Serum lipoprotein (a) levels in maintenance hemodialysis patients

To further understand lipoprotein (a) [Lp(a)] and atherosclerosis, we measured serum Lp(a), lipoprotein, and apolipoprotein levels in 55 patients (males, 24-73 years old) on maintenance hemodialysis, and compared them with those of 82 controls (males, 21-81 years old). The serum Lp(a) levels in patients on maintenance hemodialysis were significantly higher than those of the normal controls, while serum total cholesterol (TC), high-density lipoprotein-cholesterol, (HDL-C), HDL2-C, HDL3-C, apolipoprotein (apo) Al, apo All levels, and lecithin-cholesterol acyltransferase (LCAT) activities were significantly (p < 0.05) reduced in the patient group. The frequency distribution of serum Lp(a) levels in the patients was different from that in the control group, and no prognostic tendency of serum Lp(a) levels was noted by the etiology of renal failure as histologically determined by the renal biopsies. In the patient group, we also found that serum Lp(a) levels negatively correlated with serum triglycerides (TG) and total protein (TP) concentrations (p < 0.05), but no correlation was found between the duration of hemodialysis therapy or patient age and the serum levels of TC, TG, apo B and Lp(a) levels when tested for simple regression. Significant (p < 0.05) positive correlations were also found between TP and serum TG, apo B, and LCAT activities. These opposing tendencies of Lp(a) and serum TG, apo B, when measured against TP concentrations, indicate that serum TP levels may not affect serum lipoprotein and Lp(a) levels in the same direction. These data suggest that hemodialysis or end-stage renal disease itself, rather than hypoproteinemia, may hold the key to high serum Lp(a) levels in hemodialysis patients.

[Experimental study on kidney invigorating and lipid reducing decoction-yishen jiangzhi tang in the treatment of chronic renal failure]

In exploring the effect of treatment of supporting the body resistance on chronic renal failure, a chronic renal failure model of rat was created by gastroperfusion of adenine and evaluation was made on the therapeutic effect of Kidney Invigorating and Lipid Reducing Decoction (KILRD). The mental state and body weight of the treated group have recovered well with polyuria and proteinurea improving, BUN and Creatinine decreasing, which appeared to be superior to the naturally recovered group. Renal pathological examination showed that: although the renal parenchymal damage was not reversed but its compensation was satisfactory with compensatory hypertrophy appearing in unaffected nephron. The dominant reaction in the affected area was polynucleomacrocytosis, foreign body granulamatosis, and interstitial lymphocytic infiltration, the fibrosis was inevident, while the above-mentioned condition in the naturally recovered group was relatively more serious, with fibrosis being observed. It was indicated that KILRD could increase the compensatory capacity and immunity, promote protein synthetization and improve renal function. The study on KILRD proved to be a significant conservative medical treatment for chronic renal failure.

Preclinical studies on the anticancer activity of the somatostatin analog octreotide (SMS 201-995)

The antiproliferative effect of somatostatin-14 and its analog octreotide on in vitro pancreatic and breast tumor cells has led to the suggestion that octreotide may have further oncological indications in addition to gastroenteropancreatic tumors. To extend these in vitro observations, we evaluated the effect of octreotide in rodent models of pancreatic and breast tumors. Octreotide of 5 or 50 micrograms b.i.d. in nude mice bearing solid MiaPaCa pancreatic tumors (subline 21) or ZR-75-1 breast tumors induced significant inhibition of tumor growth from week 2 until the end of treatment at week 5. After 5 weeks the mean volume of ZR-75-1 tumors in animals treated with the 50-micrograms regimen was 48% that of control. Autoradiographic studies showed a high percentage (71%) of ZR-75-1 tumors to be somatostatin receptor-positive. In addition, the growth of ZR-75-1 cells in vitro was significantly inhibited by octreotide. The drug was also tested in a second breast cancer model, DMBA-induced mammary tumors in rats, and continuous administration of 10 micrograms/kg/h over 6 weeks led to an approximately 50% reduction in the number of tumors arising in the rat mammary gland. These data suggest that pancreatic and breast cancer may be among the malignant diseases clinically susceptible to octreotide.

