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The present investigation is an attempt to determine the occurrence, elemental composition and formation of microliths in the parotid of ferret. Parotids from four normal ferrets were examined by electron microscopy and X-ray microanalysis. Crystalline microliths were found in phagosomes of acinar cells, which occasionally contained secretory material, and in phagosomes situated between mitochondria of striated ductal cells. Crystalline microliths and microliths that consisted of granular material either without crystals or mixed with a component of crystals were found in lumina, where they were often associated with cellular debris. The crystals contained calcium and phosphorus. Phagy and stagnation related to pockets of inefficient secretory activity have been previously found to be features of the parotid of ferret. Thus, possibly persistent degradation of redundant cellular material, particularly secretory granules, in phagosomes results in accumulation of calcium and leads to calcified microliths, whereas consolidation of stagnant debris extracellularly does not involve such accumulation and leads to non-calcified or mixed microliths.

Immunoglobulin A (IgA) is transported into saliva by salivary cells expressing the polymeric immunoglobulin receptor (pIgR). In rat salivary glands, autonomic nerves stimulate this process. To examine how nerves affect pIgR-mediated IgA secretion, the chorda-lingual nerve was sectioned. One week after preganglionic parasympathectomy, both the stimulated and unstimulated rates of salivary IgA secretion were reduced, despite similar glandular amounts of IgA. Biochemical analysis of cells from parasympathectomised and control glands indicated reduced membrane expression of pIgR. It appears the removal of long-term parasympathetic input has affected the routing of pIgR within salivary cells and reduced the SIgA transport into saliva.

Salivary fluid secretion is dependent upon reflex stimuli mediated by autonomic nerves. In order to determine if immunoglobulin A (IgA) and salivary proteins are secreted in the absence of nerve stimulation, small volumes (< 2 microl) of saliva were consecutively collected from the submandibular duct of anaesthetised rats following rest pauses in order to sample the protein contents of the ductal system. Within the first 5 microl of such saliva collected by parasympathetic nerve stimulation, IgA and other salivary proteins reached peak concentrations that were over 20-fold greater than levels in parasympathetically stimulated saliva subsequently collected during a 5 min period of stimulation. Confocal microscopy of TRITC-labelled IgA added to live, acutely isolated submandibular acini indicated that it did not enter the lumina by paracellular leakage. IgG is thought to enter saliva by paracellular leakage but did not accumulate in luminal saliva in the present study. Electrophoresis suggested that the major proteins secreted in the absence of stimulation were the same as those present in subsequently stimulated saliva. It can be concluded that IgA and other major submandibular proteins are secreted into glandular lumina in the absence of nerve stimulation. The functional significance of such unstimulated protein secretion is at present unclear.

A variable response following ductal ligation of feline salivary glands corresponds to the human condition but contrasts with a predictable atrophy in obstructed salivary glands of rodents popularly used as a model for human salivary problems. The present investigation is concerned with a possible reason for the variable response, namely the preservation of the innervation. Ducts of feline submandibular and sublingual salivary glands were ligated with or without the inclusion of the chorda tympani. Inclusion led to a delayed initial response followed by progressive atrophy until the parenchyma was extremely atrophic, whereas avoidance of the chorda led to the variable response in which variable numbers of acini of a similar form to normal persisted. The results establish the atrophic effect of inclusion of the chorda tympani in ductal ligation and indicate the caution that should be exercised in the extrapolation of the rodent model to the human condition.

Twenty-nine parotids ligated for between 1 and 365 days were examined by light and electron microscopy. Major changes in the acini were seen at 4 days and included vacuolation, disintegration, extravasation, apoptosis, phagy and a reduction in number and size of secretory granules. There was a further reduction in secretory granules from 7 to 12 days, but acinar cells persisted even up to 365 days, some contained a luminal concentration of small secretory granules and occasionally acinar cells of a similar appearance to normal were found. These findings contrast with a reported absence of acinar cells from the obstructed parotid of rat and show that parotid acinar cells are able to persist and retain an appearance indicative of secretory activity.

