Pancreatic secretion by the anaesthetized rabbit in response to secretin, cholecystokinin, and carbachol

Considerable differences exist among species in the patterns of regulation of pancreatic secretion. Although rabbit pancreas is quite often used for in vivo and in vitro studies of pancreatic function, responses of this gland in vivo to common pancreatic stimuli have never been characterised in detail. That was the purpose of this study. The data demonstrate the existence of a spontaneous fluid secretion that can be increased by intravenous infusions of secretion (sevenfold), cholecystokinin-octapeptide (CCK8) (threefold), and carbachol (sixfold). The electrolyte composition of the secretion evoked by each of these stimuli was similar: sodium and potassium concentrations were constant and slightly higher than those in plasma at all secretory rates, whereas bicarbonate concentration rose with secretory rate to approach a plateau of about 125 mmol/L, and chloride concentration fell to a plateau of about 35 mmol/L. In terms of protein secretion, secretin caused a small but significant rise in output, while CCK8 and carbachol evoked the expected large increase. Thus, regulation of pancreatic electrolyte secretion in rabbit differs from that in dog, cat, and human, on the one hand, and rat, on the other hand, and most closely resembles the pattern observed in guinea pig.

Diphenylamine-2-carboxylate (DPC) reduces calcium influx in a mouse mandibular cell line (ST885)

Non-selective cation channels are found in many diverse cell types and have been proposed as a potential entry path for Ca2+. ST885 cells contain large numbers of these channels which are active in the resting cell. We have used Fura-2 to monitor changes in intracellular free Ca2+ ([Ca2+]i) in response to step changes in extracellular Ca2+ ([Ca2+]o). We found that DPC, a blocker of the non-selective cation channel in these cells, caused a reduction of approximately 50% in the rate of rise in [Ca2+]i following a step increase in [Ca2+]o. Since our experiments demonstrate that this phenomenon is not due to DPC blockade of Cl- channels, the Na+/Ca2+ exchanger or cyclooxygenase, we conclude that it is attributable to a direct effect of DPC on the non-selective cation channel. It thus appears that the non-selective cation channel is a significant pathway for basal Ca2+ entry in these cells.

Transient diplegia in children who fail to thrive

We describe a group of eight children seen over a 4-year period. After a few months of apparently normal health and development, the children developed feeding difficulty, failed to thrive and had mild diplegia. No other underlying pathology was demonstrated. After a period of careful attention to feeding in the stimulating environment of a child development centre, the feeding difficulty, developmental delay and diplegia all disappeared, but, by school age, the children showed learning or behavioural difficulty. It is suggested that these children suffered a subtle neurological insult during the intra-uterine period and that this predisposed them to the neurological difficulty and failure to thrive. It is important to distinguish this small group of children from those in whom non-organic failure to thrive is found and parental neglect is suspected.

A 23-pS Ca2(+)-activated K+ channel in MCF-7 human breast carcinoma cells: an apparent correlation of channel incidence with the rate of cell proliferation

In studies on the apical membranes of cultured MCF-7 human breast carcinoma cells, we found two conspicuous K+ channel types with conductances of 23 and 70 pS, respectively. Of these, the 23-pS K+ channel was most conspicuous. In cell-attached patches with KCl in the pipette, it had a linear current/voltage (I/V) relation and was activated by depolarisation and in excised inside-out patches it was highly selective for K+ over Na+ (permeability ratio of Na+ to K+, PNa/PK = 0.02). Rubidium (Rb+) had a similar permeability to K+, although it was only conducted at 20% of the rate of K+, and cesium (Cs+) had a permeability less than 30% that of K+ and was not conducted at all. Both Cs+ and Rb+ acted as partial blockers when applied internally but the channel was not blocked by external tetraethylammonium (TEA, 10 mmol/l), quinidine (200 mumol 1) or apamin (50 nmol/l). It was activated by Ca2+ in the range 10(-7)-10(-6) mol/l. In cell-attached patches at a pipette potential of O mV, the open-time histogram was described by a single exponential (time constant 1.6 ms) and the closed-time histogram by two exponentials (time constants 0.5 and 1.5 ms). The incidence of the 23-pS but not the 70-pS channel depended on the rate of cell proliferation. Thus, in studies on cell-attached patches from cells in the exponential growth phase, the 23-pS channel was observed in 78% of patches.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficient incorporation of human CD4 protein into avian leukosis virus particles

Virus envelope (Env) proteins are thought to contain specific signals for selective uptake by virus particles. In the course of attempting to define these signals by testing virus incorporation of CD4-Env chimeric proteins, normal human CD4 was found to be efficiently and selectively assembled into avian leukosis virus particles in quail cells. Viruses bearing CD4 at their surface may be useful reagents in the design of retrovirus-mediated gene therapy for the acquired immune deficiency syndrome.

