Effects of acute and chronic midthoracic spinal cord injury on neural circuits for male sexual function. II. Descending pathways.
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In normal animals, microstimulation of the medullary reticular formation (MRF) has two effects on efferent neurons in the motor branch of the pudendal nerve (PudM). MRF microstimulation depresses motoneuron reflex discharges (RD) elicited by dorsal nerve of the penis (DNP) stimulation and produces long latency sympathetic fiber responses (SFR). The midthoracic spinal location of these descending MRF-PudM projections was studied electrophysiologically using a variety of acute and chronic lesions. Chronic lesions, in 27 mature male rats, included dorsal (DHx) or lateral (LHx) hemisections or moderate/severe contusions (Cx) at spinal level T(8). Behavioral data (sexual reflex latency, bladder voiding) obtained throughout the recovery period revealed a significant impairment of urogenital function for the DHx and severe Cx groups of animals. Microstimulation-induced PudM-RDs and PudM-SFRs, obtained in terminal electrophysiological experiments 30 days postinjury in the same 27 rats (urethan-anesthetized), were tested for a combined total of 1,404 bilateral MRF sites. PudM-RD was obtained for LHx and moderate Cx groups of animals but not for DHx or severe Cx groups. PudM-SFRs were obtained for LHx, DHx (although significantly weakened) and moderate Cx groups but not for those having received either an over-DHx or a severe Cx injury. PudM responses also were tested for 6 MRF sites in six intact control rats both before and after various select acute spinal cord lesions. For MRF sites producing a robust PudM-RD and PudM-SFR, acute bilateral lesions confined to the dorsolateral quadrant (DLQ) eliminated the PudM-RD but failed to eliminate PudM-SFRs. A deeper lesion encompassing additional white matter located dorsally in the ventrolateral quadrant (VLQ) was necessary to eliminate PudM-SFRs. Overall, these electrophysiological results provide evidence for descending projections conveying information between MRF and the lower thoracic/lumbosacral male urogenital circuitry within the DLQ and the dorsal-most aspect of VLQ at the midthoracic level of spinal cord. The alterations of supraspinal projections observed after chronic injury are likely of important clinical significance for functional recovery in cases of clinically incomplete spinal cord injury at midthoracic spinal cord. (+info)
Collagen studies in late pregnant relaxin null mice.
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The relaxin knockout (rlx -/-) mouse was used to assess the effect, during pregnancy, of relaxin with regard to water, collagen content, growth, and morphology of the nipple (N), vagina (V), uterus, cervix (C), pubic symphysis (PS), and mammary gland (MG). The results presented here indicate that during pregnancy, relaxin increases the growth of the N, C, V, and PS. Large increases in water content in the PS (20%) occurred in pregnant (Day 18.5) wild-type (rlx +/+) mice but not in rlx -/- animals. This indicates that in the PS, relaxin might increase the concentration of a water-retaining extracellular matrix component (hyaluronate). In the pregnant rlx +/+ mouse, collagen content decreased significantly in the N and V but not in other tissues. There were no significant changes in the rlx -/- mouse. This contrasts with findings in the rat, in which relaxin has been found to cause decreases in collagen concentrations in the V, C, and PS. Histological analysis showed that the collagen stain was more condensed in the tissues (V, C, PS, N, and MG) of rlx -/- mice than in those of rlx +/+ mice. This phenomenon indicates that the failure of collagen degradation and lack of growth in the N underlie the inability of the rlx -/- mice to feed their young, as reported previously. Vaginal and cervical luminal epithelia, which proliferated markedly in the rlx +/+ pregnant mice, remained relatively atrophic in the rlx -/- mice. As proliferation and differentiation of uterine and vaginal epithelia are thought to be induced by a paracrine stromal factor that acts upon estrogen stimulation, our results indicate that relaxin may be this paracrine factor. (+info)
The relaxin receptor-binding site geometry suggests a novel gripping mode of interaction.
