G-protein-coupled receptors act via protein kinase C and Src to regulate NMDA receptors

The N-methyl-D-aspartate (NMDA) receptor contributes to synaptic plasticity in the central nervous system and is both serine-threonine and tyrosine phosphorylated. In CA1 pyramidal neurons of the hippocampus, activators of protein kinase C (PKC) as well as the G-protein-coupled receptor ligands muscarine and lysophosphatidic acid enhanced NMDA-evoked currents. Unexpectedly, this effect was blocked by inhibitors of tyrosine kinases, including a Src required sequence and an antibody selective for Src itself. In neurons from mice lacking c-Src, PKC-dependent upregulation was absent. Thus, G-protein-coupled receptors can regulate NMDA receptor function indirectly through a PKC-dependent activation of the non-receptor tyrosine kinase (Src) signaling cascade.

Composition of long chain polyunsaturated fatty acids in human milk and growth of young infants in rural areas of northern China

The main source of fat in the diet in rural areas of northern China is soybean oil, therefore the pattern of essential fatty acids in human milk may be assumed to differ from that in milk from women in Western countries and to be similar to that of vegans. The concentrations of long chain polyunsaturated fatty acids in human milk and information on diet were analysed for 41 lactating women in rural areas of north China, and the growth of their infants was measured. The subjects were divided into two groups (group I, 1 mo postpartum; group II, 3 mo postpartum). The dietary intake of the mothers was high in carbohydrate and low in fat, protein and energy. The concentrations of linoleic acid (LA) and alpha-linolenic acid (LNA) were high. The ratio of LA to LNA, (21.6), was higher than has been reported from other countries. The concentration of docosa-hexaenoic acid (DHA) was low and the ratio of arachidonic acid (AA) to DHA was much higher (2.8) than recommended and similar to that found in vegans. The concentrations of AA and DHA in the milk correlated positively with the infants' weight gain at the third month (p<0.05) and of DHA with length gain at the first and third months (p<0.01). Since the concentration of AA and, particularly, DHA in the milk declined during lactation, DHA deficiency may appear after 3-4 mo of age in breastfed Chinese rural infants. Further studies of Chinese rural mother-infant pairs are necessary to prove whether supplementation with suitable sources of AA and DHA, such as fish oil, should be recommended as lactation is lengthened to ensure optimal infant growth and development.

Mechanisms involved in the vasorelaxant effect of (-)-stepholidine in rat mesenteric small arteries

The purpose of the present investigation was to clarify whether the hypotensive action of the protoberberine alkaloid, and dopamine receptor antagonist, (-)-stepholidine, can be ascribed to an effect on peripheral small arteries. For this purpose isolated mesenteric small arteries were suspended in microvascular myographs for isometric tension recording. Relaxations mediated by dopamine D1 receptors were antagonized by (-)-stepholidine. (-)-Stepholidine inhibited in a concentration-dependent manner the contractile responses evoked by noradrenaline (10(-6) M), but not the contractile responses evoked by depolarizing solution (KCl, 60 mM) or 9,11-dideoxy-11alpha,9alpha-epoxymethano prostaglandin F2alpha (U46619, 10(-7) M). Mechanical endothelial cell removal, blockade of K+ channels, muscarinic receptors or adrenoceptors did not influence the inhibitory effect of (-)-stepholidine on the contractile response evoked with noradrenaline in the segments. (-)-Stepholidine caused rightward shifts of the concentration-response curves for noradrenaline and phenylephrine. The pA2 values for (-)-stepholidine were 6.05 and 5.94 against noradrenaline and phenylephrine, respectively. Electrical field stimulation induced prazosin-sensitive frequency-dependent contractions in mesenteric small arteries. These contractions were significantly inhibited by 10(-6) and 10(-5) M (-)-stepholidine. In membranes from the rat cerebral cortex labelled with [3H]prazosin, (-)-stepholidine (10(-7)-10(-4) M) completely inhibited the specific binding of the ligand with a pKi of 5.6. The present investigation suggests the inhibitory effect of (-)-stepholidine on the alpha1-adrenoceptor-mediated contractions induced by exogenously added and nerve-released noradrenaline in peripheral small arteries might contribute to a hypotensive effect of the drug.

