Cold physical plasma treatment optimization for improved bone allograft processing

In musculoskeletal surgery, the treatment of large bone defects is challenging and can require the use of bone graft substitutes to restore mechanical stability and promote host-mediated regeneration. The use of bone allografts is well-established in many bone regenerative procedures, but is associated with low rates of ingrowth due to pre-therapeutic graft processing. Cold physical plasma (CPP), a partially ionized gas that simultaneously generates reactive oxygen (O2) and nitrogen (N2) species, is suggested to be advantageous in biomedical implant processing. CPP is a promising tool in allograft processing for improving surface characteristics of bone allografts towards enhanced cellularization and osteoconduction. However, a preclinical assessment regarding the feasibility of pre-therapeutic processing of allogeneic bone grafts with CPP has not yet been performed. Thus, this pilot study aimed to analyze the bone morphology of CPP processed allografts using synchrotron radiation-based microcomputed tomography (SR-µCT) and to analyze the effects of CPP processing on human bone cell viability and function. The analyzes, including co-registration of pre- and post-treatment SR-µCT scans, revealed that the main bone morphological properties (total volume, mineralized volume, surface area, and porosity) remained unaffected by CPP treatment if compared to allografts not treated with CPP. Varying effects on cellular metabolic activity and alkaline phosphatase activity were found in response to different gas mixtures and treatment durations employed for CPP application. It was found that 3 min CPP treatment using a He + 0.1% N2 gas mixture led to the most favourable outcome regarding a significant increase in bone cell viability and alkaline phosphatase activity. This study highlights the promising potential of pre-therapeuthic bone allograft processing by CPP prior to intraoperative application and emphasizes the need for gas source and treatment time optimization for specific applications.

Dark Matter Search Results from the PICO-60 C_{3}F_{8} Bubble Chamber

New results are reported from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 52 kg of C_{3}F_{8} located in the SNOLAB underground laboratory. As in previous PICO bubble chambers, PICO-60 C_{3}F_{8} exhibits excellent electron recoil and alpha decay rejection, and the observed multiple-scattering neutron rate indicates a single-scatter neutron background of less than one event per month. A blind analysis of an efficiency-corrected 1167-kg day exposure at a 3.3-keV thermodynamic threshold reveals no single-scattering nuclear recoil candidates, consistent with the predicted background. These results set the most stringent direct-detection constraint to date on the weakly interacting massive particle (WIMP)-proton spin-dependent cross section at 3.4×10^{-41}  cm^{2} for a 30-GeV c^{-2} WIMP, more than 1 order of magnitude improvement from previous PICO results.

Improved limits on spin-dependent WIMP-proton interactions from a two liter CF3I bubble chamber

Data from the operation of a bubble chamber filled with 3.5 kg of CF3I in a shallow underground site are reported. An analysis of ultrasound signals accompanying bubble nucleations confirms that alpha decays generate a significantly louder acoustic emission than single nuclear recoils, leading to an efficient background discrimination. Three dark matter candidate events were observed during an effective exposure of 28.1  kg  day, consistent with a neutron background. This observation provides strong direct detection constraints on weakly interacting massive particle (WIMP)-proton spin-dependent scattering for WIMP masses >20  GeV/c2.

Direct dark matter search using large-mass superheated droplet detectors in the PICASSO experiment

The PICASSO experiment investigates the presence and nature of dark matter in the Universe. The experiment is based on the detection of acoustic signals generated in explosive phase transitions induced by dark matter particles. This technique is an alternative more traditional detection technique like scintillation and ionisation, which are largely employed for dark matter search. One of the main advantages of this technique, besides its sensitivity to very low nuclear recoil energies (few keV), is its excellent background suppression features. A pilot experiment consisting of six superheated droplet detectors (40 g of active mass) is presently taking data at the Sudbury Neutrino Observatory (SNO) at a depth of 2000 m. We discuss the operation, calibration and data acquisition of the experiment and also the ongoing work to increase the sensitivity and the active mass of the detectors.

