Vaccination with monoclonal anti-idiotypic antibody on immunocompetent mice bearing human ovarian carcinoma

OBJECTIVE

To observe the effects of anti-idiotypic monoclonal antibody 6B11 against ovarian carcinoma SKOV3 on immunocompetent mice BCF1 both in vivo and in vitro, so as to investigate the possibility of using it as a tumor vaccine.

METHODS

After immunization with 6B11 and normal mice (NM) IgG respectively on 2 groups of BCF1, blood, lymphocytes and tumor tissues were taken every other day. Ab3 was tested from blood samples. Subpopulations of lymphocytes were examined by FCM. The lymphocytes from immunized BCF1 were also cultured with SKOV3 to observe the chemotaxis and killing effects. Serial tissue sections were taken from BCF1 after immunization by SRCA implantation of SKOV3. TIL and visible cancer cells were examined carefully and compared with those in the controls.

RESULTS

Ab3 rose quickly after immunization with 6B11 but lowered down gradually till the 9th week. The CD4+/ CD8+ ratio of BCF1 changed markedly after immunization with 6B11. The immunized lymphocytes showed a beautiful chemotaxis with and killing effect on SKOV3. During in vivo examinations, TIL were found significantly earlier in the immunized BCF1 than in the controls and reached the peak earlier in the former (on the 6th day) than in the latter, while the viability of tumor cells was vice versa between the two groups.

CONCLUSION

6B11 may be used as a vaccine for not only active immunization but also prevention of ovarian carcinoma.

Thermodynamic hierarchy and local energetics of folded proteins

The cooperativity of local fluctuations within the folded state of a protein is demonstrated based on applying the "multiple-probe principle" to the hydrogen exchange (HX) rates of a set of amide protons of the protein. A hierarchical thermodynamic analysis is presented for the protein energetics, which includes both global two-state folding-unfolding transition and local cooperative fluctuations within the folded state. The analysis dissects the local fluctuations from the global unfolding; both lead to the HX but from the folded and unfolded states, respectively. It provides the newly observed HX behavior of proteins in mild denaturant, namely solvent and temperature dependent HX rates from the folded state, with a quantitative interpretation in terms of a set of local energetic parameters. These local energetic parameters contain much information concerning the structures and stabilities of native proteins.

[Assay of terpenes in the leaves of Ginkgo biloba extract and its preparations by in situ fluorometric TLC]

A new TLC method for the assay of terpene lactones in Ginkgo biloba extract and its preparations has been established by means of optimized development condition and post-chromatographic thermal fluorescence derivatization. Satisfactory results can be obtained through polynomial regression calibration. The data obtained by this method have been proved ten times higher in sensitivity than those obtained by HPLC-refracto-detector.

[Preparation of F(ab')2 fragment of monoclonal antibody COC166-9 and its experimental study of radioimmunoimaging for ovarian carcinoma]

OBJECTIVES

To obtain F(ab')2 fragment of monoclonal antibody (McAb) COC166-9 and to perform its radioimmunoimaging (RII) for ovarian carcinoma.

METHODS

McAb COC166-9 was digested into F(ab')2 by ficin and tested by SDS-PAGE. After purification by DEAE-32, F(ab')2, COC166-9 and normal murine IgG (nMIgG) were labelled by 131I and injected intraperitoneally into three groups of nude mice bearing human ovarian cancer xenografts respectively. 72 hours after injection, RII was performed in three groups of mice.

RESULTS

The yield of F(ab')2 was 54%, about 80% of the maximal theoretical yield. Good immunoreactivity of F(ab')2 retained with higher ratio of tumor to normal tissue radioactivity (T/NT) than that of intact COC166-9. RII showed better result with lower nonspecific background than the latter.

CONCLUSION

F(ab')2 could be obtained by ficin digestion with good yield and immunoactivity as well as better RII than intact monoclonal antibody.

Solution structure of phenol hydroxylase protein component P2 determined by NMR spectroscopy

Phenol hydroxylase from Pseudomonas sp. CF600 is a member of a family of binuclear iron-center-containing multicomponent oxygenases, which catalyzes the conversion of phenol and some of its methyl-substituted derivatives to catechol. In addition to a reductase component which transfers electrons from NADH, optimal turnover of the hydroxylase requires P2, a protein containing 90 amino acids which is readily resolved from the other components. The three-dimensional solution structure of P2 has been solved by 3D heteronuclear NMR spectroscopy. On the basis of 1206 experimental constraints, including 1060 distance constraints obtained from NOEs, 70 phi dihedral angle constraints, 42 psi dihedral angle constraints, and 34 hydrogen bond constraints, a total of 12 converged structures were obtained. The atomic root mean square deviation for the 12 converged structure with respect to the mean coordinates is 2.48 A for the backbone atoms and 3.85 A for all the heavy atoms. This relatively large uncertainty can be ascribed to conformational flexibility and exchange. The molecular structure of P2 is composed of three helices, six antiparallel beta-strands, one beta-hairpin, and some less ordered regions. This is the first structure among the known multicomponent oxygenases. On the basis of the three-dimensional structure of P2, sequence comparisons with similar proteins from other multicomponent oxygenases suggested that all of these proteins may have a conserved structure in the core regions.

Utilization of phytate phosphorus and calcium as influenced by microbial phytase, cholecalciferol, and the calcium: total phosphorus ratio in broiler diets

The present study was performed to evaluate the potential of microbial phytase and cholecalciferol (D3) for improving the utilization of phytate P and Ca and the influence of the Car:total (t) P ratio in a corn-soybean meal diet fed to broilers from hatch to 21 d of age. A 4 x 4 x 2 factorial arrangement of treatments was used: 1.1, 1.4, 1.7, and 2.0:1 Ca:tP ratio; 0, 300, 600, and 900 U of phytase/kg of diet; and 66 and 660 micrograms of D3/kg of diet. Another four treatments were included: the four Ca:tP ratios with 6,600 micrograms of D3 addition, but without phytase. Added phytase linearly increased (P < 0.001) BW gain, feed intake, toe ash content, and P and Ca retention; these measurements were negatively influenced by widening the dietary Ca:tP ratio, and synergetically improved by addition of D3. Increasing the Ca:tP ratio decreased (P < 0.001) all measurements in the presence or absence of supplemental phytase and D3. Dietary Ca:tP ratios between 1.1:1 to 1.4:1 appears critical to the efficient use of supplemental phytase and D3 for improving the utilization of phytate P and Ca. The addition of D3 in corn-soybean meal diets indicated a potential for improving the utilization of phytate P and Ca by increasing Ca and P retention by about 5 to 12% in birds, which led to an increase in toe ash content (P < 0.03). The enhanced phytate P utilization (P < 0.001) was also observed during assay of the phytase activity in the mixed diets with an addition of D3 and without added phytase. In summary, the findings of this study suggested that phytase, D3, and Ca:tP are important factors in degrading phytate and improving phytate P and Ca utilization in broilers.

