The snail's love-dart delivers mucus to increase paternity.

Many of the seemingly bizarre animal behaviours can be understood only by acknowledging the power of sex to shape evolution. A case in point is the so-called love-dart that some terrestrial molluscs shoot at their prospective sexual partners. Given that the likelihood of copulation is not different after solid hits than after complete misses, why do these suitors act so violently towards their chosen mates? Previously, it was shown that successful dart shooting enhances paternity. We conducted an experiment to determine whether the dart achieves its effect by a purely mechanical action or by transferring a bioactive substance. We found that injections of mucus from a gland associated with the dart more than doubled paternity relative to injections of saline. These results support the hypothesis that the dart transfers a substance capable of reconfiguring the spermatophore-receiving organs. While dart shooting probably evolved as the result of sperm competition, a role for cryptic female choice cannot be excluded. Our results imply that if cryptic female choice is operating in this system, it is likely to be based on the properties of the mucus and not on properties of the dart itself. Since we also found evidence of early-male sperm precedence, we conclude that snails can optimize their reproductive success by mating with virgins and shooting their darts accurately.

Medicinal herb use among asthmatic patients attending a specialty care facility in Trinidad.

BACKGROUND: There is an increasing prevalence of asthma in the Caribbean and patients remain non-compliant to therapy despite the development of guidelines for management and prevention. Some patients may self-medicate with medicinal herbs for symptomatic relief, as there is a long tradition of use for a variety of ailments. The study assessed the prevalence of use and the factors affecting the decision to use herbs in asthmatic patients attending a public specialty care clinic in Trinidad. METHODS: A descriptive, cross-sectional study was conducted at the Chest Clinic in Trinidad using a de novo, pilot-tested, researcher-administered questionnaire between June and July 2003. RESULTS: Fifty-eight out of 191 patients (30.4%) reported using herbal remedies for symptomatic relief. Gender, age, ethnicity, and asthma severity did not influence the decision to use herbs; however, 62.5% of patients with tertiary level schooling used herbs, p = 0.025. Thirty-four of these 58 patients (58.6%) obtained herbs from their backyards or the supermarket; only 14 patients (24.1%) obtained herbs from an herbalist, herbal shop or pharmacy. Relatives and friends were the sole source of information for most patients (70.7%), and only 10.3% consulted an herbalist. Ginger, garlic, aloes, shandileer, wild onion, pepper and black sage were the most commonly used herbs. CONCLUSIONS: Among patients attending the Chest Clinic in Trinidad the use of herbal remedies in asthma is relatively common on the advice of relatives and friends. It is therefore becoming imperative for healthcare providers to become more knowledgeable on this modality and to keep abreast with the latest developments.

Medicinal herb use among asthmatic patients attending a specialty care facility in Trinidad

Background: There is an increasing prevalence of asthma in the Caribbean and patients remain non-compliant to therapy despite the development of guidelines for management and prevention. Some patients may self-medicate with medicinal herbs for symptomatic relief, as there is a long tradition of use for a variety of ailments. The study assessed the prevalence of use and the factors affecting the decision to use herbs in asthmatic patients attending a public specialty care clinic in Trinidad. Methods: A descriptive, cross-sectional study was conducted at the Chest Clinic in Trinidad using a de novo, pilot-tested, researcher-administered questionnaire between June and July 2003. Results: Fifty-eight out of 191 patients (30.4 per cent) reported using herbal remedies for symptomatic relief. Gender, age, ethnicity, and asthma severity did not influence the decision to use herbs; however, 62.5 per cent of patients with tertiary level schooling used herbs, p = 0.025. Thirty-four of these 58 patients (58.6 per cent) obtained herbs from their backyards or the supermarket; only 14 patients (24.1 per cent) obtained herbs from an herbalist, herbal shop or pharmacy. Relatives and friends were the sole source of information for most patients (70.7 per cent), and only 10.3 per cent consulted an herbalist. Ginger, garlic, aloes, shandileer, wild onion, pepper and black sage were the most commonly used herbs. Conclusions: Among patients attending the Chest Clinic in Trinidad the use of herbal remedies in asthma is relatively common on the advice of relatives and friends. It is therefore becoming imperative for healthcare providers to become more knowledgeable on this modality and to keep abreast with the latest developments.

