唾液的增加加速了含羧甲基壳聚糖口香糖的抗菌效果

目的:本论文采用了含羧甲基壳聚糖的口香糖,咀嚼这种口香糖的机械效果加速了其对口腔细菌的抑制作用,还比较口腔嗽洗液和咀嚼口香糖的抗菌效果,证明了通过咀嚼这种口香糖加速了唾液的分泌.方法:从青岛大学口腔科的老师和学生中选取了12名健康的受试者.在测试前取受试者的唾液测试细菌含量.在测试口香糖的试验中,受试者咀嚼5分钟口香糖然后休息5分钟.在测试口腔嗽洗液时,受试者用10ml嗽洗液漱口30秒后,休息9分30秒.同一天中这些测试步骤在50分钟内连续不断的进行了5次.5次测试后分别在0、30和60min收集被试者的唾液测试细菌含量.在测试唾液分泌的试验中,受试者每天咀嚼三次口香糖持续两天.结果:与使用口腔嗽洗液相比,咀嚼含羧甲基壳聚糖口香糖的受试者,在三个取样时间内口腔细菌的含量基本都明显减少,但是在60分钟的取样时间结果有点差异.咀嚼含羧甲基壳聚糖的口香糖明显提高了唾液的分泌量.结论:咀嚼含羧甲基壳聚糖的口香糖具有明显的抗菌效果.目前的研究结果强有力的证明了:使用像壳聚糖以及其衍生物这样的天然物质,对我们的口腔健康以及生活质量都有很大的帮助.     

Sorbitol Gum in Xerostomics: The Effects on Dental Plaque pH and Salivary Flow Rates1

Adequate salivary flow is important for patient comfort and maintenance of oral health. Xerostomia, or dry mouth, is a common clinical complaint. Masticatory and gustatory activity can stimulate salivary flow from functional salivary tissue and the use of sugarless mints and gums have been recommended to individuals who complain of xerostomia, but there are minimum clinical data. A clinical study assessing the effect on salivary flow rates and dental plaque pH of a sorbitol-sweetened chewing gum in subjects with the complaint of xerostomia was conducted. The chewing of the gum in this present study stimulated salivary flow in the subjects with xerostomia. Statistically significant stimulated whole mouth and parotid salivary flow rate increases were found when compared to unstimulated whole mouth and parotid salivary flow rates. Chewing of the sorbitol-sweetened gum also effectively reduced the drop in pH seen following the exposure to a fermentable carbohydrate. The findings of this present study indicate that chewing of a sorbitol-sweetened gum may be of benefit to patients with the complaint of xerostomia.     

A comparative study of salivary secretion by parotid and mandibular glands of anaesthetized Capra hircus: effect of pilocarpine

A study was made of basal secretion and the effect of the infusion of pilocarpine on the flow and composition of saliva in the parotid and mandibular glands of the anaesthetized lactating goat. In the parotid gland there was a basal flow (1.6 +/- 0.29 microliter/min) which was not present in the mandibular gland. There is a statistically significant dose-effect relationship between pilocarpine and salivary flow in both glands. Salival composition and its variation with respect to the flow of saliva did not conform to either of the two glands to an exclusive monogastric or ruminant model.     

Chewing disability in older adults attributable to tooth loss and other oral conditions