[Generation of genetic engineering anti-idiotypic antibody against OC125 monoclonal antibody of ovarian carcinoma]

OBJECTIVES

To amplify and express the variable region genes of murine derived anti-idiotypic monoclonal antibody and to develop a new kind of ovarian carcinoma vaccine.

METHODS

mRNA was prepared from murine hybridoma which produces anti-idiotypic antibody against OC125. The heavy and light chain variable region genes (VH and VL) were amplified by polymerase chain reaction (PCR), joined by DNA linker fragments to form single chain FV gene (ScFv), and were ligated into phage mid vector, pCANTAB 5E. The recombinant vector was induced into competent E. coli TG1 cells. The phage displayed recombinant antibodies were detected and identified by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The VH, VL and ScFv genes were 340 bp, 325 bp and 750 bp respectively. Some of the transformed clones expressed engineered anti-idiotypic antibodies, which could specifically bind to the original antibody (OC125).

CONCLUSIONS

Genetic engineering anti-idiotypic antibody against OC125 monoclonal antibody was successfully generated. Clinical application of anti-idiotypic antibody to immunotherapy and to prevention of ovarian carcinoma may be studied.

[Gene expression of bFGF and intimal hyperplasia of autologous vein grafts in rats]

OBJECTIVE

To establish a model of autologous vein graft through translating jugular vein to aortic artery in 80 Wistar rats, and detect gene expression of basic fibroblast growth factor (bFGF).

METHOD

In situ hybridization and reverse transcription polymerase chain reaction (RT-PCR) were used.

RESULTS

The expression of bFGF mRNA was more decreased than that of normal artery and vein after transplantation, up to 1 week, the level of bFGF gene expression decreased to the lowest (P < 0.05). Two weeks after transplantation, bFGF transcripts recovered.

CONCLUSION

bFGF released from dead and damaged cells of autologous vein graft not only is an important factor that promotes SMC proliferation, but also is a potent stimulator of endothelial regrowth.

Replacement of inorganic phosphorus by microbial phytase for young pigs fed on a maize-soyabean-meal diet

Ninety-six crossbred young pigs (body weight 7.8 kg) were used in a 5-week trial to determine the effectiveness of microbial phytase (EC 3.1.3 26) in improving the bioavailabilities of P and other nutrients in maize-soyabean-meal diets and, thus, replacing inorganic P with phytase. A 2 x 5 factorial arrangement of treatments was employed with two available P (aP) levels (0.7 and 1.6 g/kg) and five phytase levels (0, 350, 700, 1050, 1400 U (the quantity of enzyme that liberates 1 mumol inorganic phosphate/min from 5.1 mm-sodium phytate at pH 5.5 and 37 degrees)/kg diet). In addition, two extra diets were formulated to supply the National Research Council (1988) recommended level of aP (3.2 g/kg) with 0 or 1400 U phytase. The addition of graded levels of phytase resulted in linear increases in average daily weight gain, average daily feed intake and weight gain:feed intake for pigs fed on diets containing 0.7 or 1.6 g aP/kg (P < 0.04). Also, the addition of phytase linearly increased apparent digestibilities of P and Ca (P < 0.01), whereas faecal P excretion was linearly decreased (P < 0.01). Linear increases in shear force, shear energy and ash content of both the metacarpal and tenth rib, and shear stress of the metacarpal were found to respond to added phytase (P < 0.01). These improvements in performance, apparent P absorption and bone measurements by phytase were also observed by increasing dietary aP levels for most measurements. Adding 1400 U phytase to the 3.2 g aP/kg diet further increased average daily weight gain, average daily feed intake, apparent absorption of P, Ca and N and metatarsal shear force and ash content (P < 0.01 to 0.05). Generally, maximum responses occurred at a phytase level of 1050 U/kg diet for the 0.7 g aP/kg diets and 700 U for the 1.6 g aP/kg diets. Based on non-linear and linear response equations generated for the phytase and aP levels, the average function of the equivalency of P (Y, g/kg) v. microbial phytase (X, U/kg) was developed across aP levels of 0.7 and 1.6 g/kg for average daily weight gain and apparent digestibility of P: Y = 2.622-2.559e 0.00185X. The replacement of 1 g inorganic P as defluorinated phosphate would require about 246 U microbial phytase. This represents 41% of released P from phytate.

Interactions between a helical residue and tertiary structures: helix propensities in small peptides and in native proteins

We compare three complete sets of helix propensities for the 20 naturally occurring amino acids. These propensities are derived from three different experimental systems: small synthetic peptides, coiled-coil dimers, and real proteins. Thermodynamic analyses show that propensities from the different sets should be perfectly correlated if (1) the helix in a protein is formed when and only when the protein is folded (tight-coupling); and (2) the amino acid side-chains are not involved in tertiary interactions. A simple thermodynamic model is proposed in order to understand those systems that fail (1). The model incorporates fluctuations in both native and unfolded states of the protein. Measurements on hydrogen-exchange rate from proteins also question the validity of (2). A complementary model that assumes a cooperation between helix formation and tertiary structures through side-chain interactions can explain the correlation between data from the peptides and proteins. One possible source of this side-chain tertiary interaction is the amphiphilicity of helices in proteins. Our model is consistent with the ideas of "minimal frustration" and "protein malleability"; it exhibits entropy-enthalpy compensation, and suggests that local unfolding and solvent penetration are correlated in a fluctuating protein. It also suggests experiments to quantitatively verify and differentiate between the models. The electrostatic nature of hydrogen bonding and its manifestations in protein helix stability is also discussed.

Effects of supplemental phytase and phosphorus on histological, mechanical and chemical traits of tibia and performance of turkeys fed on soyabean-meal-based semi-purified diets high in phytate phosphorus

Tibial traits were investigated for turkey poults fed on soyabean-meal-based semi-purified diets high in phytate P (2.2 g/kg) with added phytase and inorganic P. Dietary treatments were: (1) 2.7 g non-phytate P (nP)/kg; (2) diet 1 + 1000 U phytase/kg diet; (3) 3.6 g nP/kg; (4) diet 3 + 800 U phytase; (5) 4.5 g nP/kg; (6) diet 5 + 600 U phytase; (7) 6.0 g nP/kg. Added phytase and nP increased (P < 0.006) tibial dry matter, ash weight and content, body-weight gain, feed intake and gain:feed. The Mg and Zn concentrations in the tibial ash were also increased (P < 0.001 and P < 0.09 respectively) by added phytase or nP; tibial P and Ca concentrations tended to be increased. Hypertrophy zone width of the tibial proximal end decreased (P < 0.001), while proliferating zone width, tibial length, and widths at the long and short axes increased (P < 0.003) as phytase and nP were added. The addition of phytase also tended to enlarge the cartilaginous zone width, which was linearly increased (P < 0.05) by added nP. Disorganization scores of the hypertrophy zone and trabecular bone were low, approaching normal (P < 0.05), for turkey poults fed on diets with phytase supplementation, and tibial abnormality scores were linearly decreased (P < 0.001) as nP levels increased (zero score is considered normal). Adding phytase and nP improved the orderliness of development, mineralization and arrangement of cartilage and bone cells, and alleviated the effects of P deficiency on the histological and gross structure of the tibias. Tibial shear stress increased (P < 0.04) as phytase and nP were added. In summary, similar improvements in bone characteristics were achieved for turkey poults fed on a P-deficient diet supplemented with either phytase or nP.

