Effect of Pinacidil on Spontaneous and Evoked Contractile Activity

Uninhibited bladder contractions have been associated with a variety of bladder dysfunctions including outlet obstruction, neurogenic bladder, incontinence, and other neurologic and nonneurogenic bladder disorders. One class of compounds that is gaining popularity and support for the treatment of hyperreflexia is potassium channel openers, such as pinacidil and cromakalim. In general, these agents act by hyperpolarizing the smooth muscle membrane, resulting in an increase in membrane stability which in turn would be expected to inhibit spontaneous and evoked contraction. It is the purpose of this study to compare the potency and selectivity of pinacidil at inhibiting both hyperreflexia in vivo, and several forms of in vitro contractile stimulation in the rabbit. The following is a summary of the results. (1) Pinacidil is an effective inhibitor of hyperreflexia in the in vivo rabbit model. (2) Pinacidil is a substantially more potent inhibitor of the amplitude of the hyperreflexia than the frequency. (3) Pinacidil was substantially more potent at inhibiting the contractile response to 2-Hz stimulation than to 32-Hz stimulation, but was equally effective at inhibiting field stimulation of the bladder base and body. (4) Pinacidil was significantly more potent at inhibiting the peak response to field stimulation than the rate of tension generation. (5) Pinacidil was equally potent and effective at inhibiting the phasic and tonic components of the response to field stimulation. (6) Pinacidil was a more potent inhibitor of methoxamine stimulation of the bladder base than bethanechol stimulation of the bladder body. (7) Pinacidil was a noncompetitive or mixed inhibitor of both methoxamine and bethanechol stimulation, whereas it was a competitive inhibitor of KCl stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Linkworkers in antenatal care: facilitators of equal opportunities in health provision or salves for the management conscience?

A number of reports have highlighted non-English speaking Asian women as being at risk from limited health care provision (eg Whitehead, 1987). Of particular relevance to the present survey is their low uptake of antenatal care which may contribute to the above-average perinatal mortality rates for this group. In an attempt to ameliorate this problem, a Linkworker service was introduced in a number of multi-racial health districts. The survey reported here was an attempt to establish the efficacy of this service. From an initial sample of 30 health districts, 20 replies were obtained which provided some valuable insights on the current status of the Linkworker provision. In summary, the responses indicated that there is a worrying mis-match between client need and service planning, largely because relevant information about supply and demand is not collated. The net result is that many of the at-risk group are still denied the full and appropriate services of the Linkworker. It is concluded that if Linkworker provision is seen as a valuable commodity in enhancing equal opportunities in health care, then the service needs to be systematised. If it is perceived to be of little demonstrable value, then it should be scrapped. In either case, some clear policy decisions are required.

Longer booking intervals in general practice: effects on doctors' stress and arousal

A controlled trial was carried out to determine whether longer booking intervals at surgeries affected general practitioners' self-assessed levels of stress and arousal. Sixteen general practitioners from 10 practices took part. Surgery sessions with patients booked at 10 minute intervals (experimental sessions) were compared with the doctors' usual booking intervals of between 7.5 and 5.0 minutes (control sessions). Stress and arousal were assessed by the general practitioner before and after each surgery session using a mood adjective check list. The study included 109 experimental and 184 control sessions. The median consultation length increased from six minutes in the control sessions to seven minutes in the experimental sessions. At the end of the experimental sessions, stress scores were lower, and arousal scores higher than at the end of the control sessions (P less than 0.001). There were no significant differences between experimental and control sessions in stress or arousal at the start of the sessions. Favourable mood changes were seen more consistently in the experimental sessions than control sessions, with less than a quarter of doctors showing increased stress or decreased arousal after sessions relative to before. It is concluded that longer booking intervals are of psychological advantage to general practitioners.

