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S Ching

Publications and source records attributed to S Ching.

25 records · Page 2Linked to original sources
PubMed1993

Selection of transmitter responses at sites of neurite contact during synapse formation between identified leech neurons.

1. Pressure sensitive (P) neurons of the leech Hirudo medicinalis show both an inhibitory, Cl(-)-dependent response and a depolarizing, cationic response to pipette application of serotonin (5-HT). Serotonergic Retzius (R) neurons in culture reform inhibitory, Cl(-)-dependent synapses with P neurons but fail to elicit the extrasynaptic, depolarizing response to 5-HT. We have examined the localization of the selection of 5-HT responses by testing the sensitivity of P cell growth cones and neurites to 5-HT application. 2. As measured by intracellular recording at the P cell soma, synaptic release of 5-HT from R cell processes activated only the Cl(-)-dependent response in P cell neurites. Focal application of 5-HT from a micropipette depolarized uncontacted P cell growth cones and neurites. In contrast, processes from the same P cells that were contacted by R cells were rarely depolarized by 5-HT application unless the application pipette was moved along the neurites away from the sites of contact. 3. The channels underlying the depolarizing response to 5-HT were identified in patch clamp recordings from P cell growth cones. These cation channels showed rare, brief openings in the absence of 5-HT. Application of 5-HT in the bath (outside the patch pipette) increased channel activity in uncontacted P cell growth cones but not in growth cones of the same P cells contacted by R cells. 4. We conclude that the selection of transmitter responses during synapse formation was localized to discrete sites of contact between the synaptic partners.

Action Potentials↗
PubMed1993

One-step competitive immunochromatographic assay for semiquantitative determination of lipoprotein(a) in plasma.

Numerous studies have associated high concentrations of lipoprotein(a) [Lp(a)] with atherosclerosis. We developed a rapid, one-step competitive immunochromatographic assay to measure Lp(a) in plasma. The assay is performed on a nitrocellulose membrane strip and the result is determined by a visual readout of rust-colored colloidal selenium. The assay is based on the principle that Lp(a) in the sample will compete with Lp(a)-coated colloidal selenium for binding to the anti-Lp(a) monoclonal antibody immobilized on the assay strip in the format of four ladder bars. The number of capture bars that appear as a result of the formation of colloidal selenium color is proportional to the concentration of the Lp(a) protein in the samples. The strip assay semiquantitatively measures Lp(a) concentrations ranging from 0 to 180 mg/L of Lp(a) protein in serum, plasma, or fingerstick whole-blood samples. This assay appears very useful for quick identification of individuals with above-normal concentrations of plasma Lp(a) protein (> 70 mg/L), and has potential for monitoring a patient's response to treatment with Lp(a)-lowering drugs.

Animals↗
PubMed1992

Transferrin index: an alternative method for calculating the iron saturation of transferrin.

We surveyed 140 clinical chemistry laboratories in Australia to establish which laboratory methods they used to determine serum iron status: 125 measured serum iron (Fe), 85 measured transferrin (TRF), 47 measured total iron-binding capacity (TIBC), and 14 measured both TRF and TIBC. Of the 55 laboratories routinely reporting TRF saturation (TS), 16 calculated TS directly as (Fe/TIBC) x 100, and 9 used [Fe/(TRF x 2)] x 100. Thirty laboratories measured TRF and converted it to an equivalent TIBC concentration; the derived TIBC was then used to calculate TS. We measured iron, TIBC, and TRF concentrations in 94 control subjects, 59 patients with alcoholic liver disease (ALD), and 20 with proven genetic hemochromatosis (GH). TS was compared with a transferrin index (TI = Fe/TRF) to determine whether both methods were sensitive for GH screening and which method gave the fewest false-positive results with discrimination limits of > 55% and > 1.0, respectively. All GH patients were detected by both TS and TI at these limits. One control subject had a TI > 1.0, whereas three control subjects had a TS > 55%. Nine patients with ALD had a TI > 1.0 and 11 ALD patients had a TS > 55%. Some iron-overload patients had lower than expected TS values compared with TI, possibly because of ferritin interference in the TIBC assay. Also, the precision of the TRF assay was better than that of the TIBC assay: CVs of 1.85-3.68% vs 6.17%. We therefore recommend that calculated TI replace TS in screening for iron overload.

Australia↗
PubMed1983

Exercise parameters for the prediction of post-training increase in exercise tolerance in patient with stable angina pectoris.

Twenty cases with effort angina underwent exercise training for a mean follow-up period of 38 weeks. Various parameters were investigated to clarify whether or not such parameters can be used to predict an increase in exercise tolerance of patients with effort angina. The increase of exercise tolerance after training was found to be related to a reduction of the myocardial oxygen demand at a given external work load. The maximal heart rate (max HR) the maximal systolic blood pressure (max SBP) and the maximal rate-pressure product (max RPP) could not predict the post-training increase in exercise tolerance. Before training, the maximal oxygen intake (VO2max) was found to be lower, and the HR/VO2max and the SBP/VO2max were higher in the group (11 patients) which showed a good response to the exercise program (effective group) than those in the group (9 patients) which did not (unchanged group). Before training, the HR/VO2max and the SBP/VO2max in the effective group were also higher than those of 96 healthy adults. On the other hand, the HR/VO2max and the SBP/VO2max in the unchanged group were not different from those of the healthy adults throughout the training. It is useful to compare the values of the HR/VO2max and the SBP/VO2max of patients with effort angina to those of healthy adults for the prediction of post-training increase in exercise tolerance.

Angina Pectoris↗