doi: 10.1111/j.1741‐2358.2010.00412.x Chewing disability in older adults attributable to tooth loss and other oral conditions Background: This study evaluates associations between oral health‐related factors and chewing ability, and quantifies the risk contributed by each factor. Materials and methods: Chewing ability and information on number of teeth, dentures and dental problems over the last 12 months were collected by mailing questionnaires to a random sample of 60‐ to 71‐year‐olds from Adelaide, South Australia. Logistic regression was used to model oral status and oral symptoms as predictors of chewing disability, and to estimate the population‐attributable fraction. Results: A total of 444 persons responded (response rate = 68.8%). Among dentate subjects, 10.3% were chewing‐deficient, with chewing disability more prevalent (p < 0.05) among those with <21 teeth (26.4%), dentures (20.4%), painful aching in the mouth (25.4%), pain in the face (16.7%), broken/chipped teeth (15.6%), sensitive teeth (14.1%), loose teeth (37.1%), and sore gums (18.0%). Adjusted Odds ratios (OR) showed inadequate dentition (OR = 4.20), painful aching in the mouth (OR = 4.88), and presence of loose teeth (OR = 4.70) were associated with chewing disability (p < 0.01), and their population attributable fractions were 18.5%, 15.1% and 7.8% respectively. Conclusions: Loose teeth, number of teeth and pain in the mouth were associated with chewing disability, with an inadequate dentition and pain in the mouth contributing most to chewing disability in this population.     

Oral health-related quality of life--associations with oral health and conditions in Swedish 70-year-old individuals

doi: 10.1111/j.1741‐2358.2011.00495.x Oral health–related quality of life – associations with oral health and conditions in Swedish 70‐year‐old individuals Objective: The aim of this study was to evaluate oral health–related quality of life (OHRQoL) in relation to different chronic oral conditions and perception of oral health among elderly individuals. Background: Health‐related quality of life is important to assess and understand the impact of different diseases and conditions on individuals’ well‐being. Material and methods: Randomly selected 70‐year‐old individuals (N = 561) were included in this analysis. They were clinically examined and answered a questionnaire. Variables used were perceived oral health, satisfaction with appearance of teeth, problems with chewing and dry mouth, burning mouth syndrome, dental anxiety and dental visiting habits. To measure the participants′ perception of the impact of oral conditions on their well‐being, the Oral Health Impact Profile (OHIP‐14) was used. Results: The OHIP‐14 distribution of sum of scores showed a floor effect but revealed acceptable psychometric properties with regard to reliability and validity. Multivariable logistic regression revealed three highly predictive variables for individuals with high OHIP‐14 scores: using dentures, having chewing problems and being dissatisfied with appearance of teeth. Conclusion: Use of dentures, having chewing problems and being dissatisfied with appearance of teeth are associated with high OHIP‐14 sums, indicating strong influence on OHRQoL.     

Effect of certain organic compounds on saliva secretion in sheep.

In two sheep fitted with esophageal cannulas the stimulation of resting saliva secretion by intrabuccal injections of volatile fatty acids (VFA) and of certain organic plant compounds was investigated. Volatile fatty acids, salicin and vanillin increased saliva flow rate by 100, 76 and 72% over 2.5 min after injection. Minor positive or negative effects were obtained with quercitrin, protocatechuic acid, grass juice, anethole and agaricinic acid. Injections of volatile fatty acids and of salicin induced chewing activities, which were significantly correlated with salivary flow rates. The results indicate that organic plant compounds can provide a stimulus for saliva secretion mediated in part by chewing activities.     

Functional relationship between subfornical organ cholinergic stimulation and nitrergic activation influencing cardiovascular and body fluid homeostasis

We have studied the effects of L-NG-nitro arginine methyl esther (L-NAME), L-arginine (LAR), inhibitor and a donating nitric oxide agent on the alterations of salivary flow, water intake, arterial blood pressure (MAP) and heart rate (HR) induced by the injection pilocarpine into the subfornical organ (SFO). Rats (Holtzman 250-300 g) were anesthetized with 2, 2, 2-tribromoethanol (20 mg/100 kg b. wt.) and a stainless steel cannula were implanted into their SFO. The volume of injection was 0.2 microl. The amount of saliva secretion was studied over a 5-min period. Pilocarpine (40 microg), L-NAME (40 microg) and LAR (30 microg) were used in all experiments for the injection into the SFO. Pilocarpine (10, 20, 40, 80 and 160 microg) injected into SFO elicited a concentration-dependent increase in salivary secretion. L-NAME injected prior to pilocarpine into the SFO increased salivary secretion and water intake due to the effect of pilocarpine. LAR injected prior to pilocarpine into the SFO attenuated the salivary secretion and water intake. Pilocarpine, injected into the SFO increased the MAP and decreased heart rate (HR). L-NAME injected prior to pilocarpine into the SFO potentiated the pressor effect of pilocarpine with a decrease in HR. LAR injected into the SFO prior to pilocarpine attenuated the increase in MAP with no changes in HR. The present study suggests that the SFO nitrergic cells interfere in the cholinergic pathways implicated in the control of salivary secretion, fluid and cardiovascular homeostasis.     