Effects of manidipine and delapril on serum lipids, lipoproteins, and apolipoproteins in patients with mild to moderate essential hypertension: a randomized trial with one-year follow-up

Forty-five patients with mild to moderate essential hypertension were randomly assigned to receive 10 to 40 mg of manidipine HCl or 15 to 60 mg of delapril daily for 12 months. In the manidipine-treated group were 13 women and 5 men (mean age, 48.2 years) and in the delapril-treated group 11 women and 11 men (mean age, 53.7 years). Blood samples were taken at baseline and after 6 and 12 months of treatment and again at 2 months after treatment discontinuation. Significant reductions in blood pressure were observed in both treatment groups. The reduction in diastolic blood pressure was significantly greater in the manidipine-treated patients than in the delapril-treated patients; no significant between-groups differences in systolic blood pressure were noted. Heart rate increased significantly in the manidipine group. No changes in serum levels of total cholesterol, triglycerides, and high-density and low-density lipoprotein cholesterol were noted during or after treatment. In the manidipine group, a small but significant decrease in apolipoprotein (apo) A-I and an increase in lipoprotein(a) were found at 6 months and a significant increase in apo A-II and apo E at 12 months; in the delapril group a significant decrease in apo A-I was found at 6 months. The results indicate that both manidipine and delapril are lipid-neutral antihypertensive drugs, since neither drug greatly affected serum lipid metabolism.

[Application of serum somatomedin C level to assess the disease activity in patients with acromegaly]

Serum SMC level was measured in acromegalic patients with different disease activity. The serum SMC level of 10 untreated and 15 treated patients with active disease was 30.5 +/- 17.6 and 23.8 +/- 16.3 KU/L respectively. These levels were significantly higher than the value 2.7 +/- 2.8 KU/L in 7 patients during remitting state. The serum SMC level correlated with the basal and the nadir GH level and the area under the GH curve in glucose suppression test. The serum SMC levels in 6 patients with prolactinoma, 10 patients with Grave's disease and 8 patients with renal failure were all in normal range, but in 10 patients with liver cirrhosis it was 0.36 +/- 0.39 KU/L, which was significantly lower than the normal value. We concluded that serum SMC level is a good criterion for assessment of disease activity of acromegaly for it does not require a dynamic test and it does not increase in other diseases.

Effects of Chinese herbal drugs on serum lipids, lipoproteins and apolipoproteins in mild to moderate essential hypertensive patients

We investigated the effects of the traditional Chinese herbal drugs, Dai-saiko-to (D) and Saiko-ka-ryukotsuboreito (S) on blood pressure, pulse rates, serum lipids, lipoproteins and apolipoproteins in 30 patients with mild to moderate hypertension in an open, randomised trial. After the drug treatment, BP remained unchanged, but pulse rates declined significantly after 3 months in the S treated group. Serum total cholesterol and triglyceride values did not change, but high density lipoprotein-cholesterol increased significantly (P < 0.05) in both groups. Apo-AI (P < 0.1 in S group) and apo-AII (P < 0.05 in D group, P < 0.1 in S group) tended to increase 3 months after treatment. These data indicate that both of these traditional Chinese medicines have a preferential effect on lipid metabolism with little antihypertensive action.

Antiproliferative effects of the somatostatin analogue octreotide (SMS 201-995) on ZR-75-1 human breast cancer cells in vivo and in vitro

The somatostatin analogue octreotide (SMS 201-995) inhibits secretion and growth of certain tumor cells, and current efforts are directed toward the elucidation of its mode of antiproliferative action. In this study, the effect of octreotide on the growth of ZR-75-1 human breast cancer cells has been characterized in immunodeficient nude mice and in cell culture. These results have been related to the expression of somatostatin receptors in vivo and in vitro. Continuous infusion of 10 micrograms/kg/h of octreotide yielded plasma levels of 5.7 ng/ml and elicited highly significant growth inhibitory effects on solid ZR-75-1 breast tumors in nude mice. After 2 and 4 weeks of treatment, tumor volumes in the octreotide group were 39.1 and 36.7% of those of control animals treated with vehicle, respectively. Autoradiographic studies demonstrated that 8 of 12 ZR-75-1 tumors studied were somatostatin receptor positive. When ZR-75-1 tumor cells were exposed in vitro to nanomolar concentrations of octreotide, a dose-dependent inhibition of cell growth was observed in the presence of 5% fetal calf serum or under serum-free conditions using epidermal growth factor, insulin-like growth factor type I, or insulin as growth stimulus. In parallel receptor-binding experiments, ZR-75-1 cells were shown to express specific high-affinity somatostatin receptors (Kd value = 0.9 nM, Bmax = 6000 sites/cell). From these experiments, we conclude that octreotide is a powerful inhibitor of ZR-75-1 tumor cell growth in nude mice and in culture. This inhibitory action of octreotide and the presence of somatostatin receptors on ZR-75-1 tumor cells in vitro and in vivo suggest a direct, somatostatin receptor-mediated effect of octreotide.