Secretion of fluid and proteins by salivary cells is under the control of parasympathetic and sympathetic autonomic nerves. In a recent study we have shown that, in the rat submandibular gland, autonomic nerves can also increase the secretion of IgA, a product of plasma cells secreted into saliva as SIgA (IgA bound to Secretory Component, the cleaved poly-immunoglobulin receptor). The present study aimed to determine if parotid secretion of SIgA is increased by autonomic nerves and to compare SIgA secretion with other parotid proteins stored and secreted by acinar and ductal cells. Assay of IgA in saliva evoked by parasympathetic nerve stimulation immediately following an extended rest period under anaesthesia indicated that it had been secreted into intraductal saliva in the absence of stimulation during the rest period. The mean rate of unstimulated IgA secretion (2.77+/-0.28 microg min(-1) g(-1)) and the 2.5-fold increase in IgA secretion evoked by parasympathetic stimulation were similar to results found previously in the rat submandibular gland. Sympathetic nerve stimulation increased SIgA secretion 2.7-fold, much less than in the submandibular gland. SDS-PAGE and Western blot analysis with anti-IgA and anti-Secretory Component antibodies confirmed that SIgA was the predominant form of IgA in saliva. Acinar-derived amylase and ductal-derived tissue kallikrein were more profoundly increased by parasympathetic and particularly sympathetic stimulation than SIgA. Overall, the results of the present study indicate that SIgA forms a prominent component of unstimulated parotid salivary protein secretion and that its secretion is similarly increased by stimulation of either autonomic nerve supply. The secretion of other parotid salivary proteins that are synthesized and stored by acinar or ductal cells is upregulated to a much greater extent by parasympathetic and particularly sympathetic stimulation.

Salivary secretion of proteins from rat submandibular glands was studied using graded stimulation of the parasympathetic nerve in isolation, and then at a fixed rate in combination with graded sympathetic nerve stimulation. Increasing the frequency of parasympathetic nerve stimulation per se caused a gradual increase in the secretion of peroxidase (from acini) but only small increases in proteinase (from ductal cells) and IgA outputs. Dual stimulations, with an increasing frequency of sympathetic nerve stimulation on a background of low frequency parasympathetic nerve stimulation, showed that maximal acinar secretion of peroxidase required only a low frequency of additional sympathetic stimulation, whereas ductal secretion of kallikrein was greatest with the highest frequency of additional sympathetic stimulation (20 Hz in bursts). IgA secretion also required high frequency additional sympathetic stimulation in bursts for greatest output. Although a synergism occurred with parasympathetic plus sympathetic nerve stimulation for the secretion of both peroxidase and kallikrein it was not evident for the secretion of IgA. This presumably reflects a difference for exocytosis of proteins stored in granules (e.g. peroxidase and kallikrein) compared to those proteins continuously transported across the plasma membrane in vesicles by transcytosis. This work confirms that vesicular movement of secretory IgA can be increased by both parasympathetic and sympathetic nerve stimulation, but the frequency parameters differ for each nerve.

1. The influence of graded parasympathetic and sympathetic nerve stimulations on the secretion of protein from rat submandibular gland was studied. Peroxidase was used as a marker for the acini and rat tissue kallikrein (official nomenclature rK1) as the marker for granular ducts. Tonin (rK2) was also measured, and the ratio of rK2:rK1 was calculated as an indication of the cellular route of secretion. 2. Continuous parasympathetic nerve stimulation caused a copious flow of saliva that had a low protein content. The secretion of peroxidase (acini) showed a gradual moderate increase as the frequency increased. However, the concentrations of rK1 and rK2 (granular ducts) showed little change throughout, and the ratio of rK2:rK1 remained relatively constant. 3. Graded sympathetic stimulation was applied against a background of parasympathetic stimulation. Secretion of peroxidase was increased by the addition of 0.1 Hz continuous sympathetic stimulation. The amount increased thereafter up to 2 Hz, but showed no further increase if the stimulation was applied as bursts of 10 or 20 Hz. In comparison, the secretion of proteinase activity showed little change with superimposed continuous sympathetic stimulation, and the rK2:rK1 ratio was similar to that in saliva produced by parasympathetic stimulation alone. Sympathetic stimulation applied in bursts, however, caused a large increase in the secretion of proteinase activity, and with 20 Hz burst stimulation the rK2:rK1 ratio was indistinguishable from that of sympathetic saliva per se. There was an augmented secretion of both peroxidase and kallikrein when 20 Hz burst stimulation was combined with parasympathetic stimulation. The effects of sympathetic stimulation were abolished by alpha- and beta-adrenoceptor blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

We are concerned here with the behavior of a rotating, stratified fluid near a sloping rigid boundary, with boundary conditions of zero normal buoyancy flux and no slip. Although this is an interesting fluid dynamical problem in its own right, we have been motivated by two major, and at first sight disparate, topics in physical oceanography. The first, known as "boundary mixing", is concerned with how turbulent mixing at the sloping sides of the density-stratified ocean affects the stratification in the interior. The second topic involves the way in which the combination of strati

