Biomedical subjects
Publications and source records attributed to C H Oh.
Epithelioid vascular tumors are a heterogeneous group characterized by epithelioid-appearing endothelial cells. Included are benign vascular tumors (epithelioid hemangioma), borderline tumors (epithelioid hemangioendothelioma), and malignant tumors (epithelioid angiosarcoma). We describe a case of multiple epithelioid hemangiomas.
Water extraction with subsequent picric acid treatment and solvent washing (ethyl acetate and diethyl ether) was employed for the rapid isolation of free amino acids from non-aqueous food samples. The isolated amino acids were subjected to N(O,S)-isobutyloxycarbonylation followed by solid-phase extraction and tert.-butyldimethylsilylation for direct analysis by gas chromatography and gas chromatography-mass spectrometry. When the present method was applied to nineteen food samples (common beans, seeds, and nuts), seventeen protein amino acids and fifteen non-protein amino acids were simultaneously screened. Eleven non-protein amino acids including gamma-aminobutyric acid, pipecolic acid, pyroglutamic acid, alpha-aminobutyric acid, alpha-aminoadipic acid, and beta-alanine were tentatively identified, and four compounds assumed to be non-protein amino acids remained unidentified.
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1,2,4-Trioxane benzylic ethers 8a-e were prepared as simplified, tricyclic versions of the clinically used tetracyclic antimalarial drug artemisinin (1). Five additional artemisinin analogs (9-11) were prepared. Neither water solubility (analogs 8e and 11b) nor chelating ability (analogs 9 and 10), however, produced trioxanes of especially high in vitro antimalarial activity. Trioxane fluorobenzyl ether 8b is the most active in this series (more active than artemisinin) against Plasmodium falciparum parasites in vitro, with substantial activity also in mice infected with Plasmodium berghei parasites and with 10 times higher activity than artemisinin (1) in killing immature P. falciparum gametocytes.
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The non-protein amino acid, beta-N-methyl-amino-L-alanine (L-BMAA) from Cycas circinalis seeds, has been implicated as a causative agent of amyotrophic lateral sclerosis-Parkinsonism dementia complex (ALS-PDC), a disease known from Guam and other areas in the western Pacific. We analyzed C. circinalis seeds for additional free non-protein amino acids by a recently developed GC-MS method. The samples were prepared by water extraction of seed flour. The amino acids present in the extract were derivatized by N(O,S)-isobutyloxycarbonylation of the amine functional groups and then tert-butyldimethylsilylation of the carboxyl functional groups. Peaks for a total of seventeen derivatives of non-protein amino acids were detected by GC-MS. In addition to L-BMAA, four other non-protein amino acids were identified as beta-alanine, gamma-amino-butyric acid, pyroglutamic acid, and alpha-aminoadipic acid.
Two different derivatives of novel nonprotein amino acids in Gymnocladus dioicus seeds are prepared for gas chromatographic (GC) and mass spectrometric (MS) analysis. The interfering components in a water extract of the seeds are removed by picric acid treatment and multistep washing with organic solvents followed by N(O,S)-isobutyloxycarbonylation combined with solid-phase extraction. The resulting N(O,S)-isobutyloxycarbonyl (isoBOC) amino acids are then converted to either tert-butyldimethylsilyl (TBDMS) or trimethylsilyl (TMS) derivatives, which are analyzed by dual capillary column GC and GC-MS. The characteristic ions in the mass spectra of N(O,S)-isoBOC TBDMS and N(O,S)-isoBOC TMS derivatives enable confirmation of molecular weight and existence of functional groups containing active protons. Temperature programmed retention index sets measured on DB-5 and DB-17 capillary columns (J&W Scientific; Folsom, CA) are useful for distinguishing among structural isomers. gamma-Methylglutamic acid, diastereoisomers of 3-hydroxy-4-methylglutamic acid, cis and trans isomers of 5-hydroxypipecolic acid, and some free protein amino acids are identified in Gymnocladus dioicus seeds.
