Ca2+ solution (20 mM) for electron microscopy, electron-dense deposits (EDD) were found at or in the plasma membranes, subsurface cisterns and mitochondria of the postganglionic neurons. These EDD were proved to contain calcium by X-ray microprobe analysis. On the other hand, they were not significant in the preganglionic terminals except those in the synaptic vesicles. Addition of caffeine (10 mM) to the incubation media and fixatives caused a drastic decrease in number of EDD of the subsynaptic membranes and the subsurface cisterns. Caffeine also reduced, but less markedly, the size and number of EDD in mitochondria. Caffeine (10 mM) prolonged the afterhyperpolarization of an action potential, reduced the amplitude of the ACh (nicotinic) potential and induced slow rhythmic hyperpolarizations in a 20 mM Ca2+ solution. These effects of caffeine which were presumably the result of an increase in the intracellular free Ca2+ were discussed in relation to the morphological data.

Acetylcholine↗
PubMed1980

Oscillation of [Ca2+]i-linked K+ conductance in bullfrog sympathetic ganglion cell is sensitive to intracellular anions.

The intracellular free Ca2+ ([Ca2+]i) regulates the K+ conductance (GK) of the many types of cell membrane. The Ca2+ influx during an action potential activates this [Ca2+]i-linked GK in most neurones. In caffeine-treated sympathetic ganglion cells, however, Ca2+ released from an intracellular Ca2+ reservoir site analogous to the sarcoplasmic reticulum (SR) of the muscle (see ref. 12) causes activation of the GK, which results in slow oscillatory hyperpolarisations (caffeine hyperpolarisation, C-hyperpolarisation). Such a release of Ca2+ linked to the GK of the membrane seems important for understanding the role of the intracellular organelles in the control of membrane activities of a neurone. We report here the mechanism of the slow oscillatory hyperpolarisations recorded from the bullfrog sympathetic ganglion cell in Ringer solution. It is found that these hyperpolarisations are generated by a [Ca2+]i-linked GK system and are highly sensitive to anions in an intracellular recording electrode, probably to intracellular anions.

Animals↗