Intraluminal pressure studies on patients with congenital aganglionosis showed that the aganglionic rectum contracted in an uncoordinated manner and failed to relax. Histochemical assessment of the innervation helped to explain the variable severity of the symptoms in this condition. It is concluded that (1) absence of ganglia prevents normal coordinated peristalsis and creates an obstructive element; (2) absence of reflex relaxation adds to the obstruction; (3) the degree of uncoordinated motor activity in distal aganglionic bowel probably relates to the number of cholinesterase-positive nerves in the circular muscle and adds another variable obstructive element; and (4) deficient innervation of distal ganglionic bowel probably creates a poor propulsive force and so accentuates more distal obstructive factors. Neurohistochemical and functional studies in the anorectum of cats reveal a somewhat different innervation pattern from that in humans but show that sphincteric tone is mainly due to alpha-adrenergic neural activity. Reflex relaxation of the internal anal sphincter is a complex function in which inhibitory responses override motor responses, and it involves an important non-adrenergic non-cholinergic component. The role of cholinergic nerves in the sphincter remains uncertain. Neurohistochemical assessment of full thickness biopsy specimens of rectal muscle from patients with disabling constipation shows that developmental neuronal dysplasias of the hind-gut may be divided into three main categories: (1) aganglionosis (Hirschsprung's disease), (2) hypoganglionosis and (3) hyperganglionosis, and that the different neuronal elements may be affected to differing degrees in individuals within each group. Resection of the aganglionic bowel is required in congenital aganglionosis but the combined diagnostic-therapeutic procedure of anorectal myotomy has been found beneficial in patients with hypoganglionosis.

Previous histochemical investigations suggested that the microenvironment in the parotid of ferret would foster microlithiasis because of a combination of pockets of inefficient secretion, brisk phagy and secretory material rich in calcium. We have undertaken the present ultrastructural investigation in an attempt to provide corroborative evidence. Parotids from four normal ferrets were examined by electron microscopy. Phagosomes in which there was cellular debris and occasionally secretory granules were present in acinar cells, which indicates crinophagy, and residual bodies were present in ductal cells. Atrophic parenchymal cells, degenerate parenchymal cells and apoptotic bodies were present. Cellular debris and secretory material were present in lumina, which indicates stagnation. The results indicate that removal of redundant secretory material and cells and low flow of saliva are features of the parotid of ferret and support the concept of pockets of inefficient secretory activity.

Rat submandibular glands have been examined electron microscopically at various times after degranulating the granular tubules by injecting cyclocytidine (75 mg/kg i.p.), to study events in the reformation of secretory granules in these cells. The changes were progressive but not synchronous in the cells. The first evidence of recovery was the re-appearance of glycogen particles 6 h after injection. Residual secretory granules were small and located periluminally at that time. More granules were present at 15 h after injection but they were still small and placed periluminally. There was more glycogen in the cells and some was present in aggregates. At 1 day after injection there were more secretory granules and they tended to be larger than previously. The secretory granules increased in size and number progressively thereafter and the cells appeared like normal controls by day 7. During the recovery, fusion profiles were seen between granules from 2 days onwards. Throughout, few Golgi complexes were detected and this may be related with the low glycosylation of the secretory proteins in these cells. The results confirm that the reformation of the secretory granules in granular tubule cells is a slow process that involves fusions of smaller granules.

A variable response following ductal ligation of feline salivary glands corresponds to the human condition but contrasts with a predictable atrophy in obstructed salivary glands of rodents popularly used as a model for human salivary problems. The present investigation is concerned with a possible reason for the variable response, namely the preservation of the innervation. Ducts of feline submandibular and sublingual salivary glands were ligated with or without the inclusion of the chorda tympani. Inclusion led to a delayed initial response followed by progressive atrophy until the parenchyma was extremely atrophic, whereas avoidance of the chorda led to the variable response in which variable numbers of acini of a similar form to normal persisted. The results establish the atrophic effect of inclusion of the chorda tympani in ductal ligation and indicate the caution that should be exercised in the extrapolation of the rodent model to the human condition.