Xerostomia in the Elderly: Prevalence,Diagnosis, Complications and Treatment1

The prevalence of xerostomia was evaluated in 259 volunteers 70 ± 4.5 years old. Seventy–two (27.7%) complained of dry mouth. In 31 (11.8%) salivary secretion was under 0.1 ml/min. The xerostomic patients were compared to an age–matched control group. The main complaints of xerostomia were dry mouth during the day, dry throat, burning sensation of the tongue, difficulty in swallowing, and taste disturbances. Systemic diseases frequent in the xerostomic patients were heart failure and hypertension. Chronic renal failure, depression, rheumatoid arthritis, and hypothyroidism were also encountered. The medications most frequently used by the xerostomic patients were parasympatholytics, sympatholytics, and diuretics. A higher frequency of active caries, gingivitis, and dryness of the mucosa was detected in the xerostomic patients. A significantly higher response to stimulation, elevated salivary calcium, and lowered oral pH were found in this group. Xerostomia was found to be related o t systemic diseases, medications, or a combination of these factors. The importance of saliva for maintaining oral health was also observed. Twenty–nine patients suffering from xerostomia were treated with an artificial saliva. On reexamination after one month, most of them reported improvement, and a significant increase in salivary flow rate was found.     

Nitric oxide of the supraoptic nucleus influences the salivary secretion, sodium renal excretion, urinary volume and arterial blood pressure induced by pilocarpine

Male Holtzman rats weighting 200-250 g were anesthetized with zoletil 50 mg/Kg (tiletamine chloridrate 125.0 mg and zolazepan chloridrate 125.0 mg) into quadriceps muscle and stainless steel cannulas were implanted into their supraoptic nucleus (SON). We investigated the effects of the injection into the supraoptic nucleus (SON) of FK 409, a nitric oxide donor, and NW-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor (NOS), on the salivary secretion, arterial blood pressure, sodium excretion and urinary volume induced by pilocarpine, which was injected into SON. The drugs were injected in 0.5 microl volume over 30-60 s. Controls was injected with a similar volume of 0.15 M NaCl. FK 409 and L-NAME were injected at doses of 20 microg/0.5 microl and 40 microg/0.5 microl respectively. The amount of saliva secretion was studied over a five-minute period after injection of pilocarpine into SON. Injection of pilocarpine (10, 20, 40, 80, 160 microg/microl) into SON produced a dose-dependent increase in salivary secretion. L-NAME was injected into SON prior to the injection of pilocarpine into SON, producing an increase in salivary secretion due to the effect of pilocarpine. FK 409 injected into SON attenuating the increase in salivary secretion induced by pilocarpine. Mean arterial pressure (MAP) increase after injections of pilocarpine into the SON. L-NAME injected into the SON prior to injection of pilocarpine into SON increased the MAP. FK 409 injected into the SON prior to pilocarpine attenuated the effect of pilocarpine on MAP. Pilocarpine (0.5 micromol/0.5 microl) injected into the SON induced an increase in sodium and urinary excretion. L-NAME injected prior to pilocarpine into the SON increased the urinary sodium excretion and urinary volume induced by pilocarpine. FK 409 injected prior to pilocarpine into the SON decreased the sodium excretion and urinary volume induced by pilocarpine. All these roles of pilocarpine depend on the release of nitric oxide into the SON. In summary the present results show: a) SON is involved in pilocarpine-induced salivation; b) that mechanism involves increase in MAP, sodium excretion and urinary volume.     