[Serological analysis of antibodies by anti-idiotypic monoclonal antibody 6B11 against ovarian carcinoma]

OBJECTIVE

To establish a method for detection of serologic antibody by anti-idiotypic monoclonal antibody 6B11 against ovarian carcinoma.

METHOD

Sera-antibody exminations from 172 cases, malignant and benign ovarian and uterine tumors as well as normal individuals as control were done respectively. 15 cases of ovarian epithelial carcinoma with 133 blood samples were examined serially by enzyme linked immunoabsorbent assay during the first 12 month after treatment.

RESULTS

The cutoff value was determined and calculated from sera of normal controls. The positivity of epithelial ovarian carcinoma was 67.3%, much higher than that in the benign ovarian tumor and malignant or benign uterine tumors with statistical significant difference. The serial examinations of the sera in 15 cases of ovarian epithelial carcinoma showed that the negative result turned from the positive one was corresponding with disease status.

CONCLUSIONS

The examination of sera-antibody tested by anti-idiotypic monoclonal antibody 6B11 may give a help for the diagnosis of ovarian carcinoma and may be used as one of the tumor markers for follow up.

A clinical study on severe hydroa vacciniforme

OBJECTIVE

To describe a severe type of hydroa vacciniforme (HV) in order to provide basis for treatment and prevention of this disease.

METHODS

Nine cases of HV were collected in our outpatient department, and clinical and laboratory examinations were performed.

RESULTS

All the cases had erythemas, papules, bullae, erosions or ulcers on exposed sites, with recurrences, gradually resulting in deformation. Five patients suffered from hand deformation manifesting rigidity, flexor tetanus, or malposition of the first, second and third interphalangeal joints of hands. Two of the above mentioned patients manifested partial bone absorption of fingers. Five patients showed partial defect of auricle. Two patients showed saddle nose, and partial absorption of nasal cartilage. One patient displayed cicatricial contracture of lower lip, with incisor extrusion. Four patients showed opacity of cornea. Through laboratory examinations, porphyrinopathies were excluded. Phototests showed increased sensitivity to ultraviolet-A radiation (UVA).

CONCLUSIONS

Based on the clinical features and laboratory examinations, these patients were diagnosed as having severe HV. It is believed that this condition belongs to a disease spectrum induced by ultraviolet light. Our analysis suggests that for children with severe type of HV, preventive measures and therapeutic agents should be taken as soon as possible in order to avoid deterioration of the disease and malformations.

[SMC proliferation and its distribution in autologous vein grafts]

SMC proliferation in intimal hyperplasia is a major cause of graft failure. We induced experimental jugular vein to aortic autograft in 120 Wistar rats, and analyzed the SMC proliferation and its distribution in the graft by flow cytometry (FCM) and immunohistochemistry of proliferating cellular nuclear antigen (PCNA) from 2 hours, 6 hours, 24 hours to 1 week, 2 weeks and 4 weeks. Although the number was not apparently increased in autologous vein graft at early stage, SMC proliferation had started. At 1 week after transplantation, the activity of SMC proliferation increased to a maximum, and returned to baseline level 4 weeks. At early stage, the distribution of SMC proliferation located in the media, but at middle stage, both intima and media all presented a relatively higher proliferative activity. The intima formation occurred by the migration of a large population and the proliferation of a relatively small subpopulation of SMC. Therefore, control of SMC proliferation, and migration of autologous vein grafts must be within two weeks after transplantation.

Zinc enhances ionic currents induced in skate Müller (glial) cells by the inhibitory neurotransmitter GABA

We describe here a novel effect of zinc on GABA receptors of glial cells in the skate retina. The GABA-induced currents of skate Müller cells, the radial glia of the retina, are mediated by activation of GABA(A) receptors (GABAARS). In other parts of the nervous system, GABz*-)ediated currents are inhibited by zinc. However, in isolated, voltage-clamped Müller cells, coapplication of zinc (10 microM) and GABA (1 microM) resulted in enhancement of the GABA(A)R current. Surprisingly, zinc alone induced a current similar in many respects to that elicited by GABA, i.e. the reversal potential was the same as for the GABA-induced current, the current was blocked by bicuculline and picrotoxin, and the current-voltage relation obtained in the presence of 10 microM zinc was virtually identical to that obtained with 1 microM GABA. Both bicuculline and picrotoxin suppressed a current that was present with cells bathed only in Ringer, suggesting that some of the GABA channels were spontaneously open in the absence of externally applied GABA. This possibility was supported by cell-attached patch recordings. Under conditions in which potassium and calcium currents were suppressed, spontaneous channel activity was observed. Moreover, the frequency of these channel openings was greater when zinc was included in the pipette solution, and reduced when bicuculline was added. These findings suggest that zinc acts directly to enhance the GABA(A) receptor activity of the Müller cells, and raise the possibility that the subunit composition of the GABA(A)Rs of skate Müller cells differs from that of GABA(A)Rs identified previously in other neuronal and glial preparations.

Adverse effects of wide calcium:phosphorus ratios on supplemental phytase efficacy for weanling pigs fed two dietary phosphorus levels