Preclinical studies on the anticancer activity of the somatostatin analogue octreotide (SMS 201-995)

The antiproliferative effect of somatostatin-14 and its analogue, octreotide, on in vitro pancreatic and breast tumor cells has led to the suggestion that octreotide may have further oncological indications in addition to its use in the treatment of gastroentero-pancreatic (GEP) tumors. To extend these in vitro observations, we evaluated the effect of octreotide in rodent models of pancreatic and breast tumors. Octreotide at a dose of 5 micrograms or 50 micrograms twice a day in nude mice bearing solid MiaPaCa pancreatic tumors (subline 21) or ZR-75-1 breast tumors induced a significant inhibition of tumor growth from week 2 until the end of treatment at week 5. After 5 weeks, the mean volume of ZR-75-1 tumors in animals treated with the 50-micrograms regimen was 48% of that in controls. Autoradiographic studies showed that a high percentage (71%) of ZR-75-1 tumors were somatostatin receptor-positive. In addition, the growth of ZR-75-1 cells in vitro was significantly inhibited by octreotide. The drug was also tested in a second breast cancer model, 7,12-dimethylbenzanthracene (DMBA)-induced mammary tumors in rats, and continuous administration of 10 micrograms/kg/h over 6 weeks led to an approximate 50% reduction in the number of tumors arising in the rat mammary gland. These data suggest that pancreatic and breast cancer may be among the malignant diseases clinically susceptible to octreotide.

[The incidence of low birth weight infant in north China]

From September 1989 to August 1990, the incidence of low birth weight (LBW) infant was studied collaboratively in 8 areas in north China. 29,941 infants (14,003 males and 12,938 females) were investigated, 1,348 LBW infants included those of preterm and small for gestational age (SGA) term. The incidence of LBW infant was 5.00%. The incidence of male preterm (3.15%) was higher than that of female preterm (2.39%). The incidence of female SGA term (2.46%) was higher than that of male SGA term (1.82%). 52.09% of the infants with birth weight (BW) < 2,500g was of SGA term. 35-36 weeks premature infants accounted for 61.78% and 1,500-2,499g LBW infants for 93.28%. The incidence of SGA preterm (GA < 37 weeks) was 17.8%. In this study, the incidence of LBW infant was higher in Changchun and Huhehot than in other areas.

[Entrainment phenomenon of atrioventricular nodal reentrant and atrioventricular reentrant tachycardias]

Atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) were induced by esophageal pacing and their entrainment zones were examined in 20 patients. The results showed that the entrainment phenomenon, which was a common electrophysiological phenomenon in reentrant tachycardia, occurred during overdrive pacing in 19 cases (19/20). The entrainment zone was 10-70 (30.50 +/- 20.85, mean +/- s) ms. The tachycardias could not be interrupted by pacing within the entrainment zone, but they were terminated by burst pacing, with starting pacing cycle length shorter than the shortest entrainment cycle length.

[A new method of expanding free skin grafts]

The harvested skin was processed by a skin-cutting-machine into strips of 0.3 or 0.5 cm in width. Then, the skin strips were glued on alternate folds of a pleated sheet of paper, each fold of which was 0.3 cm or 0.5 cm in width. The paper with skin strips on it was spread flat and cut across into 0.3 cm or 0.5 cm strips. These strips were again glued to another sheet of plicate paper. After being cut across again, many small blocks of skin in equidistance were finally obtained. They were then grafted on the recipient site. The area of grafted wound was four fold or more of the original area of the harvested skin. This method has been used in 6 patients with good result.

Prevalence of growth hormone deficiency of children in Beijing

103,753 (male 51,994, female 51,759) primary and middle school students aged 6-15 years in two districts in Beijing city were surveyed from October 1987 to April 1989. The heights of the students were measured. According to the height standard of northern cities in China, 202 students with heights below the 3rd percentile for age were requested for detailed history, physical examination, screening GH test bone age, T4, SGPT, chest X-ray, routine urine test and sex chromatin (in female). If GH less than 10 micrograms/L, two provocative tests (L-dopa or clonidine and insulin hypoglycaemia test) were done. Then the heights of the short students were observed for 1/2-2 years. GHD was diagnosed in 12 cases based on the GH peak levels less than 10 micrograms/L in two provocative tests, whose growth velocity was slower than that for students of the same age and sex. Of these subjects with GHD, total GHD (GH less than 5 micrograms/L) was present in 7 and partial GHD (GH = 5-9.9 micrograms/L) in 5. The 12 GHD students (male 9, female 3) aged 8.9-15.7 years accounted for 1/8,646 in the total surveyed students. The male and female GHD accounted for 1/5,777 and 1/17,253 in the total males and females respectively.

