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Biomedical subjects

S K Choi

Publications and source records attributed to S K Choi.

122 records · Page 7Linked to original sources
PubMed1986

A representative value for 24-hour monitored ambulatory blood pressure.

Several shorter-term alternatives for whole-day ambulatory monitoring of blood pressure using Pressurometer III or conventional sphygmomanometer were evaluated in 12 male patients with mild hypertension. Averages of BP reading at 8 AM once, 3 consecutive-readings either with Pressurometer or manually, serial readings for 2-hour intervals from 8-10 AM and 2-4 PM were compared with that of 24-hour ambulatory, non-invasive BP readings by Pressurometer. Both systolic and diastolic 2-hour BP averages in the morning (8 to 10 o'clock) correlated more strongly with 24-hour averages (r = 0.91 and 0.91) than the 3 consecutive (r = 0.88 and 0.66) or single (r = 0.49 and -0.35) reading alternatives did. In conclusion, the average of serial readings obtained during 2-hour monitoring period from 8 to 10 AM is a reliable predictor of 24-hour ambulatory BP and represents it more closely than the conventional single or multiple BP readings.

Blood Pressure↗
PubMed1984

[A case of spontaneous spinal epidural hematoma presenting Brown-Séquard syndrome].

Although there have been a few reports of spontaneous spinal epidural hematoma, it may be difficult to make a correct diagnosis of the lesion because of atypical clinical symptoms. The authors reported a case of spontaneous spinal epidural hematoma presenting Brown-Séquard syndrome, with a review of literature. This 75-year-old male experienced a sudden onset of severe dorsal neck pain during sleep associated with right hemiparesis which deteriorated quickly to hemiplegia, without loss of consciousness, nausea, vomiting and vertigo. The patient has a history of hypertension and has been treated for chronic hepatitis for one year. On admission, neurological examination revealed right hemiplegia with normotensive deep tendon reflexes, and loss of pain and temperature sensations below the level of C5 on his left side. Position sense of fingers and toes was diminished on his right side, and hyperesthesia was recognized at the area of C4 level. Consciousness disturbance, cranial nerve signs, and urinary incontinence were not seen. Right retrograde vertebral angiograms showed no abnormal vascular shadow, even though anterior spinal artery was visible at the level of C8 through C5. Cervical CT scan revealed a left-side dominant extradural high density mass which situated dorsally at around the upper part of C2 body changing it's position to dorsolaterally as it descended to the lower part of C5. On contrast enhancement study, only the margin of the lesion was partially enhanced, which might be the hematoma membrane. On the third day after the onset, laminectomy from C2 to C5 was performed and the epidural hematoma was evacuated.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1979

Biologically active luteinizing hormone (LH) in plasma. III. Validation of the in vitro bioassay when applied to male plasma and the possible role of steroidal precursors.

An in vitro bioassay method for measuring LH activity was applied to male plasma. This method is based on the specific testosterone response to LH activity by interstitial cells from mouse testes. In contrast to assays conducted on female plasma, non-parallel response lines were obtained between serial dilutions of untreated male plasma and the International Reference Preparation for Human Pituitary Gonadotrophins FSH and LH/ICSH) for bioassay (code no. 69/104). In an attempt to eliminate this source of error, which would invalidate the assays, plasma was subjected to either ether extraction or charcoal adsorption prior to assay. While ether extraction was ineffective, charcoal treatment eliminated the source of non-parallelism. Evidence is presented indicating that the inclusion of a charcoal pre-treatment step provides an assay method for LH which fulfils the recognized criteria of reliability when applied to male plasma. An investigation of the likely causes of non-parallelism was undertaken by incubating mouse interstitial cells with various steroids and steroid sulphates at concentrations likely to be present in plasma. While most of the presumed precursors of testosterone were converted to testosterone, steroid sulphates (dehydroepiandrosterone sulphate and pregnenolone sulphate) at high concentrations as present in male plasma were the most active compounds in forming testosterone. However, the amount of testosterone produced from these precursors under controlled conditions was insufficient to account entirely for the deviation from parallelism observed with male plasma. Hence, the non-parallelism observed with untreated plasma samples cannot be entirely explained by the presence of steroidal testosterone precursors in male plasma.

Adsorption↗
PubMed1978

Studies on a human chorionic gonadotrophin-like material present in non-pregnant subjects.