A 25-year-old man had a 5-year history of multiple tender lesions of both extremities and trunk. Biopsy found an encapsulated subcutaneous nodule composed of numerous small, well-formed blood vessels, some filled with fibrin thrombi. This lesion was made up > 99.9% of blood vessels with only a minimal amount of adipose tissue. We believe our case is in the spectrum of angiolipoma even though it is made up almost entirely of a vascular component. These tumors may be confused with other multiple or eruptive vascular lesions that have a more ominous clinical course. This case is being reported to stress that multiple or eruptive "vascular" lesions do not always reflect an underlying immunosuppression or malignancy.
A unique derivatization procedure is described for the simultaneous determination of protein and non-protein amino acids present in aqueous samples. This procedure involves N(O,S)-isobutyloxycarbonylation combined with solid-phase extraction with subsequent tert.-butyldimethylsilylation for gas chromatographic analysis. Using this combined procedure, linear responses were obtained in the range of 10-100 ppm, with correlation coefficients varying from 0.991 to 0.999, for the free amino acids studied except for homocysteine (0.922) and homoserine (0.982). The relative standard deviations ranged from 0.7 to 5% for most amino acids with a few exceptions. Temperature-programmed retention index (I) sets as measured on DB-5 and DB-17 dual-capillary columns were characteristic of each amino acid and thus useful for the screening of amino acids by computer I matching. The mass spectral patterns of amino acid derivatives, exhibiting characteristic [M-57]+, [M-113]+, [M-131]+, [M-159]+, [M-174]+ and other ions, permitted rapid structural confirmation. The present method allowed simultaneous screening of free protein and non-protein amino acids when applied to seed samples such as almond, walnut, and sunflower seeds.
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OBJECTIVE: To determine whether selective internal pudendal pharmaco-angiography (SIPA) is the most reliable diagnostic procedure for evaluating the function of the cavernosal arteries. PATIENTS AND METHODS: Both sides of the selective internal pudendal pharmaco-angiogram taken in 35 patients (70 cases), whose history was suggestive of post-traumatic arteriogenic impotence, were evaluated separately and compared to the corresponding side using the penile brachial index (PBI), duplex scanning and cavernosal artery systolic occlusion pressure (CASOP). RESULTS: There was no significant difference in the peak flow velocity and diameter changes of the cavernosal arteries on duplex scanning, in pressure differences between the brachial artery systolic pressure and the CASOP, and in the PBI between the group with a normal appearance on SIPA and the other where the cavernosal arteries were not visualized. There was no significant difference in the results of these functional evaluations between the normal group and cases where the cavernosal arteries were not visualized accompanied by a completely obstructed internal pudendal artery or common penile artery visible on SIPA. CONCLUSIONS: This study is unable to confirm the value of SIPA in evaluating the function of the cavernosal arteries as it provides only anatomical information.
We have concluded initial preclinical studies with synthetic trioxanes numbered 3-9 and have compared them with artemisinin (numbered 1) using CD-1 mice infected with Plasmodium berghei. Based on their antimalarial effectiveness in mice, two of these synthetic trioxanes were selected for evaluation in Aotus monkeys infected with multidrug-resistant (MDR) P. falciparum. Trioxane numbered 8 (12 and 48 mg/kg), trioxane numbered 9 (12 and 48 mg/kg) and arteether (numbered 2, 48 mg/kg) were administered intramuscularly in three 12-hr doses to A. lemurinus lemurinus (Panamanian owl monkeys) infected with the Vietnam Smith/RE strain of P. falciparum and monitored for parasitemia. Trioxane numbered 8 at 12 mg/kg cleared parasitemia in two monkeys, but recrudescence occurred in one animal. Treatment of the recrudescent infection with 48 mg/kg was curative. Infections in two monkeys treated initially with 48 mg/kg were cured (six-month follow-up). Trioxane numbered 9 produced a similar outcome: 12 mg/kg suppressed parasitemia in two monkeys but was not curative; however, 48 mg/kg cured infections in all four monkeys treated. These preliminary observations show synthetic trioxanes numbered 8 and 9 to be as effective as arteether (numbered 2) against MDR in P. falciparum in the Aotus monkey.
