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Biomedical subjects

S L Yang

Publications and source records attributed to S L Yang.

191 records · Page 11Linked to original sources
PubMed1972

Further evidence concerning the autoantigenic status of the trophoblast.

Heterologous antisera were raised by inoculation of rabbits with fairly pure suspensions of trophoblast, lymphoid, fetal (excluding placental components), epidermal, decidual, and renal cells from Fischer rats. After absorption of hemagglutinins, these antisera were assayed for abortifacient activity by intramuscular inoculation into time-mated Fischer females. The anti-trophoblast serum aborted all the recipients, but had some nonspecific activity in that it caused the deaths of 12% of them. Anti-lymphocyte serum was more toxic and less potent as an abortifacient. None of the other sera harmed either the mothers or their fetuses. However, the anti-kidney cell serum caused kidney lesions. Absorption of the anti-trophoblast serum with lymphoid cells completely removed its toxicity for the pregnant females without perceptible impairment of its abortifacient activity. However, the latter could be removed by absorption with trophoblast cells. (a) The lymphocyte-absorbed anti-trophoblast serum was equally effective in aborting rats over the range 7-18 days postconception; (b) a single injection of 1 ml was sufficient in most cases, and (c) it was equally efficacious in terminating gestation in rats irrespective of their genetic constitution, and (d) its effect was highly species-specific. These findings support the premise that a unique antigen (or antigens), of possible clinical significance, is associated with trophoblast cells.

Abortion, Induced↗
PubMed1972

Maternally induced transplantation immunity, tolerance, and runt disease in rats.

A previous report that the offspring of outbred Sprague-Dawley rats, born of mothers presensitized or tolerant with respect to tissue antigens of the Lewis strain, and reinoculated with Lewis cells during their pregnancy, reject test grafts of Lewis skin in an accelerated manner has been confirmed. This "maternally induced" alteration in reactivity of the progeny has been found to be long lasting, immunologically specific, and probably not due to transfer of humoral antibody. It has been established that the reexposure of the mothers to donor cellular antigen during pregnancy augmented the influence of the prior states of tolerance or sensitivity. To obviate the complications inherent in working with the outbred Sprague-Dawley rats, the key experiments summarized above were repeated with isogenic Fischer rats as parents and Lewis rats as the tissue donors as before. With this combination it was found that a state of prior sensitization or tolerance in the mothers resulted in the apparent induction of tolerance in some of their progeny. Reinoculation of either the tolerant or sensitized mothers during pregnancy slightly increased the incidence and degree of impairment of their offsprings' capacity to reject Lewis skin grafts. A single intraperitoneal injection of 100 x 10(6) million Lewis lymphoid cells into normal Fischer rats in the 14th-16th day of pregnancy also weakened the reactivity of their progeny to Lewis test grafts. Further to test the premise that this weakened reactivity might be due to maternal induction of tolerance, by antenatal transmission of alien cells, the lymphohematopoietic tissue system of adult Fischer females was replaced by that from Lewis donors with the aid of cyclophosphamide. It was anticipated that when these animals were mated with Fischer males, sufficient Lewis leukocytes might cross the placentas to induce high degrees of tolerance. Although normal sized healthy litters were born, about 50% of the infants succumbed to graft-versus-host (GVH) or runt disease within 40 days, many of them giving evidence of being tolerant of Lewis grafts. The mothers, too, developed chronic GVH disease. The offspring of Fischer females made chimeric with cells from (Fischer x Lewis)F(1) hybrid donors, as well as their mothers, remained healthy. Intraperitoneal injection of normal Fischer females, in the 15th-17th day of pregnancy, with 100 million lymphoid cells from specifically sensitized Lewis rats, also caused fatal runt disease to develop in about 50% of their offspring, but left the mothers unscathed. Taken together, these various findings indicate that in some genetic contexts at least the extent of the natural surreptitious transplacental cellular traffic can be considerably augmented experimentally, though how this comes about and why lymphocytic cells that are foreign to the mother can apparently gain access to fetuses more readily than her own cells remain to be determined.

Animals↗
PubMedDate not supplied

Ectopic soft tissue calcium deposition following liver transplantation.

