Acidic Urine pH and Clinical Outcome of Lower Urinary Tract Infection in Kidney Transplant Recipients Treated with Ciprofloxacin and Fosfomycin

Different factors, including antimicrobial resistance, may diminish the effectiveness of antibiotic therapy, challenging the management of post-transplant urinary tract infection (UTI). The association of acidic urine pH with microbiological and clinical outcomes was evaluated after fosfomycin or ciprofloxacin therapy in 184 kidney transplant recipients (KTRs) with UTI episodes by Escherichia coli (N = 115) and Klebsiella pneumoniae (N = 69). Initial urine pH, antimicrobial therapy, and clinical and microbiological outcomes, and one- and six-month follow-up were assessed. Fosfomycin was prescribed in 88 (76.5%) E. coli and 46 (66.7%) K. pneumoniae UTI episodes in the total cohort. When the urine pH ≤ 6, fosfomycin was prescribed in 60 (52.2%) E. coli and 29 (42.0%) K. pneumoniae. Initial urine pH ≤ 6 in E. coli UTI was associated with symptomatic episodes (8/60 vs. 0/55, p = 0.04) at one-month follow-up, with a similar trend in those patients receiving fosfomycin (7/47 vs. 0/41, p = 0.09). Acidic urine pH was not associated with microbiological or clinical cure in K. pneumoniae UTI. At pH 5, the ciprofloxacin MIC90 increased from 8 to >8 mg/L in E. coli and from 4 to >8 mg/L in K. pneumoniae. At pH 5, the fosfomycin MIC90 decreased from 8 to 4 mg/L in E. coli and from 512 to 128 mg/L in K. pneumoniae. Acidic urine is not associated with the microbiological efficacy of fosfomycin and ciprofloxacin in KTRs with UTI, but it is associated with symptomatic UTI episodes at one-month follow-up in E. coli episodes.

[Unicompartmental knee prosthesis]

In a patient with severe unicompartmental knee osteoarthritis where conservative treatments have been exhausted, with painful symptoms located on the affected side and with a reducible axis, the unicompartmental knee prosthesis (UKP) is the first option for our work group. Within the study to confirm the diagnosis and plan the surgery, weight-bearing knee x-rays, Rosenberg x-rays, and teleradiographs of the lower extremities stand out. The objective of surgery is to replace the affected area, restoring the anatomy with an adequate balance of soft tissues. Regarding alignment, the challenge is not to overload the opposite side or that of the prosthesis. There are mobile and fixed plates and although the clinical and survival results are similar, in recent years with the incorporation of robotic surgery, the balance has tipped towards the use of fixed plates. The clinical and functional results are better and there are fewer complications than when total knee prostheses (TKP) are used in the same type of patients. The survival studied in registries is lower than for TKP, but when used in high-flow centers where the percentage of UKP is close to a third of the total with strict patient selection, the duration is as good as in PTR.

Seven-versus 14-day course of antibiotics for the treatment of bloodstream infections by Enterobacterales: a randomized, controlled trial

OBJECTIVE

To prove that 7-day courses of antibiotics for bloodstream infections caused by members of the Enterobacterales (eBSIs) allow a reduction in patients' exposure to antibiotics while achieving clinical outcomes similar to those of 14-day schemes.

METHODS

A randomized trial was performed. Adult patients developing eBSI with appropriate source control were assigned to 7 or 14 days of treatment, and followed 28 days after treatment cessation; treatments could be resumed whenever necessary. The primary endpoint was days of treatment at the end of follow-up. Clinical outcomes included clinical cure, relapse of eBSI and relapse of fever. A superiority margin of 3 days was set for the primary endpoint, and a non-inferiority margin of 10% was set for clinical outcomes. Efficacy and safety were assessed together with a DOOR/RADAR (desirability of outcome ranking and response adjusted for duration of antibiotic risk) analysis.

RESULTS

248 patients were assigned to 7 (n = 119) or 14 (n = 129) days of treatment. In the intention-to-treat analysis, median days of treatment at the end of follow-up were 7 and 14 days (difference 7, 95%CI 7-7). The non-inferiority margin was also met for clinical outcomes, except for relapse of fever (-0.2%, 95%CI -10.4 to 10.1). The DOOR/RADAR showed that 7-day schemes had a 77.7% probability of achieving better results than 14-day treatments.

CONCLUSIONS

7-day schemes allowed a reduction in antibiotic exposure of patients with eBSI while achieving outcomes similar to those of 14-day schemes. The possibility of relapsing fever in a limited number of patients, without relevance to final outcomes, may not be excluded, but was overcome by the benefits of shortening treatments.

Administering copper reduces hyper-excitability generated by penicillin G in motor cortex neurons from rat brain slices

Recording synaptic activity of layer III neurons from motor cortex slices, which was provoked by stimulating layer IV, generated synaptic responses of the field potential (FP) that went from mean 100 μV to 600 μV when the stimulus was increased up to twice the threshold. Administering 100 μM or 200 μM of copper, increased the responses to mean 800 μV and 820 μV, respectively. The response to 200 μM was not significantly greater than that to 100 μM. However, all FP responses were significantly lower to a copper concentration of 500 μM. The basal FP was slowly restored by removing the copper with Krebs-Ringer(K-R), resulting in similar characteristics to those observed before copper administration. Then, neurons were perfused with penicillin (2000 UI) to increase cortical excitability and to assess the depressing effect of high concentrations of copper. Administering 500 μM of copper significantly reduced the activity generated by penicillin, while removing by wash(K-R) penicillin and copper generated FP responses similar to those obtained at baseline. Our data indicate that depending on the concentration, copper can behave as an activating or blocking agent for cortical activity.