An embedded still image coder with rate-distortion optimization

It is well known that the fixed rate coder achieves optimality when all coefficients are coded with the same rate-distortion (R-D) slope. In this paper, we show that the performance of the embedded coder can be optimized in a rate-distortion sense by coding the coefficients with decreasing R-D slope. We denote such a coding strategy as rate-distortion optimized embedding (RDE). RDE allocates the available coding bits first to the coefficient with the steepest R-D slope, i.e., the largest distortion decrease per coding bit. The resultant coding bitstream can be truncated at any point and still maintain an optimal R-D performance. To avoid the overhead of coding order transmission, we use the expected R-D slope, which can be calculated from the coded bits and is available in both the encoder and the decoder. With the probability estimation table of the QM-coder, the calculation of the R-D slope can be just a lookup table operation. Experimental results show that the rate-distortion optimization significantly improves the coding efficiency in a wide bit rate range.

[Effect of vasectomy on apoptosis in spermatogenic cells of the male rat]

To explore the effect of vasectomy on apoptosis of spermatogenic cells, we have detected apoptosis in the testis of vasectomized and sham-operated adult rats within a period of 12 postoperative weeks by means of flow cytometry and TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuride triphosphate nick-end labeling) method. Flow cytometry found that, in vasectomized rat, the sub-haploid peak was higher and the percentage of cells with sub-haploid was increased. The total number of positive TUNEL cells in the vasectomized group was greater than that in the sham-operated group (P < 0.001). Compared with the same time-phased sham-operated subgroups, the number of apoptotic spermatogonia and primary spermatocytes in the testes of the subgroups 2 weeks, 6 weeks and 10 weeks after vasectomy as well as the number of spermatogonia of the subgroup 12 weeks after vasectomy were significantly higher (P < 0.05). These findings demonstrate that vasectomy could enhance the apoptosis of spermatogenic cells.

[The expression of CD11a and CD11b on leucocytes in cerebral thrombosis]

This study sought to understand the mechanism for the increased adhesion of leucocytes and endothelial cells in ischemic stroke. 20 patients with acute cerebral thrombosis and 20 healthy subjects as controls for expression of CD11a and CD11b (adhesion molecules on surface of leucocytes) were tested in vitro by flow cytometry (FCM) method. The results showed that compared with the control group, the patient group had significantly higher rates for expression of CD11a on monocytes, granulocytes and lymphocytes (P < 0.05). The CD11b expression in the patient group was positively elevated on monocytes and granulocytes (P < 0.05), but it was of lower positive rate on lymphocytes and no statistical difference was noted between the patient and control groups. These indicate that the expression of CD11a and CD11b on leucocytes increases in cerebral ischemic damage; thus adhesion of leucocytes and endothelial cells obviously increases. This change may aggravate post-ischemic delayed neuronal death.

Involvement of Ras/MAP kinase in the regulation of Ca2+ channels in adult bullfrog sympathetic neurons by nerve growth factor

The cellular mechanisms that underlie nerve growth factor (NGF) induced increase in Ca(2+)-channel current in adult bullfrog sympathetic B-neurons were examined by whole cell recording techniques. Cells were maintained at low density in neuron-enriched, defined-medium, serum-free tissue culture for 6 days in the presence or absence of NGF (200 ng/ml). The increase in Ba2+ current (IBa) density induced by NGF was attenuated by the RNA synthesis inhibitor cordycepin (20 microM), by the DNA transcription inhibitor actinomycin D (0.01 microgram/ml), by inhibitors of Ras isoprenylation (perillic acid 0.1-1.0 mM or alpha-hydroxyfarnesylphosphonic acid 10-100 microM), by tyrosine kinase inhibitors genistein (20 microM) or lavendustin A (1 microM), and by PD98059 (10-100 microM), an inhibitor of mitogen-activated protein kinase kinase. Inhibitors of the phosphatidylinositol 3-kinase (PI3K) pathway (wortmannin, 100 nM, or LY29400, 100 microM) were ineffective as were inhibitors of phospholipase C gamma (U73122 or neomycin, both 100 microM). The effect of NGF persisted in Ca(2+)-free medium that contained 1.8 mM Mg2+ and 2 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. It was mimicked by a Trk antibody that was capable of inducing neurite outgrowth in explant cultures of bullfrog sympathetic ganglion. Antibodies raised against the low-affinity p75 neurotrophin receptor were ineffective in blocking the effect of NGF on IBa. These results suggest that NGF-induced increase in Ca2+ channel current in adult sympathetic neurons results, at least in part, from new channel synthesis after Trk activation of Ras and mitogen activated protein kinase by a mechanism that is independent of extracellular Ca2+.