[The characterization of mutant No. 68 from midecamycin producing strain S. mycarofaciens 1748]

A stable mutant No. 68 was obtained by treatment of S. mycarofaciens 1748 spores at high temperature. The electromicroscopic examination has shown that the mutant No. 68 and parent strain 1748 both have the spore chains of the spiratype. The spores of both strain are cylindrical in shape. The only difference is that the spores of the mutant No. 68 are of smooth surface, but the 1748 are of thorny. The physiological characteristics of both strains are also very similar with slight differences in utilization of few carbon sources and in cultural characters in few medium. Feeding experiment has shown that the mutant No. 68 was blocked in the formation of the macrolide lactone in the midecamycin biosynthetic pathway. This suggested that the mutant No. 68 might be a polyketide synthase genes deficient mutant. The ability of the mutant No. 68 to convert spiramycin into 4"-propionylspiramycin indicated that the mutant No. 68 contained the midecamycin 4"-propionyltransferase and could be used for microbial bioconversion of spiramycin into 4"-propionylspiramycin.

Organic anion transport in HepG2 cells: absence of the high-affinity, chloride-dependent transporter

In previous studies, we identified a 55 kD organic anion-binding protein in liver cell sinusoidal plasma membrane subfractions. Other investigators identified another 55 kD bromosulfophthalein/bilirubin binding protein on the surface of rat hepatocytes and HepG2 cells and suggested that this protein served as a transporter for these ligands. In this study, transport of 35S-sulfobromophthalein by the human hepatoma cell line, HepG2, was quantified in the presence and absence of bovine serum albumin to further clarify the possible function of these plasma membrane binding proteins. In contrast to results in normal rat hepatocytes, virtually no uptake of 35S-sulfobromophthalein by HepG2 cells in the presence of bovine serum albumin was found. In the absence of albumin, HepG2 cells expressed temperature-dependent uptake of 35S-sulfobromophthalein. However, the high-affinity Cl(-)-dependent sulfobromophthalein transport that characterizes normal rat hepatocytes was absent, as indicated by an approximately 95-fold lower affinity and 170-fold higher capacity of HepG2 cells for sulfobromophthalein compared with previous results with rat hepatocytes. These results suggest that 55 kD sulfobromophthalein/bilirubin-binding protein on the liver cell surface differs from organic anion-binding protein and is not responsible for sulfobromophthalein extraction in the presence of albumin, although it may play some role in lower affinity transport by cells. Immunoblot analysis and metabolic labeling of HepG2 cells demonstrated synthesis of organic anion-binding protein. However, light microscopic immunocytochemistry and immunoprecipitation of surface iodinated rat hepatocytes and HepG2 cells with antibody to a recombinant organic anion-binding protein fusion protein indicated absence of organic anion-binding protein on the surface of HepG2 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro cytotoxicity against fresh human tumors and P388 leukemia predicts the differential in vivo activity of a series of anthracene anticancer drugs

To date, random anticancer drug screening has proven to be relatively inefficient and non-specific with respect to selecting active compounds for most tumor types (except for leukemia/lymphoma). Although large numbers of compounds from diverse sources were evaluated for many years in the P388 mouse leukemia model, only a few clinically useful drugs have been identified by this in vivo screening method. Thus, there is intense interest in the development of more effective in vitro screening models for new anticancer drugs. In the present paper we have compared the discriminating power for fresh human tumors from patients, human tumor cell lines developed from 11 patients and murine P388 leukemia in tumor colony forming assays as indicators of cytotoxicity for a series of anthracene antitumor agents. Two of a series of 21 novel bisantrene analogs, R6 (N,N1-bis[2-(dimethylamino)ethyl]-9,10-anthracene-bis(methylamine)) and R26 (N,N1-bis(1-ethyl-3-piperidinyl)-9,10-anthracene-bis(methylamine] produced significant cytotoxicity against the 11 human tumor cell lines and were therefore selected for additional in vitro and in vivo studies. R26 was specifically selected for further testing since it had similar in vitro potency as mitoxantrone, but showed no cross-resistance against mitoxantrone-resistant WiDr colon or doxorubicin-resistant 8226 myeloma cell lines. In contrast to the cell line data, only of the 22 fresh human tumors showed significant in vitro sensitivity (i.e. less than 50% survival of tumor colony forming units) to either R6 or R26 tested at high concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemic non-A, non-B hepatitis in Xinjiang. Clinical and pathologic observations