Dexamethasone modulates expression of genes involved in the innate immune system, growth and stress and increases susceptibility to bacterial disease in Senegalese sole (Solea senegalensis Kaup, 1858)

Cortisol, the main glucocorticoid in fish, undertakes pleiotropic biological effects in response to stressors to maintain homeostasis. It can exert several actions on the immune system, growth and cellular metabolism, establishing a fine-tune regulation stress response and cross-talk interactions with other regulatory pathways. In this study, we investigated a causal relationship between high levels of glucocorticoids and susceptibility to pathogens and modification of gene expression profiles in Senegalese sole. For this purpose, we carried out two experiments using post-metamorphic individuals (21 days after hatching) that were exposed to dexamethasone (DXM), a potent glucocorticoid, in order to mimic cortisol effects. We quantified transcript levels of a wide set of genes involved in innate immune system (g-type lysozyme and hepcidin (hamp1)), HPI axis (crf, crfbp, pomcα, pomcβ, gr1 and gr2), HPT axis (tgb), cellular stress defense system (hsp70 and hsp90aa), GH/IGF axis (igf-I and igf-Ir) and the neuropeptide trh. Short-term exposure to 0.1, 1 and 10 ppm DXM provoked a reduction of pomcβ transcripts and an increase of crfbp mRNAs in a dose-dependent manner at 48 and 72 h after treatment. Moreover, g-type lysozyme transcript levels decreased significantly at 72 h whereas hamp1 mRNA levels increased at 48 h after exposure. Long-term DXM treatment (10 ppm DXM) affected negatively weight of soles (~20% lower than controls). Moreover, reduced mRNA levels were observed for pomcβ after 1 week and igf-I and hamp1 after 2 weeks. In contrast, crfbp and crf increased mRNA levels after 2 weeks. hsp70 exhibited a dual response increasing transcript levels at 1 week after treatment and reducing thereafter. No significant changes in gene expression were observed at any time during this study for tgb, trh, hsp90aa, pomcα, gr1 and gr2. Finally, a challenge experiment using the pathogen Photobacterium damselae subsp piscicida confirmed earlier and higher mortalities in DXM-treated animals. Taken together, these data indicate that a prolonged exposure to DXM increases the susceptibility to pathogens and reduces growth. Moreover, DXM can trigger a wide cellular response modulating the expression of genes involved in the innate immune system, HPI and GH/IGF axes as well as cellular stress defense. These results are highly valuable to evaluate responses associated to aquaculture stressful conditions and discriminate specific glucocorticoid-mediated effects.

A combined RT-PCR and dot-blot hybridization method reveals the coexistence of SJNNV and RGNNV betanodavirus genotypes in wild meagre (Argyrosomus regius)

AIMS

To detect the possible coexistence of striped jack nervous necrosis virus (SJNNV) and red-spotted grouper nervous necrosis virus (RGNNV) genotypes in a single fish, a methodology based on the combination of PCR amplification and blot hybridization has been developed and applied in this study.

METHODS AND RESULTS

The degenerate primers designed for the PCR procedure target the T4 region within the capsid gene, resulting in the amplification of both genotypes. The subsequent hybridization of these amplification products with two different specific digoxigenin-labelled probes resulted in the identification of both genotypes separately. The application of the RT-PCR protocol to analyse blood samples from asymptomatic wild meagre (Argyrosomus regius) specimens has shown a 46.87% of viral nervous necrosis virus carriers. The combination of RT-PCR and blot hybridization increases the detection rate up to 90.62%, and, in addition, it has shown the coexistence of both genotypes in 18 out of the 32 specimens analysed (56.25%).

CONCLUSIONS

This study reports the coexistence of betanodaviruses belonging to two different genotypes (SJNNV and RGNNV) in wild fish specimens.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report demonstrating the presence of SJNNV and RGNNV genotypes in the same specimen. This study also demonstrates a carrier state in this fish species for the first time.

Detection of infectious pancreatic necrosis virus (IPNV) from asymptomatic redbanded seabream, Pagrus auriga Valenciennes, and common seabream, Pagrus pagrus (L.), using a non-destructive procedure

A non-destructive procedure based on nested RT-PCR and dot-blot hybridization has been developed for the detection of asymptomatic IPNV-carrier fish. The pair of primers designed for RT-PCR amplified a 599-bp fragment of the pVP2 region within the polyprotein gene, resulting in the detection of IPNV genotype III.1. The use of a nested RT-PCR allowed the amplification of IPNV genotypes III.1 and I.2. In addition, a 191-bp probe was designed for hybridization studies used in combination with the nested RT-PCR. The application of the nested RT-PCR to analyse blood samples from asymptomatic redbanded seabream, Pagrus auriga, and common seabream, P. pagrus, specimens showed a 53.1% and 77.8% prevalence of IPNV-carriers, respectively. The combination of nested RT-PCR and dot-blot hybridization increased the detection rates up to 100% for redbanded seabream and 94.4% for common seabream. Therefore, the protocol described in this study is highly sensitive and specific for the detection of IPNV in asymptomatic carrier fish, and, in addition, the results demonstrate the carrier state in two newly cultured sparid species in southern Spain.

Poly I:C induces Mx transcription and promotes an antiviral state against sole aquabirnavirus in the flatfish Senegalese sole (Solea senegalensis Kaup)

Mx is an interferon-induced protein that protects against viral infections. In this study the absolute number of Mx transcripts after poly I:C injection (a synthetic dsRNA) or sole aquabirnavirus (solevirus) inoculation in Senegalese sole (Solea senegalensis Kaup) has been quantified. Mx expression profiles differed clearly in both experimental conditions; the induction response was faster and more intense after poly I:C injection than after solevirus inoculation. Moreover, pre-injection of soles with poly I:C prior to solevirus infection eliminated the induction of Mx expression associated with this virus. To evaluate the possible interference of poly I:C treatments on solevirus replication, the mRNA levels of the virus capsid protein (VP2) were determined by RT-PCR. VP2 transcripts were hardly detected in poly I:C pre-injected animals from 12 to 72 h after solevirus inoculation. All these data suggest that poly I:C is able to induce an antiviral state that interferes with solevirus replication, and support the suitability of Mx expression analysis as a marker to study the defensive response against solevirus.

Insulin-like growth factors I and II in the sole Solea senegalensis: cDNA cloning and quantitation of gene expression in tissues and during larval development

Insulin-like growth factors I and II (IGF-I and IGF-II) play an important role as modulators of development, growth, and reproduction. This study aimed to isolate the IGF-I and IGF-II cDNAs and determine their temporal expression pattern in different organs and throughout larval development in Senegal sole. The rapid amplification of cDNA ends (RACE) was used to obtain both full-length IGFs sequences. A high sequence similarity with other teleosts sequences was observed. Domains B and A revealed as the most evolutionary conserved. Steady-state copy numbers of IGF-I and IGF-II were also quantified in different Senegal sole tissues by real-time PCR. IGF-I and IGF-II expressed ubiquitously with the highest mRNA levels in liver (88 x 10(6) molecules/microg total RNA) and gills (14.0 x 10(6) molecules/microg total RNA) respectively. IGF-II mRNA levels were higher than IGF-I in prehatching embryos and premetamorphic larvae with a significant drop before the commencement of eye migration in metamorphosis. The abundance of IGF-II transcripts correlated positively with the growth rate during larval development. The putative role of IGF-II on metamorphosis and larval growth is discussed.