[Detecting expression of the multidrug resistance gene product (P170) in human tumor tissues and cells by flow cytometry]

We have detected the human multidrug resistance gene (MDR1) product P170 in 29 solid tumor samples and K562 cell line through indirectimmunoflourence staining by flow cytometry using mouse monoclonal antibody (McAb). The results showed that the expression of P170 was detected in 18 samples, the positive ratio being 62.1%; the expression was not detected in 11 samples, the negative ratio being 37.9%; and 99.9% of K562 cells expressed P170. In 16 of the 18 positive samples, the percent ratio of tumor cells for expression of P170 was less than 30%; in the other 2, more than 30%. This indicated that the positive ratio of P170 of most tumor samples was high, but their percent ratio of P170 was low. Thus it provided a parameter for reference in evaluating the efficacy of clinical antitumor treatments.

Relationship between fatty acid compositions and taurine concentration in breast milk from Chinese rural mothers

Long chain ω3 and ω6 fatty acids and taurine have been suggested to have structural and/or functional roles in the brain. In this study the levels of fatty acids and taurine in breast milk and their correlations were investigated in 46 lactating women from an area 100 km north-east of Beijing, China. The subjects consisted of two groups: group 1 was 22-47 days postpartum and group 2 was 75-106 days postpartum. Fatty acids and taurine in breast milk were measured by gas-liquid chromatography and high-performance liquid chromatography, respectively. The relative compositions of long chain ω6 and ω3 fatty acids decreased significantly (20:3 ω6, 20:4 ω6, 22:4 ω6, 22:5 ω6 and 22:6 ω3; all P < 0.01) in the course of lactation, while long chain saturated (20:0, 22:0) and monounsaturated (20:1, 22:1) fatty acids tended to increase. The ratio of ω6/ω3 fatty acids in breast milk fat appeared to be higher (12.3 ± 4.3 for group 1, and 16.5 ± 7.4 for group 2) than the desired range of 4-10. Breast milk taurine concentrations from Chinese rural mothers were 186 ± 48 nmol/mL and 157 ± 65 nmol/mL for groups 1 and 2, respectively. A significantly inverse relationship was observed between breast milk taurine concentration and the ratio of arachidonic acid ω6 to docosahexaenoic acid ω3 (r = -0.323, P = 0.028). Further studies on the physiological function(s) of taurine as an antioxidant and as a neurotransmitter are worth pursuing in relation to the balance of long chain ω6 and ω3 fatty acids, especially as regards its role in retina and brain development.

[Effect of tetrandrine on pulmonary vascular morphology in rats with hypoxia pulmonary hypertension]

To investigate the effect of Tetrandrine on pulmonary vascular morphology in rats with hypoxia pulmonary hypertension. We established the model of hypoxia pulmonary hypertension and observed the small pulmonary arterial morphologic changes under light microscope and electron microscope after the rats were treated with Tetrandrine; also, we made morphometric analysis. The results showed that the small pulmonary arteria in rats with hypoxia pulmonary hypertension was thinner than normal ones and had proliferation of smooth muscular cells. Morphometry displayed that the external diameter became smaller and that the ratio of vascular wall thickness to external diameter (M/T%) and the ratio of vascular wall area to total area (MA%) increased. The pathologic change significantly decreased after the rats were treated with Tetrandrine, indicating that Tetrandrine inhibited hypoxia-induced thickening and muscularization of small pulmonary arteria by inhibiting the proliferation of collagenous fibers so that narrowing of small pulmonary arteria was significantly slackened and pulmonary hypertension was alleviated. Therefore, we conclude that tetrandrine may partly prevent the development of pulmonary hypertension.

