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Biomedical subjects

D Kim

Publications and source records attributed to D Kim.

At least 451 records · Page 25Linked to original sources
PubMed1989

G-protein beta gamma-subunits activate the cardiac muscarinic K+-channel via phospholipase A2.

Muscarinic receptors of cardiac pacemaker and atrial cells are linked to a potassium channel (IK.ACh) by a pertussis toxin-sensitive GTP-binding protein. The dissociation of G-proteins leads to the generation of two potential transducing elements, alpha-GTP and beta gamma. IK.ACh is activated by G-protein alpha- and beta gamma-subunits applied to the intracellular surface of inside-out patches of membrane. beta gamma has been shown to activate the membrane-bound enzyme phospholipase A2 in retinal rods. Arachidonic acid, which is produced from the action of phospholipase A2 on phospholipids, is metabolized to compounds which may act as second messengers regulating ion channels in Aplysia. Muscarinic receptor activation leads to the generation of arachidonic acid in some cell lines. We therefore tested the hypothesis that beta gamma activates IK.ACh by stimulation of phospholipase A2. When patches were first incubated with antibody that blocks phospholipase A2 activity, or with the lipoxygenase inhibitor, nordihydroguaiaretic acid, beta gamma failed to activate IK.ACh. Arachidonic acid and several of its metabolites derived from the 5-lipoxygenase pathway, activated the channel. Blockade of the cyclooxygenase pathway did not inhibit arachidonic acid-induced channel activation. We conclude that the beta gamma-subunit of G-proteins activates IK.ACh by stimulating the production of lipoxygenase-derived second messengers.

Animals↗
PubMed1989

Convulsant properties of GABA antagonists and anticonvulsant properties of ethanol in selectively bred long- and short-sleep mice.

The convulsant potency of bicuculline, a GABA antagonist, was shown to be greater in Short-Sleep (SS) mice than in Long-Sleep (LS) mice. LS mice, selectively bred for lengthy ethanol-induced narcosis, had longer latencies to myoclonus and clonus following administration of bicuculline and picrotoxin than did ethanol-resistant SS mice. SS mice were also more susceptible to pentylenetetrazol-induced myoclonus, but not clonus. F1 hybrids showed bicuculline seizure sensitivity intermediate to the two parent lines. Ethanol weakly inhibited bicuculline-induced myoclonus in both LS and SS mice. Clonus was clearly antagonized by ethanol in both lines, but to a similar degree. These data provide evidence for a GABAergic role in genotype-dependent sensitivity to ethanol.

Animals↗
PubMed1989

Surgical significance of popliteal arterial variants. A unified angiographic classification.

Distal popliteal arterial variations may influence the success of femorodistal popliteal and tibial arterial reconstructions. Two patients whose bypass procedures were initially unsatisfactory because of a poor choice for anastomosis stimulated a review of variations in the distal popliteal artery in 1000 femoral arteriograms. The popliteal arterial anatomy could be assessed in 605 extremities and the tibial arterial anatomy in 495 extremities. Seventy-five variant cases were identified. Normal branching of the popliteal artery was present in 92.2%. Among the 7.8% incidence of variants, the majority (72%) were either high origin of the anterior tibial artery or a trifurcation pattern. Of variant patterns to the foot (5.6%), the most common was that in which the supply to the distal posterior tibial artery arose from the peroneal artery. We propose a unified classification of the popliteal and tibial arterial variations that encompasses both anatomic areas. Variant arterial supply to the foot can be suspected when the infrapopliteal vessels show a hypoplastic or aplastic anterior or posterior tibial artery and compensatory hypertrophy of the peroneal artery. Knowledge of these variants is important to angiographers and vascular surgeons.

Angiography↗
PubMed1989

Simon nitinol inferior vena cava filter: initial clinical experience. Work in progress.

The Simon nitinol filter for percutaneous interruption of the vena cava to prevent pulmonary embolism is currently undergoing a multicenter clinical trial. Preliminary clinical results are reported as work in progress. The results in 44 patients at two centers are analyzed in detail, and major events are reported from 103 patients in 17 centers in the United States during a 10-month period. The filter was successfully inserted via the femoral or jugular route in all patients through a 9-F catheter. The placement procedure was easy and without significant complications. Follow-up studies included plain radiography, ultrasonography, magnetic resonance (MR) imaging, and clinical evaluation. No filter migration or perforation occurred among the 103 patients. Symptomatic occlusions occurred in 7%-9%, comparable to other series, and some asymptomatic occlusions were detected with MR imaging only. The implications of occlusion of the filter are discussed.

Adult↗
PubMed1989

Projection arteriography and venography: initial clinical results with MR.

Motion currently limits the applications of magnetic resonance (MR) angiography in certain regions of the body. To overcome this problem, a series of breath-hold, two-dimensional, flow-compensated gradient-echo images were acquired. These images were then processed by means of the maximum intensity projection algorithm to produce projection angiograms. The method was evaluated in 10 healthy subjects and in 12 patients and validated by comparing conventional angiograms, contrast material-enhanced computed tomographic scans, and duplex sonograms with MR projection arteriograms and venograms of the chest, abdomen, and pelvis. The aorta and pulmonary arteries and their branches were demonstrated, as was detailed anatomy of the hepatic and portal venous systems and inferior vena cava. Renal arteries and veins could be studied in both native and transplanted kidneys. The method permits determination of flow direction and differentiation of arteries and veins and is superior to three-dimensional acquisition techniques for imaging slow blood flow. Initial results suggest that the method may have clinical applications for a variety of vascular disorders.