Secretion of fluid and proteins by salivary cells is under the control of parasympathetic and sympathetic autonomic nerves. In a recent study we have shown that, in the rat submandibular gland, autonomic nerves can also increase the secretion of IgA, a product of plasma cells secreted into saliva as SIgA (IgA bound to Secretory Component, the cleaved poly-immunoglobulin receptor). The present study aimed to determine if parotid secretion of SIgA is increased by autonomic nerves and to compare SIgA secretion with other parotid proteins stored and secreted by acinar and ductal cells. Assay of IgA in saliva evoked by parasympathetic nerve stimulation immediately following an extended rest period under anaesthesia indicated that it had been secreted into intraductal saliva in the absence of stimulation during the rest period. The mean rate of unstimulated IgA secretion (2.77+/-0.28 microg min(-1) g(-1)) and the 2.5-fold increase in IgA secretion evoked by parasympathetic stimulation were similar to results found previously in the rat submandibular gland. Sympathetic nerve stimulation increased SIgA secretion 2.7-fold, much less than in the submandibular gland. SDS-PAGE and Western blot analysis with anti-IgA and anti-Secretory Component antibodies confirmed that SIgA was the predominant form of IgA in saliva. Acinar-derived amylase and ductal-derived tissue kallikrein were more profoundly increased by parasympathetic and particularly sympathetic stimulation than SIgA. Overall, the results of the present study indicate that SIgA forms a prominent component of unstimulated parotid salivary protein secretion and that its secretion is similarly increased by stimulation of either autonomic nerve supply. The secretion of other parotid salivary proteins that are synthesized and stored by acinar or ductal cells is upregulated to a much greater extent by parasympathetic and particularly sympathetic stimulation.

Salivary secretion of immunoglobulin A (IgA) in response to electrical stimulation of the parasympathetic nerve supply was assessed bilaterally in the submandibular glands of anaesthetized rats 1 week following unilateral pre-ganglionic sympathectomy (decentralization). Nerve-mediated stimulation on the non-denervated side increased IgA secretion several fold above an unstimulated rate of secretion whereas sympathetic decentralization reduced the parasympathetically stimulated secretion of IgA without affecting the basal rate. Glandular levels of IgA were increased following decentralization compared to the control glands. Salivary levels of free secretory component (FSC), the cleaved polymeric immunoglobulin receptor (plgR), were increased by parasympathetic stimulation and reduced by sympathectomy, though not as much as IgA. The decreased secretion of FSC suggests a reduced production of plgR and may account in part, for reduced IgA secretion following long-term removal of sympathetic nerve impulses.

Salivary secretion of proteins from rat submandibular glands was studied using graded stimulation of the parasympathetic nerve in isolation, and then at a fixed rate in combination with graded sympathetic nerve stimulation. Increasing the frequency of parasympathetic nerve stimulation per se caused a gradual increase in the secretion of peroxidase (from acini) but only small increases in proteinase (from ductal cells) and IgA outputs. Dual stimulations, with an increasing frequency of sympathetic nerve stimulation on a background of low frequency parasympathetic nerve stimulation, showed that maximal acinar secretion of peroxidase required only a low frequency of additional sympathetic stimulation, whereas ductal secretion of kallikrein was greatest with the highest frequency of additional sympathetic stimulation (20 Hz in bursts). IgA secretion also required high frequency additional sympathetic stimulation in bursts for greatest output. Although a synergism occurred with parasympathetic plus sympathetic nerve stimulation for the secretion of both peroxidase and kallikrein it was not evident for the secretion of IgA. This presumably reflects a difference for exocytosis of proteins stored in granules (e.g. peroxidase and kallikrein) compared to those proteins continuously transported across the plasma membrane in vesicles by transcytosis. This work confirms that vesicular movement of secretory IgA can be increased by both parasympathetic and sympathetic nerve stimulation, but the frequency parameters differ for each nerve.

Saliva is essential for oral health and influences all events in the mouth. In 1850 Ludwig discovered that autonomic nerve impulses evoke salivary secretion and all work since has shown that the nerves normally control the flow and protein output of saliva. This publication, written by international experts, is the first one devoted to the neuroglandular mechanisms of this control. The chapters contained deal with: the intimate details of the nerves and their different transmitters in the glands; central connections of the glandular nerves; receptors in the glands; nerve-induced glandular secretion of proteins; autonomic transmitters on salivary cells; the roles of non-conventional transmitters in the glands; the effects of denervations on the glands, on their capacity to synthesize and secrete proteins, and the development of supersensitivities to transmitter substances. Further chapters prescribe the inter-relationship between taste and saliva formation, and the reflexes involved in salivary secretion. The book lays a sound platform of knowledge to all with an interest in and around the mouth including dentists, pharmacologists, biochemists and cell biologists as well as neurobiologists working on autonomic nerve activities.