Regulation of N- and L-type Ca2+ channels in adult frog sympathetic ganglion B cells by nerve growth factor in vitro and in vivo

To examine mechanisms responsible for the long-term regulation of Ca2+-channels in an adult neuron, changes in whole cell Ba2+ current (IBa) were examined in adult bullfrog sympathetic ganglion B cells in vitro. Cells were cultured at low density in defined, serum free medium. After 15 days, total IBa was similar to the initial value, whereas IBa density was reduced by approximately 36%, presumably due to an increase in neuronal surface area. By contrast, IBa density remained constant after 6-15 days in the presence of murine beta-NGF (200 ng/ml), and total IBa was almost doubled. Inclusion of cytosine arabinoside (Ara-C; 10 microM) to inhibit proliferation of nonneuronal cells, did not affect the survival of neurons in the absence of nerve growth factor (NGF) nor did it attenuate IBa. Ara-C did not prevent the effect of NGF on IBa. There were three independent components to the action of NGF; during 6-9 days, it increased omega-conotoxin-GVIA-sensitive N-type IBa (IBa,N); increased nifedipine-sensitive L-type IBa (IBa,L) and decreased inactivation of the total Ba2+ conductance (gBa). The latter effect involved a selective decrease in the amplitude of one of the four kinetic components that describe the inactivation process. Total IBa was also 55.8% larger than control in the somata of B cells acutely dissociated from leopard frogs that had received prior subcutaneous injections of NGF. By contrast, injection of NGF antiserum decreased total IBa by 29.4%. There was less inactivation of gBa in B cells from NGF-injected animals than in cells from animals injected with NGF antiserum (P < 0.001). These data suggest that NGF-like molecule(s) play(s) a role in the maintenance of IBa in an adult amphibian sympathetic neuron; the presence of NGF may allow the neuron to maintain a constant relationship between cell size and current density. They also show that IBa inactivation in an adult neuron can be modulated in a physiologically relevant way by an extracellular ligand.

[Histopathologic and immunochemical changes in Sjögren's syndrome]

To research into the causes of sjögren's syndrome, we investigated the lacrimal gland tissues of 6 cases of sjogren's syndriome by using electronmicroscopy and immunochemical methods. The results revealed that at the early stage the lacrimal gland cells showed degeneration, irregular arrangement and many intracellular vacuoles. At the middle stage, some lymphocytes infliltrated into the gland tissues. And at the advanced stage, lymphocytes and collagenous fibers were there in substitution of gland cells.

Influence of activity and dietary energy on broiler performance, carcase yield and sensory quality

1. A total of 2560 male and female Ross broilers were raised to 42 days of age in a 2 X 2 treatment factorial arrangement experiment to investigate the influence of different degrees of physical activity and dietary energy on broiler performance, abdominal fat content, carcase yield and sensory quality. 2. Vertical fans were used to force the treatment birds to walk 3 to 4 times as far as the normal activity birds: birds were fed a normal and a high energy diet (12.55 compared with 13.81 MJ ME/kg) with the same energy/protein, energy/lysine and energy/methionine + cystine ratios. 3. High activity birds had greater body weight (+4.1%), food intake (+5.1%) and ME intake (+5.1%) than normal activity birds. Birds receiving high energy diet had a lower food conversion and food intake than birds receiving normal energy diet. There were no significant differences in body weight or ME intake between birds with different diets. 4. Slaughter yields, both absolute and relative to live body weight, were affected by activity or dietary energy to varying degrees. Breast meat was increased with more activity. The absolute weight of abdominal fat was independent of activity and in males the relative weight of abdominal fat was decreased in high activity birds. 5. Different degrees of activity and dietary energy had only minor influences on broilers sensory quality.