Simulation of special bubble detectors for PICASSO

The PICASSO project is a cold dark matter (CDM) search experiment relying on the superheated droplet technique. The detectors use superheated freon liquid droplets (active material) dispersed and trapped in a polymerised gel. This detection technique is based on the phase transition of superheated droplets at about room temperature and ambient pressure. The phase transition is induced by nuclear recoils when an atomic nucleus in the droplets interacts with incoming subatomic particles. This includes CDM particles candidate as the neutralino (a yet-to-discover particle predicted in extensions of the standard model of particle physics). Simulations performed to understand the detector response to neutrons and alpha particles are presented along with corresponding data obtained at the Montreal Laboratory.

Deep Brain Stimulation in Intraoperative MRI Environment - Comparison of Imaging Techniques and Electrode Fixation Methods

We performed 118 consecutive DBS cases from November 1999 to June 2002. Intraoperatively there were 10 cases studied with fluoroscopy, 73 with 0.2 Tesla (T) MRI and 35 with 1.5 T MRI. Ten electrodes were secured by Medtronic caps, 25 by methyl methacrylate with titanium miniplates, and 82 by Navigus caps. The 3-dimensional displacement between the planned target and actual electrode position (3DD) was determined by fusing the postoperative MRI with the preoperative imaging. The 3DD for using Medtronic caps, methyl methacrylate with miniplates, and Navigus caps were 4.80 +/- 3.16, 2.64 +/- 1.26 and 2.23 +/- 1.15 mm (mean +/- SD), respectively. Navigus caps had statistically significant accuracy (P = 0.03) in holding the electrode when compared with Medtronic caps, and it facilitated electrode revision. The fixation devices significantly affect the final vertical position of the electrode. The 3DD for fluoroscopy, 0.2 T and 1.5 T MRI cases were 4.80 +/- 3.16, 2.31 +/- 1.21 and 2.34 +/- 1.14 mm (mean +/- SD), respectively. No statistically significant difference (P = 0.91) in 3DD was demonstrated between 0.2 T and 1.5 T MRI cases. The presence of intraoperative 1.5 T MRI allowed near real-time electrode position confirmation and early detection of hemorrhagic complications. Satisfactory microelectrode recording was feasible in low-field 0.2 T and high-field 1.5 T MRI environments. Further studies on performing DBS in real-time intraoperative MRI are warranted.

Functional Neurosurgery in the MRI Environment

OBJECTIVE

The purpose of this study was to evaluate the feasibility of microelectrode recording, electrical stimulation, and electrode position checking during functional neurosurgical procedures (DBS, lesion) in the interventional magnetic resonance imaging (iMRI) environment.

METHODS

Seventy-six surgical procedures for DBS implant or radiofrequency lesion were performed in an open 0.2 T MRI operating room. DBS implants were performed in 54 patients (72 surgical procedures) and unilateral radiofrequency lesions in three for a total of 76 surgeries in 57 patients. Electrophysiological studies including macrostimulation and microelectrode recordings for localization were obtained in the 0.5 to 10 mT fringes of the magnetic field in 51 surgeries. MRI confirmation of the electrode position during the procedure was performed after electrophysiological localization.

RESULTS

The magnetic field associated with the MRI scanner did not contribute significant noise to microelectrode recordings. Anatomical confirmation of electrode position was possible within the MRI artifact from the DBS hardware. Symptomatic hemorrhage was detected in two (2.6 %) patients during the operation. Image quality of the 0.2 T MRI scan was sub-optimal for anatomical localization. However, image fusion with pre-operative scans permitted excellent visualization of the DBS electrode tip in relation to the higher quality 1.5 T MRI anatomical scans.

CONCLUSION

This study shows that conventional stereotactic localization, microelectrode recordings, electrical stimulation, implant of DBS hardware, and radiofrequency lesion placement are possible in the open 0.2 T iMRI environment. The convenience of having an imaging modality that can visualize the brain during the operation is ideal for stereotactic procedures.

Subclinical myocardial injury in small-for-gestational-age neonates

OBJECTIVE

Small-for-gestational-age (SGA) infants are at risk for premature death from cardiovascular disease (myocardial infarction and stroke), hypertension, and diabetes in adult life. Severe intrauterine growth restriction is often associated with subclinical cardiovascular abnormalities detectable during fetal echocardiography. The objective of this study was to determine whether SGA newborns have evidence of myocardial injury at birth.