Persistent müllerian duct syndrome

Persistent müllerian syndrome is rare. A case of phenotypically normal male with persistent müllerian structures that consisted of a bicornuate uterus, fallopian tubes, and upper third of the vagina is reported. These unusual structures were found in association with bilateral cryptorchidism and a right inguinal hernia, and were diagnosed while repairing the hernia in the neonatal period. The uterus and fallopian tubes were removed via laparotomy when the child was eighteen months old; at the same time a bilateral orchiopexy was performed. To avoid damage to the vas deferens, which lay in closely to the müllerian structures and could not be separated from the vaginal wall, a small segment of the upper third of the vagina was retained. The testicles, although normal on pathologic examination, have shown poor response to hormonal stimulation with human chorionic gonadotropin. Long-term follow-up for these patients is necessary because they have an increased risk of testicular tumors developing.

Maternal serum Down syndrome screening: free beta-protein is a more effective marker than human chorionic gonadotropin

The use of quantitative human chorionic gonadotropin measurement in obstetrics has a long and successful history. Prior studies on the utility of human chorionic gonadotropin in Down syndrome screening have utilized assays that measure the intact human chorionic gonadotropin molecule. This study targeted a distinct marker, the human chorionic gonadotropin free beta-protein, which is present in second-trimester maternal serum at much lower concentrations than is intact human chorionic gonadotropin. Our study of 29 cases of trisomy 21 and 450 control samples shows 80% detection efficiency with maternal serum alpha-fetoprotein, the free beta-protein, and maternal age in pregnancies under 17 weeks' gestation. We conclude that the combination of maternal serum alpha-fetoprotein and the human chorionic gonadotropin free beta-protein will be useful in the prenatal detection of trisomy 21.

Elafin: an elastase-specific inhibitor of human skin. Purification, characterization, and complete amino acid sequence

A potent inhibitor of human leukocyte elastase (EC 3.4.21.37) and porcine pancreatic elastase (EC 3.4.21.36) was purified to homogeneity from human horny layers. It inhibits human leukocyte elastase and porcine pancreatic elastase in a 1:1 molar ratio and shows equilibrium dissociation constants of 6 x 10(-10) M and 1 x 10(-9) M, respectively. Inhibition of plasmin, trypsin, alpha-chymotrypsin, and cathepsin G was not observed. This inhibitor proved to be an acid stable basic peptide with an isoelectric point of 9.7. The complete amino acid sequence appears to be unique with 38% homology to the C-terminal half of antileukoprotease. The sequence shows that the inhibitor is composed of 57 amino acids and predicts a Mr of 7017. The high affinity as well as the apparent specificity for elastases suggests a functional role in preventing elastase-mediated tissue proteolysis. It is suggested that the term "elafin" be used to designate this inhibitor.

Characterization of a 25-pS nonselective cation channel in a cultured secretory epithelial cell line

We have studied a 25-pS nonselective cation channel from the apical membranes of cell line ST885, derived from neonatal mouse mandibular glands. Its Cl- permeability was not significantly different from zero. The permeabilities (relative to Na+) for inorganic cations were NH4+ (1.87) greater than K+ (1.12) greater than Li+ (1.02) greater than Na+ (1) greater than Rb+ (0.81) greater than Mg2+ (0.07) greater than Ca2+ (0.002), and for organic cations, guanidinium (1.61) greater than ethanolamine (0.70) greater than 4-aminopyridine (0.66) greater than diethylamine (0.54) greater than piperazine (0.25) greater than Tris (0.18) greater than N-methylglucamine (0.12). The Tris and N-methylglucamine permeabilities differed significantly from zero. Fitting the Renkin equation indicated that the channel had an equivalent pore radius of 0.49 nm. The channel was activated by Ca2+ on the cytosolic surface (greater than 0.1 mmol/liter) with a Hill coefficient of 1.2; it was also activated by depolarization. Open- and closed-time histograms indicated that it had at least two open and two closed states. The channel was blocked by cytosolic AMP or ATP (0.1 mmol/liter). It was also blocked by the Cl- channel blocker, diphenylamine-2-carboxylate (DPC; 0.1 mmol/liter), applied to the extracellular but not the cytosolic surface. 4-Amino-pyridine, which permeated the channel when applied to the extracellular surface, blocked it when applied in low concentrations (5 mmol/liter) to the cytosolic surface. Quinine (0.1 mmol/liter) blocked from both the extracellular and cytosolic surfaces, blockade from either side being enhanced by depolarization. The channel was held open by application of SITS (0.1 mmol/liter) to the cytosolic surface. The channel shows striking similarities to the nicotinic acetylcholine receptor channel, viz., both channel types are abnormally permeable to 4-aminopyridine applied externally, and their selectivity sequences for inorganic ions are similar and for organic cations are identical.