Antibodies as tools to study the structure of membrane proteins: the case of the nicotinic acetylcholine receptor

The nicotinic acetylcholine receptor is the prototype of the ionotropic receptor superfamily of proteins, which includes the closely related gamma- aminobutyric acid type A and glycine receptors, and more distantly related serotonin type-3 and glutamate receptors. Several models of the transmembrane topology of the nicotinic acetylcholine receptor subunits were originally proposed based on hydropathy analysis of their deduced amino acid sequences. Antibodies specific to different epitopes of the nicotinic acetylcholine receptor have proven to be valuable probes for examining the validity of those models. Despite important caveats, a viable model for the transmembrane structure and functional topology of the nicotinic acetylcholine receptor subunits has been obtained from the antibody mapping studies. This model, and the associated methodological shortcomings and obstacles that were overcome in the process of its formulation, can legitimately be extended to other members of the ionotropic receptor superfamily and to other membrane proteins as well.

[Effect of tetrandrine on intraacinar pulmonary arterial structural remodelling and pulmonary hypertension]

Rat's pulmonary hypertension was induced by a single subcutaneous injection of monocrotaline. The influences of tetrandrine (Tet) upon the structure of intraacinar pulmonary arteries (IAPA) was studied by light and electron microscopy. The results indicated that Tet reduced the thickness of IAPA medial membrane, the ratio of the thickness of IAPA medial membrane to the diameter of IAPA, the number of circular muscular artery and partially muscular artery about 16.4%, 30.5%, 24.3% and 16.4% respectively, and Tet increased the number of nonmuscular artery about 24.7%. It also decreased the degeneration of IAPA, collagen of medial membrane, prolife-ration and myoid differentiation of the pericyte, and it increased the number of IAPA. The authors discussed why Tet caused such changes.

Nif- phenotype of Azotobacter vinelandii UW97. Characterization and mutational analysis

We have identified the molecular basis for the nitrogenase negative phenotype exhibited by Azotobacter vinelandii UW97. This strain was initially isolated following nitrosoguanidine mutagenesis. Recently, it was shown that this strain lacks the Fe protein activity, which results in the synthesis of a FeMo cofactor-deficient apodinitrogenase. Activation of this apodinitrogenase requires the addition of both MgATP and wild-type Fe protein to the crude extracts made by A. vinelandii UW97 (Allen, R.M., Homer, M.J., Chatterjee R., Ludden, P.W., Roberts, G.P., and Shah, V.K. (1993) J. Biol. Chem. 268 23670-23674). Earlier, we proposed the sequence of events in the MoFe protein assembly based on the biochemical and spectroscopic analysis of the purified apodinitrogenase from A. vinelandii DJ54 (Gavini, N., Ma, L., Watt, G., and Burgess, B.K. (1994) Biochemistry 33, 11842-11849). Taken together, these results imply that the assembly process of apodinitrogenase is arrested at the same step in both of these strains. Since A. vinelandii DJ54 is a delta nifH strain, this strain is not useful in identifying the features of the Fe protein involved in the MoFe protein assembly. Here, we report a systematic analysis of an A. vinelandii UW97 mutant and show that, unlike A. vinelandii DJ54, the nifH gene of A. vinelandii UW97 has no deletion in either coding sequence or the surrounding sequences. The specific mutation responsible for the Nif- phenotype of A. vinelandii UW97 is the substitution of a non-conserved serine at position 44 of the Fe protein by a phenylalanine as shown by DNA sequencing. Furthermore, oligonucleotide site-directed mutagenesis was employed to confirm that the Nif- phenotype in A. vinelandii UW97 is exclusively due to the substitution of the Fe protein residue serine 44 by phenylalanine. By contrast, replacing Ser-44 with alanine did not affect the Nif phenotype of A. vinelandii. Therefore, it seems that the Nif- phenotype of A. vinelandii UW97 is caused by a general structural disturbance of the Fe protein due to the presence of the bulky phenylalanine at position 44.

