Quantitative and qualitative control of antineoplastic preparations: Gravimetry versus HPLC.

This article compares gravimetry vs. high-performance liquid chromatography (HPLC) as quality control (QC) methods for paclitaxel, docetaxel and oxaliplatin preparations. We aimed at assessing the preparation method reliability in our hospital, evaluating compounding accuracy and estimating the influence of personnel training and standardized homogenization on compounding accuracy. Agreement, correlation, concordance, accuracy and precision between methods were evaluated for each drug. Conforming preparation percentages (CPs) at different tolerance limits (TLs) and compounding accuracy were calculated for each method and drug. Compounding accuracy was compared before and after personnel training and standardized homogenization implantation. SPSS v 20.0 and Ene v 2.0 were used. A total of 222 samples (58 docetaxel, 95 paclitaxel and 69 oxaliplatin) were analyzed. Gravimetry and HPLC are comparable methods. Overall CP was 81% for gravimetry at 10% TL and 85% for HPLC at 15% TL. Compounding accuracy is shown to be good for all methods and drugs. Homogenization optimization and personnel training make measurements more accurate for docetaxel and paclitaxel HPLC, but seem to worsen accuracy for docetaxel gravimetry. Gravimetry has shown to be a good alternative to HPLC for routine QC. Coupling with electronic methods should be considered in the future.

Mothers and offspring: The rabbit as a model system in the study of mammalian maternal behavior and sibling interactions.

UNLABELLED: This article is part of a Special Issue "Parental Care". Jay Rosenblatt effectively promoted research on rabbit maternal behavior through his interaction with colleagues in Mexico. Here we review the activities of pregnant and lactating rabbits (Oryctolagus cuniculus), their neuro-hormonal regulation, and the synchronization of behavior between mother and kits. Changing concentrations of estradiol, progesterone, and prolactin throughout gestation regulate nest-building (digging, straw-carrying, fur-pulling) and prime the mother's brain to respond to the newborn. Nursing is the only mother-young contact throughout lactation. It happens once/day, inside the nest, with ca. 24h periodicity, and lasts around 3min. Periodicity and duration of nursing depend on a threshold of suckling as procedures reducing the amount of nipple stimulation interfere with the temporal aspects of nursing, though not with the doe's maternal motivation. Synchronization between mother and kits, critical for nursing, relies on: a) the production of pheromonal cues which guide the young to the mother's nipples for suckling; b) an endogenous circadian rhythm of anticipatory activity in the young, present since birth. Milk intake entrains the kits' locomotor behavior, corticosterone secretion, and the activity of several brain structures. Sibling interactions within the huddle, largely determined by body mass at birth, are important for: a) maintaining body temperature; b) ensuring normal neuromotor and social development. Suckling maintains nursing behavior past the period of abundant milk production but abrupt and efficient weaning occurs in concurrently pregnant-lactating does by unknown factors. CONCLUSION: female rabbits have evolved a reproductive strategy largely dissociating maternal care from maternal presence, whose multifactorial regulation warrants future investigations.

Hypothyroidism affects differentially the cell size of epithelial cells among oviductal regions of rabbits.

Oviductal regions show particular histological characteristics and functions. Tubal pathologies and hypothyroidism are related to primary and secondary infertility. The impact of hypothyroidism on the histological characteristics of oviductal regions has been scarcely studied. Our aim was to analyse the histological characteristics of oviductal regions in control and hypothyroid rabbits. Hypothyroidism was induced by oral administration of methimazole (MMI) for 30 days. For both groups, serum concentrations of thyroid and gonadal hormones were determined. Sections of oviductal regions were stained with the Masson's trichrome technique to analyse both epithelial and smooth muscle layers. The percentage of proliferative epithelial cells (anti-Ki67) in diverse oviductal regions was also quantified. Data were compared with Student t-test, Mann-Whitney U-test, or Fischer's test. In comparison with the control group, the hypothyroid group showed: (i) a low concentration of T3 and T4, but a high level of TSH; (ii) similar values of serum estradiol, progesterone and testosterone; (iii) a large size of ciliated cells in the ampulla (AMP), isthmus (IST) and utero-tubal junction (UTJ); (iv) a large size of secretory cells in the IST region; (v) a low percentage of proliferative secretory cells in the fimbria-infundibulum (FIM-INF) region; and (vi) a similar thickness of the smooth muscle layer and the cross-sectional area in the AMP and IST regions. Modifications in the size of the oviductal epithelium in hypothyroid rabbits could be related to changes in the cell metabolism that may impact on the reproductive functions achieved by oviduct.