In parasympathetic saliva from rat submandibular glands the relative proportions of the various tissue kallikreins differ from those in sympathetic saliva. Kallikreins in sympathetic saliva arise from exocytosis of prepackaged granules in granular tubules, so the kallikreins in parasympathetic saliva must come from a non-granular pool, and are likely to be secreted through a constitutive vesicular route. During periods devoid of stimulation in anaesthetised rats, the kallikreins have been found to accumulate progressively in glandular lumina in parasympathetic-like proportions. As this transport of kallikrein into lumina occurs continuously in vivo, independently of any stimulation or any secretion of fluid, it must arise by constitutive vesicular secretion. During parasympathetic stimulation, the kallikreins are secreted into the saliva at a greater rate than in the resting state but their proportions remain the same and the means by which this increase occurs is open to debate. Constitutively secreted true tissue kallikrein (rK1) has been found to have a different molecular form from that in secretory granules. The submandibular glands also contribute to the kallikreins normally circulating in the blood. Serum levels of kallikrein increased equally during either parasympathetic or sympathetic stimulation and were independent of the amounts secreted into the saliva, so are likely to have arisen from constitutive secretion via the basal sides of the cells, morphological evidence for which has been found in the mouse (PenschowCoghlan, 1993).

Blood flow in salivary glands is regulated mainly by sympathetic and parasympathetic nerve activity. This study was carried out to determine the relative contributions of cholinergic, adrenergic and peptidergic neurotransmitters to the control of submandibular blood flow in the rat using laser-Doppler flowmetry. Parasympathetic impulses caused a rapid atropine-sensitive vasodilation followed by a maintained increase in blood flow, a portion of which remained in the presence of both atropine and L-NAME. In contrast, continuous sympathetic stimulation caused an intense vasoconstriction that was followed by a prolonged after-vasodilation. The same number of impulses delivered in bursts resulted in a cyclic vasoconstriction followed by a rapid vasodilation. Alpha-adrenoceptor blockade largely abolished the vasoconstriction, and the duration and magnitude of the after-vasodilation were reduced. Inhibition of nitric oxide (NO) synthase by L-NAME reduced the vasodilation. The addition of a beta-adrenoceptor antagonist eliminated the sympathetic vasodilator response, but in the presence of complete alpha- and beta-adrenoceptor blockade and L-NAME a small vasoconstriction remained. We conclude that the vasoconstrictor effects of sympathetic stimulation of the rat submandibular gland are due to alpha-adrenergic receptor activation and probably also NPY, and the vasodilator effects are due to NO and beta-adrenergic activity. Parasympathetic vasodilation was due to NO-independent mechanisms mediated by acetylcholine and substance P, and NO-dependent mechanisms mediated by VIP.

Historical introduction to salivary secretion microstructure of mammalian salivary glands and its relationship to diet electrophysiological correlates of fluid secretion by salivary acini secretion of electrolytes and water by salivary glands secretory protein synthesis and constitutive (vesicular) secretion by salivary glands the dynamics of exocytosis of performed secretory granules from acini in rat salivary glands autonomic control of salivary blood flow capillary dynamics in salivary glands myoepithial activity in salivary glands movements of organic molecules from blood to saliva and from glands to blood synthesis and secretion of human salivary immunoglobulins hormonal regulation of salivary glands, with particular reference to experimental diabetes.

Sequential secretory changes in granular tubule cells caused by the secretagogue cyclocytidine (75 mg/kg i.p.) were studied at the ultrastructural level, in perfusion (n = 5 animals) and immersion (n = 8 animals) fixed rat submandibular glands, using the periodic acid-thiocarbohydrazide-silver proteinate technique (PA-TCH-SP). The onset of secretion varied from 45 to 75 minutes after administering the cyclocytidine. During the initial stages of overt secretion, structural changes occurred irregularly in a progressive fashion with: (1) an increase in granule membrane staining with PA-TCH-SP and a parallel alignment of the secretory granules with the adjacent apical plasma membrane, which developed a honeycomb-like appearance; (2) docking of these secretory granules to the apical plasma membrane; (3) early secretion of some secretory granules in a semiclassical exocytotic fashion (but this was rarely witnessed). During stages (1) and (2), the cytochemical characteristics of the membrane of the secretory granules, as well as of the plasma membrane, suggest a priming process is occurring. After these initial preparatory phases, further structural changes occurred in the granule membranes with a gradually progressive formation of microvesicles and granule fusions; secretion continued in an explosive manner with proteinaceous material being transferred to lumina in at least three different ways: (1) by typical exocytosis (but it was infrequent); (2) from granules fused intracellularly into aggregates (compound exocytosis); and (3) some apocrine-type of secretion through bleb formation. The formation of these intracellular aggregations was associated with the microvesicles in the granule membranes and some aggregates became very large. Secretion of their contents into lumina occurred through elongated membrane channels. The material secreted included microvesicular forms that had become interiorised in the granular aggregates, and any cytoplasm that may also have been entrapped.