Ninety-six weanling pigs (initial BW = 9.3 kg, initial age = 37 d) were used in a 4-wk experiment to evaluate the response to three Ca: total (t) P ratios (1.2:1, 1.6:1, or 2.0:1) fed in combination with two P levels (.07 or .16% available that correspond to .36 or .45% tP) and two phytase levels (PY; 700 or 1,050 units/kg of diet). A 3 x 2 x 2 factorial arrangement of treatments was employed using a corn-soybean meal diet. Performance, serum mineral concentrations and alkaline phosphatase (ALP) activity, Ca and P digestibility and excretion, and bone mechanical measurements were examined. Average daily gain (P < .001), average daily feed intake (P < .01), and gain:feed (P < .05) were decreased linearly as the Ca:tP ratio became wider. The digestibility of P and Ca were decreased (P < .001) linearly as the Ca:tP ratio became wider. The digestibility of P (P < .001) and fecal P excretion (P < .01) were increased at the higher level of P. Increasing PY from 700 to 1,050 units (U)/kg of diet increased (P < .05) P digestibility and decreased (P < .01) P excretion but did not improve bone measurements. Shear force, stress and energy, and percentage of ash of both metacarpal and 10th rib linearly decreased (P < .001 to .05) as the Ca:tP ratio became wider, and bone measurements were generally greater for pigs fed the higher P level. Serum Ca concentration increased (P < .01) and the P concentration decreased (P < .001) as the Ca:tP ratio increased, but Mg, Zn, and ALP activity were not influenced by the Ca:tP ratio. Serum Ca and P concentrations were affected by PY supplementation over the 4-wk trial, but serum Mg and Zn concentrations were not affected by dietary treatments. Adverse effects of a wide Ca:tP ratio were greater at the low P diet for all responses. In addition, the activity of supplemental PY in diets seemed to be decreased as the Ca:tP ratio became wider and this negative effect of Ca:tP ratio seemed greater at the low P level, and seemed to parallel the effects of Ca:tP ratio on performance, P digestibility, bone, and serum measurements. Narrowing the dietary Ca:total P ratio from 2.0:1 to 1.2:1 led to an approximate 16% increase in phytase efficacy for improving performance, digestibility, bone measurements, and serum Ca levels.

[The study of immunotherapy of ovarian carcinoma with anti-idiotypic antibody]

OBJECTIVES

To study the role of anti-idiotypic antibody in immunotherapy of ovarian carcinoma, and to investigate the effect of anti-idiotypic antibody (Ab2) on ovarian carcinoma in vivo.

METHODS

Six to eight week-old female BCF1 mice were immunized three times at 28 days intervals with 50-100 micrograms of anti-idiotypic antibody Ab2 of ovarian carcinoma. The initial immunization was given with complete Freund's adjuvant (CFA), followed by incomplete Freund's adjuvant (IFA). The control mice were immunized with normal mouse IgG. The ovarian carcinoma cells (SKOV3) passaged from nude mice were transplanted to the subrenal capsules of immunized BCF1 mice after the last injection. Then the mice were bred separately on the 2nd, 4th, 6th, 8th and 10th days after the transplantation operations. Specific anti-Ab2(Ab3) in sera was detected by using inhibition assay of enzyme-linked immunospecific assay. Tumor infilitration lymphocytes (TIL) and tumor cells from the tumor tissue of BCF1 were observed microscopically.

RESULTS

The sera levels of Ab3 in Ab2 immunized mice were higher than those of the controls. TIL in the former were found to reach their highest peak on the 6th day, where as the highest peak for the controls was on the 8-10th days, tumor cell viability rate in the former decreased rapidly after 6 days, but in the controls decreased only gradually.

CONCLUSIONS

Ab2 could induce specific immuno rejection to ovarian carcinoma in vivo. It is predicted that anti-idiotypic antibody Ab2 might be used in immunotherapy of ovarian cancer patients and also as a preventive for post treatment clinical recurrence of ovarian carcinoma.

Effects of supplemental phytase and phosphorus on histological and other tibial bone characteristics and performances of broilers fed semi-purified diets

Two trials with day-old chicks were conducted to investigate the effects of supplemental phytase (Natuphos) on histological, mechanical, and chemical properties of tibia, and performances of broilers fed semi-purified diets containing soybean meal as the only organic P source [0.11% nonphytate P (nP)]. Dietary treatments in Trial 1 were: 1) 0.20% nP, 2) Diet 1 + 800 U of phytase/kg of diet, 3) 0.27% nP, 4) Diet 3 + 600 U of phytase, 5) 0.34% nP, 6) Diet 5 + 400 U of phytase. Supplemental phytase and inorganic P increased tibial length (P < 0.01), shear force (P < 0.001), shear stress (P < 0.05), ash content (P < 0.001), and BW gain and feed intake (P < 0.001) during Trial 1. The hypertrophic zone width at the proximal end of the tibia was decreased (P < 0.05), and the tibial width (P < 0.05) of the long axis of the tibia was increased by the phytase and P supplementation. Supplemental phytase enlarged the cartilaginous and proliferative zones of the tibial proximal end (P < 0.05), and an increase in nP levels produced similar effects. Supplementation of phytase and P also tended to improve the orderliness of development and arrangement of cartilage and bone cells. Dietary treatments in Trial 2 were: 1) 0.27% nP, 2) Diet 1 + 350 U of phytase, 3) Diet 1 + 1,050 U of phytase, 4) 0.45% nP, 5) 0.54% nP, 6) Diet 5 + 1,050 U of phytase. Broilers fed diets containing relatively high levels of nP and phytase supplementation in Trial 2 gave results similar to those observed in Trial 1. Marked improvements (P < 0.05) in the ash content, shear force, shear stress, length of tibia, BW gain, and feed intake, and reduced hypertrophic zone width were achieved for broilers fed the P-deficient diet supplemented with phytase. Also, supplemental phytase tended to increase the width of cartilaginous and proliferative zones, to increase trabecular bone density, and to improve the orderliness of development and mineralization of cartilage and bone cells. In summary, supplementing a low-nP diet with inorganic P or phytase resulted in similar beneficial effects on bone development.

[The study of radioimmunoimaging on the nude mice bearing human ovarian carcinoma by labelling monoclonal antibody with 99mTc]

OBJECTIVE

To investigate the feasibility of radioimmunoimaging (RII) on the nude mice model by labelling anti-ovarian carcinoma monoclonal antibody (McAb, COC166-9) with 99mTc, and the possibility for clinical application.

METHODS

McAb reduced by beta-mercaptoethanol was labelled directly with 99mTc. Imaging positive rate, negative rate and tumor/non-tumor (T/N) ratio were calculated.

RESULTS

(1)McAb COC166-9 labelled with 99mTc reacted with ovarian carcinoma. (2) 8 nude mice models were injected with the labelled antibodies and were then imaged. In the experimental group the positive imaging rate of tumor was 100%, in the control group the negative rate was 100%. The results were the same as those of T/N ratios. (3)In two groups (10 nude mice), intraperitoneal (i.p.) or intravenous (i.v.) injection of McAb labelled with 99mTc, positive imaging rates of tumor 100%. The IV group was better than IP group in the radio-background.

CONCLUSIONS

Immunoactivity of 99mTc-COC166-9 used for RII on the nude mice models was good, and the imaging effect was specific. Clinical application is promising.