Beta-Adrenergic Stimulation of Transmembrane Potential and Short Circuit Current of Isolated Rabbit Oviduct

THE secretions of the mammalian oviduct provide the immediate environment for fertilization and the first 3–4 days of embryonic development. While the importance of oestrogen and progesterone in modifying oviductal secretions is well established, there have been few investigations of the influence of autonomic drugs. Bishop¹ showed that pilocarpine, a parasympathomimetic agent, stimulated the rate of oviductal fluid secretion in anaesthetized rabbits, but others², using unanaesthetized rabbits, found that pilocarpine, scopolamine (a parasympathetic blocking agent) and phenoxybenzamine (an alpha-adrenergic . blocking agent) had no such effect.     

HMG-CoA reductase inhibitor decreases small dense low-density lipoprotein and remnant-like particle cholesterol in patients with type-2 diabetes

Our studies have focused on the effect of injection of L-NAME and sodium nitroprussiate (SNP) on the salivary secretion, arterial blood pressure, sodium excretion and urinary volume induced by pilocarpine which was injected into the medial septal area (MSA). Rats were anesthetized with urethane (1.25 g/kg b. wt.) and a stainless steel cannula was implanted into their MSA. The amount of saliva secretion was studied over a five-minute period after injection of pilocarpine into MSA. Injection of pilocarpine (10, 20, 40, 80, 160 microg/microl) into MSA produced a dose-dependent increase in salivary secretion. L-NG-nitro arginine methyl-esther (L-NAME) (40 microg/microl), a nitric oxide (NO) synthase inhibitor, was injected into MSA prior to the injection of pilocarpine into MSA, producing an increase in salivary secretion due to the effect of pilocarpine. Sodium nitroprussiate (SNP) (30 microg/microl) was injected into MSA prior to the injection of pilocarpine into MSA attenuating the increase in salivary secretion induced by pilocarpine. Medial arterial pressure (MAP) increase after injections of pilocarpine into the MSA. L-NAME injected into the MSA prior to injection of pilocarpine into MSA increased the MAP. SNP injected into the MSA prior to pilocarpine attenuated the effect of pilocarpine on MAP. Pilocarpine (40 ug/ul) injected into the MAS induced an increase in sodium and urinary excretion. L-NAME injected prior to pilocarpine into the MSA increased the urinary sodium excretion and urinary volume induced by pilocarpine. SNP injected prior to pilocarpine into the MSA decreased the sodium excretion and urinary volume induced by pilocarpine. All these roles of pilocarpine depend on the release of nitric oxide into the MSA. We may also conclude that the MSA is involved with the cholinergic excitatory mechanism that induce salivary secretion, increase in MAP and increase in sodium excretion and urinary volume.     

Salivary tests associated with elderly people’s oral health

doi: 10.1111/j.1741‐2358.2012.00627.x Salivary tests associated with elderly people’s oral health Introduction: The saliva constitutes essential condition for the individual’s health. Aim: Identify the relation of the salivary flow and saliva pH with medicine use and oral discomfort in elderly. Methods and materials: Cross‐sectional study with 68 elderly living in a long staying institution. Salivary tests were performed based on Bo Krasse’s methodology. For pH, the Universalindikator – Merck tape was used. A questionnaire was applied, organising data through Software SPSS version 17. Pearson’s qui‐square distribution, Fisher’s exact test and t‐test for paired data were used, with significance level of 5% and confidence interval of 95%. Results: Among the 68 elderly (average of 70.4 years, SD ± 7.27), 80% showed normal pH. The rate of salivary flow was as follows: very low, 32.3%; lowered, 41.2%; and normal, 25.5%; 30.9% reported dry mouth; 22.1% problems with taste; 17.6%, dysphagia; and 14.7%, burning mouth. 76.5% used medicines. There was statistical significance between medicine use and dry mouth (p = 0.015). They showed an association between salivary flow and medicine use (p = 0.048), feels dry mouth (0.018) and difficulty to swallow (p = 0.046), and saliva pH without stimulation and feels dry mouth (p = 0.003), difficulty to swallow (p = 0.006) and burning mouth sensation (p = 0.014). Conclusion: Low salivary flow and saliva pH interfere on elderly people’s health and medicine use influences on results.     