Sugared water consumption by adult offspring of mothers fed a protein-restricted diet during pregnancy results in increased offspring adiposity: the second hit effect.

Poor maternal nutrition predisposes offspring to metabolic disease. This predisposition is modified by various postnatal factors. We hypothesised that coupled to the initial effects of developmental programming due to a maternal low-protein diet, a second hit resulting from increased offspring postnatal sugar consumption would lead to additional changes in metabolism and adipose tissue function. The objective of the present study was to determine the effects of sugared water consumption (5% sucrose in the drinking-water) on adult offspring adiposity as a 'second hit' following exposure to maternal protein restriction during pregnancy. We studied four offspring groups: (1) offspring of mothers fed the control diet (C); (2) offspring of mothers fed the restricted protein diet (R); (3) offspring of control mothers that drank sugared water (C-S); (4) offspring of restricted mothers that drank sugared water (R-S). Maternal diet in pregnancy was considered the first factor and sugared water consumption as the second factor - the second hit. Body weight and total energy consumption, before and after sugared water consumption, were similar in all the groups. Sugared water consumption increased TAG, insulin and cholesterol concentrations in both the sexes of the C-S and R-S offspring. Sugared water consumption increased leptin concentrations in the R-S females and males but not in the R offspring. There was also an interaction between sugared water and maternal diet in males. Sugared water consumption increased adipocyte size and adiposity index in both females and males, but the interaction with maternal diet was observed only in females. Adiposity index and plasma leptin concentrations were positively correlated in both the sexes. The present study shows that a second hit during adulthood can amplify the effects of higher adiposity arising due to poor maternal pregnancy diet in an offspring sex dependent fashion.

Pediatric living donor liver transplantation: results of laparoscopic vs. open graft removal. / Trasplante hepático pediátrico de donante vivo, resultados en función de extracción del injerto por laparotomía vs. laparoscopia.

INTRODUCTION: Laparoscopic graft removal for pediatric living donor liver transplantation (PLDLT) reduces morbidity and surgical aggressiveness for the donor. It is important to assess whether the approach used for removal purposes compromises implantation. The objective of this study was to analyze PLDLT progression in children according to whether the graft had been removed laparoscopically or through open surgery. MATERIAL AND METHODS: A retrospective, analytical cohort study of PLDLTs carried out in our institution from 2009 to 2020 was carried out. RESULTS: Transplantation was performed in 14 patients, with a median age of 34.5 (R: 6-187) months. In 6 donors (42%), graft removal was conducted laparoscopically. In 1 donor (7%), removal was initiated laparoscopically, but conversion was required. This patient was included within the open surgery group, which consisted of 8 (58%) donors. No differences were found in terms of operating times, ICU stay, hospital stay, complications during admission, or complications post-admission in the recipient. The surgical approach did not compromise the length of the vessels to be anastomosed in any graft, and it added no extra difficulty to implantation. No differences were found in terms of removal times or hospital stay for the donor. Only 1 donor from the laparoscopy group required re-intervention due to bleeding following port insertion. CONCLUSION: PLDLT patients had similar results regardless of the removal approach used, which did not compromise the structures of the graft to be anastomosed, or add any extra difficulty to implantation.

INTRODUCCION: La extracción laparoscópica del injerto para el trasplante hepático pediátrico de donante vivo (THPDV) es una herramienta que reduce la morbilidad y agresividad quirúrgica en el donante. Es importante estudiar si la vía de extracción compromete el implante. El objetivo del estudio es analizar la evolución del THPDV en el niño en función de si el injerto fue extraído por vía abierta o laparoscopia. MATERIAL Y METODOS: Estudio de cohortes retrospectivo y analítico de los THPDV realizados entre 2009 y 2020 en nuestro centro. RESULTADOS: Se trasplantaron 14 pacientes, con edad mediana de 34,5 (R: 6-187) meses. En 6 donantes (42%) se realizó la extracción del injerto vía laparoscópica. En un donante se inició la extracción por laparoscopia, pero fue necesaria la conversión (7%), esté se clasificó en el grupo de laparotomía, compuesta por 8 (58%) donantes. No se encontraron diferencias en el tiempo quirúrgico, en los días en la unidad de cuidados intensivos, en la estancia hospitalaria, en las complicaciones durante el ingreso ni en las complicaciones postingreso en el receptor. El abordaje quirúrgico no comprometió en ningún injerto la longitud de los vasos a anastomosar, sin suponer una dificultad en el implante. No se evidenciaron diferencias en el tiempo de extracción ni en los días de hospitalización del donante. Solo un donante del grupo de laparoscopia precisó reintervención por sangrado de la incisión de un trocar. CONCLUSION: Los pacientes con THPDV presentan resultados similares, independientemente de la vía de extracción del injerto. La vía de abordaje no comprometió las estructuras del injerto a anastomosar, ni dificultó el momento del implante.