STUDY DESIGN

Cardiac troponin I, a specific marker of myocardial injury widely used for the diagnosis of myocardial infarction in adults, was determined in umbilical cord blood. Umbilical cord venous blood was obtained at the time of birth from 72 SGA newborns (birth weight below the 10th centile for gestational age) and 309 newborns whose birth weights were appropriate for gestational age (AGA). Cardiac troponin I was determined with a commercially available immunoassay (sensitivity 0.2 ng/ml) employed in clinical laboratories (Immulite 2000, Diagnostic Products Corp., Los Angeles, CA).

RESULTS

Cardiac troponin I was not detectable in any of the blood samples from AGA infants. In contrast, 4.2% (3/72) of SGA infants had detectable cardiac troponin I in umbilical cord blood (Fisher's exact test, p = 0.007).

CONCLUSION

A subgroup of SGA newborns undergoes myocardial injury before birth. This insult may predispose to the development of adult premature cardiovascular disease and death.

Staged bilateral pallidotomy for treatment of Parkinson disease

OBJECT

Several investigators have described the motor benefits derived from performing unilateral stereotactic pallidotomy for the treatment of Parkinson disease (PD), but little is known about the efficacy and complication rates of bilateral procedures. The goal of this study was to assess both these factors in 12 patients.

METHODS

Eleven patients with medically intractable PD underwent staged bilateral pallidotomy and one patient underwent a simultaneous bilateral procedure. Unilateral pallidotomy resulted in an improvement in the patients' Unified Parkinson Disease Rating Scale (UPDRS) total scores and motor subscores, Hoehn and Yahr stages, and Schwab and England Activities of Daily Living scores. There were no complications. The second procedures were performed 5 to 25 months after the first, and nearly complete 3-month follow-up data are available for eight of these patients. Staged bilateral pallidotomy did result in further improvements in some symptoms, but the patients proved to be less responsive to levodopa. In contrast to outcomes of the initial unilateral pallidotomy, there were significant complications. One patient suffered an acute stroke, two patients suffered delayed infarctions of the internal capsule, four patients had mild-to-moderate worsening of speech and increased drooling, and one patient complained of worsening memory.

CONCLUSIONS

Bilateral pallidotomy results in modest benefits but is associated with an increased risk of complications.

Cerebral microdialysis combined with single-neuron and electroencephalographic recording in neurosurgical patients. Technical note

Monitoring physiological changes in the brain parenchyma has important applications in the care of neurosurgical patients. A technique is described for measuring extracellular neurochemicals by cerebral microdialysis with simultaneous recording of electroencephalographic (EEG) and single-unit (neuron) activity in selected targets in the human brain. Forty-two patients with medically intractable epilepsy underwent stereotactically guided implantation of a total of 423 intracranial depth electrodes to delineate potentially resectable seizure foci. The electrodes had platinum alloy contacts for EEG recordings and four to nine 40-microm microwires for recording single-unit neuron activity. Eighty-six electrodes also included microdialysis probes introduced via the electrode lumens. During monitoring on the neurosurgical ward, electrophysiological recording and cerebral microdialysis sampling were performed during seizures, cognitive tasks, and sleep-waking cycles. The technique described here could be used in developing novel approaches for evaluation and treatment in a variety of neurological conditions such as head injury, subarachnoid hemorrhage, epilepsy, and movement disorders.

Motor, cognitive, and behavioral performance following unilateral ventroposterior pallidotomy for Parkinson disease

OBJECTIVE

To evaluate the effects of ventroposterior pallidotomy on motor disability and on behavior and cognition in patients with medically intractable idiopathic Parkinson disease.

DESIGN

Detailed motor testing both while receiving and discontinuing levodopa medication, posturography, and neurocognitive and behavioral assessments were performed before and 3 to 6 months after unilateral ventroposterior pallidotomy.

SETTING

University-based movement disorder program.

PATIENTS

Thirty-two patients without dementia with medically refractory idiopathic Parkinson disease were studied.

