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Biomedical subjects

T Lai

Publications and source records attributed to T Lai.

At least 37 records · Page 2Linked to original sources
PubMed1997

Mechanical workload-myocardial water content relationship in isolated rat hearts.

We tested the hypothesis that the mechanical workload of the heart inversely determines the rate of myocardial edema formation in an isolated, perfused rat heart preparation. Heart rate (HR) was varied in three groups by pacing at 125 (HR125), 250 (HR250), or 350 beats/min (HR350). Left ventricular pressure (LVP) was varied in two additional groups by pacing at 250 beats/min and with the addition of either epinephrine (Epi) or propranolol (Pro) to the perfusate. In five otherwise identical groups, variation of coronary vascular resistance was minimized by adenosine. Myocardial water content (MWC) varied significantly and inversely with HR in the HR125, HR250, and HR350 groups. MWC of the HR250 group was significantly less than that of the Pro group but did not differ from the Epi group. However, when adenosine was used, MWC had significant inverse relationships with HR and LVP. We concluded that the mechanical workload of the heart inversely determines the rate and degree of myocardial edema formation in this isolated heart preparation, and both HR and LVP are determinants of this relationship.

Adenosine↗
PubMed1993

Verapamil enhances doxorubicin activity in cultured human renal carcinoma cells.

Cells from 22 renal cell carcinomas (RCC) were established in culture. Sensitivity of the tumour cells to doxorubicin alone and in combination with racemic verapamil, which reverses multidrug resistance, was tested using a [75Se]selenomethionine uptake assay to measure protein synthesis. The effect of verapamil was expressed as a potentiation index: LD50doxorubicin/LD50doxorubicin + verapamil. The potentiation index in 15 of these carcinomas was determined for cells within the first 14 days of culture. At 3.3 mumol/l concentration of verapamil, of the tumours sensitive to doxorubicin alone (LD50 < 0.75 microgram/ml) five of seven showed a potentiation index of > 2. For the less sensitive tumours the analogous proportion was seven of eight. Tumour cell expression of glycoprotein P-170, associated with multidrug resistance, was estimated using the monoclonal antibody C-219. Initial expression levels were unrelated to the action of verapamil. In five tumours the proportion of cells expressing P-170 declined as the period of culture increased. This was not associated with any consistent change in the LD50 for doxorubicin or in potentiation of doxorubicin sensitivity by verapamil. Cell cloning associated with prolonged cell growth in vitro could mimic tumour cell cloning which accompanies the formation of metastases. Thus reduced expression of P-170 on prolonged cell growth in vitro may be a pointer to the efficacy of combination therapy in the treatment of patients with metastatic renal cell carcinoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1990

Development of the nurse tutor's attitude subscale: a pilot study.

This study attempts to develop an instrument to measure a nurse-tutor's attitude toward teacher-pupil relationship. The Nurse Tutor's Attitude Subscale comprised of 37 items was adapted from the Minnesota Teacher Attitude Inventory. Although sample size of this survey was too small to allow confident generalisation, the author wishes to share her experience and problems in developing an instrument for measuring teaching attitude of a nurse-tutor in Hong Kong. It is also hoped that through this preliminary communication, more awareness and attention be directed to helping the nurse-tutors to understand that their classroom attitudes affect effectiveness of their teaching and, henceforth, student learning.

Attitude↗
PubMed1990

The effect of verapamil on the anti-tumour action of mitozantrone and doxorubicin against renal carcinoma cells in vitro.

Ten renal carcinomas were established in culture and their sensitivity to mitozantrone +/- verapamil, as measured by (75Se) selenomethionine incorporation, was studied. The 5 tumours with spread beyond the kidney were those in which sensitivity to mitozantrone was enhanced by verapamil. With 4 of the 10 tumours and 1 further carcinoma, similar experiments were performed using doxorubicin. This drug was more active, its anti-tumour action being related to concentration. Verapamil was more effective in potentiation of doxorubicin and this action increased in proportion to the concentration of verapamil added.

Dose-Response Relationship, Drug↗
PubMed1990

Combined flexor and extensor release for activation of voluntary movement of the fingers in patients with cerebral palsy.

Twenty deformed hands of 19 Japanese patients with cerebral palsy were treated with release of the flexor digitorum profundus, the flexor digitorum sublimis, and the extensor digitorum communis. The results were satisfactory and included enhanced daily activities, voluntary grasp, and release of the fingers. Simultaneous cocontraction of the multiarticular muscles inhibits voluntary movement of the fingers and causes rigidity and involuntary movements. Use of the intrinsic muscles is facilitated by reducing hypertonicity of the multiarticular muscles and by activation of voluntary movements of the fingers. Many such patients can then become functionally independent.