[Effect of tetrandrine on pulmonary hypertension induced by monocrotaline in rats]

The effects of Tetrandrine (Tet) on intraacinous pulmonary arteries (IAPA) and bemodynamics were studied by means of a rat pulmonary hypertension model induced by monocrotaline. The results showed that Tet could reduce the contractive pressure of pulmonary artery, right ventricle and right atrium of heart by 28.0%, 28.3%, and 31.5% respectively. It could also decrease the vascular degeneration of endoepithelial cells of IAPA, the endoepithelial subcavity, the collagens of medial membrane and the numbers of smooth muscles of IAPA.

Binding of monoclonal antibodies against the carboxyl terminal segment of the nicotinic receptor delta subunit suggests an unusual transmembrane disposition of this sequence region

Monoclonal antibodies (mAbs) specific for the carboxyl terminal region of the delta subunit of Torpedo nicotinic acetylcholine receptor (AChR), derived from mice immunized with AChR or a synthetic carboxyl terminal sequence of the delta subunit (C delta-mAbs), were used to determine the transmembrane disposition of their epitope(s) by immunoelectron microscopy, using AChR-rich postsynaptic membrane fragments from Torpedo electroplax. Some C delta-mAbs recognized only the cytoplasmic side of the membranes, some both sides to a similar extent, and others bound mostly, but not exclusively, to the cytoplasmic side. Binding of C delta-mAbs to the membranes was specifically blocked by synthetic peptides containing the carboxyl terminal region of the delta subunit. Control anti-AChR mAbs specific for the alpha or the delta subunits, whose epitopes have known transmembrane topology, uniquely recognized the expected side of the postsynaptic membrane. Residues involved in C delta-mAb binding were identified using single residue substituted peptide analogues of the sequence delta 481-501. All C delta-mAbs recognized epitopes within the same sequence segment, delta 485-493, at the carboxyl terminal of the AChR delta subunit. These results suggest that the delta subunit of the AChR might have alternative conformations, leading to exposure of the same sequence region on the extracellular or the cytoplasmic surface. Several Pro residues are present in this region. The alternative cis or trans conformation of one or more of them might result in different folding patterns of the carboxyl terminal sequence of the delta subunit, as described for a viral protein [Liddington, R. C., Yan, Y., Moulai, J., Sahli, R., Benjamin, T. L., & Harrison, S. C. (1991) Nature 354, 278-284.

Clustering of B and T epitopes within short sequence regions of the nicotinic acetylcholine receptor

The epitope repertoire of B cells, due to their selective ability to process their specific antigen and the potential bias imposed on the resulting peptides by the surface immunoglobulins bound to the antigen, may influence the T-helper repertoire. Immunization of C57B1/6 mice with Torpedo acetylcholine receptor (TAChR) causes experimental autoimmune myasthenia gravis (EAMG). Anti-TAChR CD4+ cells recognize epitopes within three sequence regions of the TAChR alpha subunit ('dominant epitopes'). Immunization of mice with denatured or synthetic TAChR antigens sensitizes CD4+ cells to other TAChR sequence regions ('cryptic epitopes'). We investigated here whether clustering of B and T epitopes within the same short sequence segments occurs during the anti-TAChR response, as previously described for the response to hexogenous antigens unrelated to homologous self proteins. Twelve 19-20 residue synthetic sequences of the TAChR alpha, gamma and delta subunits, containing dominant or cryptic CD4+ epitopes for C57B1/6 mice, were tested for ability to induce anti-peptide antibody production. C57B1/6 mice were immunized with the individual peptides. Ten peptides stimulated antibody production. Therefore > 80% of these short TAChR sequences also contain B epitopes. Therefore also in the anti-TAChR response leading to EAMG T and B cell epitopes frequently reside within the same short sequence segment.