The presence of an hCG-like material in urinary and pituitary extracts and plasma obtained from non-pregnant subjects was investigated. Two assay methods were used to detect this material following fractionation of pituitary and urinary extracts by gel filtration (Ultrogel AcA 54) and/or isoelectrofocusing: a) a radioimmunoassay employing an antiserum raised against a specific sequence of the carboxy terminal region (residues 115--145) of the beta-subunit of hCG, and b) an in vitro bioassay method which measures both hLH and hCG activities. The fractionation procedures employed provide a satisfactory separation of highly purified hCG and hLH preparations. In the pituitary and urinary extracts hCG beta-peptide-like immunoactive (PIA) material was found consistently, which co-eluted with iodinated hCG following gel filtration and possessed pI values similar to those of hCG when subjected to isoelectrofocusing. The PIA material also exhibited in vitro biological activity similar to that shown by hLH and hCG. Detectable levels of immunoactive material were also found in plasma; however, the plasma levels of this PIA material were not influenced by classical endocrine measures such as the stimulation or inhibition of gonadotrophin secretion. The low levels of this material in plasma precluded its further characterization by gel filtration or electrofocusing. Whereas the present data and those reported by other investigators seem to suggest the presence of some hCG-like material in urinary and pituitary extracts and possibly in plasma of non-pregnant subjects, it is emphasized that the available evidence is not sufficiently conclusive to exclude other interpretations as to the nature of this material.

Biological Assay↗
PubMed1977

[Suppression of the cell-mediated immunity in minor histoincompatible rat kidney allograft recipients (author's transl)].

To study the immunological status of recipients of major compatible and minor incompatible kidney allografts, we transplanted FiS and FLF1 kidneys into LEW rats. Most of the FiS kidneys were rejected within 55 days. Of 24 recipients, only 4 survived longer than 4 months. However, two-thirds of the FLF1 recipients survived longer than 4 months. The other third died with 64 days. During the first postoperation week a high level of lymphocytotoxin was detected in the serum of the FiS kidney recipients. Thereafter hardly any alternation of its titer was found, and no variation among the recipients of major histocompatible kidney allografts was shown. The FLF1 kidney recipients showed a low titer of antibody. The hemagglutinin titer showed the same trend as the lymphocytotoxin titer. A blocking serum factor could not be found in the serum of the kidney recipients with the microcytotoxity assay method or with the allorosette-formation inhibition test. Cellular immunity, which was studied with the GvH-reaction and microcytotoxity assay, was detected in the first postoperative week. However, this immunity was gradually supressed, and after 6 weeks was no longer to be found. This immunological status remained unchanged in the indefinitive surviving kidney-recipients in spite of antigen inoculation with two skin allografts of donor origin. This immunological status could be defined as "graft acceptance".

Animals↗
PubMed1977

Detection of serum-blocking factors by inhibition of allorosette formation in rats with long-surviving renal allografts following short-term postoperative ALS treatment.

Thirty-nine (LEW x BN)F1 kidneys were transplanted to LEW rats. Twenty-four untreated recipients survived for a mean time of 16.1 +/- 1.7 days (group 1). Fifteen recipients received 4 ml of antilymphocytic serum per rat (group 3). In the last group 10 recipients survived for more than 4 months. The spleen cells of these permanently surviving 10 rats were obtained by splenectomy and used in a graft-versus-host assay, and this assay showed that the reactivity of these cells was normal. Following splenectomy the animals were given an (LEW x BN)F1 skin allograft, followed 18 days by a second. After another 18 days (LEW x Buf)F1 "third party" skin allografts were transplanted to the same animals. Animals of group 2 rejected their first grafts with a mean survival time of 12.2 +/- 1.2 days, whereas the second grafts were rejected normally as were the third party grafts. Attempts were made to detect lymphocytotoxic antibodies and haemagglutinins before and after the transplantation of skin grafts and none could be found up to day 53. The sera of group 2 inhibited allorosette formation by 38%. This serum-blocking factor was donor specific. It is probable that the survival of the kidney transplants following antilymphocytic serum treatment was brought about by the development of blocking antibodies.

Animals↗
PubMed1977

[Is permanent survival of kidney allograft receivers in weak histo-incompatible combinations dependent on enhancement?].

To study the immunological status of indefinitely surviving recipients of histocompatible (minor histoincompatible) allografts we transplanted Fi or (Fi x LEW)F1-kidneys to LEW-rats. At the same time bilateral nephrectomy was performed. To examine the cellular immune response we carried out local GvHR, microcytotoxicity assay and allorosette-formation test with recipient cells. We also studied lymphocytotoxins in the serum of recipients. To detect a blocking serum factor we used allorosette-formation inhibition test and microcytotoxicity assay. A blocking serum factor could not be found. In spite of stimulation with donor specific skin graft the cellular immune response of prolonged surviving recipients was inhibited. Our results suggest that prolonged survival of minor histoincompatible renal allograft recipients was caused by suppression of cellular immune response.

Animals↗