Medicinal herb use among asthmatic patients attending a specialty care facility in Trinidad

BACKGROUND: There is an increasing prevalence of asthma in the Caribbean and patients remain non-compliant to therapy despite the development of guidelines for management and prevention. Some patients may self-medicate with medicinal herbs for symptomatic relief, as there is a long tradition of use for a variety of ailments. The study assessed the prevalence of use and the factors affecting the decision to use herbs in asthmatic patients attending a public specialty care clinic in Trinidad. METHODS: A descriptive, cross-sectional study was conducted at the Chest Clinic in Trinidad using a de novo, pilot-tested, researcher-administered questionnaire between June and July 2003. RESULTS: Fifty-eight out of 191 patients (30.4 per cent) reported using herbal remedies for symptomatic relief. Gender, age, ethnicity, and asthma severity did not influence the decision to use herbs; however, 62.5 per cent of patients with tertiary level schooling used herbs, p = 0.025. Thirty-four of these 58 patients (58.6 per cent) obtained herbs from their backyards or the supermarket; only 14 patients (24.1 per cent) obtained herbs from an herbalist, herbal shop or pharmacy. Relatives and friends were the sole source of information for most patients (70.7 per cent), and only 10.3 per cent consulted an herbalist. Ginger, garlic, aloes, shandileer, wild onion, pepper and black sage were the most commonly used herbs. CONCLUSIONS: Among patients attending the Chest Clinic in Trinidad the use of herbal remedies in asthma is relatively common on the advice of relatives and friends. It is therefore becoming imperative for healthcare providers to become more knowledgeable on this modality and to keep abreast with the latest developments.

Modulation of heart activity during withdrawal reflexes in the snail Helix aspersa.

The beating activity of the molluscan heart is myogenic, but it is influenced by nervous signals of central origin. Previous studies have demonstrated changes in cardiac output during feeding and other behaviors. Here, we describe a short latency, transient cardiac response that accompanies withdrawal reflexes. When evoked by electrical stimulation of peripheral nerves, the response was detected within one or two heartbeats. Beat amplitudes increased on average 11.6%, and inter-beat intervals decreased on average 2.1%. The mean duration of the response was 28.1 s. A transient inhibitory phase often preceded the excitatory response. Results from testing various nerves and tissues show that the cardiac responses invariably occur whenever contractions of the tentacle retractor muscle are elicited. Even stimulation of the ovotestis and the kidney elicit responses despite their protected locations within the mantle cavity. Three excitatory cardioactive neurons are identified in the central nervous system of Helix aspersa, and their involvement in the reflex response is documented. The results suggest that the heart output is initially inhibited to relax the hydroskeleton and thereby aid withdrawal movements. A delayed increase in cardiac output then facilitates the re-inflation, hence eversion, of the withdrawn body parts.

Sensory innervation of the ovotestis in the snail Helix aspersa.

Because oviposition in the land snail Helix aspersa is a metabolically expensive process coupled to a high fixed cost, one expects oviposition to occur only when the clutch size surpasses a minimum value at which the reproductive benefit exceeds the cost. We propose that neural innervation of the gonad allows H. aspersa to monitor oocyte production and ensure an adequate supply of gametes prior to ovulation. The ovotestis is innervated by a branch of the intestinal nerve in which the majority of axon fibres measure <0.2 microm in diameter. We found a strong positive correlation between the number of mature oocytes in the ovotestis and the frequency of spontaneous afferent spikes in the nerve branch. Tactile stimulation of the ovotestis resulted in a 20-fold increase in afferent spikes and an efferent reflex directed towards the ovotestis and the pericardium. Afferent activity also increased 10-fold after an experimentally induced increase in the volume of the ovotestis. These results suggest that the growing oocytes expand the walls of the acini and trigger action potentials in the mechanosensitive nerve terminals that lie within the acinar walls. We hypothesize that the resulting tonic signal is permissive for ovulation. In addition, a phasic sensory signal may occur during ovulation to trigger CNS motor output related to oviposition.