Potential of vetiver (vetiveria zizanioides (L.) Nash) for phytoremediation of petroleum hydrocarbon-contaminated soils in Venezuela

Venezuela is one of the largest oil producers in the world. For the rehabilitation of oil-contaminated sites, phytoremediation represents a promising technology whereby plants are used to enhance biodegradation processes in soil. A greenhouse study was conducted to determine the tolerance of vetiver (Vetiveria zizanioides (L.) Nash) to a Venezuelan heavy crude oil in soil. Additionally, the plant's potential for stimulating the biodegradation processes of petroleum hydrocarbons was tested under the application of two fertilizer levels. In the presence of contaminants, biomass and plant height were significantly reduced. As for fertilization, the lower fertilizer level led to higher biomass production. The specific root surface area was reduced under the effects of petroleum. However, vetiver was found to tolerate crude-oil contamination in a concentration of 5% (w/w). Concerning total oil and grease content in soil, no significant decrease under the influence of vetiver was detected when compared to the unplanted control. Thus, there was no evidence of vetiver enhancing the biodegradation of crude oil in soil under the conditions of this trial. However, uses of vetiver grass in relation to petroleum-contaminated soils are promising for amelioration of slightly polluted sites, to allow other species to get established and for erosion control.

Interference of chronically ingested copper in long-term potentiation (LTP) of rat hippocampus

The objective of our study was to find the evidence of copper interaction in LTP, motivated by copper involvement in neurodegenerative illness, like Parkinson, Alzheimer and Amyotrophic Lateral Sclerosis, and we initiated the study of this element in the LTP. For this purpose we used hippocampus slices of rats chronically consuming copper dissolved in water (CuDR; n=26) and non-copper-consuming rats (CR; n=20). The CuDR rats received 8--10 mg/day during 20--25 days. Electrophysiological tests showed absence of LTP in CuDR slices, contrary to CR slices. The stimulus-response test applied before and after LTP showed significant increases of synaptic potential in the CR group. This did not occur in the CuDR group, except for the initial values, which probably seem associated to an early action of copper. The paired-pulse (PP) test, applied to CR and CuDR prior to tetanic stimulation, showed a significant reduction in PP, for the 20-, 30- and 50-ms intervals in CuDR. At the end of the experiments, copper concentration was 54.2 times higher in CuDR slices, compared to the concentration present in CR slices. Our results show that copper reduces synaptic sensibility and also the facilitation capability. These effects represent a significant disturbance in the plasticity phenomenon associated with learning and memory.

Phytoremediation in the tropics--influence of heavy crude oil on root morphological characteristics of graminoids

When studying species for phytoremediation of petroleum-contaminated soils, one of the main traits is the root zone where enhanced petroleum degradation takes place. Root morphological characteristics of three tropical graminoids were studied. Specific root length (SRL), surface area, volume and average root diameter (ARD) of plants grown in crude oil-contaminated and uncontaminated soil were compared. Brachiaria brizantha and Cyperus aggregatus showed coarser roots in polluted soil compared to the control as expressed in an increased ARD. B. brizantha had a significantly larger specific root surface area in contaminated soil. Additionally, a shift of SRL and surface area per diameter class towards higher diameters was found. Oil contamination also caused a significantly smaller SRL and surface area in the finest diameter class of C. aggregatus. The root structure of Eleusine indica was not significantly affected by crude oil. Higher specific root surface area was related to higher degradation of petroleum hydrocarbons found in previous studies.

Induction and blockade of epileptic foci by intracerebral injection of glutamatergic agonists and antagonists in frerly moving cats

The aim of the present work was to test in adult cats the capability of three glutamatergic agonists, NMDA, AMPA and ACDP as epileptogenic agents. Drugs were microinjected in amygdala or hippocampus, and once generated an epileptic focus three selective glutamatergic antagonists NMDA, CNQX and MCPG, were tested. Before and after injection both the EEG and the behavior were continuously monitored. The results were as follows: 1) AMPA showed a greater capability than NMDA or ACPD to generate a chronic epileptic focus; 2) AMPA elicited a greater epileptogenic effect in hippocampus than in amygdala; NMDA had similar epileptogenic effect in both cited structures, and ACPD had not effect; 3) of the three glutamatergic antagonists used to block a long lasting focus, the most effective one was CNQX, which showed a greater effect in hippocampus than in amygdala; 4) comparison between the epileptogenic effect of AMPA and kainic acid (first paper) in the same structure, showed that kainic acid is about 15 fold more epileptogenic. A discussion of the probable mechanisms of these results was undertaken.

Comparative study of the epileptogenic effect of kainic acid injected into the cerebral cortex, hippocampus and amygdala in adult cats chronically implanted

Intracerebral injection of kainic acid in cerebral cortex, hippocampus or amygdala in cats chronically implanted showed that: 1) Hippocampus and amygdala presented a greater sensitivity than the cerebral cortex, while hippocampus presented a greater sensitivity than the amygdala to the generation of an epileptic focus. 2) Comparison of latency, mean duration of afterdischarges, and the mean time period to obtain the peak intensity of the afterdischarge in the three cited structures, showed that mean latency of the first afterdischarge was significantly shorter in hippocampus and amygdala compared with the cerebral cortex. Moreover the mean time period to reach the peak intensity of the afterdischarge was again shorter in the subcortical structures. 3) The epileptic foci both in hippocampus and amygdala were blocked by CNQX and muscimol. 4) The behavioral changes depended on the intensity of the epileptic process. Tonic-clonic convulsions appeared only when the motor cerebral cortex was involved. Finally, 5) kainic acid injections in hippocampus and amygdala elicited an intense neuronal destruction and gliosis of these structures. We conclude that intracerebral injection of low doses of kainic acid in cats represent a good model to study focal epileptic thresholds in the CNS.