MAIN OUTCOME MEASURES

Motor function and disability were measured using the Unified Parkinson's Disease Rating Scale, Hoehn and Yahr stage, and the Schwab and England Activities of Daily Living Scale. Dynamic balance was measured by sway (amplitude and velocity) using the Chattecx Balance System. Detailed cognitive and behavioral assessments were also performed both before and after surgery.

RESULTS

Eighty-three percent of patients experienced improvement of their total Unified Parkinson's Disease Rating Scale score at 3 to 6 months after surgery. Significant improvements were also seen in the contralateral Unified Parkinson's Disease Rating Scale motor subscore (78%) as well as in the contralateral Unified Parkinson's Disease Rating Scale total score both during the on and off period (78% and 79%, respectively). The Hoehn and Yahr stage, Schwab and England Activities of Daily Living Scale score, and dynamic balance when standing on foam also improved following unilateral pallidotomy in many patients. Cognitive performance remained relatively unchanged following surgery with the exception of category fluency, which exhibited a modest decline (P < .04). A significant improvement in depression was found on the Beck Depression Inventory.

CONCLUSIONS

Ventroposterior pallidotomy significantly improves motor performance and daily level of function in Parkinson disease. Cognition and behavior are not adversely affected in patients without dementia, and a cognitive screening battery is proposed.

Amniotic fluid prostanoid concentrations increase early during the course of spontaneous labor at term

OBJECTIVE

The purpose of this study was to determine whether amniotic fluid concentrations of prostanoids increase during spontaneous labor at term.

STUDY DESIGN

Amniotic fluid was retrieved transabdominally from 168 patients in spontaneous labor and from 82 patients not in labor. Prostaglandin E2, prostaglandin F2 alpha, 13, 14-dihydro-15-keto-prostaglandin F2 alpha, thromboxane B2, and 6-keto-prostaglandin F1 alpha concentrations were measured with sensitive and specific radioimmunoassays previously validated for amniotic fluid. Statistical analysis was conducted with Kruskal-Wallis analysis of variance, followed by Dunn's test for multiple comparisons.

RESULTS

(1) Amniotic fluid concentrations of all prostanoids were significantly higher in patients in early labor (cervical dilatation of < or = 3 cm) than in patients not in labor. (2) The magnitude of the increase in amniotic fluid prostanoid concentrations during early labor was significantly greater for prostaglandin F2 alpha and 13,14-dihydro-15-keto-prostaglandin F2 alpha than for prostaglandin E2, thromboxane B2, and 6-keto-prostaglandin F1 alpha. (3) Patients in the active phase of labor with cervical dilatations between 4 and 7 cm did not have higher prostanoid concentrations than those in early labor (cervical dilatation of < or = 3 cm). (4) A significant increase in amniotic fluid concentrations of prostaglandin F2 alpha and 13,14-dihydro-15-keto-prostaglandin F2 alpha was found in patients with advanced cervical dilatation (8 to 10 cm) in comparison with those in early labor (< 3 cm).

CONCLUSION

Amniotic fluid prostanoid concentrations increase early during the course of spontaneous labor at term.

The value of amniotic fluid interleukin-6, white blood cell count, and gram stain in the diagnosis of microbial invasion of the amniotic cavity in patients at term

PROBLEM

Subclinical microbial invasion of the amniotic cavity occurs in 18.8% of women with term labor and intact membranes and in 34% of patients with term PROM and is a risk factor for the development of puerperal infection related morbidity. Although amniotic fluid white blood cell count, interleukin-6 determination, and Gram stain examination have been used for the diagnosis of intrauterine infection in patients with preterm labor and preterm premature rupture of membranes, no information is available about the accuracy and specific cut-off values for these tests in patients at term. The purpose of this study was to compare the performance of the amniotic fluid Gram stain examination, white blood cell count, and interleukin-6 determination in the identification of microbial invasion of the amniotic cavity in patients at term with and without PROM.

METHOD

Amniotic fluid was retrieved from 148 patients with term gestations (90 patients with spontaneous labor and intact membranes and 58 patients with PROM). Samples were cultured for bacteria and Mycoplasma species. Amniotic fluid Gram stain, white blood cell count, and interleukin-6 determinations (ELISA, sensitivity: 43 pg/ml) were performed in all samples. Microbial invasion of the amniotic cavity was defined as a positive amniotic fluid culture for microorganisms. Analysis was conducted using Mann-Whitney U test, Fisher's exact test, receiver operating characteristic curves and logistic regression.