Arteries↗
PubMed1989

Toward a quantitative comparative toxicology of organic compounds.

Correlation equations between logP (P = octanol water partition coefficient) and the biological activity of alcohols has been derived for 101 examples on all sorts of systems, from simple proteins to whole animals. This provides an overview of the toxic nature of hydrophobic compounds which can be used as a basis for comparison of more complex chemicals. About 100 examples of the hydrophobic effects of chemicals, other than alcohols, to various living systems or their parts are presented for comparison. It is clear that hydrophobic xenobiotics are toxic to almost every form of life, including humans (or parts there of).

Animals↗
PubMed1988

Randomised controlled trial of recombinant tissue plasminogen activator versus urokinase in the treatment of acute pulmonary embolism.

The effect of intravenous recombinant human tissue-type plasminogen activator (rt-PA) was compared with that of urokinase in 45 patients with angiographically documented pulmonary embolism (PE) in a randomised controlled trial. The two principal end-points were clot lysis at 2 h, as assessed by angiography, and pulmonary reperfusion at 24 h, as assessed by perfusion lung scanning. All patients received the full dose of rt-PA but urokinase infusions were terminated prematurely (on average after 18 h) in 9 patients because of allergy in 1 and uncontrollable bleeding in 8. By 2 h, 82% of rt-PA-treated patients showed clot lysis, compared with 48% of urokinase-treated patients (p = 0.008; 95% CI for the difference = 10-58%). Improvement in lung scan reperfusion at 24 h was identical in the two treatment groups. The reduction in fibrinogen did not differ significantly between the rt-PA and urokinase groups (45% vs 39% at 2 h and 34% vs 40% at 24 h). The results indicate that in the dose regimens employed, rt-PA acts more rapidly and is safer than urokinase in the treatment of acute PE.

Acute Disease↗
PubMed1988

Construction, expression, and function of a new yeast amber suppressor, tRNATrpA.

The number of different tRNA species in Saccharomyces cerevisiae known to be capable of suppressing termination of translation at UAG, UAA, and UGA codons is limited to those which insert tyrosine, leucine, and serine. Suppressor tRNAs that insert other amino acids, even those whose anticodons differ from the expected recognition sequences for nonsense codons by a single nucleotide, have never been identified via classical genetic analysis. We have used site-directed mutagenesis to convert the anticodon of a cloned tRNATrp gene from CCA to CTA with the expectation that this gene would produce tRNA molecules capable of interacting with the UAG terminator codon. We show that this form of the gene can be transcribed and spliced in vitro to produce mature tRNA with the expected base sequence. The putative suppressor gene has been introduced into several S. cerevisiae host strains using the centromere vector YCp19. Efficient suppression of amber mutations met8-1, tyr7-1, and lys2-801 results from the presence of the CTA form of tDNATrp. Two UAA mutants, leu2-1 and ade2-101, and the UGA marker his4-260 are not suppressed.

Bacterial Proteins↗
PubMed1988

Vascular complications of percutaneous femoral cardiac interventions. Incidence and operative repair.

Of 7333 patients undergoing percutaneous left-heart catheterization procedures during a seven-year seven-month period, 73 patients (1%) underwent 75 operative repairs of catheterization-related vascular complications. The overall incidence of operative repair varied according to the type of percutaneous femoral artery procedure performed: 0.6% for diagnostic heart catheterization, 0.9% for percutaneous transluminal angioplasty, 5.2% for transfemoral balloon valvuloplasty, and 11.5% for intra-aortic balloon pump placement. This suggests that (1) femoral and iliac artery occlusions can and should be repaired promptly while the patient is under local anesthesia; (2) false aneurysms in this clinical setting can be approached directly through the aneurysm cavity; (3) the diagnosis of false aneurysm or arteriovenous fistula can usually be made on clinical grounds alone, without resorting to angiography; (4) venous or arterial patch angioplasty is the preferred technique for small or severely traumatized femoral arteries; and (5) the necessity for operative repair of these lesions will continue to increase in frequency as percutaneous cardiologic diagnostic and therapeutic interventions are used more widely.

Adult↗
PubMed1988

Cholecystojejunostomy intussusception.

Intermittent prolapse of a jejunal loop into the gallbladder lumen was observed following cholecystojejunostomy in a patient with advanced carcinoma of the pancreas. This unusual complication was documented by cholangiography and sonography.

Aged↗
PubMed1988

False-positive aortography following blunt chest trauma: case report.

We describe a patient in whom thoracic aortography performed following blunt chest trauma revealed what appeared to be a traumatic tear of the proximal descending aorta. As the patient initially refused surgery, aortography was repeated 18 days later, confirming these findings. At thoracic aortotomy the aorta appeared normal; there was no hematoma or tear. We believe this to be the first reported case of false-positive aortography following blunt chest trauma (see Note added in proof).

Adult↗