Calcium signaling defects underlying salivary gland dysfunction

Salivary glands secrete saliva, a mixture of proteins and fluids, which plays an extremely important role in the maintenance of oral health. Loss of salivary secretion causes a dry mouth condition, xerostomia, which has numerous deleterious consequences including opportunistic infections within the oral cavity, difficulties in eating and swallowing food, and problems with speech. Saliva secretion is regulated by stimulation of specific signaling mechanisms within the acinar cells of the gland. Neurotransmitter-stimulated increase in cytosolic [Ca²⁺] ([Ca²⁺]_i) in acinar cells is the primary trigger for salivary fluid secretion from salivary glands, the loss of which is a critical factor underlying dry mouth conditions in patients. The increase in [Ca²⁺]_i regulates multiple ion channel and transport activities that together generate the osmotic gradient which drives fluid secretion across the apical membrane. Ca²⁺ entry mediated by the Store-Operated Ca²⁺ Entry (SOCE) mechanism provides the essential [Ca²⁺]_i signals to trigger salivary gland fluid secretion. Under physiological conditions depletion of ER-Ca²⁺ stores is caused by activation of IP3R by IP3 and this provides the stimulus for SOCE. Core components of SOCE in salivary gland acinar cells are the plasma membrane Ca²⁺ channels, Orai1 and TRPC1, and STIM1, a Ca²⁺-sensor protein in the ER, which regulates both channels. In addition, STIM2 likely enhances the sensitivity of cells to ER-Ca²⁺ depletion thereby tuning the cellular response to agonist stimulation. Two major, clinically relevant, conditions which cause irreversible salivary gland dysfunction are radiation treatment for head-and-neck cancers and the autoimmune exocrinopathy, Sjögren's syndrome (pSS). However, the exact mechanism(s) that causes the loss of fluid secretion, in either condition, is not clearly understood. A number of recent studies have identified that defects in critical Ca²⁺ signaling mechanisms underlie salivary gland dysfunction caused by radiation treatment or Sjögren's syndrome (pSS). This chapter will discuss these very interesting and important studies.     

Salivary flow rate and risk of malnutrition – a study among dentate,community‐dwelling older people

doi: 10.1111/j.1741‐2358.2012.00679.x Salivary flow rate and risk of malnutrition – a study among dentate, community‐dwelling older people Objective: To analyse the relation between unstimulated and stimulated salivary secretion and the risk of malnutrition among home‐dwelling elderly people. Background: Saliva has an important role in eating. Despite this, there are only a few studies on the role of salivary secretion in the development of malnutrition among elderly people. Materials and methods: The study population consisted of 157 subjects aged 75 or older. This was a part of GeMS study carried out in Kuopio, in eastern Finland. The data used in this study were collected by means of interviews and geriatric and oral clinical examinations. The risk of malnutrition was measured using the Mini Nutritional Assessment Short‐Form. Logistic regression models were used to estimate odds ratios (OR) and their 95% Confidence Intervals (CI). Results: Subjects with a low unstimulated salivary flow rate (<0.1 ml/min) or stimulated salivary flow rate (<1.0 ml/min) had no statistically significant increase in risk of malnutrition, OR: 1.3, CI: 0.5–3.9, OR: 1.5, CI: 0.5–4.2, respectively, when compared with those with a normal unstimulated and stimulated salivary flow rate. Conclusion: Our results do not support the concept that low salivary secretion is an important risk factor for malnutrition among community‐dwelling elders.     