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Relaxin has a unique, clearly identifiable, mixed function receptor-binding region comprising amino acid residues that evolve sequentially from the central portion of the B chain alpha-helix. Two arginine residues in positions B13 and B17 that project like forefinger and middle finger from the helix provide the electrostatic element opposed by the hydrophobic (thumb) element isoleucine (B20), offset from the arginines by about 40 degrees. The binding intensity of relaxin to its receptor decreases by 3 orders of magnitude if alanine is substituted for the newly discovered binding component isoleucine in position B20. The arginine residues cannot be replaced by other positive charges, nor can the guanidinium group be presented on a longer or shorter hydrocarbon chain. In contrast, the hydrophobic interaction is incremental in nature, and the contribution to the total binding energy is roughly proportional to the number of hydrocarbon units in the side chain. It appears that a hydrophobic surface exists on the receptor that offers optimal van der Waals' interaction with beta-branched hydrophobic amino acids. The binding energy increases roughly 10-fold with each methylene group whereby beta-branching is more effective per surface unit than chain elongation. Aromatic side chains appear to demarcate the extent of the binding region in so far as residues larger than phenylalanine decrease receptor binding. The exceptional clarity of binding site geometry in relaxin makes for an excellent opportunity to design peptido-mimetics. (+info)
Diastasis of the pubic symphysis peculiar to horse riders: modern aspects of pelvic pommel injuries.
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Diastasis of the pubic symphysis is a well documented injury typically associated with high energy trauma. Three cases in horse riders are here described, emphasising the appropriate modern investigation, including computed tomography, and orthopaedic and urological management. (+info)
Octreotide scanning in the detection of a mesenchymal tumour in the pubic symphysis causing hypophosphataemic osteomalacia.
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Oncogenic hypophosphataemic osteomalacia is a rare condition. The causative tumour is often difficult to locate. Primary tumours have been reported in the head and neck, skeleton, and soft tissue. Octreotide scanning was used in this case and detected a mesenchymal tumour in the pubic symphysis. (+info)
Symphysis-fundal height growth chart of an obstetric cohort of 817 Mozambican women with ultrasound-dated singleton pregnancies.
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Our aim was to construct a new symphysis-fundus height (SFH) growth chart, based on Mozambican women with ultrasound-dated singleton pregnancy, who represent the largest obstetric cohort in a developing country followed for this purpose. Two antenatal clinics were chosen in the suburban area of Maputo City. A cohort of 904 consecutively recruited antenatal clients was followed until delivery. The growth of the SFH was measured every second to third week. Gestational age was determined by ultrasound at enrolment. Women with multiple pregnancy or with gestational age > 21 weeks at enrolment were excluded. The average number of antenatal SFH measurements per woman was 7.8 (SD 2.4). The drop out rate was 9.6%. Mean birthweight was 2909 g. Pre-term deliveries occurred in 15% and low birthweight deliveries (< 2500 g) in 16%. Using proper longitudinal methods, we constructed an FH growth chart and compared it with various previously published SFH charts, which showed the Mozambican chart to be 0-3 cm below the others. Nulliparous women were 0.5 cm below multiparous women. We did not find any difference in the SFH growth charts between women with or without overt morbidity. Women with a body mass index (BMI) < 19 and women with a BMI > 27 had approximately 1 cm lower and 1 cm higher readings, respectively, than women with normal BMI. The Mozambican SFH growth chart is an example of an elaborated growth chart for a well-defined population in a low-income country. It constitutes the basis for further studies to predict the small-for-gestational age newborn from anthropometrical data obtained by use of appropriate technology. (+info)
The impact of adjustment for parity and mid-upper-arm circumference on sensitivity of symphysis-fundus height measurements to predict SGA foetuses in Mozambique.