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The effect of ouabain, an inhibitor of the membrane Na+/K+ ATPase, on smooth muscle of the corpus cavernosum was investigated. In an in vivo study using dogs, the intracorporeal pressures (ICPs) were measured before and during electrical stimulation of the cavernous nerve, and during nerve stimulation following intracorporeal injection of ouabain (1 x 10(-7) M). There was a significant drop of ICP following intracorporeal injection of ouabain (P < 0.001). In the in vitro study, ouabain increased the basal tone of the isolated cavernosal strip from the rabbit. When the strip was pretreated with tetrodotoxin (5 x 10(-7) M), phentolamine (1 x 10(-5) M), propranolol (1 x 10(-5) M) and atropine (1 x 10(-5) M), ouabain was still capable of contraction of the strip. The ouabain partly inhibited the relaxation effect of acetylcholine (1 x 10(-6) M), VIP (vasoactive intestinal polypeptide: 1 x 10(-8) M) and 2-chloro-adenosine (1 x 10(-6) M). The ouabain acts directly on the smooth muscle of the corpus cavernosum, increases its basal tone and diminishes the relaxation effect of acetylcholine, VIP and adenosine.
The corporeal blood gas changes in accordance with the duration of the prolonged erection which developed after intracorporeal pharmacotherapy with papaverine and phentolamine were investigated in 62 impotence patients. The picture of the corporeal blood taken from 15 psychogenic impotence patients (a control group) at 10 minutes after intracavernous injection when they showed full erections was arterial but there was pCO2 rise and pH drop compared to femoral artery blood taken simultaneously. As the erection lasted longer, significant gas changes of the cavernous blood began to appear (p < 0.0001): increase in pCO2 and decrease in pO2 from 4 hours, decrease in pH from 5 hours, decrease in O2 saturation from 6 hours. Erections lasting for more than 16 hours showed significantly worse hypoxia (p < 0.05). Therefore, to prevent hypoxia and metabolic acidosis, drug-induced prolonged erection would be better decompressed before it lasts for more than 4 hours.
New, racemic, tricyclic trioxane alcohol 3 was designed and synthesized as a structurally simple analog of clinically useful, tetracyclic, antimalarial artemisinin. A series of 20 ester and ether derivatives of alcohol 3 were prepared easily, without destruction of the essential trioxane system. Chemical structure-antimalarial activity for each derivative was evaluated in vitro against chloroquine-resistant and chloroquine-sensitive Plasmodium falciparum parasites. Many of these derivatives were highly efficacious; carboxylate ester 9f, carbamate ester 10a, and sulfonate ester 12a had antimalarial potency similar to that of artemisinin, and carboxylate esters 9b and 9d, carbamate esters 10b and 10c, and phosphate esters 11a-c had antimalarial potency up to 7 times higher than that of artemisinin. Several of these most active analogs (e.g., carboxylate 9b and carbamates 10a and 10c) are stable crystalline solids, a feature of considerable practical value for any new drug candidate.
An RF excitation technique with which one can improve the effective dynamic range of the receiver and reduce the interference between slices for 3D volume-selective multislice MRI is described. The basic idea of the technique is to use phase scrambling in conjunction with slice encoding through the use of RF pulses. The spins in each slice are encoded by RF pulses which have the scrambled as well as slice-encoded phase components along the slice-selection direction. The scrambled, or randomly distributed, phase reduces the peak signal intensity, thereby reducing the dynamic range of the signal. Since the proposed technique utilizes RF slice encoding together with phase scrambling, interslice image interference is greatly reduced and the dynamic range is improved. In addition, the method has several advantages such as a reduction in the power requirement for the RF pulses and the elimination of the necessity for hardware such as nonlinear gradient coils.