Adolescent↗
PubMed1989

Testing the chemosensitivity of renal carcinoma in vitro.

Tumour cells from 23 renal carcinomas were exposed in vitro to increasing concentrations of medroxyprogesterone acetate (MPA) or one of several cytotoxic agents. Thereafter the uptake of 75Selenomethionine (75SeM) was compared to that of tumour cells not exposed to the drug. Using drug concentrations similar to those seen following in vivo administration in patients, MPA produced greater than or equal to 50% inhibition of 75SeM uptake in 5 of 23 cases. The comparable proportion for doxorubicin was 4 of 5 and for mitozantrone 7 of 12. Methotrexate and Vinblastine were much less effective. In all cases where greater than or equal to 50% inhibition was obtained with doxorubicin and mitozantrone the carcinoma had spread beyond the kidney. Thus drug sensitivity may be associated with a high mitotic rate.

Aged↗
PubMed1987

Chronotropic response of an activity detecting pacemaker compared with the normal sinus node.

We compared the rate responsiveness of an activity-detecting multiprogrammable, single chamber pacemaker (Medtronic Activitrax) to rate responsiveness of the normal sinus node. This pacemaker changes its basic pacing rate in response to physical activity. The rate responsiveness is programmable by selecting one of three activity thresholds, and one of 10 rate response settings. The study included a group of six normal volunteers and 12 patients implanted with Activitrax to examine the similarity of the pacemaker rate to normal sinus rhythm during acceleration and deceleration. The pacemaker was set to Activity mode, at a basic rate of 60 bpm. In volunteers, the device was externally secured on the chest wall and tested at two programmed settings. When programmed at a high threshold of activity and high rate response in volunteers, there was no significant difference in maximum normal sinus rates and pacemaker rates during arm waving, jumping in place, and walking during stress testing. At a medium activity threshold, the only significant difference occurred during submaximal stress testing, when the maximum sinus rate achieved was 141 +/- 19 bpm and the maximum pacing rate was 105 +/- 8 bpm (p less than .02). The pacemaker behaved in a similar manner in patients, successfully simulating the typical fast acceleration and slow deceleration of a normal sinus node in exercise testing. There was no difference in pacer response when implanted in abdominal or infraclavicular locations. The implanted units have functioned normally over a follow-up period of nine to 22 months. Activitrax can be programmed to achieve physiologic pacing rates in response to normal daily activities with appropriate programming.

Abdomen↗
PubMed1987

Morphological and functional characteristics of mouse mammary carcinoma cells separated on Nycodenz columns.

Tissue from four mouse mammary carcinomas was enzymatically disaggregated and cells from the resulting cell suspension were fractionated on a discontinuous density gradient column (5-20%) of Nycodenz (Nycomed A.S. Oslo). The cell fractions separating at the 10-15% and 15-20% interfaces (density 1.082 and 1.110 g/ml respectively) contained a mean of 83.2 +/- 10.8 (s.d.) and 79.9 +/- 17.4 tumour cells. Compared with the original cell suspension these cell bands contained less cell aggregates and cell debris. The cells in the bands also showed an equivalent ability to grow in tissue culture and to form pulmonary tumours on i.v. injection into isogenic mice, when compared with the tumour cells in the original suspension. The relatively pure preparations of carcinoma cells thus separated may be of value in limiting the unwanted effect of normal cell contamination when testing neoplastic cells in vitro for sensitivity to drugs or hormones.

Animals↗
PubMed1985

Treatment of bladder carcinoma with tumor-immune pig lymph node cells. Phase I study.

A total of 77 patients with invasive TCC of the urinary bladder each received a single arterial injection of tumor-immune pig lymph node cells (LNC), into the tumor blood supply. The patients were divided into 4 groups: those receiving pig LNC as the only treatment (16 patients); those who received pig LNC on relapse (judged by EUA cystoscopy and biopsy) following radical radiotherapy, 5,500 cGy (34 patients); those who received pig LNC followed after an interval of six weeks by radiotherapy, 4,000 cGy (10 patients); as in Group 3 but with the dose of radiotherapy increased to 5,500 cGy (17 patients). Complete remission was characterized by complete disappearance of the tumor (for a varying time) following treatment. Partial remission was defined as: a reduction in the level of symptoms and a decrease in tumor size on EUA and/or cystoscopy. There were 1 complete and 3 partial remissions among the patients in Group 1, 5 complete and 7 partial in Group 2, 6 complete and 2 partial in Group 3, and 8 complete and 1 partial in Group 4. Of the 20 patients showing complete remission, 7 lived for more than five years after treatment.