RESULTS

Patients with spontaneous labor and intact membranes: The prevalence of microbial invasion of amniotic cavity in this group was 15.6% (14/90). The most sensitive test for the detection of microbial invasion of the amniotic cavity was amniotic fluid interleukin-6 determination (sensitivity for: interleukin-6 > or = 5.7 ng/ml = 86%, white blood cell count > or = 20 cells/mm3 = 64%, Gram stain = 28%). The most specific test was the Gram stain of the amniotic fluid (specificity for: Gram stain = 84%, interleukin-6 = 79% and white blood cell count = 63%). Multiple logistic regression demonstrated that amniotic fluid interleukin-6 concentration was the only covariate that retained statistical significance when intrauterine infection was used as outcome variable. Patients with PROM: The prevalence of a positive amniotic fluid culture in this group was 39.7% (23/58). Logistic regression demonstrated that only interleukin-6 retained a significant relationship with the results of amniotic culture when all variables were entered simultaneously into a model to predict amniotic fluid culture results. The most sensitive tests for the detection of intrauterine infection were interleukin-6 determination and white blood cell count (sensitivity for interleukin-6 > or = 3.4 ng/ml and white blood cell count > or = 20 cells/mm3 = 69.6% for both). The most specific test was Gram stain (97.1%).

CONCLUSIONS

Amniotic fluid interleukin-6 determination is the best rapid test for the detection of microbial invasion of the amniotic cavity in patients at term with and without PROM. When this test is not available, amniotic fluid Gram stain and white blood cell count represent valid diagnostic tools to assess the microbial state of amniotic cavity.

Is oligohydramnios a risk factor for infection in term premature rupture of membranes?

Our objective was to determine if a reduced volume of amniotic fluid is a risk factor for microbial invasion of the amniotic cavity in women with rupture of membranes at term. Transabdominal amniocentesis under ultrasound guidance was used to evaluate the microbiological state of the amniotic cavity in 53 patients with term premature rupture of membranes before vaginal examination. Amniotic fluid index was measured prior to the procedure in all cases. The prevalence of microbial invasion of the amniotic cavity was 32.1% (17/53). Women with microbial invasion of the amniotic cavity had a significantly lower median amniotic fluid index than did women without evidence of infection (median 4.4 cm, range 1.0-8.1 vs. median 7.8 cm, range 1.3-14.4, respectively; p < 0.001). An amniotic fluid index of < 5 cm had a sensitivity of 71% (12/17) a specificity of 89% (32/36), a positive predictive value of 75% (12/16) and a negative predictive value of 87% (32/37) in the prediction of microbial invasion of the amniotic cavity. Among women who delivered vaginally, those with an amniotic fluid index of < 5 cm had a higher rate of endometritis than those with an amniotic fluid index of >or= 5 cm (19% (3/16) vs. 0% (0/26), respectively; p < 0.05). We conclude that women with term premature rupture of membranes and an amniotic fluid index of < 5 cm are at an increased risk for microbial invasion of the amniotic cavity and puerperal infection after a vaginal delivery.

Topographic differences in amniotic fluid concentrations of prostanoids in women in spontaneous labor at term

These studies were designated to determine if there are differences in prostanoid concentrations between amniotic fluid (AF) retrieved transvaginally from the membrane forebag (lower or forebag compartment) and fluid retrieved by transabdominal amniocentesis from the 'upper compartment' in women in labor. Fluid was retrieved from 53 women in active labor who underwent transabdominal and transvaginal amniocentesis. Fluid was assayed for prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2 alpha), 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM), thromboxane B2 (TXB2), and 6-keto-prostaglandin F1 alpha (6-k-PGF1 alpha) using sensitive and specific radioimmunoassays. Concentrations of all prostanoids measured were significantly higher in fluid retrieved by transvaginal than transabdominal amniocentesis; the magnitude of the increase (measured as the ratio of concentrations in the lower/upper compartment) was higher for PGF2 alpha and TXB2 than for the other prostanoids measured; for each prostanoid measured, there was a significant correlation between the concentration in the upper and lower compartment.