New effective treatment regimen for children infected with a double-resistant Helicobacter pylori strain.

BACKGROUND: The increasing number of pediatric patients infected with multiresistant Helicobacter pylori strains calls for evaluation of treatment regimens. Second-line antibiotics such as tetracycline or quinolones are not licensed for children. Because in vivo resistance to metronidazole may be overcome in vivo by a high dose and prolonged intake, we evaluated the eradication rate and side effects of a high-dose triple therapy in pediatric patients with culture-proven double resistance. PATIENTS AND METHODS: In this open multicentre trial, 62 children (<18 years, body weight >15 kg) infected with an H pylori strain resistant to metronidazole and clarithromycin were treated according to body weight classes with amoxicillin (∼ 75 mg/kg/day), metronidazole (∼ 25 mg/kg/day) and esomeprazole (∼ 1.5 mg/kg/day) for 2 weeks. Adherence and adverse events were assessed by a 2-week diary and telephone interviews at days 7 and 14 of treatment. Primary outcome was a negative C-urea breath test after 6 weeks. RESULTS: Of 62 patients, 5 were lost to follow-up, 12 were nonadherent, and 45 treated per protocol. Eradication rates were 66% (41/62) [confidence interval 54-78] (intention to treat) and 73% (33/45) [confidence interval 60-86] (per protocol). Success of treatment was not related to dose per kilogram body weight. Mild to moderate adverse events were reported by 21 patients, including nausea (10.8%), diarrhoea (8.9%), vomiting (7.1%), abdominal pain (5.4%), and headache (3.6%), and led to discontinuation in 1 child. CONCLUSION: High-dose amoxicillin, metronidazole, and esomeprazole for 2 weeks is a good treatment option in children infected with a double resistant H pylori strain.

Eosinophilic esophagitis, celiac disease, and immunoglobulin E-mediated allergy in a 2-year-old child.

Celiac disease, eosinophilic esophagitis, and urticaria are 3 manifestations of food allergy with different pathogenic mechanisms. We report the case of a 2-year-old child with digestive symptoms, slow growth, and severe asthma. The results of skin prick tests were positive to several foods. Endoscopy revealed eosinophilic esophagitis and celiac disease. Treatment consisted of a gluten-free diet and a 1-month course of oral corticosteroids. Endoscopy and biopsy findings were normal at 5 years of age. A gluten-free diet is the basis of treatment of celiac disease, but the role of an elimination diet in eosinophilic esophagitis is not well established. Our patient also developed urticaria when exposed to milk and egg.We present, to our knowledge, the first report of a patient with celiac disease, eosinophilic esophagitis, and immediate-type immunoglobulin E-mediated food allergy.

Utility of preoperative polymerase chain reaction testing during SARS-CoV-2 pandemic: The challenge of evolving incidence.

INTRODUCTION: Due to its high transmissibility, measures aimed at reducing the spread of SARS CoV2 have become mandatory. Different organizations have recommended performing polymerase chain reaction tests (PCR) as part of the preoperative screening of surgical patients. We aimed to determine the performance of PCR testing to detect asymptomatic carriers. METHODS: Observational study carried out at a tertiary care center. We compared the results of preoperative real-time reverse-transcription-PCR test (RT-PCR) performed on a cohort of patients pending surgery with the results we would have expected assuming the epidemiological data released by government offices. RESULTS: We registered no positives in the 2,722 preoperative RT-PCR tests performed in our health care area between epidemiological Weeks 18 to 21, meaning a cumulative incidence trending to zero. Assuming public epidemiological data, the probabilistic projection of potential asymptomatic individuals ranged from 0.27 × 10e-4 (according to official data of new cases diagnosed by PCR) to 4.69 × 10e-4 if we assumed cases confirmed by IgG test in our province. Assuming a RT-PCR sensitivity of 95%, to obtain a positive result we should perform 38,461 and 2,028 tests respectively. CONCLUSIONS: In scenarios of very low prevalence and despite high sensitivity scores, indiscriminate preoperative RT-PCR screening is of a questionable effectiveness for detecting asymptomatic carriers. Our findings evidence the difficulty of establishing reliable predictive models for the episodic and rapidly evolving incidence of infections such as has characterized the SARS CoV2 pandemic.