Animals↗
PubMed1984

The use of pig mononuclear cells to inhibit pulmonary tumor formation in isogenic mice.

A-strain mice received 1 X 10(5) A-strain mammary carcinoma, B72, cells iv on Day 0. At the same time fragments of the same tumor were implanted into the ileal mesentery of a pig together with fragments of cellulose sponge. The middle third of the pig mesenteric lymph node chain was resected. Sponge fragments of equivalent size, shape, and total weight were implanted alone into the jejunal mesentery. Seven days later, separate cell suspensions were made from the (disconnected) proximal (nonimmune) and distal (tumor-immune) segments of lymph node chain. Cells were also expressed by digital pressure from the sponges removed from the jejunal (nonimmune) and ileal (immune) segments of mesentery. A comparison was made between the antitumor action of immune lymph node cells and the two categories of sponge cell. Cells (4 X 10(6] were injected iv into the mice on Day 7 and the number of pulmonary tumors counted after killing the mice on Day 14. Cells obtained from the "immune" sponges were significantly more effective in reducing the number of pulmonary tumors than cells from the "nonimmune" sponge, or from the immune lymph nodes. The antitumor action of all cell suspension was abolished when 4 X 10(6) cells from the "interface" layer, following centrifugation on a Ficoll-triosil column, were injected into the mice. Antitumor activity was found to be correlated with the presence of "blast" cells in the pig mononuclear cell suspensions.

Animals↗
PubMed1978

Transfer of adoptive immunity by intra-arterial injection of tumor-immune pig lymph node cells: treatment of recurrent urinary bladder carcinoma after radical radiotherapy.

Twenty-four patients with invasive transitional cell carcinoma of the urinary bladder, recurrent after radiotherapy, were treated by intra-arterial infusion of tumor-immune pig lymph node cells. In 11 patients there was a remission of the disease process, and 3 patients remain alive and free of disease in excess of one year after treatment.

Aged↗
PubMed1978

Adoptive immunotherapy and radiotherapy in the treatment of urinary bladder cancer.

Thirty-one patients with invasive transitional cell carcinoma of the urinary bladder were treated either by infusion of tumour immune pig mesenteric lymph node cells into the tumour blood supply, followed 6 weeks later by 5500 rad, or by radiotherapy alone. The patients were paired prior to treatment, using 4 criteria: age (nearest decade), sex, clinical stage (T3 or T4) and histological grade (average or high). The first patient in each pair then received combined treatment and the second radiotherapy alone. Administration of pig cells before radiotherapy offered no advantage to the patient in terms of the incidence of remission or the length of survival after treatment.

Animals↗
PubMed1976

Physical aspects of wet granulations I: distribution kinetics of water.

The kinetics of wetting during the process of making tablet granulations were studied; the process progresses through an intermediate (overwetted) nonequilibrium granule to a final, equilibrated granule. In systematic formulation changes, there is an optimum composition from the point of view of hardness and content of equilibrium granules.

Drug Compounding↗
PubMed1976

The comparative effectiveness of rabbit anti-mouse thymocyte sera in potentiating the survival of mouse skin or tumour allografts made across the H-2 barrier.

A group of fifteen rabbits were immunized five times, at weekly intervals, by intravenous injection of mouse thymocytes. After an interval of 3 months the rabbits were then re-immunized three times at intervals of 7 days. The rabbits were bled prior to the commencement of immunization to obtain normal rabbit serum (NRS), and 7 days after the first, third, fifth, sixth and eigth immunizations. Thus pulse (P), P1, P3, P5, P6 and P8 rabbit anti-mouse thymocyte serum (RAMTS) was obtained. Further pairs of rabbits were immunized three times, at intervals of 7 days, by injection of thymocytes pre-incubated with NRS, or P3, P6 or P8 RAMTS. Thus RAMT(NRS)S, RAMT(P3)S, RAMT(P6)S and RAMT(P8)S were obtained. The immunosuppressive potency of the antisera were compared by their ability to promote the survival of A-strain skin grafts made to CBA mice and A-strain mammary carcinoma transplants in CBA mice. Administration of P3, P5, P6, P8, RAMT(P3)S and RAMT(P6)S led to progressive tumour growth, but only P3 and P5 prolonged skin graft survival. Pre-incubation of tumour cells in the several RAMTS samples did not enhance their growth in sub-lethally irradiated (350 rad) CBA hosts. It is thus suggested that the preferential survival of tumour allografts was due to their ability to outgrow a degree of host response able to destroy a skin graft.

Animals↗