Experimental hyperreflexia: effect of intravesical administration of various agents

In anesthetized rabbits, we can induce a significant degree of spontaneous activity in the urinary bladder by placing a ligature around the proximal portion of the external urethra. Previous studies characterized the activity as primarily reflex in nature, since intravesical hexamethonium selectively inhibited the hyperreflexia. In this current study we determined the effect of intravesical administration of a variety of compounds to inhibit the induced hyperreflexia. The following agents were tested at concentrations of 1, 10, 100 and 500 mumol/l (intravesically): verapamil, cromakalim, nifedipine, diltiazem, and atropine; lidocaine was tested in 0.05, 0.5 and 5% solutions. The results are summarized as follows: (1) Lidocaine was the most effective agent tested, virtually eliminating both the amplitude and frequency of the spontaneous activity at the lowest concentration (0.5%). (2) Verapamil and nifedipine were somewhat more potent than cromakalim and diltiazem. Atropine sulfate was the least potent, inhibiting both the amplitude and frequency of the hyperreflexia by less than 50% at 500 mumol/l. (3) In all cases, the amplitude of the spontaneous activity was inhibited to a significantly greater degree than the frequency of the spontaneous activity. (4) In general, there was no effect of any of the agents on mean arterial pressure at 1 or 10 mumol/l. At 100 and 500 mumol/l, all agents except for lidocaine and cromakalim decreased arterial pressure. These two agents produced no consistent fall in blood pressure at any concentration. In conclusion, the acute hyperreflexic (rabbit) preparation provides a highly reproducible and consistent model for the study of the effect of drugs on hyperreflexia.(ABSTRACT TRUNCATED AT 250 WORDS)

Basal and stimulated release of substance P from dissociated cultures of vagal sensory neurons

Substance P, the widely distributed 11 amino acid neuropeptide, is present in up to 20% of vagal sensory cell bodies and the fibers emanating from them. To study the factors regulating the release of SP, vagal sensory (nodose or nodose/jugular) ganglia were obtained from neonatal rats and dissociated using neutral protease. Survival of plated neurons on collagen substrate was 10-20% at 2 weeks and 20-30% when neurons were plated over previously dissociated rat atriacytes. Substance P content was low in cultures for the first several days, then rose linearly to 0.1-0.2 pg/surviving neuron. Substance P was released into a 4.5 mM potassium medium at a steady rate of 0.036%/min. In 50 mM K+ supplemented medium, total release during 20 min increased 5-8-fold and steady-state release increased 4-5-fold to 0.15%/min. The sensory neuron specific excitatory neurotoxin, capsaicin, evoked SP release in similar amounts to 50 mM K+. Both net K(+)- and capsaicin-evoked, but not basal release were completely inhibited by 3.5 mM cobalt chloride. Bradykinin, 1-100 nM, stimulated SP release 2-4 times above basal levels. Forskolin and phorbol ester also increased SP release 1.5-3 times basal amounts. In summary, substance P is present in cultured vagal sensory neurons in amounts similar to in vivo and is released in response to sensory specific stimuli. These cultures should allow exploration of some of the tissue specific factors regulating neurotransmitter release in the sensory vagus nerve.

Non-pyramidal hippocampal projection neurons: a light and electron microscopic study

Following injections of horseradish peroxidase conjugated with wheat germ agglutinin into the medial nucleus accumbens of the rat, a large number of projecting pyramidal neurons in the hippocampus were retrogradely labelled. In addition to this major projection, a few retrogradely labelled cells were tentatively identified at the light microscopic level as non-pyramidal neurons. These presumptive non-pyramidal neurons were found in all hippocampal layers, although they were mainly outside the stratum pyramidale, in the stratum oriens. Ultrastructurally, in serial sections, the non-pyramidal nature of 20 of these neurons was confirmed by their characteristic features such as deeply indented nuclei, occasional intranuclear inclusions, and symmetric and asymmetric synaptic contacts with their somata. Possible transmitters used by these neurons are discussed.

A comparison of the white cell counts of cord blood from babies of different ethnic origins

Cord blood samples were collected from 242 babies of five different ethnic groups. All had a birth weight of at least 2.5 kg, but they were otherwise unselected. No ethnic differences were found in the total white cell count, neutrophil, lymphocyte, monocyte or eosinophil counts. Thus the lower total white cell and neutrophil count which has been observed in adults of African and Afro-Caribbean origin is not present in neonates. Similarly eosinophil counts did not differ between the different ethnic groups suggesting that high eosinophil counts previously reported in Indian and African subjects have an environmental cause.