131 cases of epidemic hepatitis from two villages in Xinjiang, were admitted to the provisional infectious diseases hospital from February to April 1987. In 125 (95%) patients neither anti-HAV IgM nor anti-HBc IgM were positive. 118 (90%) were drinking water from a local stream of the Hotan River. The study was conducted on 125 patients aged from 5 to 90 years, with a mean of 26.4 years. There were slightly more males than females, a ratio of 1.5 to 1. The incubation period was roughly estimated to be 17 to 37 days (mean 24.8 days). All subjects were jaundiced. 12 patients (including 6 pregnant women) had cholestatic symptoms. Except one woman who died of postpartum bleeding, all patients ran a benign course without fulminant hepatic failure. Pathologic changes of liver biopsies from 35 cases included lobular damage and inflammation, ballooned hepatocytes with clear cytoplasm and delineated cell membrane which were named "clear cell". There were cholestasis of different degrees in the acute icteric stage and fatty changes in the convalescent stage. It was seen under the electron microscope that the livers of 8 cases had neither tubular structure nor sponge-like inclusions, but had nuclear changes including curled edge of nuclear membrane and nuclear heterochromatin condensed in masses. Liver biopsies were repeated in 7 cases followed up for 6-13 months, and hepatohistology was normal in 5. Of the other two cases there was one of each.

Clinical trial with somatonorm in idiopathic growth hormone deficiency in children

This article reports the efficacy and safety of treatment with Somatonorm in 9 children with idiopathic growth hormone (GH) deficiency in China. The growth velocity increased from 2.6 +/- 0.2 cm/year before treatment to 10.7 +/- 0.5 cm/year at the end of 1-year treatment. The increment of human growth hormone (hGH) level and area under the response curve above the baseline level were larger after one injection of Somatonorm at the dose of 0.1 IU/kg sc than that of 0.17 IU/kg im. Increments of delayed bone age were not significant. There was no correlation between the increase of height growth velocities and the serum Somatomedin-C (SMC) levels during hGH therapy (r = -0.055). Blood sugar levels and blood alkaline phosphatase concentrations increased significantly after therapy. There were no significant side effects. Serum T4 levels of 3 patients dropped below normal after treatment. Serum anti-hGH antibody appeared at 3-12 month in 2 patients, but it did not attenuate the growth velocity.

Modification of the clonogenic assay for the detection of lymphokine activated killer cell activity

The soft agar clonogenic assay using [3H]thymidine uptake as an endpoint was adapted for the detection of human LAK activity against the Daudi lymphoma cell line and human tumor cells obtained by biopsy. Using Daudi cells as the target population the modified agar assay was more sensitive than the conventional 4 h 51Cr release assay. Use of a single layer agar assay allowed the assessment of LAK cytotoxic/cytostatic activity against Daudi lymphoma cells after cell to cell contact, while a two layer system permitted evaluation of the role of soluble mediators in LAK/target cell interactions. This study shows that LAK cells can either kill or inhibit the proliferation of Daudi cells by two mechanisms: one which requires cell-to-cell contact, and a second via soluble mediators. As determined by the use of neutralizing antisera, the soluble factor(s) are not tumor necrosis factor and interferon-gamma. Of the nine individual human tumor samples obtained by biopsy. 89% were sensitive to allogeneic LAK cells when the two populations were admixed. Of these nine tumors 44% were inhibited by LAK-derived soluble factors. The soft agar assay system should serve as a useful tool for determining the sensitivity of human tumors to LAK cells and for studying the mechanisms of LAK anti-tumor activity.