At least fourteen separate bands of proteinase activity, labelled A-N, were identified by an enzyme overlay membrane technique, using oligopeptide-7-amino-4-trifluoromethylcoumarin (AFC) substrates in rat submandibular gland extracts fractionated on pH 4-6.5 isoelectric focusing gels. The proteinases were eluted into an ammonium bicarbonate buffer pH 9.8 containing 0.1% Triton X-100 and the relative contribution of each band to total activity evaluated using D-Val-Leu-Arg-AFC (DVLR-AFC) and Z-Val-Lys-Lys-Arg-AFC (ZVKKR-AFC) as substrates. Immunoblotting of band eluants run on sodium dodecyl sulphate gels with antibodies showed that band A was identical with tonin and bands K-N contained tissue kallikrein. Tonin was found to hydrolyse ZVKKR-AFC but not DVLR-AFC. Estimates of the Km values of tissue kallikrein for DVLR-AFC and tonin for ZVKKR-AFC were found to be similar (approx. 20 microM) yet the former enzyme hydrolysed its substrate five times faster. Tonin was inhibited by soybean trypsin inhibitor (SBTI) but not by aprotinin. Tissue kallikrein, on the other hand, was inhibited by aprotinin but was considerably more resistant to inhibition by SBTI. In tissue extracts 95% of the ZVKKR-AFC lytic activity in the presence of 1 microM aprotinin is due to tonin and a similar percentage of the DVLR-AFC hydrolysing activity in the presence of 10 microM SBTI is due to tissue kallikrein. These findings were used for the specific measurement of these two proteinases in submandibular gland extracts and in saliva without prior purification. Using these inhibitor based assays we revealed qualitative differences in the composition of proteinases secreted into saliva during parasympathetic versus sympathetic stimulation of the submandibular gland. The distribution of proteinases in sympathetic saliva is very similar to that found in submandibular extracts but on parasympathetic stimulation, although much less proteinase is released, the contributions of the more acidic isomers of tissue kallikrein are increased and that of tonin and other proteinases dramatically decreased. The data suggest that parasympathetic and sympathetic nerves induce proteinase secretion via different pathways.

Homogenates of rat submandibular glands were electrophoresed on isoelectric focussing gels and bands of proteinase activity demonstrated by means of overlay membranes impregnated with fluorogenic oligopeptide substrates. Inhibition characteristics of individual proteinase bands were tested within the gels and after excision and subsequent elution from the gels. Some bands of activity were resistant to inhibition by pre-incubation of the gel with certain inhibitors, but were subsequently found to be inhibited when tested with the same substrate after elution. These inconsistencies were influenced by the use of different substrates. The results indicate that, though some useful screening information may be obtained by applying inhibitors to the gels, this system does not permit a reliable assessment of inhibition characteristics which require subsequent elution and assay.

Stimulation of the nerves to the rat parotid gland demonstrated that increases in serum amylase levels can originate exclusively from this gland. However, whilst parasympathetic nerve stimulation caused a significant movement of parotid amylase into the blood, sympathetic nerve stimulation did not, despite the higher concentration of amylase in the saliva evoked. Experiments in which conscious animals were fed for a short period showed that parotid amylase reaches the blood during normal activity. The mechanisms underlying the movement of parotid amylase into the circulation are still unknown but there appears to be some dependence on the volume of saliva being produced.

The protein constituents in parasympathetically evoked saliva from normal and short-term sympathectomized parotid glands were compared. There was a reduction in all proline-rich proteins (PRP) in the saliva following sympathectomy. The decrease was quantified for acidic PRP by high-performance ion-exchange chromatography, which showed an increase in the ratio of amylase to other proteins. These results suggest that sympathetic impulses influence the synthesis of PRP and amylase in opposite directions.