Utility of preoperative polymerase chain reaction testing during SARS-CoV-2 pandemic: The challenge of evolving incidence. / Utilidad de la prueba de reacción en cadena de la polimerasa preoperatoria durante la pandemia por SARS-CoV-2: el desafío de la incidencia cambiante.

INTRODUCTION: Due to its high transmissibility, measures aimed at reducing the spread of SARS CoV2 have become mandatory. Different organizations have recommended performing polymerase chain reaction tests (PCR) as part of the preoperative screening of surgical patients. We aimed to determine the performance of PCR testing to detect asymptomatic carriers. METHODS: Observational study carried out at a tertiary care center. We compared the results of preoperative real-time reverse-transcription-PCR test (RT-PCR) performed on a cohort of patients pending surgery with the results we would have expected assuming the epidemiological data released by government offices. RESULTS: We registered no positives in the 2,722 preoperative RT-PCR tests performed in our health care area between epidemiological Weeks 18 to 21, meaning a cumulative incidence trending to zero. Assuming public epidemiological data, the probabilistic projection of potential asymptomatic individuals ranged from 0.27*10e -4 (according to official data of new cases diagnosed by PCR) to 4.69*10e -4 if we assumed cases confirmed by IgG test in our province. Assuming a RT-PCR sensitivity of 95%, to obtain a positive result we should perform 38,461 and 2,028 tests respectively. CONCLUSIONS: In scenarios of very low prevalence and despite high sensitivity scores, indiscriminate preoperative RT-PCR screening is of a questionable effectiveness for detecting asymptomatic carriers. Our findings evidence the difficulty of establishing reliable predictive models for the episodic and rapidly evolving incidence of infections such as has characterized the SARS CoV2 pandemic.

Chronic stress and high sucrose intake cause distinctive morphometric effects in the adrenal glands of post-weaned rats.

We investigated the effects of chronic stress combined with high sucrose intake on the morphology of the adrenal glands in young rats. Male Wistar rats were fed a standard chow diet and allocated into control (C; tap water), chronic restraint stress (St), 30% sucrose diet (S30) and 30% sucrose diet + chronic restraint stress (S30 + St) groups. St consisted of 1 h daily sessions, 5 days/week for 4 weeks. Chronic stress reduced the thickness of the zona glomerulosa (ZG) and zona fasciculata (ZF) in both right and left glands; the thickness of the zona reticularis (ZR) was increased in the right gland. Cell density was greater in the ZF and medulla of both right and left glands, whereas cell density increased in the ZR of only the left gland. The percentage of small cells was lower in the ZG, whereas more large cells were found in the left gland. A similar result was obtained for the ZF, ZR and medulla in both right and left glands. Chronic stress increased the area covered by blood vessels in the ZR of the right gland, but decreased the area in the ZR of the left gland. The area covered by blood vessels was reduced in the medulla of both right and left glands in rats subjected to chronic stress. Infiltration of immune cells was increased by chronic stress in all layers of the cortex of the left gland, but was reduced in the medulla of the right gland. A high sucrose diet reduced the thickness of the medulla in the left gland. Cell proliferation increased in the ZG of the right gland and the weight of the right adrenal gland increased. Reduced cell proliferation in the ZG of the left gland was associated with a reduction in the area covered by blood vessels. In addition, the area covered by blood vessels decreased in the medulla of both glands. Our findings demonstrate that exposure to chronic stress during early life causes morphometric changes in adrenal glands.

Spinal cord neuronal components involved in the reflex activity of female rat pubococcygeus motoneurons.

Evoked EMG reflex activity from the pubococcygeus muscle of female Wistar rats has been reported, but has not been carefully analyzed. Here, we studied this reflex activity through mechanical stimulation of the clitoris, perigenital skin, caudal vagina and foot, all of which produced bilateral reflex multiunit electromyographic (MEMG) tonic "on" activity and displayed a rapid adaptation. However, deep vagina and cervical stimulation did not modify MEMG baseline activity even if it was combined with clitoris, perigenital skin and foot stimulation. Electrical stimulation of the dorsal nerve of the clitoris produced bilateral MEMG activity that when recorded at fast sweep speed, it was possible to observe that the ipsilateral response had an 8 ms latency, while the contralateral response had a 10 ms latency. These data suggest that bilateral reflex activation of pubococcygeus muscle motoneurons is produced by several sensory sources in which a specialized neural circuitry of afferent and efferent components and several spinal cord interneurons are involved. This is in accordance with the multi functionality of this muscle in reproductive and behavioral processes.