Prediction of alpha-helices in proteins based on thermodynamic parameters from solution chemistry

Current studies on the protein folding problem are chiefly pursued by two approaches; one statistically investigates the three-dimensional structures of proteins and the other focuses on their thermodynamic properties in solution. It remains to be demonstrated that information from these two sources are consistent and complementary. Using two sets of thermodynamic parameters experimentally obtained from solution studies, namely the helix propensities derived from small model peptides and hydrophobicity based on solvent transfer free energies for amino acids, we predict alpha-helices in native proteins. The correlation coefficient of our predictions on 98 non-homologous proteins is 0.26, a value comparable to that of the statistical prediction of Chou & Fasman but less than that from the state of the art prediction (0.39) based on neural network methodology. Helix propensities derived from different experimental systems in aqueous solutions are highly consistent for predicting alpha-helices in proteins. The helix propensities and amphiphilicity in primary sequences make independent contributions to the occurrence of alpha-helices. We also show that, with appropriate models, statistical analyses of known three-dimensional structures can provide thermodynamically relevant quantities. These findings indicate that for practical helix prediction, various sets of propensities have reached reasonable consensus. The report also suggests integrating solution thermodynamic studies with protein structural analyses, and the role of supersecondary structures on helices in proteins.

Phosphorus equivalence of microbial phytase in turkey diets as influenced by calcium to phosphorus ratios and phosphorus levels

Male day-old turkey poults (n = 768) were fed 0, 300, 600, or 900 U of phytase/kg of a corn-soybean diet in combination with four Ca:total P (tP) ratios of 1.1, 1.4, 1.7, and 2.0:1, and two levels of nonphytate P (nP) of 0.27 and 0.36% in a 21-d trial. Dietary Ca:tP ratios were obtained by varying defluorinated phosphate and limestone at the expense of cornstarch. The calculated dietary percentage of phytate P was 0.266 for all diets. Phytase additions linearly increased (P < 0.05) BW gain, feed intake, gain:feed, toe ash content, and apparent retentions of Ca and P at each Ca:tP ratio and nP level, but the response was influenced by dietary Ca:tP ratios and P levels. The detrimental effect (P < 0.02) of widening the Ca:tP ratio was observed for all measurements at each phytase and P level, and was greatest at lower phytase and P levels. Widening the Ca:tP ratio from 1.4 to 2.0 decreased the phytase efficacy by 7.4 and 4.9%, respectively, for 0.27 and 0.36% nP diets, which was close to the decrease in the phytase activity in vitro by 7.5 and 6.7%, respectively. The largest responses to supplemental phytase were achieved when poults were fed diets with 600 and 900 U of phytase/kg diet, respectively, for 0.36 and 0.27% nP, and for Ca:tP ratios ranging from 1.1 to 1.4:1. Second-order translog equations were generated for the phytase, Ca:tP ratio, and P effect, and nonlinear and linear equations for the phytase and Ca:tP ratio effect. Based on an assessment for the R2 and P values of equations, BW gain, feed intake, toe ash content, and P retention were sensitive measurements of the response to phytase addition. Equivalent equations were developed to determine the P equivalency of supplemental phytase. About 652 and 963 U of phytase were equivalent to 1 g nP, respectively, for 0.27 and 0.36% nP diets in turkey poults from hatch to 21 d of age.

GABAA and GABAC receptors on hybrid bass retinal bipolar cells

1. gamma-Aminobutyric acid (GABA) responses from solitory hybrid bass retinal bipolar cells were studied with the use of conventional and perforated whole cell patch-clamp recording. 2. GABA elicited a chloride current in bipolar cells that had both transient and sustained components. The transient component was sensitive to bicuculline and resembled GABAA-mediated currents, whereas the more sustained component was resistant to bicuculline and resembled the responses mediated by GABAC receptors. 3. The bicuculline-resistant GABA responses recorded from the bipolar cells could not be modulated by either diazepam or pentobarbital sodium, and they were unaffected by phaclofen and 2-hydroxysaclofen, GABAB receptor antagonists. On the other hand, the bicuculline-resistant GABA responses could be blocked substantially by imidazole-4-acetic acid (I4AA), a competitive antagonist of GABAC receptors. 4. Noise analysis of the GABA-elicited currents suggested a different single channel conductance for GABAA (10.1 pS) and GABAC receptors (3.6 pS). 5. Zinc, a putative modulator of synaptic transmission, strongly inhibited the GABAC responses on bipolar cells, whereas the GABAA responses were not significantly affected by zinc. 6. The proportion of the GABAC to GABAA responses varied widely between bipolar cells. Local application of GABA onto dendrites or axon terminals showed that both types of GABA receptors are present on both regions of the cell. 7. The distinct properties of these two GABA receptor types suggest that they play different roles in retinal function.

[The significance of p53 gene mutations and expressions in human colorectal tumors]

Using a polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) approach we analyzed 18 human colorectal adenocarcinomas for mutations in exons 5, 6, 7, 8 of p53 gene. At the same time, p53 gene product expression was studied immunohistochemically in these 18 cases in frozen sections. The expression of p53 protein was also immunohistochemically studied in formalin-fixed paraffin embedded specimens of 76 colorectal adenocarcinomas and 112 colorectal polyps. Eight out of 18 cases (44%) tested showed a variant band indicative of a mutation in exons 5-6 of p53 gene. Seven out of 8 cases (88%) with p53 gene mutations were positively stained for p53. There was no significant correlation between p53 expression and clinicopathological manifestations and prognosis. But the strongest staining was encountered in those cases with well differentiated and early stages of adenocarcinomas, while weaker staining was encountered in poorly differentiated and mucoid adenocarcinomas. p53 expression was not observed in proliferative polyps and adenomas with low grade dysplasia. The frequency of p53 expression reached 88% (P < 0.001) when adenoma showed malignant change. Among three types of adenomas, p53 expression was most frequent in villous type (P < 0.05). The frequency of p53 expression in adenoma, adenoma with malignant change and adenocarcinoma was 4%, 88% and 51% respectively. These indicate that genetic changes of p53 gene play an important role in the transformation from benign adenoma to adenocarcinoma. p53 immunohistochemistry can be used as a surrogate marker for p53 gene mutation for early discovery of colorectal adenocarcinomas.

[Clinical analysis of 6 cases of gestational trophoblastic neoplasms complicated by cardiotoxicity after chemotherapies]

Gestational trophoblastic neoplasm treated by large dosage of 5-fluorouracil and actinomycin could cause cardiotoxicity. In 6 cases of gestational trophoblastic neoplasms admitted to our hospital from March to December 1993, cardiotoxicity was found to have occurred after chemotherapies in 10/21 courses. There were 2 cases with heart failures, 4 cases with palpitation and 4 cases with feelings of oppression and (or) chest pains. In 7 cases the electrocardiogram (EKG) findings were abnormal (70.0%) and in 5 cases there were increased sera glutamic oxalacetic transaminase enzyme (AST). 90.0% of these complications were brought under control after decreasing the dosages and changing the methods of administration. If the proper managements were not given on time, patient may even expire. So attention should be paid to this complication. It is suggested that attention should be paid to patients' subjective symptoms, and proper surveillance by EKG and serum AST determinations should be conducted to minimize deaths due to chemotherapeutic complications.