Forty-two submandibular, 32 sublingual and 31 parotid glands have been examined microscopically after ductal ligation avoiding the nerves for periods from 1 day to 1 yr. After an initial increase in size, there was over-all atrophy in all three glands. In the parotid gland the response was uniform and there was progressive atrophy until most of the acini were extremely atrophic. However, in the submandibular and sublingual glands the response was very variable, and although in some glands most of the acini were extremely atrophic, in other glands there was far less atrophy and most of the remaining acini appeared more or less similar to normal despite prolonged ligation. These results contrast with those of earlier experimental studies on ductal ligation, but have similarities with observations on the behaviour of human salivary glands.

1. The effects of continuous stimulation of the peripheral end of the ascending cervical sympathetic nerve were compared with those of intermittent stimulation, so arranged as to deliver the same total number of impulses, in cats under chloralose anaesthesia. 2. Continuous stimulation caused a flow of saliva at 5-10 Hz, but not at 2 Hz. In contrast, the same total number of impulses delivered intermittently in bursts elicited a prompt secretion at a frequency as low as 20 Hz for 1 s at 10 s intervals (corresponding to 2 Hz continuously) and a significantly higher rate of secretion at 50 Hz in bursts than that obtained in response to 5 Hz continuously. 3. Continuous stimulation also caused a rise in submandibular vascular resistance (s.v.r.), which persisted throughout the period of stimulation, and was followed immediately thereafter by an intense but transient fall in s.v.r. During stimulation in 1 s bursts, each burst was followed first by a brief rise in s.v.r. and shortly after by a fall. The balance between these two components varied widely between individual animals but often led to an overall fall in s.v.r. during stimulation i.e. complete reversal of the mean vascular effect. A further fall in s.v.r. was then recorded when the stimulus was discontinued. 4. Propranolol (1.0 mg/kg) reduced but failed to abolish the secretory response. It also altered the balance between the two phases of the vascular response slightly in favour of a rise in s.v.r. during stimulation, without apparently affecting the size of the after-dilatation. 5. Pre-treatment with dihydroergotamine (1.0 mg/kg) invariably blocked secretion and revealed a small vasodilator response during sympathetic stimulation with either pattern of stimulation; it also blocked the after-dilatation. 6. Following combined pre-treatment with propranolol and dihydroergotamine, to produce total adrenergic blockade, there was a small residual vasoconstrictor component which amounted to an increase in mean s.v.r. of about 20% during stimulation at 10 Hz continuously. This may have been due to release of neuropeptide Y (NPY). 7. Small but significantly greater amounts of NPY were released into the effluent blood during stimulation of the ascending cervical sympathetic nerve at 70 Hz in bursts than during continuous stimulation. No significant release of vasoactive intestinal peptide (VIP), somatostatin, bombesin, substance P or calcitonin gene-related peptide (CGRP) was observed during stimulation at any frequency.(ABSTRACT TRUNCATED AT 400 WORDS)

Implantation of amalgam induced a cellular reaction, and a rapid loss of copper and zinc and a more gradual loss of tin and mercury occurred. The silver remaining was generally associated with sulphur and was present either as a diffuse fuzz around remaining masses or in a finely particulate form.

1. Smooth muscle activities in rectum and internal anal sphincter have been recorded using intraluminal balloons. 2. Reflex activation of the sphincter, caused by distension of the rectum, has been assessed before and after various combinations of blocking drugs. 3. Responses to stimulation of hypogastric or sacral nerves, or to the administration of drugs with autonomic actions have been tested before and after various combinations of blocking drugs. 4. Results indicate that the tone of the internal anal sphincter is influenced by a number of neural mechanisms. These include motor pathways involving both α-adrenergic and cholinergic mechanisms and inhibitory pathways involving both β-adrenergic and non-adrenergic non-cholinergic mechanisms. 5. Cholinergic contractions of the sphincter were converted to relaxations after α-adrenergic blockade. This indicates that the contractions are an indirect effect operating through an adrenergic reflex. Cholinergic relaxations may also be indirect and operate through reflex inhibition secondary to rectal contractions. 6. Sphincteric motor activity is controlled largely through α-adrenergic mechanisms by adrenergic nerves acting directly on the muscle. β-Adrenergic inhibitory mechanisms are thought to operate indirectly via ganglia. 7. The over-all control of the sphincter is by complex reflex mechanisms involving numerous pathways and the activity of the sphincter at any one time is determined by the net balance between motor and inhibitory influences. 8. Sacral nerve stimulation indicated that it contains cholinergic nerves to the rectum, non-adrenergic non-cholinergic inhibitory axons to the sphincter and variable numbers of adrenergic axons to the sphincter. 9. Responses of the sphincter to drugs and nerve stimulation were often variable, as has been described many times in the literature. It is considered that this is due to complex combinations of indirect reflex effects, secondary to activation of structures outside the sphincter, operating with or against direct effects on the sphincter itself.