Correlation of serum oestrogen with salivary calcium in post-menopausal women with and without oral dryness feeling

doi: 10.1111/j.1741‐2358.2011.00580.x
Correlation of serum oestrogen with salivary calcium in post‐menopausal women with and without oral dryness feeling Objective: The aim of this study was to verify the association between salivary calcium and serum oestrogen levels with oral dryness in post‐menopausal women. Also, the correlation between these variables was evaluated. Methods: A case‐control study was carried out on 60 selected menopausal women with and without oral dryness feeling (30 as case and 30 as control) conducted in the Department of Oral Medicine and Radiology, Maharishi Markandeshar University, Mullana, India. Paraffin‐stimulated saliva samples were obtained by expectoration. Salivary calcium concentrations were assessed colorimetrically using Arsenazo III reaction. The serum oestrogen concentration was measured using ELISA. Statistical analysis of Student’s t‐test and Pearson correlation was used. Results: There was significant difference in mean values of both salivary calcium concentration and serum oestrogen between case and control groups. The result obtained also showed that an inverse correlation was found between salivary calcium concentration and serum oestrogen levels in both the groups and in total sample size. Conclusion: Oral dryness in post‐menopausal women is associated with high levels of salivary calcium and low levels of serum oestrogen. The concentrations of salivary calcium and serum oestrogen are inversely correlated in post‐menopausal women, regardless of the presence or absence of oral dryness.     

Factors affecting photosynthesis and its seasonal variation in the seagrasses Cymodocea nodosa (Ucria) Aschers,and Posidonia oceanica (L.) Delile in the mediterranean

Measurements of photosynthesis, dark respiration, and leaf chlorophyll content were made in the laboratory on both shallow (1 to 5 m) and deep (25 to 33 m) leaves of Cymooceu nodosa (Ucria) Aschers, and Posidonia oceanica (L.) Delile in Malta in April and August. Light saturated photosynthetic rates in Cymodocea were similar in spring (18 μg C cm^?2h^?1) and summer (25μg Ccm^?2h^?1) if the 9 C increase in water temperature in summer is taken into account: however, photosynthetic rates in Posidonia were higher in spring than in summer, especially in shallow leaves which fixed ≈ 10 μg C cm^?2h^?1 in spring but less than half that in summer when rates of carbon accretion were close to compensation point. Levels of irradiance at which photosynthesis was light saturated (Iλ were ≈ 3 mW cm^?2 PAR for Cymodocea and 2 mW cm^?2 PAR for Posidonia: underwater irradiance at the lower depth limit for these plants (≈33 m) was ≈3 mW cm^?2 PAR. corresponding closely to the saturation irradiances. Compensation irradiance for both species was between 0.3 and 0.5 mW cm^?2 PAR.Photosynthesis in both species had a temperature optimum at about 30 C (slightly higher in Cymodocea in summer). Dark respiration rates were generally similar in spring and summer, in the region of 3 μg C cm^?2 h^?1 in Cymodocea and 1.5 to 2 μg C cm^?2 h^?1 in Posidonia. Increase in dark respiration rates with increased temperature was considerably greater in spring than in summer in both species. Photosynthesis was directly proportional to chlorophyll content in Posidonia in the range encountered (up to 58 μg Chl cm^?2) and the summer reduction in photosynthesis was closely correlated with reduction in chlorophyll content. It seems unlikely that environmental factors such as seasonal changes in light intensity, nutrient availability or water temperature were directly responsible for this loss of chlorophyll and it is suggested that this is a manifestation of general leaf senescence, probably induced by daylength changes but possibly enhanced by increased water temperature. Cymodocea showed a similar reduction in chlorophyll content in summer but this was not reflected in reduced photosynthesis. Thus, although Cymodocea may grow rapidly throughout the spring and summer with an overall productivity of 3.6 g C m^?2 day^?1 in shallow water, the luxuriant growths of Posidonia must develop in the first half of the year when a dense meadow may produce up to 2.1 g C m^?2 day^?1 in shallow water, declining to ?0.6 g C m^?2 day^?1 in summer.     