[Influence of radioimmunoimaging on the survival rate of ovarian carcinoma patients]

Two groups of patients suffered from ovarian carcinoma were studied retrospectively after similar treatments; in one group of 22 patients radioimmunoimaging (RII) had been used, which was not used in the other group of 15 patients. Other factors were similar in the two group such as hospitalization period, courses of surgical treatment and regimes of chemotherapy after surgery. The staging according to FIGO was also similar in the two groups except that the number of patients in stage III was 14 in the RII group but 8 in the non-RII group. Neither the age distribution nor the histopathological diagnosis was of much difference. 131I labeled monoclonal antibody against ovarian serous adenocarcinoma, generated in our laboratory, was given to all patients intraperitoneally either before or after the surgery; 7 cases before the initial operation, 9 cases before the second look operation and 6 cases for follow up after surgery and chemotherapy. The death rates of stage III were 42.9% and 75.0% in the RII group and non-RII group respectively. By means of Kaplain Meir's life table calculation the 3 year survival rates for the two groups were 63.5% and 25.0% respectively. The RII group was obviously higher than the non-RII group even though not statistically significant. These results were similar to those reported in the literature. Three very late cases of ovarian carcinoma were reported, in whom RII had been used, are still living after follow-up for more than 5 years. The beneficial role of induction of the idiotypic network was discussed, and the possibility of innoculation is under investigation.

[The analysis of tumor growth rate and histopathology of xenografts of nude mice bearing human ovarian carcinoma in immunocompetent mice]

Xenografts of nude mice bearing human ovarian carcinoma cell line SKOV3 were transplanted using subrenal capsule assay (SRCA) in immunocompetent C57BL/6 mice. Multiple locations were chosen on both sides of the kidneys obtaining a total of 129 tumors. The volumes of the tumors were measured and histopathological examinations were conducted on the 4th, 6th, 8th, 10th, 12th and 14th days after transplantation surgery. The growth rates were noticed to be high on the 6-8th days. Lymphocytic infiltration reached a peak on the 8-12th day. On the 14th days the leukocytic infiltration and fibrosis almost surrounded the tumors. Tumor cells that could be found amounted to about 77.25%, 65.38%, and 52.17% respectively on the 4th, 6th and 8th days, but significantly decreased on 12-14th days. The above results suggested: (1) multiple SRCA on both sides proved to be practical and economical; (2) the xenografts of nude mice bearing hman ovarian carcinoma could be transplanted viably by SRCA for 8-10 days; (3) microscopic measurements of the transplanted tumor volume did not represent the real status of the tumor growth, and microscopic evaluation was necessary.

Growth of Thuja plicata seedlings along a light gradient

To improve understanding of light – growth response relationships in western red cedar, seedlings were grown on three environmentally comparable sites representing nearly optimum growth conditions for the species in coastal British Columbia. On each site, the seedlings were planted on transects extending from a clearcut to the interior of an adjacent old-growth stand. After three growing seasons, seedling mortality, vigour, growth characters, and foliar nutrients were compared across five light classes and between study sites using analysis of variance and related to the percentage of above-canopy light available to each seedling using regression analysis. Three-year mortality was ≤ 27%, and most mortality (≥ 85%) occurred at ≤ 20% of above-canopy light. Seedling growth improved consistently with increasing light; however, the actual growth response at > 40% of above-canopy light varied with study site. The pattern of variation in the growth characters suggested that planted seedlings were able to acclimate morphologically to varying light conditions in three structural traits typically associated with shade adaptation: specific leaf area, height to caliper ratio, and aboveground to root biomass ratio. Specific leaf area and height to caliper ratio decreased and aboveground to root biomass ratio increased with increasing light. This study does not support the contention that under optimal moisture and nutrient conditions carbohydrate deficiency increases the allocation of net biomass production to aboveground structures. We consider western red cedar in the study area to be a. very shade-and exposure-tolerant species but not one that is specifically adapted to an understory environment. Key words: Thuja plicata seedlings, light – growth response relationships, specific leaf area, height to caliper ratio, aboveground to root biomass ratio, shade tolerance.

A novel action of quinine and quinidine on the membrane conductance of neurons from the vertebrate retina

The cinchona alkaloids quinine and quinidine have been shown to block a broad range of voltage-gated membrane conductances in a variety of excitable tissues. Using the whole-cell version of the patch clamp technique, we examined the effects of these compounds on voltage-dependent currents from horizontal cells dissociated enzymatically from the all-rod retina of the skate. We report here a novel and unexpected action of quinine and quinidine on isolated horizontal cells. In addition to blocking several of the voltage-activated currents of these cells, the introduction of the alkaloids evoked a large outward current when the cells were held at depolarized potentials. Using tail current analysis, the reversal potential of the outward current was close to O mV, and the current was markedly suppressed by extracellularly applied cobalt, acetate, and halothane. Depolarization in the presence of quinine also permitted entry into the cells of extracellularly applied Lucifer yellow (MW = 443 D), whereas a 3-kD fluorescein-dextran complex was excluded. These findings suggest that the large, apparently nonselective conductance induced by quinine and quinidine results from the opening of hemi-gap junctional channels.

A thermodynamic model for the helix-coil transition coupled to dimerization of short coiled-coil peptides

A simple thermodynamic formalism is presented to model the conformational transition between a random-coil monomeric peptide and a coiled-coil helical dimer. The coiled-coil helical dimer is the structure of a class of proteins also called leucine zipper, which has been studied intensively in recent years. Our model, which is appropriate particularly for short peptides, is an alternative to the theory developed by Skolnick and Holtzer. Using the present formalism, we discuss the multi-equilibriatory nature of this transition and provide an explanation for the apparent two-state behavior of coiled-coil formation when the helix-coil transition is coupled to dimerization. It is found that such coupling between multi-equilibria and a true two-state transition can simplify the data analysis, but care must be taken in using the overall association constant to determine helix propensities (w) of single residues. Successful use of the two-state model does not imply that the helix-coil transition is all-or-none. The all-or-none assumption can provide good numerical estimates when w is around unity (0.35 < or = w < or = 1.35), but when w is small (w < 0.01), similar estimations can lead to large errors. The theory of the helix-coil transition in denaturation experiments is also discussed.