Inflammatory cells were studied in submandibular, sublingual and parotid glands of cat following ductal ligation. Macrophages were seen within the parenchyma and associated with extravasated mucin, and were possibly of importance in removing secretory material. Neutrophils were seen interstitially and within the parenchyma. Eosinophils were involved in an initial inflammatory response in interstitial tissue. Fibrous connective tissue was more apparent.

Proteases present in mast cell granules have been harnessed to demonstrate mast cells in human tissues. A number of substrate mixtures were tested. D-Val-Leu-Arg-4-methoxy-2-naphthylamide (MNA) plus Fast Blue B was the best for identifying human mast cells, yielding the most specific and complete staining. The procedure is simple and the results are permanent. Cryostat sections of aldehyde-fixed routine preparations or paraffin sections of Carnoy-fixed tissues give the most satisfactory results. Mast cells are stained a strong red color that stands out distinctly from the surrounding tissues, so that they can be easily identified by simple microscopy. A double-staining technique, first for protease and subsequently using Alcian Blue, showed that as progressive protease staining occurs, the alcianophilia of mast cells is lost. This procedure demonstrated that mast cells in the mucosa of human gut generally required longer incubations to develop protease staining than in other connective tissue sites. In post-mortem tissues, mast cells retain their protease activity well and so can be demonstrated in cryostat sections of aldehyde-fixed material, giving a more complete picture than with Alcian Blue. The synthetic substrate D-Val-Leu-Arg-MNA can be recommended for routine identification of mast cells in human tissues.

Continuous sympathetic stimulation at 8-10 Hz caused intense vasoconstriction in the gland, so stimulation was generally given in an interrupted pattern to minimize this detrimental effect on secretion. Only a small increase in fluid secretion occurred; it became thick and tended to block the cannula; therefore in later experiments the main duct was not cannulated. After sympathetic stimulation there was substantial degranulation of acinar cells. However, as this was accompanied by little movement of water, the secreted mucosubstance distended the ductal lumina. The granular tubule cells were unchanged by sympathetic stimulation. Use of selective blocking agents revealed that the sympathetically-evoked secretion of acinar mucin was mediated mainly via beta-adrenoreceptor activation. As stimulation of the sympathetic nerves alone caused little additional formation of fluid, the effects of superimposing continuous low frequency sympathetic stimulation onto a background of low parasympathetic secretion were compared with similar parasympathetic stimulation alone of the contralateral gland. These double nerve stimulations did not augment the volume of fluid secreted, or cause morphological changes additional to those from parasympathetic stimulation alone. Nevertheless, it is likely that, under natural reflex conditions, sympathetic impulses can increase the amount of acinar mucosubstance secreted.

Does the harbour of an artificial island need a bottom? The excitation of waves inside a partially immersed open circular cylinder is considered. An incident plane wave is expanded in Bessel functions and for each mode the problem is formulated in terms of the radial displacement on the cylindrical interface below the cylinder. The solution is obtainable either from an infinite set of simultaneous equations or from an integral equation. It is shown that the phase of the solution is independent of depth and resonances are found at wave-numbers close to those of free oscillations in a cylinder extending to the bottom. If the resonances of the cylinder are made sharper (by increasing the depth of immersion) the peak response of the harbour increases, but the response to a continuous spectrum remains approximately constant. Numerical results are obtained by minimizing the least squares error of a finite numberNof simultaneous equations. Convergence is slow, but the error is roughly proportional to 1/Nand this is exploited. The solution obtained from a variational formulation using the incoming wave as a trial function is found to give a very good approximation for small wave-numbers, but is increasingly inaccurate for large wave-numbers. Away from resonance the amplitude of the harbour oscillation is less than 10% of the amplitude of the incoming wave provided the depth of the cylinder is greater than about ¼ wavelength, and it is argued that in practice at the resonant wave-number oscillations excited through the bottom of the harbour will leak out through the entrance before they can reach large amplitudes. In an appendix the excitation of harbour oscillations through the harbour entrance is discussed, and some results of Miles & Munk (1961) on an alleged harbour paradox are re-interpreted.

Editors' Note: The above article is a re-joinder to “How to Sacrifice Academic Quality,” which appeared in the Spring 1979 issue of Improving College and University Teaching. The editors welcome thoughtful responses to any article appearing in the journal.