The effect of acute ethanol exposure on the chronotropic and inotropic function of the rat right atrium.

Consumption of ethanol (CH2CH3OH), both acutely and chronically, is known to affect cardiac function and may alter the autonomic control of the heart. This study investigated the effects of two modes of acute exposure to ethanol on the chronotropy and inotropy of the rat right atrium with emphasis on alterations in the adrenergic responses. Atria from rats infused with an anesthetizing level of ethanol for 21 h showed a tendency for a greater increase of the unstimulated beating rate with isoproterenol (ISO), while both unstimulated inotropy and the inotropic response to ISO were significantly decreased compared with the control. Right atria in the presence of ethanol in-vitro demonstrated decreased basal active tension development and decreased inotropic responses to ISO. No alteration of the chronotropic response to ISO was evident with any concentration of ethanol. These results demonstrate both an immediate as well as a persistent effect of ethanol on right atrial chronotropy and inotropy. Alterations in the G-stimulatory subunit of the adenylate cyclase system and alterations in myofilament binding of Ca2+ are consistent with these observed ethanol effects.

Disease signs reported in south-eastern Australian dairy cattle while grazing Brassica species.

OBJECTIVE: To estimate the relative frequency of various disease signs in dairy cattle fed brassicas in south-eastern Australia, to estimate the incidence of disease signs within affected groups and to identify risk factors for commonly reported signs in brassica-fed dairy cows. DESIGN: A case series study and a case-control study. PROCEDURES: Case data was collected using an incident reporting system. Herd managers and veterinarians recorded details about disease incidents in brassica-fed dairy cattle in summer and autumn 1995 using a standard questionnaire. Potential risk factors for photosensitisation were assessed using a case-control study. RESULTS: Disease signs were reported in 66 groups of brassicated dairy cattle. Photosensitisation and bloat were the more frequently reported signs. While high incidences were reported in some groups, the incidence of disease signs was low within most affected groups. Photosensitisation occurred more frequently among groups of cows fed brassica crops treated with nitrogenous fertilisers or which were low yielding. Risks of other disease signs were greatest while the first one quarter of the crop was grazed. CONCLUSIONS: In the study population, most disease outbreaks occurring in brassica-fed cattle were of low incidence. However, some high incidence outbreaks occurred. Results from this study suggest that important risk factors exist for disease signs in brassica-fed dairy cattle. Further studies are required if these risk factors are to be fully identified. This would allow the development of preventative strategies for high incidence disease outbreaks while feeding brassicas to dairy cattle.

Postnatal development of the putative neuropeptide-Y-mediated sympathetic--parasympathetic autonomic interaction.

OBJECTIVE: Intense stellate ganglion stimulation causes a long-lasting inhibition of cardiac vagal responses in adult dogs. This inhibition is thought to result from the release of neuropeptide Y from sympathetic nerve terminals, which, in turn, blocks the release of acetylcholine from parasympathetic neurons. The purpose of this study was to characterize the developmental expression of this autonomic interaction in the dog. METHODS: We studied and compared the effects of 5-min trains of right stellate ganglion stimulation on cardiac chronotropic responses to supramaximal vagal stimulation trains in 10 neonatal dogs, 8 one-month-old puppies, 8 two-month-old puppies and 8 adult dogs. RESULTS: In the adult group, after 5 min of stellate stimulation, inhibition of the vagal chronotropic response was observed in 7 of 8 (87.5%). Inhibition was observed in 100% of the one-month-olds and in 87.5% of the two-month-olds. In contrast, in the neonates, inhibition was observed in only 4 of 10 (40%) (P < 0.05). The maximum percent inhibition of the cardiac vagal response was significantly less in the neonates than in the older puppies (P < 0.001) and adults (P < 0.01), and the summated inhibition also tended to be less in the neonates (P < 0.05 compared to one- and two-month-old puppies). Finally, in 60% of the neonates and 37.5% of all other animals vagal responses after stellate stimulation were facilitated, i.e. at least 20% greater than the pre-stellate stimulation values. CONCLUSION: The putative neuropeptide-Y-mediated, sympathetic-parasympathetic interaction is not fully expressed in the canine neonate. It appears to develop quite rapidly postnatally, being fully expressed by 1 month of age. We hypothesize that this developmental change is likely the result of maturation of sympathetic nervous system function after birth. The facilitation of the vagal chronotropic response, observed in some animals after stellate stimulation, is a new finding, and may represent yet another type of autonomic interaction.

Using a single-subject research design to evaluate the effectiveness of treatment.

Single-subject designs allow therapists to evaluate the effects of treatment on individual students, the effects of individualized occupational therapy services across a group of students, and the effects of a specific treatment procedure on a group of students. The purpose of this article is to provide information to enable therapists to use single-subject designs effectively in public school occupational therapy programs.

Therapeutic programming for students with severe handicaps.

Therapeutic methods that use facilitation and inhibition to alter dysfunctional patterns of movement were implemented in children with multiple handicaps within educational settings. Desired movement patterns such as reach and manipulation skills were performed by students throughout the classroom day and across a variety of contextual uses. Data collected on several students indicated that more normal patterns of movement were attained at more rapid rates where students were provided the opportunity to practice the desired movement more frequently. Successful contextual programming depends on accurate and consistent implementation of therapeutic methods by all individuals who come in contact with a student. The therapist must identify the targeted movement pattern, determine appropriate intervention procedures, and train others to implement the procedures accurately. While such an approach shows promise as a means of developing function movement patterns with severely handicapped children, the increased opportunities to practice appropriate movement enhance the effectiveness of direct therapy but do not necessarily replace required individual intervention.