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BACKGROUND: With a new symphysis-fundus height (SFH) growth chart, based on Mozambican women with ultrasound-dated singleton pregnancies, the aim was to examine the possibility to enhance sensitivity of predicting small for gestational age (SGA) newborns by attempts to adjust the chart for parity and for mid-upper-arm circumference (MUAC). METHODS: Two antenatal clinics were chosen in the suburban area of Maputo City. A cohort of 904 consecutively recruited antenatal clients was followed until birth. Gestational age was determined by ultrasound at enrolment. The growth of the SFH was measured every 2-3 weeks. Women with multiple pregnancy or with gestational age >21 weeks at enrolment were excluded. Attempts were made to adjust SFH measurements for parity and MUAC by developing a mathematical model to increase sensitivity of the SFH method to predict a foetus being SGA. RESULTS: Parous women had on average 0.5-1 cm higher SFH readings than nulliparous women. Women with a body mass index (BMI) <19 and women with BMI >27 had approximately 1 cm lower and 1 cm higher readings, respectively, compared with women of normal BMI. There was a significant correlation between BMI and MUAC (r = 0.621; P < 0.001). The usefulness of SFH measurements to predict SGA newborns was analysed. The sensitivity was 49%, the specificity was 66%, the positive predictive value was 14% and the negative predictive value, 93%. By using the correlation between BMI and MUAC we tried to find a simple and useful method to improve the sensitivity of SFH to detect SGA foetuses. By reducing the SFH measurement by 1 cm for women with MUAC >29 and by 1 cm for multiparous women the sensitivity raised to 65% at the expense of reducing the specificity to 51%. Using a linear function of BMI, MUAC and parity to adjust the SFH measurement for each individual woman, it was possible to get a sensitivity of 70% with a corresponding specificity of 56%. CONCLUSION: By using BMI, MUAC and parity, it might be possible to improve the sensitivity of the SFH growth chart in predicting newborn being SGA but mostly at the expense of specificity. (+info)
Guinea-pig interpubic joint (symphysis pubica) relaxation at parturition: underlying cellular processes that resemble an inflammatory response.
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BACKGROUND: At term, cervical ripening in coordination with uterine contractions becomes a prerequisite for a normal vaginal delivery. Currently, cervical ripening is considered to occur independently from uterine contractions. Many evidences suggest that cervical ripening resembles an inflammatory process. Comparatively little attention has been paid to the increased flexibility of the pelvic symphysis that occurs in many species to enable safe delivery. The aim of this study was to investigate whether the guinea-pig interpubic joint relaxation process observed during late pregnancy and parturition resembles an inflammatory process. METHODS: Samples of pubic symphysis were taken from pregnant guinea-pigs sacrificed along gestation, parturition and postpartum. Serial sections of paraffin-embedded tissues were used to measure the interpubic distance on digitalized images, stained with Giemsa to quantify leukocyte infiltration and to describe the vascular area changes, or studied by the picrosirius-polarization method to evaluate collagen remodeling. P4 and E2 serum levels were measured by a sequential immunometric assay. RESULTS: Data showed that the pubic relaxation is associated with an increase in collagen remodeling. In addition, a positive correlation between E2 serum levels and the increase in the interpubic distance was found. On the other hand, a leukocyte infiltration in the interpubic tissue around parturition was described, with the presence of almost all inflammatory cells types. At the same time, histological images show an increase in vascular area (angiogenesis). Eosinophils reached their highest level immediately before parturition; whereas for the neutrophilic and mononuclear infiltration higher values were recorded one day after parturition. Correlation analysis showed that eosinophils and mononuclear cells were positively correlated with E2 levels, but only eosinophilic infiltration was associated with collagen remodeling. Additionally, we observed typical histological images of dissolution of the connective tissue matrix around eosinophils. CONCLUSION: The present study shows that a timely regulated influx of infiltrating leukocytes is associated with an extensive collagen remodeling process that allows the pubic separation for a normal delivery in guinea-pig. Thus, the findings in this study support the hypothesis that the guinea-pig pubic symphyseal relaxation at parturition resembles an inflammatory process. (+info)