Biomedical subjects
Publications and source records attributed to S J Liu.
A substantial number of substance P-like immunoreactive nerve fibers were found in the anterior pituitary of macaque monkeys. Most of them were thin fibers with abundant varicosities, which were often in close proximity to the glandular cells. They were found only in the median part of the gland and were distributed chiefly in its dorso-posterior region.
Three hundred seventy-seven pediatric intussusception patients were treated by normal saline hydrostatic enema under ultrasound guidance from October 1985 to April 1987. Before reduction, the rate of correct diagnosis by ultrasonography was 100%, and the rate of successful reduction was 95.5% in this group. With this technique there is no risk of x-ray exposure to the patient. The definite criteria for reduction are discussed. Clear echogram was shown during reduction and the ileo-ileo-coli intussusception can be diagnosed. Intestinal perforation, if any, can be accurately recognized at once. This technique is believed to be one of the most promising methods in nonoperative treatment of pediatric intussusception.
Proton beam therapy for uveal malignant melanoma has been advocated as effective therapy because of documented reduction in tumor size and few clinical complications. However, some eyes have been removed because of adverse effects. The authors report the clinical courses and pathologic findings of five eyes enucleated after proton beam irradiation. Neovascular glaucoma had developed in three eyes, two eyes had vitreous hemorrhage, and two had extraocular extension. The tumors in the radiation treatment field showed continued postirradiation growth clinically in four of the five eyes, and mitotic activity histologically in all five cases. Two and one half years after irradiation, and nearly 2 years after subsequent enucleation, one of those two patients had biopsy-proven liver metastases, and later died. Despite the considerable success rate of proton beam irradiation, the potential for clinical complications and subsequent tumor growth remains.
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Radioimmunoassay of rabbit aqueous humor one hour after Nd:YAG laser anterior capsulotomies revealed increased concentrations of 6-keto-prostaglandin F1 alpha (PGF1 alpha), and thromboxane B2 (TBB2). Coincidental rises in intraocular pressure (IOP) and aqueous humor protein were observed. These changes correlated with the laser power used. Pretreatment with topical 1% prednisolone acetate or 1% indomethacin prior to anterior capsulotomies inhibited the post laser rise in PGF1 alpha and TBB2, but did not eliminate the post laser rise in IOP. Small rises in IOP and the concentrations of aqueous PGF1 alpha, TBB2, and protein were observed after Nd:YAG laser iridectomies. These changes were not affected by prior treatment with 1% topical prednisolone acetate. Although PGF1 alpha and TBB2 are elevated after Nd:YAG laser anterior segment procedures, a causal relationship between post treatment IOP rise and PGF1 alpha or TBB2 release could not be determined.
Interferons are known to have modulatory effects on hemopoiesis. Human bone marrow mononuclear cells were employed to test the effects of human recombinant beta-interferon on myeloid and erythroid hemopoietic stem cell growth. Results demonstrated that 1,000 U/ml of beta-interferon significantly inhibited myeloid growth [colony-forming unit (CFU)-granulocyte macrophage] by 40-50%, whereas a higher concentration (10,000 U/ml) abolished CFU-granulocyte macrophage growth by 80-100%. The inhibitory effects of beta-interferon were partially reversible by increasing the concentrations of colony stimulating activity in the culture and could not be abrogated by addition of toxic oxygen radical scavengers such as superoxide dismutase and catalase. The inhibitory effect of interferon was found to be partially dependent on the presence of accessory cells, since less inhibition was seen using T-cell and monocyte depleted bone marrow cells. Lower concentrations of beta-interferon (10-100 units/ml) were without effect. In contrast to myeloid cells, the human erythroid progenitors (CFU-erythroid, burst-forming unit-erythroid) appear to be more sensitive to the inhibitory effects of beta-interferon. In this regard it was found that 100 U/ml of beta-interferon suppressed erythroid growth by 40-50%. These results suggest that human recombinant beta-interferon is capable of suppressing hemopoietic colony growth.
The role of immunocompetent cells in hemopoiesis remains controversial. We used an autologous system in which activated peripheral blood mononuclear cells (LAK) and interleukin-2 (IL-2) are administered to patients with cancer. We found little change in the numbers of circulating erythroid progenitors. Cocultures of these progenitors with LAK or supernatants lead to a decrease in the numbers of detectable burst forming units-erythroid (BFU-E) in culture. However, using an assay for burst promoting activity (BPA) we noted production of this hemopoietin by these LAK cells. We could not detect circulating levels of gamma interferon (IF). Variable levels were found in the LAK supernatants. We could not detect circulating eosinophil progenitors (CFU-Eo), but we did find evidence of production of a colony stimulating factor (CSF), which gave rise to a high number of eosinophil colonies in cultures of bone marrow. These results suggest that administration of LAK/IL-2 has potent effects on hemopoiesis and that these effects may emphasize the anemia and eosinophilia seen in patients receiving this therapy.
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Rats given 2-day oral administration of methadone (15 mg/kg, twice on day 1 and once on day 2) by gastric tube developed dispositional tolerance to methadone analgesia as demonstrated by a decrease in analgesic response and by an increase in methadone metabolism. The increased metabolism of methadone was evidenced by a decrease in brain concentration of 14C-methadone and increases in the percentages of total 14C in liver or urine as 14C-water-soluble metabolites (14C-WSM) after the rats were challenged with a test dose of 14C-methadone. Two-day pretreatment with a combination of desipramine (DMI) (10 mg/kg, ip) and methadone (15 mg/kg, po) enhanced the development of dispositional tolerance to methadone analgesia which was evidenced by a greater decrease in the brain concentration of methadone and a greater increase in methadone metabolism as compared to those changes in rats pretreated with only methadone. Repeated treatment with DMI alone neither decreased the analgesic effect of methadone nor stimulated methadone metabolism. It is suggested that DMI given together with methadone promoted the induction of methadone metabolism in the liver by prolonging the enzyme-stimulating state of methadone, thus enhancing the development of dispositional tolerance to methadone.
Morphine sulfate (5 mg/kg s.c.) given 30 min prior to administration of methadone prolonged methadone analgesia and increased the brain level of methadone measured 60, 120 and 180 min after administration of methadone. Rats rendered tolerant to morphine analgesia by subcutaneous implantation of two pellets, each containing 75 mg of morphine base, for 1-3 days showed cross-tolerance to methadone analgesia regardless of the presence or absence of morphine pellets. Decreases in the brain concentrations of methadone measured at 60 and 120 min time points accompanied the decreased analgesia. Neither acute nor chronic morphine pretreatment affects the biotransformation of methadone. The results suggest that the cross-tolerance to methadone analgesia seen in chronic morphine-implanted rats was partly associated with a decrease in the brain concentration of methadone occurring by a mechanism not directly related to a change in the biotransformation of methadone. In view of the known inhibitory effect of chronic morphine pretreatment on drug metabolism, our findings might demonstrate a unique phenomenon between morphine and methadone.
A modified centripetal approach to parotidectomy is reported. A total of 422 benign parotid tumors, 383 of which were primary and 39 of which were recurrent, were treated by this technique. The pleomorphic adenoma was the most common type (94.79%) in the series. Superficial parotidectomy was done in 178 cases, and total parotidectomy, in 244 cases. No permanent facial paralysis occurred after parotidectomy in the primary tumor group. Seven recurrences were observed after surgery in the recurrent tumor group.
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A methadone maintenance patient with a decreased plasma methadone level, possibly due to phenobarbital-induced acceleration of methadone biotransformation, experienced opioid withdrawal symptoms. This finding suggests that when phenobarbital is used with methadone the plasma methadone level must be monitored.
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