We observed ectopic soft tissue calcification affecting seven patients following orthotopic liver transplantation. The cause of such calcification is unknown, but potential pathogenetic factors include hyperparathyroidism, calcium administered during and following surgery, renal failure, acid-base changes and citrate in fresh frozen plasma. To investigate some of the mechanisms underlying ectopic calcification following liver transplantation, we determined preoperative levels of ionized serum calcium, phosphate, magnesium, parathyroid hormone (midmolecule assay) and 1,25-(OH)2 vitamin D in 20 patients who underwent 24 liver transplants. In addition, these parameters were measured weekly in 15 patients during the first month after liver transplantation. Preoperatively, 5 of the 20 patients had elevated serum levels of parathyroid hormone, and 9 others had low levels of 1,25-(OH)2 vitamin D. After liver transplantation, ectopic calcification was found in seven patients (47%). The organs affected in order of frequency were lungs, liver graft, colon, vascular walls, kidneys, adrenal glands and gastric mucosa. One patient with ectopic calcification of both lungs had markedly restricted pulmonary function as well as radiologic evidence of osteopenia and pathologic fractures of three vertebrae. Postoperatively, increased parathyroid hormone levels were found in all patients who developed soft tissue calcification. Parathyroid hormone levels peaked during the second week after transplantation and were higher at all times compared to subjects without calcification. Five of the seven patients with ectopic calcification had associated renal failure. Individuals who developed calcification had received significantly more fresh frozen plasma, red blood cells and elemental calcium postoperatively, but showed no difference in serum levels of calcium, magnesium, vitamin D, total plasma CO2 or phosphate levels when compared to patients without calcification.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗
PubMedDate not supplied

The clearance of cyclosporine by hemodialysis.

The pharmacokinetics of cyclosporine were studied in five liver transplant patients when they were on and off hemodialysis. There was no significant difference in the blood clearance of cyclosporine between these two periods. Less than 1 per cent of the dose of cyclosporine was recovered in the dialysate. The mean dialysis clearance was less than 1 ml/min. This represents less than 1 per cent of the total blood clearance of cyclosporine. Dosage alterations of cyclosporine during or after hemodialysis do not appear to be necessary.

Adult↗
PubMedDate not supplied

Renal autotransplantation and extracorporeal reconstruction for complicated benign and malignant diseases of the urinary tract.

Renal autotransplantation was performed in five patients and extracorporeal vascular reconstruction was required in two of these cases. One had a carcinoma of the mid-ureter with a solitary kidney. Two patients had ureteral injury. One was iatrogenic from a prior operation, and the other had intrinsic ureteral disease secondary to schistosomiasis. The fourth patient had renovascular hypertension with disease extension into the interlobar renal arteries and a single kidney. The final patient had a large, renal arteriovenous malformation and polycystic kidneys. All have functioning grafts at follow-up ranging from 10 to 36 months. There is no evidence of tumor recurrence after 30 months in the patient with ureteral malignancy. The patient with renovascular hypertension has adequate blood pressure control with medication 12 months after surgery. His creatinine which had risen in the post-operative period to 4.2 mg/dl, has returned to its pre-operative valve of 1.8 mg/dl. None of the other four patients had any post-operative decline in renal function. These cases illustrate that the technique of nephrectomy, extracorporeal surgery, and renal autotransplantation can be applied to a variety of benign and malignant diseases of the kidney and ureter not amenable to conventional in-situ correction, thus allowing maximal preservation of renal parenchyma. We also have demonstrated that the procedure can be successfully performed in the presence of significant infectious risk (Case 2: indwelling nephrostomy), and retroperitoneal infection (Case 3: schistosomiasis). We feel that this procedure is currently underutilized.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Inhibition of nociceptive discharges of parafascicular neurons by direct electrical stimulation of nucleus centrum medianum.

Pain evoked unit discharges in the parafascicular nucleus could be inhibited by direct electrical stimulation of the centromedian nucleus of thalamus, with residual inhibitory effect lasting for several minutes after cessation of stimulation. The optimal frequency of stimulation for production of the inhibitory effect was found to be 4--8 pulses per second. The duration of inhibition following each stimulating pulse lasted for 100--170 msec. Analysis of oscillographic records shows that there exists before the onset of the inhibition of parafascicular discharges a latent period of 10--20 msec which far exceeds the time required for impulse conduction between the two closely related structures, suggesting that a long tortuous neuronal circuit is involved in elaboration and transmission of the inhibitory effect.

Acupuncture Therapy↗