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Biomedical subjects

W I Li

Publications and source records attributed to W I Li.

31 records · Page 2Linked to original sources
PubMed1991

Viscoelastic properties of transformed cells: role in tumor cell progression and metastasis formation.

The micropipette aspiration technique was used to investigate the deformation properties of a panel of nontransformed and transformed rat fibroblasts derived from the same normal cell line. In this method, a step negative pressure is applied to the cell via a micropipette and the aspiration distance into the pipette as a function of time is determined using video techniques. A standard solid viscoelastic model was then used to analyze the viscoelastic properties of the cell. From these results, it is concluded that a direct correlation exists between an increase in deformability and progression of the transformed phenotype from a nontumorigenic cell line into a tumorigenic, metastatic cell line.

Animals↗
PubMed1989

Characterization of a temperature-sensitive beta-endorphin-secreting transformed endometrial cell line.

An endometrial cell line (HRE-H9) was established and characterized to study the mechanism by which gene expression of POMC-derived peptides is controlled in uterine tissues. The HRE-H9 cell line was isolated by transforming primary rabbit endometrial cell cultures, derived from hCG-treated pseudopregnant rabbits, with a temperature-sensitive A209 mutant (tsA209) simian virus 40 at a permissive temperature (33 C). The resulting cells exhibited temperature sensitivity in growth and synthesis of immunoreactive beta-endorphin (ir-beta END). The ir-beta-END present in the cell extracts and culture media was assayed by a specific beta END RIA. Sephadex G-50 gel filtration chromatography of the transformed cell extracts showed three peaks of beta END immunoreactivity. The first peak eluted at the void volume, the second peak coeluted with the beta-lipotropin standard, and the third peak coincided with the porcine beta END standard, ir-beta-END was also detectable in endometrial culture media, suggesting that the transformed endometrial cells secreted POMC-derived peptides. Our data indicate that the tsA209 mutant virus-transformed endometrial cell line provides a suitable model for study of the synthesis and regulation of POMC-derived peptides in extrapituitary tissues.

Animals↗
PubMed1987

Running and shipping elevate plasma levels of beta-endorphin-like substance (B-END-LI) in thoroughbred horses.

A specific RIA for beta-endorphin (B-END) was developed to measure horse plasma levels of B-END-like material (B-END-LI) during exercises and shipping. Three exercise speeds and durations were: trot at 260-300 m/min for 10 min; slow gallop at 390-420 m/min for 5 min and fast gallop at 700-800 m/min for 2 min. Blood samples were taken from 4 horses before, immediately after, 30 and 60 min after exercise. Trotting increased plasma B-END-LI from a basal level of 109 +/- 7 pg/ml to 172 +/- 22 at the end of exercise and returned to 127 +/- 17 and 107 +/- 10 pg/ml at 30 and 60 min after exercise. Similar results were obtained in slow gallop (121 +/- 6 to 210 +/- 17 then 155 +/- 8 and 131 +/- 11 pg/ml). However, fast gallop caused the greatest increase (352%) in B-END-LI to concentrations of 544 +/- 93 pg/ml and 276 +/- 74 pg/ml at 5 and 30 min after exercise. Plasma B-END-LI returned to 199 +/- 46 pg/ml in 1 hr. Sequential exercises of trot, slow and fast gallop were conducted in 6 horses. Plasma B-END-LI were 116 +/- 19 pg/ml (pre-exercise), 198 +/- 21 (trot), 361 +/- 51 (slow gallop), 500 +/- 57 (fast gallop) and 248 +/- 29, 171 +/- 24, 143 +/- 20 and 139 +/- 21 pg/ml at 0.5, 1, 2 and 3 hr, respectively, following exercises. Transportation in horse trailer also significantly increased plasma levels of B-END-LI from a basal level of 138 +/- 12 to 196 +/- 24 pg/ml within 30 min and this levels were maintained at 45 min (177 +/- 3 pg/ml). Plasma levels of B-END-LI began to decline at 60 min of shipping. These results showed that plasma B-END-LI was increased in all speeds of exercise and by shipping and returned to pre-exercise and pre-shipping level in 30 min except fast gallop which returned to pre-exercise level in 1 hr.

Animals↗
PubMed1987

Beta-endorphin in uterine secretions of pseudopregnant and ovariectomized, ovarian steroid-treated gilts.