Effects of granulocyte-macrophage colony-stimulating factor on in vitro growth of human solid tumors

Solid tumor biopsies from 33 patients were tested in vitro to evaluate the growth modulatory effects of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF). In 29 of 33 studies (88%), addition of GM-CSF either had no effect on in vitro growth, or induced growth inhibition. While significant growth inhibition was observed in 10 studies, marked inhibition was only observed in three studies. However, all dose-response curves were usually flat, suggesting indirect effects. Moderate growth stimulation was observed in four instances, which may have been due to residual granulocyte-macrophage progenitors within the biopsies. We conclude that GM-CSF has little or no growth-modulatory effect on most nonhematopoietic neoplasms. The primary role of GM-CSF in patients with solid tumors appears to be in prevention or reversal of myelosuppression associated with therapy. Thus, while GM-CSF seems unlikely to have a role in monotherapy of cancer, it is also unlikely to have its utility compromised by enhancement of tumor growth.

Superconducting Gap in Bi-Sr-Ca-Cu-O by High-Resolution Angle-Resolved Photoelectron Spectroscopy

Detailed studies indicate a superconducting gap in the high-temperature superconductor Bi(2)Sr(2)CaCu(2)O(8). Photoemission measurements with high energy and angle resolution isolate the behavior of a single band as it crosses the Fermi level in both the normal and superconducting states, giving support to the Fermi liquid picture. The magnitude of the gap is 24 millielectron volts.

In vitro evaluation of cisplatin interaction with doxorubicin or 4-hydroperoxycyclophosphamide against human gynecologic cancer cell lines

Doxorubicin, cisplatin, and cyclophosphamide are the three drugs most commonly used in the treatment of ovarian cancer, but no effect greater than additivity was observed for any combination of these drugs in the present study. Only a few studies have been reported concerning the degree of their additivity or their best order of sequencing. In our in vitro studies, cisplatin in combination with doxorubicin or 4-hydroperoxycyclophosphamide (4HC) was tested against seven human gynecologic tumor-cell lines in different sequences, using a double-agar layer tissue-culture system. Drug interactions with respect to inhibition of tumor clonogenicity were evaluated by isobologram and fractional survival methods. Doxorubicin and 4HC were sequenced simultaneously and at 1, 6 and 24 h after cisplatin, and cisplatin was sequenced at 1, 6 and 24 h after 4HC. The isobolograms constructed for doxorubicin or 4HC plus cisplatin revealed strict additivity between these agents against ovarian cancer clonogenicity. Both doxorubicin and 4HC showed the greatest additivity when used simultaneously and at 1 h vs 6 or 24 h after cisplatin. Although the mechanisms by which these sequencing effects occur are unknown, these studies provide new leads for the design of clinical trials with combinations of these three agents.

Amdinocillin: interaction with other beta-lactam antibiotics for gram-negative bacteria

Amdinocillin was studied alone and in combination with three other beta-lactam antibiotics (aztreonam, cefoperazone, and ceftriaxone) for activity against gram-negative bacilli. These antibiotic combinations failed to show synergy by the checker-board double-dilution test or by killing kinetic studies. However, amdinocillin did show additive killing action when combined with the other beta-lactam antibiotics studied. Amdinocillin failed to induce or inhibit beta-lactamase production in species of Enterobacteriaceae, but with Pseudomonas aeruginosa, beta-lactamase production was induced. It is concluded that the activity of amdinocillin alone or in combination with another beta-lactam antibiotic should not be more effective in the treatment of infections by gram-negative bacilli than just using the beta-lactam antibiotic alone at a higher dose.

Structurally different neuronal nicotinic acetylcholine receptor subtypes purified and characterized using monoclonal antibodies

Acetylcholine receptors that bind nicotine with high affinity but do not bind alpha-bungarotoxin have recently been immunoaffinity purified from brains of chickens and rats (Whiting and Lindstrom, 1986a, b; Whiting and Lindstrom, 1987a). Antisera to these receptors bind to the nicotinic receptors that regulate cation channel opening on chick ciliary ganglion neurons (Stollberg et al., 1986) and rat PC12 cells (Whiting et al., 1987c). Here we report the preparation and characterization of monoclonal antibodies to chicken brain acetylcholine receptors. These monoclonal antibodies are used to identify 2 nicotinic receptor subtypes in the chicken brain. The 2 subtypes have very similar affinities for nicotine and other cholinergic agonists and antagonists. However, they are structurally distinct, having very similar or identical alpha subunits (Mr 49,000), but different beta subunits (Mr 59,000, or for beta' subunit, Mr 75,000). Evidence is presented that suggests that the subunit stoichiometry of these neuronal nicotinic acetylcholine receptors is alpha n = 2 - 3 beta n = 2 - 3. Different levels of receptor subtype expression were detected in embryonic, compared to adult, chicken brain.