Prevalence of malocclusion and orthodontic treatment need in children and adolescents in Bogota, Colombia. An epidemiological study related to different stages of dental development

The aim of the study was to assess the prevalence of malocclusion in a population of Bogotanian children and adolescents in terms of different degrees of severity in relation to sex and specific stages of dental development, in order to evaluate the need for orthodontic treatment in this part of Colombia. A sample of 4724 children (5-17 years of age) was randomly selected from a population that attended the Dental Health Service; none had been orthodontically treated. Based on their dental stages the subjects were grouped into deciduous, early mixed, late mixed and permanent dentition. The registrations were performed according to a method by Björk et al. (1964). The need for orthodontic treatment was evaluated according to an index used by the Swedish National Board of Health. The results showed that 88 per cent of the subjects had some type of anomaly, from mild to severe, half of them recorded as occlusal anomalies, one-third as space discrepancies, and one-fifth as dental anomalies. No clear sex differences were noted, except for maxillary overjet, spacing, tooth size (all more frequent in boys), and crowding (more frequent in girls). Occlusal anomalies and space discrepancies varied in the different dental developmental periods, as did tipped and rotated teeth. Little need for orthodontic treatment was found in 35 per cent and moderate need in 30 per cent. A great need was estimated in 20 per cent, comprising children with prenormal occlusion, maxillary overjet, or overbite (> 6 mm), posterior unilateral crossbite with midline deviation (> 2 mm), severe crowding or spacing, congenitally missing maxillary incisors, impacted maxillary canines or anterior open bite (> 3 mm in the permanent dentition). Urgent need for treatment was estimated to be 3 per cent, comprising subjects with extreme post- and pre-normal occlusion, impacted maxillary incisors or extensive aplasia.

Behavioural motor effects of MK-801 and DNQX parenteral administration in adult cats: dose-response analysis. Modulatory role of dopaminergic D1 and D2 antagonists on MK-801 induced motor behaviours

1. Administration of MK-801 a selective antagonist of the NMDA receptors (50, 100 and 150 micrograms/kg, s.c.) elicited in adult cats ataxia and loss of equilibrium. A dose-response effect was observed. 2. Administration of DNQX, a selective antagonist of the non-NMDA receptors, even with doses 20 times higher than those employed with MK-801, did not produce any behavioural disturbances. 3. Previous injection of SCH 23390, a selective parenteral antagonist of dopamine D1 receptor, reduced significantly the intense ataxic effects of MK-801, while sulpiride only increased the latency of the symptoms. 4. The results are discussed considering the reported interactions between the dopaminergic and glutamatergic systems.

GMAP-210, A cis-Golgi network-associated protein, is a minus end microtubule-binding protein

We report that a peripheral Golgi protein with a molecular mass of 210 kD localized at the cis-Golgi network (Rios, R.M., A.M. Tassin, C. Celati, C. Antony, M.C. Boissier, J.C. Homberg, and M. Bornens. 1994. J. Cell Biol. 125:997-1013) is a microtubule-binding protein that associates in situ with a subpopulation of stable microtubules. Interaction of this protein, now called GMAP-210, for Golgi microtubule-associated protein 210, with microtubules in vitro is direct, tight and nucleotide-independent. Biochemical analysis further suggests that GMAP-210 specifically binds to microtubule ends. The full-length cDNA encoding GMAP-210 predicts a protein of 1, 979 amino acids with a very long central coiled-coil domain. Deletion analyses in vitro show that the COOH terminus of GMAP-210 binds to microtubules whereas the NH2 terminus binds to Golgi membranes. Overexpression of GMAP-210-encoding cDNA induced a dramatic enlargement of the Golgi apparatus and perturbations in the microtubule network. These effects did not occur when a mutant lacking the COOH-terminal domain was expressed. When transfected in fusion with the green fluorescent protein, the NH2-terminal domain associated with the cis-Golgi network whereas the COOH-terminal microtubule-binding domain localized at the centrosome. Altogether these data support the view that GMAP-210 serves to link the cis-Golgi network to the minus ends of centrosome-nucleated microtubules. In addition, this interaction appears essential for ensuring the proper morphology and size of the Golgi apparatus.

Effects of bilateral ablation or 6-OHDA lesion of the frontal cortex upon the behaviors induced by apomorphine and amphetamine in adult cats

The main aim of this study was to compare the effects of bilateral 6-OHDA lesion of the prefrontal, frontal and media cerebral cortex, with those of suction ablation of the same areas, upon apomorphine and amphetamine evoked behaviors. Twenty five cats were distributed in four groups: 1) 8 cats received bilateral, injection of 6-OHDA (32 micrograms per hemisphere), and the behaviors elicited by separate injection of apomorphine (2.0 mg/kg s.c.) and amphetamine (2.5 mg/kg s.c.) before and after the lesion were compared; 2) 3 cats received a unilateral injection of 6-OHDA into the cited areas and dopamine concentration on the lesioned site and the contralateral non-lesioned side were compared; 3) 8 cats had bilateral suction ablation of the cited cortical areas and the results of apomorphine and amphetamine evoked behaviors before and after ablation were compared, and 4) the effects of solvent injections and sham operations were studied in 6 additional cats. 6-OHDA lesion had scanty effects on the behaviors evoked by apomorphine and amphetamine. Only two (fear like behavior and lack of food motivation) out of 9 behaviors elicited by apomorphine were modified, while two of five behaviors elicited by amphetamine (immobility and food motivation) showed a change. On the other hand, the ablation procedure had a much wider effect on the behaviors elicited by the dopaminergic agonist drugs. All 5 behaviors evoked by amphetamine were modified, while only 4 of nine behaviors induced by apomorphine did change. These results show the importance of the interplay between dopamine and the target tissue that receive the dopaminergic fibers in the production of the behaviors evoked by parenteral injection of apomorphine and amphetamine.

Chronic variable stress induces supersensitivity of central alpha2-adrenoceptors which modulate the jaw-opening reflex in the rat

In a previous study, we found that the sensitivity of central postsynaptic alpha2-adrenoceptors which modulate, in an inhibitory way, the activity of the jaw-opening reflex (JOR) is reduced after chronic repeated stress (tail pinch) in the rat. The aim of this study was to assess the effects of exposure to a chronic variable stress regime on these adrenoceptors. To do this, the digastric electromyographic responses elicited by orofacial electrical stimulation after the intravenous administration of cumulative doses (x3.3) of the alpha2-adrenoceptor agonist, clonidine (0.1-10000 microgram/kg), were recorded. As expected, in unmanipulated control rats, clonidine inhibited the reflex, in a dose-dependent manner, until abolition (ED50 = 17.3 +/- 2.2 microgram/kg). Single tail pinch did not significantly alter the ability of clonidine to abolish the reflex. However, chronic variable stress led to an enhancement of the inhibitory effect of clonidine on the amplitude of JOR, resulting in a shift to the left of the dose-response curve in comparison with that of the control group (ED50 was reduced by 37%, P = 0.032), without affecting either the estimated maximum effect for the agonist or the slope of the inhibitory function. This in vivo result indicates that chronic variable stress leads to an increased sensitivity of central alpha2-adrenoceptors which modulate JOR, in contrast to the desensitization of these adrenoceptors found after repeated exposure to the same stressor.