Innervation of the American cockroach salivary gland: neurophysiological and pharmacological investigations

Application of 5-hydroxytryptamine to the gland in vitro in concentrations as low as 10^?12 M effected continuous secretion of fluid. This suggests that 5-HT or a related compound may be the neurotransmitter substance. In vivo injections of p-chorophenylalanine did not affect secretion. Applications of pilocarpine and acetylcholine had only a transitory effect upon secretions. Nerve-section studies implicate the salivary duct nerves coming from the suboesophageal ganglion as motor nerves controlling secretion. The oesophageal salivary nerves from the brain were not severed due to excessive trauma. Simultaneous electrical recordings of the salivary nerves show no common activity. Nerve section demonstrates that the activity in these nerves is efferent. Central inhibition of nervous activity occurs during sensory stimulation, etc. Electrical stimulation of the salivary duct nerve in vitro effects salivary secretion for several hours; however, the loss of secretion is not due to failure of the nerves, but to unknown factors. Histological sections of the stimulated glands failed to show cytological changes.     

The effect of L-arginine/nitric oxide pathway on salivary amylase secretion in conscious rats

In a recent study we have demonstrated the presence of nitric oxide synthase immunoreactive neurons and also perivascular, periacinar and periductal nerve fibres in feline submandibular salivary gland. The role of nitric oxide (NO) in salivary vasoregulation has been suggested by other data too, but the effect of NO on salivary amylase secretion has not been investigated yet. Under ether anaesthesia a catheter was introduced into the oesophagus for salivary juice collections, and a cannula was inserted into the jugular vein for infusions. After postanaesthesia recovery, submaximal carbachol infusion was given as a background to obtain steady secretion because of the low basal secretory rate. Then different groups of animals received NO synthase inhibitor NOLA (N^G-nitro-L-arginine), L-arginine, D-arginine or NO donor SIN-1 (3-morpholinosydnonimine). Volume and amylase activity were determined in mixed saliva samples collected for 30 min. Carbachol background infusion alone induced an elevated, sustained salivary secretion. NOLA (30 mg/kg) increased both volume and amylase output (P < 0.001). This effect was prevented by L-arginine but not by D-arginine. SIN-1 did not change either volume or amylase secretion. The present results suggest that the L-arginine/NO pathway has a modulatory effect on salivary fluid and amylase secretion, which is probably not related to its effect on salivary blood flow. NO may block certain presently unidentified secretagogue mechanisms and/or may relax myoepithelial cells.     

Influence of planting geometry on photosynthetically active radiation interception and dry matter production relationships in pearl millet

A field experiment was conducted at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) Center, Patancheru, India to study photosynthetically active radiation (PAR) interception and dry matter production relationships in pearl millet (Pennisetum americanum (L.) Leeke). Two pearl millet genotypes, BJ 104 (G₁) and ICH 226 (G₂) were sown at three planting geometries obtained by using combinations of row and plant spacings (S₁: 37·5 cm × 26·6 cm; S₂: 75·0 cm × 13·3 cm; S₃: 150·0 cm × 6·6 cm) such that plant population was constant at 100 000 ha⁻¹ in all treatments. Cumulative intercepted PAR was maximum (330 MJ m⁻²) in G₂S₂ and minimum (268 MJ m⁻²) in G₁S₃. Conversion efficiency values ranged from 1·87 g MJ⁻¹ in G₁S₂ to 2·32 g MJ⁻¹ in G₂S₃. Final above-ground dry matter followed the pattern of cumulative intercepted PAR and maximum dry matter (7·22 Mg ha⁻¹) was produced by G₂S₂ while G₁S₃ produced minimum dry matter (4·97 Mg ha⁻¹).