Fine needle aspiration cytology of salivary gland lesions

Eighty-eight fine needle aspirates from 79 salivary gland lesions in 77 patients were examined. The overall diagnostic sensitivity was 84% and the specificity 98.41%. When the 14 unsatisfactory specimens were excluded the sensitivity rose to 95.45%. Correct identification of the disease process was possible in nearly 80% of cases with a final benign diagnosis. The histological tumour type was correctly predicted in 75% of the malignancies. In the others the cytological diagnosis was anaplastic malignant neoplasm.

Effect of K+ channels in the apical plasma membrane on epithelial secretion based on secondary active Cl- transport

Models of epithelial salt secretion, involving secondary active transport of Cl- [9], locate the K+ conductance of the plasma membrane exclusively in the basolateral membrane, although there is considerable experimental evidence to show that many secretory epithelia do have a significant apical K+ conductance. We have used an equivalent circuit model to examine the effect of an apical K+ conductance on the composition and flow rate of the fluid secreted by an epithelium in which secretion is driven by the secondary active transport of Cl-. The parameters of the model were chosen to be similar to those measured in the dog tracheal mucosa when stimulated with adrenaline to secrete. We find that placing a K+ conductance in the apical membrane can actually enhance secretion provided the proportion of the total cell K+ conductance in the apical membrane is not greater than about 60%, the enabling effect on secretion being maximal when the proportion is around 10-20%. We also find that even when the entire cell K+ conductance is located in the apical membrane, the secreted fluid remains relatively Na+ rich. Analysis of the sensitivity of model behavior to the choice of values for the parameters shows that the effects of an apical K+ conductance are enhanced by increasing the ratio of the paracellular resistance to the transcellular resistance.

Characteristics of ankle-foot orthoses for management of the spastic lower limb

A retrospective study was done on the effects of a change in the design of ankle-foot orthoses used in the treatment of 29 hemiplegic children. Nine of 13 children treated with plantarflexed ankle-foot orthoses required surgery, compared with only one of 16 with dorsiflexed ankle-foot orthoses. This difference is highly significant.

Acetate stimulates secretion in the rabbit mandibular gland

In isolated perfused rabbit mandibular glands undergoing stimulation with 0.8 microM acetylcholine, replacement of HCO3- with acetate (25 mM) increased fluid secretion by more than 100%. Other short-chain fatty acids, except for propionate, had a similar effect. We focused our further studies on acetate, and in order to find out the cause of its stimulatory effect we investigated whether acetate itself was transported. In the absence of any other transportable anions 25 mM acetate supported secretion at the same rate as 25 mM HCO3- or 25 mM Cl-, i.e. 20% of the control rate. In solutions containing acetate as the only major anion (146 mM), fluid secretion was maintained at about 50% of the control rate. Amiloride (1 mM) inhibited this secretion by about 90%. In glands perfused with acetate/Cl- solutions, when the stimulatory effect was normally observed, amiloride (1 mM) inhibited secretion by 50-60% and SITS (0.1 mM) had no effect. Probenecid reversibly inhibited 75% of secretion in these glands, but it also inhibited 92% of secretion in glands perfused without any acetate. Interestingly, the acetate effect was abolished in glands stimulated with a higher concentration of acetylcholine (80 microM). Results of this study suggest that acetate can be transported by salivary endpieces and that this transport involves an amiloride-sensitive Na+-H+ antiport. We postulate that acetate may in addition have some regulatory or modifier role in salivary secretion.