Repeated tail pinch leads to desensitization of postsynaptic alpha2-adrenoceptors which modulate the jaw-opening reflex in the rat

There are few in vivo studies which have investigated the modulation of central postsynaptic alpha2-adrenoceptors functionality provoked by stress. We assessed in the rat the effects of either single or repeated tail pinch on clonidine-induced inhibition of the jaw-opening reflex (JOR) via activation of postsynaptic central alpha2-adrenoceptors. At the end of each experimental period, the progressive inhibition of the digastric electromyographic responses elicited by orofacial electrical stimulation after the i.v. administration of cumulative doses (x3.3) of clonidine (0.1-10000 microg/kg) was recorded. Single tail pinch did not significantly modify the ability of the agonist to inhibit the JOR, although there was a tendency to decrease the basal amplitude of the reflex (a 40% reduction) immediately after exposure to the single stressor. However, the dose-response curve for clonidine-induced inhibition of the JOR was clearly shifted to the right in rats exposed to repeated tail pinch (ED50 was increased by 152%, P < 0.0001) when compared with the unstressed control group, without affecting the slope of the inhibitory function and the estimated maximum effect for the agonist. These results show that repeated stress leads to a subsensitivity of the alpha2-adrenoceptors which modulate the JOR, suggesting the development of adaptive mechanisms in postsynaptic alpha2-adrenoceptors in response to stress.

Study of the behavioral effects of bilateral nucleus accumbens lesions on amphetamine and apomorphine in adult cats

The aim of the present work was to study the effects of three different types of bilateral lesions performed on the nucleus accumbens, upon the behaviors elicited in adult cats by parenteral administration of amphetamine and apomorphine, and to obtain an understanding of the functional role played by the cited structure. To this end, 10 cats received bilateral injections of 6-OHDA, 18 microg in each accumbens; 8 cats received a similar treatment with ibotenic acid (20 microg), and 11 cats were submitted to bilateral electrolytic damage. Before and after performing these lesions, in separate sessions, amphetamine (2.5 mg/kg SC) and apomorphine (2.0 mg/kg SC) were administered and their respective behaviors were compared. Besides, in a group of 10 cats, 6 of them were bilaterally injected with the above cited dose of 6-OHDA into the accumbens to determine dopamine concentration and the other four served as control. In three cats, ibotenic acid (20 microg) was unilaterally injected into the accumbens for histological analysis. The contralateral structure served as control. Finally, four cats were sham operated. The results obtained show that the accumbens in cats participates in locomotion, in stereotyped motor behaviors, and in emotional fear-like behavior. Its role in the production of motor behaviors apparently is not as important as has been reported in rodents.

NA14 is a novel nuclear autoantigen with a coiled-coil domain

The serum from a patient with Sjögren's syndrome (RM serum) was used to screen a human testis cDNA expression library. A cDNA of 865 base pairs containing the entire coding sequence for a novel protein was isolated. The 14-kDa predicted protein contains an acidic domain (amino acids 6-80) with a high frequency of heptad repeats characteristic of alpha-helices that form dimeric coiled-coil structures and an alkaline carboxyl-terminal domain (amino acids 81-119). It seems to be widely expressed, but its expression level varies depending on tissues. A protein of apparent molecular mass of 14 kDa was immunoprecipitated from cell lysates by the autoimmune serum, and it was recognized by rabbit antibodies raised to a recombinant bacterial fusion protein generated from the cDNA clone. Conventional and confocal immunofluorescence microscopy on HeLa and 3T3 cells transiently transfected with a tagged form of the protein showed numerous punctate structures scattered throughout the nucleus. This novel protein has been termed NA14 for Nuclear Autoantigen of 14 kDa.

Adenosine deaminase is a specific partner for the Grb2 isoform Grb3-3

Grb3-3 is an isoform of Grb2, thought to arise by alternative splicing, that lacks a functional SH2 domain but retains functional SH3 domains, which allow interaction with other proteins through binding to prolinerich sequences. Several evidences suggest that besides common partners for Grb2 and Grb3-3, specific targets could exist. In order to find specific partners for Grb3-3, we have screened a human cDNA library by the yeast two-hybrid system with Grb3-3 as a bait. We have identified adenosine deaminase, an enzyme involved in purine metabolism whose deficiency is associated with severe combined immunodeficiency, as a Grb3-3 binding protein that is not able to bind to Grb2. This interaction has been confirmed in vitro with GST fusion proteins and in vivo by coimmunoprecipitation experiments in NIH3T3 cells stably transfected with Grb3-3. The functional significance of this finding is discussed.

Deuterium equilibration time in infant's body water

OBJECTIVE

Equilibration time of deuterium oxide was studied in infants with no restriction of food intake, as in field work stringent conditions have to be relaxed.

SUBJECTS

Ten children recovering from marasmatic undernutrition in an Infant Nutrition Centre (CONIN).

METHODS

Four males and six females [mean 253 +/- 38 (SD) days old] exclusively bottle-fed were administered a deuterium dose in their first morning feed and followed for a 12 day period. The intercept method was used as the reference to validate the isotope equilibration time within the body water pool calculated with the plateau method. Mean equilibration was found to be 291 +/- 78 (SD) (4.85 +/- 1.3 h).

RESULTS

Total body water (TBW) values calculated with both methods differed only by 0.6%, confirming that the deuterium oxide was homogeneously distributed within the body water pool at the plateau equilibration time (4.85 +/- 1.3 h). This period is much larger than the one commonly utilized, 120-180 min (2-3 h).

CONCLUSION

Regarding TBW measurements, the intercept method provides the same information as the plateau method. However, the intercept method seems more suitable for field studies when working conditions cannot be controlled. The plateau method can be useful for specific short studies providing a faster assessment of the body water pool in infants.