Pharmacology of novel GABA receptors found on rod horizontal cells of the white perch retina

A novel type of GABA receptor is present on rod-driven (H4) horizontal cells of the white perch retina (Qian and Dowling, 1993a). These receptors have been tentatively termed GA-BAC receptors. In this study, the pharmacological properties of these receptors were further investigated by applying several conformationally restricted GABAA receptor agonists, GABAA antagonists, and a GABAB agonist to the H4 horizontal cells. GABA analogs locked in a partially folded conformation had a variety of effects. Isonipecotic acid had no effect on these receptors, whereas isoguvacine activated them but with low potency (EC50 = 137 microM). THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol) acted as a competitive antagonist on these receptors with an inhibition constant of 82.5 microM. P4S (piperidine-4-sulfonic acid) activated the receptors at high concentrations (> 1 mM), but at lower concentrations it was a competitive antagonist with an inhibition constant of 80.9 microM. 14AA (imidazole-4-acetic acid), a GABA analog with an extended conformation, potently inhibited the GABA responses on H4 horizontal cells with an inhibition constant of 1.67 microM. Muscimol, which can assume both partially folded and extended conformations, acted as a mixed agonist-antagonist. The GABA responses on H4 horizontal cells were resistant to several competitive GABAA receptor antagonists including bicuculline, hydrastine, and SR-95531, but they were very sensitive to picrotoxin (IC50 = 237 nM). The inhibition by picrotoxin was both competitive and noncompetitive in nature. On the other hand, TBPS (tert-butyl-bicyclophosphorothionate), another GABAA receptor channel blocker, had minimal effects on these receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

RFLP-based phylogenetic analysis of wide compatibility varieties in Oryza sativa L

Twenty-one wide compatibility varieties (WCVs) of rice together with three indica and three japonica testers were assayed with 160 DNA probes that were selected to represent the entire RFLP map at an average interval of 11 cM. On the basis of four enzyme digestion 125 probes detected polymorphisms among the WCVs and subspecies' testers. Among these polymorphic probes there were 68 that could distinguish the indica from the japonica testers. Two dendrograms were constructed on the basis of 398 polymorphic fragments of 125 probes and 139 polymorphic fragments of 68 subspecies' differentiating probes in combination with single enzymes, respectively. The reliability and representativeness of the testers and the levels of DNA variations among WCVs were estimated. The potential of WCVs in the utilization of intersubspecific heterosis is discussed.

Inactivation of the Streptococcus mutans wall-associated protein A gene (wapA) results in a decrease in sucrose-dependent adherence and aggregation

A 0.8-kb HindIII-BamHI internal fragment of the Streptococcus mutans wall-associated protein A gene (wapA) was ligated to the 5.1-kb HindIII-BamHI fragment of the chimeric Streptococcus-Escherichia coli plasmid pVA891 (Emr Cmr). The resulting construct was used to transform S. mutans GS-5, and erythromycin-resistant mutants were isolated and analyzed. Directed mutagenesis of the wapA gene by plasmid insertion through homologous recombination was demonstrated by Southern blot hybridization with the wapA and pVA891 probes. Stable mutants were obtained, and the alteration of the wapA gene by insertional inactivation was associated with a significant decrease in S. mutans sucrose-dependent aggregation and binding to smooth surfaces. Thus, WapA may play an important role in the colonization of the tooth surface by S. mutans and in the buildup of dental plaque. These findings provided an explanation for previous studies which indicated that WapA was effective in the prevention of dental caries in animal models. Thus, the use of recombinant WapA in the preparation of a safe and effective human dental vaccine should be investigated further.

Single-residue substitution in homopolypeptides: perturbative helix-coil theory at a single site

Based on Lifson-Roig's helix-coil transition theory, substitution of a single heteroresidue into a homopolymer host is studied. This study models recent experiments that substitute a single amino acid into a small peptide in water [A. Chakrabartty, J. A. Schellman, and R. L. Baldwin (1991), Nature, Vol. 351, pp. 586-688]. Our formalism, which is based on a perturbation method, differs from the existing theory for sequenced polymers and is naturally analogous, hence likely to be useful, to substitution experiments in the laboratory. It is shown that the intrinsic helix propensity w is directly proportional to the equilibrium constant for the helix-coil equilibrium of a single residue in a host peptide. This intuitive new result will simplify experimental data interpretations for measurements of the helical conformation on the single amino acid level. It is also shown that substitution affects the total helicity of the host peptide according to two considerations: the helicity of the replaced residue prior to the substitution, and the sensitivity of the site, a measure of neighboring interactions. The relationship between substitution stability and thermal stability is explored.

The energetics of ion-pair and hydrogen-bonding interactions in a helical peptide

A single pair of Glu and Lys residues has been placed at four different spacings, and in both orientations, in an otherwise neutral alanine-glutamine peptide helix, and the contribution to helix stability of the different Glu-Lys interactions has been measured. The contribution from the interaction of each charged side chain with the helix macrodipole has also been determined. A side-chain interaction between Gln and Glu, when the spacing is (i,i+4), has been detected and quantified. The interactions have been divided into contributions from hydrogen bonds (independent of the concentration of NaCl) and from electrostatic interactions (present in 10 mM NaCl, absent in 2.5 M NaCl). The major results are as follows: (1) The (i,i+3) and (i,i+4) Glu-Lys interactions are helix-stabilizing and are similar in strength to each other, regardless of the orientation of the side chains. (2) Hydrogen bonds provide the major contribution to these side-chain interactions, as shown by the following facts. First, the major part of the interaction observed in 10 mM NaCl, pH 7, is still present in 2.5 M NaCl. Second, the interaction found at pH 2 is equally as strong as that found in 2.5 M NaCl at pH 7. (3) The (i,i+4) Gln-Glu side-chain hydrogen bond is as strong as the hydrogen-bond component of the Glu-Lys interaction at both pH 2 and pH 7. The Gln-Glu interaction differs from the Glu-Lys interaction in being specific both for the orientation and the spacing of the residues. (4) No significant hydrogen-bonding interaction was found for the (i,i+1) or (i, i+2) Glu-Lys spacings, either at pH 2 or at pH 7, in 2.5 M NaCl. At 10 mM NaCl and pH 7, these spacings show a helix-destabilizing electrostatic interaction which probably results from stabilization of the coil conformation.

Evidence for hemi-gap junctional channels in isolated horizontal cells of the skate retina

Prolonged depolarization of isolated, voltage-clamped skate retinal horizontal cells produces an outward current that exhibit a late onset and develops slowly with time. This current, which we refer to as the Q-current, is associated with an increase in membrane conductance, and is present when other voltage-gated conductances have been pharmacologically blocked. The reversal potential for the Q-current, obtained using tail current analysis, was close to 0 mV. The magnitude of the current was greatly reduced by superfusion with 25 mM acetate, and by 4 mM cobalt chloride, 2 mM 1-octanol, and a saturated solution of the general anesthetic halothane. In addition, the low-molecular weight fluorescent dye Lucifer yellow, applied extracellularly, entered the cells during activation of the Q-current, whereas a 3 kD dextran-fluorescein complex did not cross the cell membrane. The effects of divalent cations, the non-specific nature of the ionic current suggested by its reversal potential, the entry of Lucifer yellow, and the ability of acetate, halothane, cobalt, and octanol to block the current lead us to hypothesize that the Q-current results from the opening of hemi-gap junctional channels that mediate electrical coupling between skate horizontal cells.