Characterization of antihistamine-human serum protein interactions by capillary electrophoresis.

An important topic in the drug discovery and development process is the role of drug binding to plasma proteins. In this paper the characterization of the interaction between antihistamines (cationic drugs) towards human serum albumin (HSA) and alpha(1)-acid glycoprotein (AGP) under physiological conditions by capillary electrophoresis-frontal analysis is presented. Furthermore, the binding of these drugs to all plasma proteins is evaluated by using ultrafiltration and capillary electrophoresis. Antihistamines present a wide-ranging behaviour with respect to their affinities towards plasma proteins. Orphenadrine, phenindamine, tripelenamine and tripolidine principally bind to HSA; carbinoxamine, dimetindene and etintidine principally bind to AGP; brompheniramine, chlorpheniramine and ranitidine present an important binding to lipoproteins and/or globulins and finally, chlorcyclizine, cinarizine, cyclizine, doxylamine, hydroxyzine, perphenazine and terfenadine do not bind to lipoproteins and/or globulins but bind to HSA and AGP in different extension. The interaction of antihistamines with HSA is determined by the hydrophobicity (direct relationship) and the polar surface area (indirect relationship) of the compounds. The steric parameters and hydrogen bonding character of compounds seems to be related with the binding of antihistamines to AGP. The antihistamine-HSA affinity constants were evaluated and the K(1) values ranged from 7 x 10(2)M(-1) (for doxylamine) to 4 x 10(4)M(-1) (for phenindamine).

[Therapeutic education in asthma management]. / La educación terapéutica en el asma.

All guidelines, protocols and recommendations underline the importance of therapeutic education as a key element in asthma management and control. Considerable evidence supports the efficacy and effectiveness of this measure. Health personnel, as well as patients and their parents, can and should be educated with two main objectives: to achieve the best possible quality of life and to allow self control of the disease. These goals can be attained through an educational process that should be individually tailored, continuous, progressive, dynamic, and sequential. The process poses more than a few difficulties involving patients, health professionals, and the health systems. Knowledge of the various psychological factors that can be present in asthmatic patients, as well as the factors related to the highly prevalent phenomenon of non-adherence, is essential. Awareness of the factors influencing physician-patient-family communication is also highly important to achieve the objectives set in therapeutic education. The educational process helps knowledge and abilities to be acquired and allows attitudes and beliefs to be modified. Patients and caregivers should be provided with an individual written action plan based on symptoms and/or forced expiratory volume in 1 second. Periodic follow-up visits are also required.

Hypothyroidism Induces a Moderate Steatohepatitis Accompanied by Liver Regeneration, Mast Cells Infiltration, and Changes in the Expression of the Farnesoid X Receptor.

Hypothyroidism is associated with the development of non-alcoholic steatohepatitis, but cellular mechanisms have been scarcely analyzed. Thyroid hormones regulate the synthesis and secretion of bile acids that are endogenous ligands of the farnesoid receptor (FXRα), which have been involved in the development of non-alcoholic steatohepatitis. However, the relationship between thyroid hormones and FXRα expression in the liver is yet unknown. Control (n=6) and methimazole-induced hypothyroid (n=6) female rabbits were used to evaluate the amount of lipids and glycogen, vascularization, hepatocytes proliferation, immune cells infiltration, and expression of FXRα. Student-t or Mann-Whitney U tests were carried out to determine significant differences. Hypothyroidism induced steatosis, glycogen loss, fibrosis, and a minor vascularization in the liver. In contrast, hypothyroidism increased the proliferation of hepatocytes and the infiltration of mast cells, but did not modify the number of immune cells into sinusoids. These changes were associated with a minor anti-FXRα immunoreactivity of periportal hepatocytes and pericentral immune cells. Our results suggest that hypothyroidism induces a moderate non-alcoholic steatohepatitis, alllowing the hepatic regeneration. The FXRα may be involved in the development of non-alcoholic steatohepatitis in hypothyroid subjects.

Chiral separation of oxprenolol by affinity electrokinetic chromatography-partial filling technique using human serum albumin as chiral selector.