[Socioeconomic variables in public health research in Mexico]

The results presented here show that there is no single variable nor a particular set of variables which are ideal to stratify the Mexican population in socioeconomic terms. This means that it is necessary to select indicators appropriate to each case, taking into consideration their specificity of meaning, their meaning with regard to the study problem and, naturally, also the objective and conceptual framework of the research, in the present case, public health research. The selection of indicators needs to be based on practical/methodological and theoretical considerations. Some of these are discussed in the present paper. Regaining the conceptual meaning of the indicators is fundamental and this is why a discussion of the concepts of social class, social strata, social inequality and poverty was undertaken. The practical/methodological criteria which were examined, include such elements as the type of variable used (dichotomic, categorical, continuous, etc.). To this end, socioeconomic variables of the National Fertility and Health Survey were analyzed, as well as the variable "poverty", which was constructed with data from the National Household Income and Expenditures Survey. As a result, outlines were drawn for a better understanding, utilization and measurement of socioeconomic indicators in public health research in Mexico.

Neurological and behavioral effects of a unilateral frontal cortical lesion in fetal kittens. II. Visual system tests, and proposing an "optimal developmental period" for lesion effects

Nine fetal kittens sustained removal of the left frontal cortex during the last third of gestation (E 43-55) and were compared to animals sustaining a similar lesion postnatally (P 8-14) as well as to intact littermates. Beginning after 6 months of age, the animals' visual field and depth perception were assessed. In addition, pupil size as well as eye alignment were measured. On two visual field tests the fetal-lesioned cats showed test dependent decrements for some angles of vision. In terms of depth perception, only the prenatal-lesioned animals showed a higher binocular threshold; they also showed ocular misalignment which may have contributed to their depth perception impairment. Moreover, these animals had a larger ipsilateral pupil. The neonatal-lesioned animals were like normal cats for all tests and measurements. We conclude that, as for the tests reported in the preceding paper, the outcome for visual related behaviors of a prenatal frontal cortical lesion in the cat is also worse than that of a similar lesion sustained neonatally. Dysgenetic anatomical changes of the visual system induced indirectly by the frontal lesion are proposed as a possible explanation for these age-at-lesion differences. Based on the present work as well as on the literature, we propose the existence of an "optimal developmental period" for the best behavioral and anatomical outcome of perinatal brain lesions. We argue that this concept fits contemporary data and can better explain the different age-at-lesion effects of brain injury across animals species than the "Kennard Principle" (or "infant-lesion effect").

[Infant nutrition in Mexico and its relationship with the utilization of maternal health services]

In addition to describing recent infant feeding patterns in Mexico, this paper attempts to answer the following questions: what are the mechanisms through which the socioeconomic level affects both infant feeding and the utilization of maternal and child health care practices? b) what is the effect of the socioeconomic level on the relationship between utilization of services and infant feeding practices? The research is based on bivariate and stratified analyses of the ENFES (1987) information. The data obtained prove that: a) even when there is a relationship between socioeconomic factors and, the utilization of services and feeding practices, the social dimension affects differently each of the two variables; b) there is a relationship between the utilization of services and infant feeding; and c) this relationship is explained, in part, by the association of both variables with socioeconomic factors. Operative strategies are proposed for the health services, as well as technical guidelines for future research in this field.

Smoking during pregnancy and lactation and its effects on breast-milk volume

The influence of cigarette smoking on daily breast-milk volume was measured by the dose-to-mother deuterium-dilution method in 10 smoking and 10 nonsmoking mothers. After administration of deuterium to the mother, breast milk and infant saliva were sampled over 14 d and analyzed by mass spectrometry. Nonsmoking mothers had a significantly greater breast-milk volume than did smokers [961 +/- 120 vs 693 +/- 110 g/d, mean +/- SD; t = 5.21, P less than 0.0001). Growth rates of the infants were also measured. Weight increase of infants of non-smoking mothers was 550 +/- 130 g whereas of infants of smoking mothers it was only 340 +/- 170 g (t = 3.11, P less than 0.01). These results indicate that cigarette smoking has a negative influence on breast-milk volume whereas the lower infant-growth rates of the smoking mothers suggest also that their breast-milk output was insufficient to support the energy requirements of their infants.

The effects of lesioning both the superior colliculus and the substantia nigra of cats on turning behavior

In twenty two adult cats, distributed in four groups, stainless steel electrodes were implanted in the superior colliculus and the substantia nigra of both sides in order: 1) to find the current intensity threshold values necessary to evoke turning behavior, and record their variations after lesion of the cited structures; 2) to study the effects of lesioning two of these structures, specifically related to the direction of turning behavior, and 3) to assess the time-course of recovery from postural asymmetry after damaging two structures involved in rotation behavior, located either in the same or in the opposite side, as well as the importance of performing these lesions simultaneously or at different periods. Three main results were observed: 1) a large proportion of lesioned cats showed an increase in threshold values necessary to evoke rotation of the implanted structures located either in the same or in the opposite side; 2) the lesions induced in a significant number of cats a transient postural asymmetry. After lesioning the superior colliculus, the direction of turning was towards the damaged hemisphere. Apomorphine injected fourteen days later demonstrated the existence of an occult asymmetry, and the direction of turning was maintained. In the substantia nigra lesioned animals, the direction of turning, was towards the non-lesioned side. Apomorphine reversed the direction of turning; 3) the cats showed a remarkable capacity to recover from the postural asymmetry produced by the lesion. This experimental series further support the hypothesis of a close functional relationship between structures of both cerebral hemispheres related to turning behavior.

The dose-to-mother method to measure milk intake in infants by deuterium dilution: a validation study

A validation study of the dose-to-mother deuterium dilution method to measure breast-milk intake has been carried out on ten infants from a Nutrition Recovery Centre in Santiago, Chile. Formula milk labelled with exponentially decreasing doses of deuterium oxide represented milk from a 'pseudo mother' of these exclusively bottle-fed infants. Unlabelled formula represented milk from other sources. Deuterium levels in the infants' body water were measured on saliva samples by mass spectroscopy. The data were fitted in a two-compartment steady-state model of the mother-child system to estimate the flow of labelled water from the 'mother' to the infant and the 'mother' and infant's water elimination constants. A dose-to-child experiment was also carried out on each infant to determine the deuterium dilution space and total daily water intake. Total and labelled water flows from deuterium dilution were used to calculate total, labelled and unlabelled formula milk intakes which were compared to the same quantities measured by bottle weighing. Water elimination constants calculated from the dose-to-mother experiments underestimated by 17 per cent the initially set mother constant and overestimated by 21 per cent the infant constants calculated from the dose-to-child experiments. Rate constants, however, have little effect on the estimated water flows so that there was good agreement between values from deuterium dilution and from direct weighing. Mean (SD) total formula, labelled formula and unlabelled formula intakes were 865 (129) g/d, 417 (74) g/d and 448 (106) g/d, respectively, when measured by deuterium dilution, compared with 856 (116) g/d, 414 (71) g/d and 441 (68) g/d when measured by direct weighing. The mean per cent differences were 1.1 per cent, 0.7 per cent and 1.6 per cent and the mean absolute differences for individuals, 4.3 (1.9) per cent, 4.8 (3.1) per cent and 9.7 (6.6) per cent, respectively.