Overexpression of HER2/neu oncogene in pancreatic cancer correlates with shortened survival

For the purpose of determining the prognostic significance of HER2/neu oncogene in pancreatic and ampullary cancers, 21 pancreatic cancers of ductal origin and six cancers of the ampulla of Vater were studied immunohistochemically using the monoclonal antibody (MAb) CB11, specifically reactive with HER2/neu product. Staining of the epithelium of the normal duct and acini was negative or weakly positive. Moderately and strongly positive reactions indicated the overexpression of this gene, and were found in 10 of 21 (47.6%) pancreatic cancers of ductal origin and in 2 of 6 (33.3%) ampullary adenocarcinomas. Overexpression of HER2/neu was closely and inversely related to the survival of the patients with pancreatic cancer of ductal origin: 19.1 +/- 11.7 mo for those not overexpressing vs 7.3 +/- 3.8 mo for the overexpressors (p < 0.01). Among the pancreatic cancer group, 11 patients underwent cancer resection. The average survival for the 7 with nonoverexpressing cancer was 21.4 +/- 14.3 mo vs 10.5 +/- 3.6 mo for those with overexpressing tumor. Among those not undergoing resection, the average survival for the 4 with nonoverexpressing cancer was 15.0 +/- 3.8 mo as contrasted to 5.2 +/- 2.1 mo for the overexpressors (p < 0.01). Although the number of patients is small, these findings suggest that the overexpression of HER2/neu gene product may be frequently found in pancreatic cancer of ductal origin and may be one of the useful prognostic biomarkers for this cancer.

Pancreatic cancer. Cytologic study of peritoneal washings

OBJECTIVE

To delineate the frequency and significance of free cancer cells in the peritoneal cavity of patients with pancreatic exocrine adenocarcinoma.

DESIGN

Randomly selected patients with pancreatic cancer had peritoneal washings performed at the beginning and conclusion of laparotomy. Results of cytologic studies were correlated with the clinical findings, size, spread, and resectability of the tumor and with the survival time of the patient. All patients were followed up until the present or until their deaths.

SETTING

Tertiary care, referral hospitals in Toledo, Ohio.

PATIENTS

Only patients with biopsy-proven adenocarcinoma of the pancreas were included. Thirty-six patients, yielding 62 specimens for cytologic study, were included.

INTERVENTION

Peritoneal washings were performed at the beginning and completion of laparotomy. Each washing was evaluated independently by two skilled cytologists. If present, ascites was quantitated and studied cytologically. Biopsy specimens were obtained in each patient at the time of the study.

MAIN OUTCOME MEASUREMENTS

Presence or absence of malignant cells in peritoneal fluid; maximal diameter, grade, and spread of cancer; presence and volume of ascitic fluid; resectability of cancer; and length of survival of the patient.

RESULT

Of the 36 patients studied, three had positive cytologic findings. All three had peritoneal carcinomatosis. Of 11 patients with ascites, only one had positive cytologic findings.

CONCLUSIONS

Results of cytologic studies of peritoneal washings or of ascitic fluid are seldom positive with pancreatic exocrine carcinoma. When positive, they denote a very grave prognosis.

Preferential pairing of T and B cells for production of antibodies without covalent association of T and B epitopes

T cell from H-2b mice recognize at least 12 sequence regions on the Torpedo acetylcholine receptor (TAChR) alpha, gamma and delta subunits. Immunization of C57BL/6 mice with individual synthetic TAChR sequences known to contain CD4+ epitopes resulted in most cases (10 out of 12 peptides) in anti-peptide antibody (Ab) production, indicating that short TAChR sequences contain both CD4+ and B epitopes. Immunization of C57BL/6 mice with a mixture of a CD4+ epitope peptide, from the TAChR or from an unrelated protein, plus another TAChR sequence forming a "pure" B epitope (T alpha 63-80), induced in most cases anti-peptide Ab and CD4+ cell sensitization only against the peptide containing the CD4+ epitope. However, when the T epitope peptide T alpha 360-378 was co-injected with the B epitope, Ab were also produced against the B epitope peptide. Injection of the individual peptides T alpha 360-378 and T alpha 63-80 at different and distant sites along the back of mice elicited sensitization of CD4+ cells and Ab production only against peptide T alpha 360-378. Therefore, when optimal cooperation between T and B cells occurs, spatial proximity but not covalent association of the B and the CD4+ epitope is necessary for production of Ab against the B epitope.