The intrinsic characteristics of capillary electrophoresis have made this technique a powerful tool in the chiral separation field. The present paper deals with the enantiomeric separation of oxprenolol enantiomers by affinity electrokinetic chromatography-partial filling technique using human serum albumin (HSA) as chiral selector. Several experimental conditions and variables affecting the separation such as pH, HSA concentration and plug length, background electrolyte concentration, temperature and voltage were studied. Baseline separation of oxprenolol enantiomers was obtained in less than 8 min under the following selected conditions: electrophoretic buffer composed of 50 mM Tris-(hydroximethyl)-aminomethane (Tris) at pH 8.5; 190 microM HSA solution applied at 50 mbar for 225 s as chiral selector; oxprenolol samples contained 190 microM HSA solution injected hydrodynamically at 30 mbar for 2s and the electrophoretic runs performed at 30 degrees C applying 15 kV voltage. The proposed methodology was applied for the analysis of two pharmaceutical preparations. Resolution, accuracy, reproducibility, speed and cost of the proposed method make it suitable for quality control of the enantiomeric composition of oxprenolol in drugs. The results show that a different affinity between oxprenolol enantiomers and HSA exists and can contribute to the pharmacokinetic differentiation of these enantiomers.

Differences and similarities in the perception of everyday odors. A Japanese-German cross-cultural study.

To investigate the influence of experience on odor perception the responses of 40 Japanese and 44 age-matched German women to everyday odorants were compared. Subjects were presented with six 'Japanese,' six 'European' and six 'international' odorants and asked to rate them on intensity, familiarity, pleasantness and edibility, and to describe associations elicited by them, and if possible to name them. Significant differences were found between the two populations on all measures, with a close association of pleasantness ratings and edibility judgments suggesting the particular influence of eating habits on odor perception. Positive correlations between familiarity and pleasantness, strength of hedonic judgment and intensity, and familiarity and intensity were also found in both groups and for most individuals. The generality of these findings was supported by the results obtained from testing 40 Mexican women with the same odorants.

Visceral and postural reflexes evoked by genital stimulation in urethane-anesthetized female rats.

The present study describes several muscular reflexes produced by genital stimulation, the nerves that subserve them, and the visceral and postural effects induced by these reflexes. Electrical stimulation of the iliococcygeus (ic) and pubococcygeus (pc) (striated) muscles produced movement of the vaginal orifice and wall, membranous urethra, tail and pelvis. Electrical stimulation of the psoas major (pm) or iliacus (i) (striated) muscles produced movements of the lumbar vertebrae and extension of the ipsilateral hindlimb. Sensory mechanostimulation elicited responses of these muscles as follows: stimulation of the perineal skin, clitoral sheath or distal vagina produced reflex contraction of the ic and pc muscles. Stimulation of the cervix produced reflex contraction of the pm and i muscles and also blocked the above reflex contraction of the ic and pc muscles. Both the cervical stimulation-induced blockage of the ic and pc reflex response, and the cervical stimulation-induced activation of pm and i muscles was prevented by bilateral transection of the viscerocutaneous branch of the pelvic nerve. Based on the above observations, it is proposed that stimulation of the vaginal surface of the cervix resulting from penile intromission and/or seminal plug deposition during mating behavior in the rat may reflexively active pm and i, thereby contributing to the hindleg postural rigidity and lordotic dorsiflexion that are characteristic of the normal mating posture in female rats.

Somato-motor components of the pelvic and pudendal nerves of the female rat.

The efferent innervation of the pelvic and pudendal nerves was characterized in this study by identifying the muscles activated by electrical stimulation of the nerves distal to the point at which they bifurcate from the L6-S1 trunk. Pelvic nerve electrical stimulation produced EMG-monitored contraction of the ipsilateral ilio- and pubococcygeus muscles, which was abolished by cutting one ('muscular') branch of the bifurcated nerve. (This 'muscular' branch receives proprioceptive input activated by tail displacement, whereas the other, 'viscero-cutaneous' branch receives sensory innervation from the midline perineal region.) Pudendal nerve electrical stimulation produced contraction of the coccygeus, external anal sphincter, and ischiocavernosus muscles. Movements of the orifice and wall of the vagina were directly visualized during electrical stimulation of the two nerves. Intravaginal pressure measured by balloon was increased by pelvic nerve stimulation and decreased by pudendal nerve stimulation. Reflexive contraction of the ilio- en pubococcygeus muscles was produced by mechanostimulation of the perineum, clitoral sheath and distal vagina. This response was abolished by gentle cervical mechanostimulation. One implication of this finding is that passage of the fetuses through the cervix during parturition may relax the ilio- and pubococcygeus muscles, thereby facilitating delivery.