[Prenatal care in Latin America]

Available data on the coverage of prenatal care in Latin America were reviewed. In recent years, only Bolivia had a coverage of prenatal care of less than 50 per cent. More than 90 per cent of pregnant women received prenatal care in Chile, Cuba, the Dominican Republic, and Puerto Rico. Prenatal care increased between the 1970 and 1980 in the Dominican Republic, Ecuador, Guatemala, Honduras, Mexico, and Peru. The coverage of prenatal care decreased in Bolivia and Colombia. The mean number of visits increased in Cuba and Puerto Rico. The increase of prenatal care in Guatemala and Honduras is due to increased care by traditional birth attendants, compared to the role of health care institutions. We compared the more recent data on tetanus immunization of pregnant women to the more recent data on prenatal care. The rates of tetanus immunization are always lower than the rates of prenatal care attendance, except in Costa Rica. The rates of tetanus immunization was less than half as compared to the rates of prenatal care in Bolivia, Guatemala, and Peru. To improve the content of prenatal care should be an objective complementary to the increase of the number of attending women.

[Advances in public health investigation. 5 years' work of the Center for Research in Public Health, 1984-1989]

Five years after the creation of the Center for Public Health Research (SPHR), this essay reviews its origins and evolution and points to the challenges it will face in the future. The seven basic organizational principles underlying the academic development of the Center are described. In the quantitative aspect, the institution's growth is reflected in the rapidly increasing trend in the number of researchers, projects and scientific publications, as well as in the volume of the external financial resources received. In the qualitative aspect, the article highlights the ever growing number of themes approached by the seven lines of research, the elaboration of conceptual models, the creation of data bases and the methodological development. Among the most important challenges of the CPHR in the future are: (1) solving existing organizational problems; (2) building links with the decision makers and (3) establishing an equilibrium between relevance and excellence in public health research.

[Liquid intake measurement based on deuterium dilution]

Studies were carried out to ascertain methodological aspects and the validity of the deuterium dilution technique to determine maternal milk intake. Our study, conducted in 2-3 months-old normal infants, indicated that isotopic equilibrium is reached 6-8 hours after administration of an initial dose of 16.5% deuterium solution. Comparisons of liquid intake measured on a group of infants recovering from marasmic undernutrition, by the isotopic method and by direct recording of bottle-fed milk, revealed a good correlation of the respective values when the infants' body water was estimated using the Friis-Hansen formula. These findings suggest that the deuterium dilution technique is a valuable alternative to the current methods used to the measurement of maternal milk intake.

Output pathway for turning behavior from the neostriatum and substantia nigra in cats

The goal of the present work was to study the output pathway of the information for turning behavior originating in the striatum and coursing through the substantia nigra pars reticulata (SNR). In 45 adult cats distributed in 3 groups, Ni-Cr electrodes were implanted in the caudate nucleus and substantia nigra pars reticulata and depending on the animal group in the superior colliculus (SC), nucleus ventralis lateralis/nucleus ventralis medialis (VL/VM) complex or nucleus tegmenti pedunculopontinus (TPP) of one cerebral hemisphere. The threshold current required to evoke turning behavior was determined in each animal for each implantation site. An electrolytic lesion of the superior colliculus, the VL/VM complex or the nucleus tegmenti pedunculopontinus was carried out in each group of cats. The effects of the lesions on behavior and on the electrical threshold currents were determined and compared with the prelesion values. Finally the extent of the lesions and electrode positions were analyzed. The results show that the substantia nigra pars reticulata is the structure with the lowest thresholds for turning and that the superior colliculus appears to be more relevant for carrying the information for turning than either the VL/VM complex or the nucleus tegmenti pedunculopontinus.

Extracellular unit responses in the pulvinar-lateral posterior complex of the cat through electrical stimulation of substantia nigra reticulata and lateralis

Extracellular single-unit responses of neurons in the ipsilateral pulvinar-lateral posterior complex were recorded in 10 encéphale isolé cats with stimulating electrodes implanted in the substantia nigra pars reticulata and pars lateralis. Fifteen percent of 101 pulvinar-lateral posterior complex thalamic neurons increased their spike discharges when the substantia nigra was stimulated and none decreased its activity. The excitatory effect of this stimulation is discussed in relation to the eventual excitatory or inhibitory character of the efferent projection from the substantia nigra pars reticulata and lateralis to the pulvinar-lateral posterior complex.

Study of the morphological, electrophysiological and behavioral effects of unilateral kainic acid injection into the cat's substantia nigra

Morphological, electrophysiological and behavioral studies were carried out in cats after unilateral kainic acid injection in the substantia nigra. A forced contralateral head turning and compulsive circling was observed after surgery. Fifteen days after, when asymmetry disappeared, apomorphine induced an ipsilateral head and body turning, that was blocked by haloperidol. The percentage of turning, after electrical stimulation in the superior colliculus or pulvinar-lateralis posterior complex, was affected by substantia nigra lesion. This work demonstrates that the nigro-pulvinar-lateral posterior and the nigrotectal projection modulate the capability of electrical stimulation of the target structures to elicit turning, and after unilateral substantia nigra lesion, two opposite directions of asymmetry appear, which are time-dependent and modulated by different neurotransmitters.