Levels of beta-endorphin-like immunoreactivity (beta END-LI) in uterine secretions were studied in pseudopregnant and ovariectomized gilts treated with ovarian steroids. Pseudopregnancy was induced in 7 gilts by daily injection of estradiol valerate (5 mg/day) between days 11 and 15 of the estrous cycle. Between days 60 and 90 of pseudopregnancy, uterine secretions were collected by flushing the uterus with 0.9% saline. Uterine flushings were extracted with a Sep-Pak C-18 column and assayed for beta END-LI by a specific RIA. The RIA cross-reacted only with beta-lipotropin (15%). Significant amounts of total immunoreactive beta END-LI were detected in the uterine flushings. The inhibition curve for extracts was parallel to the standard END inhibition curve. Extracted uterine flushings were applied to a Sephadex G-50 column. Three peaks of immunoreactive beta END-LI were detected. One peak eluted at the void volume. The second peak eluted at a Kav of 0.21, which was near the Kav of a lipotropin standard (0.23). The highest peak (Kav = 0.53) eluted similar to standard END (Kav = 0.51). In the second experiment, 12 gilts were ovariectomized on day 4 of the estrous cycle and randomly assigned to 4 groups of 3 gilts each. Each group received 1 of the following daily injections: vehicle (corn oil), 0.1 mg 17 beta-estradiol (E2), 200 mg progesterone (Prog), or a combination of E2 and Prog (E2 + Prog). After treatment for 30 days, beginning on the day of ovariectomy, the uterine flushings were assayed for beta END-LI and total protein. Treatment with Prog increased (P less than 0.05) total beta END-LI 532% (12.4 ng) compared to corn oil treatment (2.3 ng), and levels were significantly higher than with E2 (2.9 ng) or E2 + Prog treatment (5.1 ng). Opiate receptor assay showed that extracts of uterine flushing had a displacement curve parallel to that of standard porcine beta END. Results suggest that significant amounts of immunoreactive beta END-LI are present in uterine secretions of gilts and that the accumulation of beta END-LI is influenced by ovarian steroids.

Animals↗
PubMed1986

Effects of thyrotropin-releasing hormone on serum concentrations of thyroxine and triiodothyronine in healthy, thyroidectomized, thyroxine-treated, and propylthiouracil-treated dogs.

Effects of thyrotropin-releasing hormone (TRH) on serum concentrations of thyroid hormones were studied in 36 mixed-bred dogs. Dogs were randomly assigned to 7 groups. Significant increases (P less than 0.05) of serum thyroxine (T4) values occurred as early as 2 hours and reached a peak at 6 to 8 hours after IV injection of 300 to 1,100 micrograms of TRH. Thyroxine concentrations in response to a TRH dose greater than 500 micrograms were similar to those observed with the 300-micrograms dose. Transient coughing, vomiting, salivation, and defecation after large doses (900 and 1,100 micrograms) were observed. Mean serum T4 concentration decreased from 2.1 micrograms/dl to 0.9 micrograms/dl within 1 day of thyroidectomy. Clinical signs of hypothyroidism, including lethargy, dry coats, and diffuse alopecia, were present in 2 dogs at a month after surgical operation. Thyroxine concentrations were detectable for greater than 2 months. Injection (IV) of 700 micrograms of TRH 6 weeks after surgical operation had no effect on serum concentration of T4 in thyroidectomized dogs. In 5 T4-treated dogs, TRH (700 micrograms, IV) significantly increased the serum T4 value, indicating that pituitary thyrotropes were responsive to TRH, in spite of daily medication of 0.8 mg of T4. Four dogs were treated orally with 200 mg of propylthiouracil/day for 5 weeks. Intravenous injection of 700 micrograms of TRH in propylthiouracil-treated dogs had no effect on the serum T4 concentration, indicating that TRH had no effect on serum T4 values in these dogs during the experimental period. These results indicate that TRH can replace bovine thyrotropin for the canine thyroid function test.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

The effects of acclimation temperature on pituitary and plasma beta-endorphin in rats at 32.5 degrees C.

Endocrine and thermoregulatory responses were studied in male rats exposed to heat (32.5 +/- 0.1 degrees C) from acclimation temperatures of either 24.5 +/- 0.1 degrees C or 29.2 +/- 0.1 degrees C. After 1 hr in the heat, evaporative water loss and tail skin temperature changes in the 24.5 degrees C acclimated rats were greater than in the 29.2 degrees C acclimated rats; both groups displayed similar changes in metabolic rate and rectal temperature. At the respective acclimation temperatures, 29.2 degrees C rats displayed lowered plasma thyroid hormones, elevated beta-endorphin-like immunoreactivity (beta-END-LI) in the plasma, neurointermediate and anterior lobes of the pituitary gland, and no change in plasma corticosterone levels compared to 24.5 degrees C rats. After exposure to 32.5 degrees C for 1 hr, both groups of rats maintained similar plasma corticosterone levels; however, only the 24.5 degrees C group increased plasma thyroxine and beta-END-LI. These data suggest that beta-endorphin may be involved in body temperature regulation during acclimation to elevated environmental temperatures.