Epidermal and transforming growth factor alpha in patients with breast tumours

Measurements of transforming growth factor alpha (TGF-alpha) in cancer patients have produced variable results. We have now used a specific radioimmunoassay (RIA) and a mitogenic assay to evaluate TGF-alpha content of tumour and urine samples separated by an analytical HPLC system. Urine samples from patients with breast tumours and from age matched controls gave TGF-alpha amounts ranging from 0 to 61.5 ng 24 h-1 compared to urogastrone epidermal growth factor figures of 3.0-26.2 micrograms 24 h-1. The quantities of TGF-alpha in patient and control groups were not significantly different. The majority of breast tumour extracts contained mitogenic material eluting from the HPLC system at the TGF-alpha calibration point. Measurement by RIA of combined samples from each group showed that steroid receptor positive tumours had a mean figure of 14.8 ng g-1 tissue and steroid receptor negative 7.4 ng g-1. Receptor positive tumours from patients treated with an antioestrogen, tamoxifen citrate (Nolvadex), had 0.16 ng g-1. Thus TGF-alpha is found in tumours as a biologically active entity and in quantities sufficient to promote cell division. In addition the observation that tamoxifen causes a significant reduction in the content of TGF-alpha may be an additional beneficial action.

Fine needle aspiration cytology of salivary glands

The historical development, technique, interpretation and diagnostic reliability of FNAC of the salivary glands are reviewed. The advantages, difficulties, and limitations of the method are considered.

Characterization of beta-adrenoceptor subtypes in rabbit mononuclear leukocytes

Computer analysis of [125I]iodocyanopindolol competition studies using the relatively selective beta 1-adrenoceptor antagonist, ICI 89406, and the beta 2-selective antagonist, ICI 118551, on rabbit mononuclear leukocyte plasmalemmal preparations favored a two-site model indicating that both beta 1- and beta 2-adrenoceptor subtypes were present in approximately equal numbers. In contrast, similar studies performed on rabbit cardiac sarcolemma favored a one site model consistent with the presence of beta 1-adrenoceptors. Consequently, rabbit mononuclear leukocytes may provide a useful model for studying selective modulatory mechanisms of beta 1- and beta 2-adrenoceptors.

Functional characterization of beta-adrenoceptor subtypes in rabbit right atria

The advent of radioligand binding studies has allowed the classification of receptor subtypes in various tissues. However, the presence of a receptor subtype in a heterogenous tissue does not insure that the receptor has a significant physiological role. beta 1- and beta 2-Adrenoceptors have been reported to coexist in the rabbit right atria. The purpose of the present investigation was to determine the physiological role of beta-adrenoceptor subtypes in catecholamine-induced chronotropic responses in the rabbit right atria through comparison of data from functional and radioligand binding studies. Rank order of potency was determined using isoproterenol, epinephrine and norepinephrine for both chronotropic and inotropic responses in the rabbit right atria and right ventricular papillary muscles, respectively. These studies indicated that the beta 1-adrenoceptor was primarily responsible for catecholamine-induced responses. Next, the beta 1-selective antagonist, atenolol, was found to inhibit the chronotropic responses of the nonselective beta-agonist, isoproterenol, and the beta 2-selective agonist, terbutaline, to the same extent. These data indicate that terbutaline produces its chronotropic effects in the rabbit right atria through stimulation of beta 1-, not beta 2-adrenoceptors. Finally, competition studies for [125I]iodocyanopindolol and the relatively selective beta 1- and beta 2-adrenoceptor antagonists (ICI 89406 and ICI 118551, respectively) indicated that the ratio of beta 1- to beta 2-adrenoceptor subtypes is 6:1. It is concluded that while both receptors may be present in the rabbit right atria, the beta 1-adrenoceptor is the predominant subtype both in density and physiological significance, while the beta 2-adrenoceptor plays little, if any role, in the chronotropic responses induced by catecholamines.

Intraperitoneal cisplatin with intravenous cyclophosphamide and doxorubicin for previously untreated stage III and IV ovarian carcinoma

Eighteen evaluable patients with previously untreated Stage III and IV ovarian carcinoma were treated with six cycles of intraperitoneal cisplatin with intravenous cyclophosphamide and doxorubicin. Significant chemotherapy-related toxicities were observed, including one patient with fatal neutropenia and sepsis, two patients with transient severe nephrotoxicity, one patient with severe autonomic and motor neuropathy, and one patient with generalized debility. One patient had Tenckhoff catheter-related peritonitis, but no other morbidity was associated with the peritoneal catheters. Three of eight patients with optimal tumor bulk and none of 10 patients with suboptimal tumor bulk achieved pathologic complete response. The overall estimated median survival is 22 months. This treatment approach is associated with formidable toxicity, and the contribution of intraperitoneal cisplatin to the treatment of newly diagnosed ovarian carcinoma patients must be evaluated in randomized trials.