Evidence for a nigro-pulvinar-lateralis posterior complex projection in the cat using horseradish peroxidase neuronal retrograde technique

The possible existence of a direct projection from the substantia nigra to the pulvinar-lateral posterior complex (Pul-LP) was investigated in the cat by using the horseradish peroxidase technique. In particular horseradish peroxidase was injected in the Pul-LP of 8 animals, either unilaterally or bilaterally. Tissue sections obtained from the cat's brain 24-48 hrs. after injection were prepared according to Mesulam's method as slightly modified by the authors. Retrogradelly labelled neurons were observed in substantia nigra pars lateralis and reliculata ipsilaterally to the injected pulvinar-lateral posterior complex. A small number of labelled cells were also found in the contralateral substantia nigra. These findings demonstrate the existence of a close connection between two system which are involved in turning behavior: the nigrostriatal and the pulvinar-lateral posterior complex-superior colliculus.

Simultaneous unitary neuronal activity in both superior colliculi and its relation to eye movements in the cat

The analysis of simultaneous unitary neuronal activity related to eye movement and recorded in both superior colliculi has shown a mirror-functioning image. Increase of the frequency discharge in a collicular unit, was associated with a decrease of the frequency discharge in the contralateral superior colliculus unit. This unitary neuronal reciprocal behaviour was observed each time a horizontal or oblique eye movement was produced. It is possible that this reciprocal functioning between neurones in both superior colliculi could exert an important influence on oculomotor brainstem structures. These results give a better idea of the role played by both superior colliculi in the control of conjugate eye movements.

Electrophysiological projections of pulvinar-lateralis posterior complex (P-LP) upon superior colliculus units in the cat

The effect of Pulvinar-Lateral Posterior (P-LP) electrical stimulation on superior colliculus unitary responses and eye movements is analyzed in 17 encéphale isolé cats. Twelve of them were curarized. Out of a total of 190 recorded units, 117 were localized in the superior colliculus and 73 units in the Mesencephalic Reticular Formation (MRF) below the superior colliculus. Thirty eight per cent (n = 45) of the collicular units modified their discharge frequency when the ipsilateral P-LP was electrically stimulated. The current intensity thresholds of transynaptic activation had a range between 0.5 and 2.0 mA. Most of the orthodromic responses were produced by ipsilateral P-LP stimulation and were localized in the intermediate and deep layers of the superior colliculus. Three types of responses were obtained: short latency responses between 2 and 10 ms (57%); intermediate latency responses between 15 and 40 ms (29%), and long latency responses between 50 and 200 ms (14%). Thirty one per cent (n = 18) of the units recorded in the MRF responded to P-LP stimulation with 10 ms pulse-trains duration. In the MRF 3 types of responses were observed: 1) a decrease or blockade in the resting discharge during 20 to 100 ms after stimulation (20%); simple responses with a latency between 25 and 150 ms (40%), and complex responses with an early response and a latency between 15-40 ms, and a late response with a latency between 150 and 200 ms (40%).(ABSTRACT TRUNCATED AT 250 WORDS)

Isotope dilution measurement of breast-milk production in Chilean urban mothers

A heavy-water dilution technique has been used to measure mean daily breast-milk output in a group of nursing mothers from an urban community in Santiago, Chile. Infant milk intake was found to correlate significantly with weight (r = 0.646, P less than 0.005) and with weight-for-age (r = 0.640, P less than 0.005), but a much stronger and highly significant correlation was found with infant birth-weight (r = 0.802, P less than 0.001). Milk output was also found to depend on the mother's nutritional status at the beginning of pregnancy and was significantly higher in overweight mothers. An even more marked difference was obtained if mothers were divided into two subgroups, above and below normal, according to their weight-for-height values at the first antenatal check-up (x+ = 1148.1 ml/d, x- = 814.2 ml/d, P less than 0.02). Relationships between milk output and duration of lactation and parity were also apparent from the study but the latter was probably mediated through maternal nutritional status.

Correlation between pulvinar-lateralis posterior complex unit activity and eye movements in the cat

In 15 encéphale isolé cats, 130 units were recorded in the pulvinar-lateralis posterior complex (P-LP); 19 units responded in relation to horizontal eye movements (15%), 9 of which discharged when ipsiversive movements were recorded and the remaining 10 to contraversive movements. Three units discharged during spontaneous nystagnoid eye movement. All units always responded after initiation of the eye movement, with a latency range between 50 and 250 ms. The eye movement-related units were preferentially located (80%) in the border between the pulvinar and the lateralis posterior complex. Our results show the presence of eye movement-related units in the cat's P-LP, and their probable participation in ocular motility.

Rotational behavior in the cat induced by electrical stimulation of the pulvinar-lateralis posterior nucleus complex: role of the cholinergic system

We studied the involvement of the cholinergic system in the contralateral head-eye-body turning induced in the cat through stimulation of the pulvinar-lateralis posterior nucleus complex (P-LP). In 17 cats through a cannula aimed at the P-LP, agonists and antagonists of the cholinergic system were injected. The electrical activity of the P-LP could be recorded through the same cannula or through electrodes attached to it. In addition, electrodes were implanted ipsilaterally in the dorsal hippocampus, caudate nucleus, amygdala, and superior colliculus to record through them and through one screw placed on the skull the electrical activity of those structures and of the cortical P-LP projection. Seven days after surgery, carbachol, an agonist of the cholinergic system was injected in the P-LP, and the behavior and electrical activity of the unrestrained cat (previously accustomed to a plastic cage) were recorded. A control volume of 0.9% NaCl was always injected previously. The usual drug volume injected was 1 microliter; occasionally, 2 microliter were injected. Weekly or biweekly sessions were conducted to determine (a) the threshold for cholinergic activation, (b) the threshold for turning behavior, (c) the blocking effect of local atropine sulfate injected previously, (d) the effect of haloperidol previously injected (locally or systemically), and (e) the effect of dioxolane, an exclusive muscarinic agonist. In 14 of 17 cats, contralateral turning behavior was evoked by carbachol. In two of the three cats that did not respond to carbachol, dioxolane induced turning. The effect of dioxolane was similar to that of carbachol when tried in five cats. Besides turning behavior, carbachol produced numerous symptoms due to cholinergic activation. Atropine blocked the rotational effect of carbachol in all cats, and haloperidol blocked it in 68% of them. Electrolytic coagulation of the dorsal hippocampus surrounding the P-LP did not disturb the effects induced by carbachol. These experiments show that both systems of the P-LP, cholinergic and catecholaminergic, are involved in the contralateral turning. We conclude that the effect induced by carbachol is due to activation of muscarinic receptors because it is totally blocked by local atropine sulfate and is reproduced by dioxolane, an exclusive muscarinic agonist.