Acclimatization↗
PubMed1983

Segmental replacement of superior vena cava with spiral vein graft.

Following resection of a leiomyosarcoma, the superior vena cava (SVC) was successfully replaced by means of a spiral graft constructed from autogenous saphenous vein. This technique has previously been applied only as a bypass operation in patients with total occlusion of the SVC causing SVC syndrome. Our patient had mild SVC obstruction and absence of venous hypertension in the upper body before the operation in which segmental SVC replacement was employed. She has remained free from signs or symptoms of SVC obstruction, and graft patency was demonstrated ten months after operation. The literature concerning use of the spiral graft is reviewed, and our operative technique is described. Use of a spiral vein graft should be considered whenever large veins must be replaced.

Female↗
PubMed1982

Isolation and identification of swine rotavirus in Taiwan.

Large numbers of viral particles resembling rotavirus were detected with negative stained electron microscopy in bacteria free fecal filtrate obtained from 10-day old diarrheal suckling piglets of a conventional pig farm in Taiwan. The clinical signs of vomiting and diarrhea were reproduced in colostrum deprived piglets artificially infected with the fecal filtrates. Rotavirus particles persisted in the fecal samples after two in vivo serial passages, and was not seen in the uninfected control animal. The Cytoplasm of infected jejunal and ileal enterocyte fluoresced when standard anti-porcine rotavirus conjugate was applied in an direct immunofluorescent staining test. In the experimentally infected piglets, moderate villous atrophy of the small intestine was the main microscopic lesion observed. The virus was identified by the above evidence to be rotavirus.

Animals↗
PubMed1979

Reversal of exertional hypotension after coronary bypass grafting.

A decrease in systolic blood pressure that occurs with treadmill exercise testing may be a sign of reversible ischemic left ventricular dysfunction. To test this hypothesis, we examined retrospectively the postoperative treadmill responses of 37 patients who had exertional hypotension (end exercise systolic blood pressure less than or equal to initial preexercise levels) before coronary arterial bypass grafting. This group of 37 patients was characterized preoperatively by an abnormal exercise electrocardiogram (36 patients), multiple vessel occlusive disease (36 patients) and a normal ejection fraction at rest (32 patients). Postoperative exercise tests showed improvement in hemodynamic and electrocardiographic changes with reversal of exertional hypotension (33 patients), and conversion to a normal exercise electrocardiogram (29 patients). Coronary bypass surgery can be expected to reverse exertional hypotension in patients with symptomatic angina pectoris and evidence of ischemia in the exercise electrocardiogram.

Adult↗
PubMed1979

Intraoperative management of renal cell carcinoma with supradiaphragmatic caval extension.

A new technique for inferior vena caval tumor thrombectomy is described. Vascular isolation of the cava from the right atrium to the pelvis is achieved by temporary circulatory arrest of the lower torso. Removal of the neoplastic thrombus under direct vision with minimal blood loss was accomplished in a patient with renal carcinoma, whose tumor extended into the intrapericardial vena cava.

Adenocarcinoma↗
PubMedDate not supplied

Immunoreactive gonadotropin-releasing hormone in porcine reproductive tissues.

Studies were aimed to identify and characterize IR-GnRH in the porcine endometrium, ovary, oviduct, and compare that with GnRH of hypothalamic and placental origin. RP-HPLC profiles revealed that all tissue extracts contained three peaks of IR-GnRH. Extraction with radioiodinated 125I-GnRH also resulted in three similar peaks, indicating these two extra peaks as an extraction artifact. Radioreceptor assay showed endometrial and ovarian ultrafiltrates displaced binding of 125I-GnRH analog to pituitary membrane. Secretion of uterine IR-GnRH was increased in ovariectomized, progesterone-treated gilts, as compared to the control. Treatment with estradiol + progesterone in ovariectomized gilts further increase uterine secretion of IR-GnRH. These results demonstrate that IR-GnRH identified in the porcine reproductive tissues possesses hydrophobicity similar to those in hypothalamus and placenta; endometrial IR-GnRH binds to pituitary GnRH receptors; and uterine secretion of IR-GnRH is modulated by ovarian steroids.

Animals↗