Lesion-induced myelin formation in the retina

In the normal rat retina ganglion cell axons are not myelinated until they enter the optic nerve. After a lesion to the retina made via the sclera and choroid, Schwann cells invade the retina and myelinate ganglion cell axons. The lesion-induced myelin formation is most conspicuous in animals operated between the day of birth and 20 days of age. A lesion to the retina made from the vitread surface does not produce Schwann cell invasion. We suggest that the Schwann cells migrate into the retina from extraocular structures via the sclera. These observations provide a valuable system for the study of interactions between CNS axons and Schwann cells.

Comparison of rosaramicin and erythromycin stearate for treatment of cervical infection with Chlamydia trachomatis

The macrolide antibiotic rosaramicin inhibits in vitro growth of Chlamydia trachomatis. Rosaramicin (1 g daily given to 18 patients for seven days) and erythromycin stearate (2 g daily given to 19 patients for seven days) were compared in the treatment of chlamydial cervicitis. Cultures of cervical specimens obtained nine to 11 days and 24-32 days after commencement of therapy were negative for all rosaramicin-treated patients seen at follow-up. The first follow-up culture of one erythromycin recipient was positive. The extent of cervicitis decreased in all patients after treatment, but the only patients to achieve a completely normal cervical appearance were those with minimal-to-moderate lesions before treatment. Gastrointestinal side effects, including nausea, vomiting, and abdominal pain, occurred in ten of 19 patients given erythromycin and in 13 of 18 given rosaramicin. Minimally elevated levels of alanine aminotransferase in serum occurred in four (22.2%) of 18 rosaramicin recipients. It is concluded that rosaramicin and erythromycin stearate both eradicate C. trachomatis cervical infection but frequently cause adverse gastrointestinal effects.

Behavioral tests in monkey infants exposed embryonically to an oral contraceptive

The behavior of rhesus monkey infants exposed to high levels (20 to 100 X the human therapeutic dosage) of an estrogen-progesterone contraceptive (Norlestrin) during embryogenesis was compared to that of untreated controls. No serious deficiencies in regulation of activity, motor maturity, manual dexterity or discrimination learning were recorded in the 3 to 5 month old infants. In addition, age appropriate sex-differentiated behavior was observed in social groups of treated infants at 5 and 11 months of age. On the basis of this information it seems unlikely that accidental use of birth control pills during early pregnancy will seriously affect behavioral competence of offspring during infancy.

Adolescent pregnancy

This paper reviews the literature of the past seven years concerning adolescent pregnancy. Social and motivational factors leading to pregnancy are discussed and weighed. Obstetric aspects of adolescent pregnancy are reviewed as well as the repercussions of this event. Goals and objectives are proposed, including: (1) assurance of health education, including family life and sex education, in all private and public schools, from elementary grades through high school; (2) assuring that family planning services are available, accessible, and acceptable to all school-aged individuals who desire such services; (3) assuring availability of inexpensive, or free, and easily accessible pregnancy testing, backed up by counseling about alternatives available to the pregnant school-aged woman; (4) assuring that pregnant adolescents have alternatives to childbirth, ie, abortion services, foster care services, adoption services; (5) assuring that pregnant adolescents receive optimal prenatal care, including social and other support services as well as medical care, and that their families are involved in the care process; (6) assuring that school-aged individuals and their families receive postnatal and follow-up care that includes social and other support services as well as medical care.

Determination of less than a nanomol of cerebrosides by high performance liquid chromatography with gradient elution analysis

A gradient elution high performance liquid chromatography method with detection at 230 nm for the analysis of perbenzoylated cerebrosides containing hydroxy and nonhydroxy fatty acids is described. The quantitative range of the method is 0.5-10 nmol of cerebrosides. The limit of detection for injected sample is about 10 picomol. The analysis time by liquid chromatography is less than 5 minutes and prior purification of the cerebrosides from other lipids in brain lipid extracts is not necessary. The cerebrosides are first perbenzoylated with 50 micronl of 10% benzoyl chloride in pyridine and then separated on a chromatographic column of Zipax. The gradient elution is with 2.8-5.5% of dioxane in hexane. This gradient elution micromethod is at least 10 times more sensitive than isocratic elution methods with detection at 280 nm. The method is applicable to other biological materials containing minute amounts of cerebrosides if the glycolipid fraction is first isolated from the lipid extracts. A further fourfold increase in the sensitivity is achieved by replacing air in the reference cell of the detector by gradient elution solvent.