The use of cytodex microcarrier beads in patch-clamp studies on cultured epithelial cells

This paper describes an economical attachment substratum for use in patch-clamp experiments on cultured epithelial cells. It consists of Cytodex microcarrier beads on which growing cells present a unique profile perspective that increases the ease with which patch-clamp seals can be obtained. Cells from the mouse mandibular gland cell line, ST885, were grown on the beads and studied using standard patch-clamp techniques. The results were indistinguishable from those obtained from cells grown in monolayers on Petri dishes. The method can be applied in many types of patch-clamp experiment and used with a wide variety of cell types. It is especially useful if one wishes to do experiments in the cell-attached or whole-cell configurations and needs to add drugs or hormones to the external surface of the cell.

Ca2+ not cyclic AMP mediates the fluid secretory response to isoproterenol in the rat mandibular salivary gland: whole-cell patch-clamp studies

We have performed whole-cell patch-clamp studies on dispersed secretory cells of the rat mandibular gland to determine how beta-adrenergic stimulation causes fluid secretion. When the pipette contained a high K+ solution, the resting membrane potential averaged -33 mV +/- 1.1 (SEM, n = 34) and the clamped cell showed strong outward rectification. We monitored K+ and Cl- currents for periods of 15 min by recording the currents needed to clamp the cell potential at 0 and -80 mV, respectively. Isoproterenol (1-2 mumol/l) caused increases in the clamp current at 0 mV (the K+ current) and at -80 mV (the Cl- current) in about 80% of cases, although the responses were variable in size and time-course; the responses were indistinguishable from those induced by acetylcholine or the Ca2+ ionophore, A23187. The alpha-adrenergic antagonist, phentolamine (1-2 mumol/l), had no effect on the response, but the beta-adrenergic antagonist, propranolol (10 mumol/l), blocked it completely. The isoproterenol response could not be mimicked by application to either surface of the cell membrane, of cyclic AMP (100 mumol/l), forskolin (1 or 20 mumol/l) or cholera toxin (2.5 micrograms/ml). However, increasing the Ca2+-chelating capacity of the pipette solution by raising its EGTA concentration from the customary 0.5 to 20 mmol/l, blocked the response to isoproterenol, suggesting that beta-adrenergic agonists activate Cl- and K+ channels by raising cytosolic Ca2+. Since neomycin, which blocks phospholipase C, blocked the action of isoproterenol without impairing the cell responsiveness to A23187, it appears that isoproterenol, like muscarinic agonists, increased cytosolic Ca2+ via the phosphatidylinositol cycle.

The accuracy of aspiration cytology in the diagnosis of rejection following orthotopic liver transplantation

The role of aspiration cytology (AC) and the total corrected increment (TCI) in the diagnosis of hepatic rejection was assessed in 30 patients following 36 liver transplants. A total of 174 AC specimens were "blindly" evaluated. Patients underwent protocol AC twice weekly and when biochemical or clinical parameters suggested rejection. Hepatic rejection was only confirmed when clinical and biochemical changes were accompanied by positive histological diagnosis. In all, 103 specimens were matched against histology, the remainder assessed against retrospective clinical and biochemical diagnoses. There were 80 cytological diagnoses of rejection, confirmed in 69 specimens, and 94 diagnoses of no rejection, confirmed in 73 specimens. These figures give a sensitivity of 76.7%, a specificity of 86.9% and a positive predictive value of 86.3%. Overall, 39.7% of specimens taken more than 2 months after grafting proved to be incorrectly diagnosed. However, the accuracy was higher in 145 specimens taken within 8 weeks of transplantation, with a sensitivity of 81.3%, a specificity of 90%, a positive predictive value of 89.7% and an accuracy of 85.5%. Although histology remains the gold standard in the diagnosis of acute rejection after hepatic grafting, AC using a TCI with a positive predictive value of 86.3% may prove to be of value in monitoring liver transplant patients in the first 2 months after grafting.

Fine needle aspiration cytology in the management ENT of patients

Aspirates were obtained from 142 masses in 120 patients who presented with palpable swellings in the head and neck region. 120 specimens (84.51 per cent) were adequate for diagnostic purposes and the remaining 22 (15.49 per cent) were unsatisfactory. Final diagnosis was based on resection histology in 87 cases and close clinical follow-up in 55 patients. The overall sensitivity and specificity including unsatisfactory aspirates was 81.37 per cent and 93 per cent respectively (if the technically inadequate specimens were deleted 98.81 per cent and 94.44 per cent). In comparison with the final diagnosis typing of malignant tumours was possible in 58.33 per cent. The correct diagnosis was made in 63.89 per cent of benign lesions.