The effects of lowered extracellular sodium on gamma-aminobutyric acid (GABA)-induced currents of Muller (glial) cells of the skate retina

1. The effects of external sodium on GABA-induced chloride currents were examined with whole-cell voltage-clamp recordings obtained from enzymatically dissociated solitary Muller cells in culture. Our goal was to determine whether a sodium-dependent GABA uptake mechanism influences the GABAa-mediated responses of skate Muller cells. 2. At low concentrations of GABA (0.01 to 0.5 microM), removal of sodium from the external solution resulted in a marked increase in the ligand-gated currents mediated by activation of GABAa receptors. The enhancement by lowered sodium was greatest at hyperpolarizing potentials and decreased progressively as the cell was depolarized. 3. The reversal potential for the GABA-induced response was not significantly altered by the removal of sodium, suggesting that sodium ions did not directly contribute to the GABAa-mediated current. 4. Lowering external sodium had no effect on the currents induced by the GABAa-agonist muscimol, consistent with its much lower affinity for the GABA transport carrier. 5. Application of the GABA uptake blocker nipecotic acid also abolished the effects of lowered sodium. 6. These findings suggest that the effects of lowered external sodium resulted from a decrease in the uptake of GABA into the Muller cells, thus raising the effective concentration of GABA acting upon the GABAa receptors.

Gap-junctional properties of electrically coupled skate horizontal cells in culture

Whole-cell voltage-clamp recordings were used to examine the unusual pharmacological properties of the electrical coupling between rod-driven horizontal cells in skate retina as revealed previously by receptive-field measurements (Qian & Ripps, 1992). The junctional resistance was measured in electrically coupled cell pairs that had been enzymatically isolated and maintained in culture; the typical value was about 19.92 M omega (n = 45), more than an order of magnitude lower than the nonjunctional membrane resistance. These data and the intercellular spread of the fluorescent dye Lucifer Yellow provide a good indication that skate horizontal cells are well coupled. The junctional conductance between cells was not modulated by the neurotransmitters dopamine (200 microM) or GABA (1 mM), nor was it affected by the membrane-permeable analogues of cAMP or cGMP, or the adenylate cyclase activator, forskolin. Although resistant to agents that have been reported to alter horizontal-cell coupling in cone-driven horizontal cells, the junctional conductance between paired horizontal cells of skate was greatly reduced by the application of 20 mM acetate, which is known to effectively reduce intracellular pH. Together with the results obtained in situ on the receptive-field properties of skate horizontal cells, these findings indicate that the gap-junctional properties of rod-driven horizontal cells of the skate are fundamentally different from those of cone-driven horizontal cells in other species. This raises the possibility that there is more than one class of electrical synapse on vertebrate horizontal cells.

Novel GABA responses from rod-driven retinal horizontal cells

gamma-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the central nervous system. Two classes of GABA receptors (GABAA and GABAB) have been identified. GABAA receptors are ligand-gated chloride channels that are competitively antagonized by bicuculline, noncompetitively blocked by picrotoxin, and often allosterically modulated by barbiturates and benzodiazepines. GABAB receptors regulate potassium and calcium channels through G-protein and intracellular second-messenger pathways, are selectively activated by baclofen, and are antagonized by phaclofen and 2-hydroxysaclofen. For some years, evidence has accumulated that there are GABA receptors, especially prominent along visual pathways, which are neither antagonized by bicuculline nor activated by baclofen, but are activated by certain conformationally restricted analogues of GABA, including cis-4-aminocrotonic acid (CACA). These receptors have been designated GABAC receptors. As yet, membrane current responses from isolated neurons that reflect this novel pharmacology have not been reported, although such responses have been recorded from oocytes injected with retinal messenger RNA. Here we describe a chloride-mediated current response from isolated rod-driven horizontal cells (H4) of the white perch retina that has this novel pharmacology.

Receptive field properties of rod-driven horizontal cells in the skate retina

The large receptive fields of retinal horizontal cells result primarily from extensive intercellular coupling via gap (electrical) junctions; thus, the extent of the receptive field provides an index of the degree to which the cells are electrically coupled. For rod-driven horizontal cells in the dark-adapted skate retina, a space constant of 1.18 +/- 0.15 mm (SD) was obtained from measurements with a moving slit stimulus, and a comparable value (1.43 +/- 0.55 mm) was obtained with variation in spot diameter. These values, and the extensive spread of a fluorescent dye (Lucifer Yellow) from the site of injection to neighboring cells, indicate that the horizontal cells of the all-rod retina of skate are well coupled electrically. Neither the receptive field properties nor the gap-junctional features of skate horizontal cells were influenced by the adaptive state of the retina: (a) the receptive field organization was unaffected by light adaptation, (b) similar dye coupling was seen in both dark- and light-adapted retinae, and (c) no significant differences were found in the gap-junctional particle densities measured in dark- and light-adapted retinas, i.e., 3,184 +/- 286/microns 2 (n = 8) and 3,073 +/- 494/microns 2 (n = 11), respectively. Moreover, the receptive fields of skate horizontal cells were not altered by either dopamine, glycine, GABA, or the GABAA receptor antagonists bicuculline and picrotoxin. We conclude that the rod-driven horizontal cells of the skate retina are tightly coupled to one another, and that the coupling is not affected by photic and pharmacological conditions that are known to modulate intercellular coupling between cone-driven horizontal cells in other species.

Clinical evaluation of radioimmunoimaging with 131I-C0C183B2 monoclonal antibody against ovarian carcinoma by intraperitoneal injection

Forty-eight cases subjected to radioimmunoimaging (RII) by intraperitoneal injection with 131I-C0C183B2 monoclonal antibody (MAb) prepared in our laboratory were studied. Thirteen of 14 cases of proved primary ovarian carcinoma were positive. In 11 follow-up cases of ovarian carcinoma after initial surgery and chemotherapy, 5 recurrences were positive and 6 cases without recurrence were negative; all were confirmed histopathologically after a second operation. One false negative was ovarian mucinous adenocarcinoma, which also negatively stained with C0C183B2 by the peroxidase anti-peroxidase method. Twenty of 23 cases of nonepithelial or metastatic carcinoma of the ovary, benign tumors, and benign diseases were negative. The sensitivity and specificity were 94.7 and 89.7%, respectively. If patients had complications with ascites, the MAb which positively stained with the cancer cells in the ascites was chosen for RII. For follow-up cases PAP staining with the tumor tissue from the initial surgery and the MAb should be done before RII. These are the principal factors that increase the positive rate and accuracy of RII. The intraperitoneal route seems to be a valuable method for clinical staging and tumor localization as well as for follow-up use.