Microbial invasion of the amniotic cavity during term labor. Prevalence and clinical significance

The purpose of this study was to determine the prevalence and clinical significance of microbial invasion of the amniotic cavity during spontaneous parturition at term. Amniotic fluid was retrieved by transabdominal amniocentesis from 90 women in spontaneous term labor with intact membranes. Fluid was cultured for aerobic and anaerobic bacteria, including Mycoplasma. The prevalence of positive amniotic fluid cultures was 18.8% (17/90). The most common microbial isolates were Ureaplasma urealyticum, Streptococcus agalactiae, Lactobacillus species and Mycoplasma hominis. Clinical signs of chorioamnionitis were present in three patients, and only one of them had a positive amniotic fluid culture. Five patients (5.5%) had puerperal endometritis; three of them had an amniotic fluid culture positive for microorganisms. All neonates were free of clinical signs of infection. The data indicate that microbial invasion of the amniotic cavity occurs frequently during spontaneous labor at term, and it may be both the cause and the consequence of labor.

The relationship between spontaneous rupture of membranes, labor, and microbial invasion of the amniotic cavity and amniotic fluid concentrations of prostaglandins and thromboxane B2 in term pregnancy

OBJECTIVE

The purpose of this study was to examine the relationship between rupture of membranes, labor, and microbial invasion of the amniotic cavity and amniotic fluid concentrations of eicosanoids in patients with spontaneous rupture of membranes at term.

STUDY DESIGN

Amniotic fluid was retrieved by transabdominal amniocentesis from patients with rupture of membranes and patients with intact membranes at term. Studies to determine the microbial state of the amniotic cavity included culture for bacteria and mycoplasmas, Gram stain, amniotic fluid white blood cell count, and Limulus amebocyte lysate. Eicosanoids (prostaglandin E2, prostaglandin F2 alpha and its stable metabolite, 6-keto-prostaglandin F1 alpha, and thromboxane B2) were determined with sensitive and specific radioimmunoassays validated for human amniotic fluid. Statistical inference was conducted with analysis of variance and linear contrast.

RESULTS

(1) Spontaneous rupture of membranes at term was associated with a significant increase in amniotic fluid concentrations of all eicosanoids measured in this study except 6-keto-prostaglandin F1 alpha. (2) Early labor in patients with rupture of membranes was associated with a significant increase in the amniotic fluid concentration of all eicosanoids. (3) A significant increase in amniotic fluid eicosanoids in women with microbial invasion of the amniotic cavity could not be documented.

CONCLUSIONS

Whereas preterm labor in the absence of microbial invasion of the amniotic cavity is not associated with a significant increase in amniotic fluid concentrations of prostaglandins, a clear increase was documented in women with early labor after spontaneous rupture of membranes. These observations suggest that there are fundamental differences in the biochemistry of term and preterm parturition.

Infection and labor. VII. Microbial invasion of the amniotic cavity in spontaneous rupture of membranes at term

OBJECTIVE

The purpose of this study was to determine the frequency, microbiologic characteristics, and clinical significance of microbial invasion of the amniotic cavity in women with premature rupture of membranes at term.

STUDY DESIGN

Amniocentesis was performed in 32 women with term premature rupture of membranes and amniotic fluid cultured for aerobic and anaerobic bacteria and Mycoplasmas.

RESULTS

The prevalence of positive amniotic fluid cultures was 34.3% (11/32). The most common isolates were Ureaplasma urealyticum, Peptostreptococcus sp., Lactobacillus sp., Bacteroides fragilis, and Fusobacterium sp. Clinical chorioamnionitis occurred only in one patient with a positive amniotic fluid culture. Her neonate had ophthalmitis. Three patients (9.4%) had endometritis. Among women who were delivered vaginally, those with a positive amniotic fluid culture had a significantly higher rate of endometritis than those with a negative culture (33% [3/9] vs 0% [0/20], respectively, p = 0.023).

CONCLUSIONS

These data indicate that microbial invasion of the amniotic cavity occurs in approximately one third of patients with preterm premature rupture of membranes. Microbial invasion of the amniotic cavity is a risk factor for endometritis in women with term premature rupture of membranes.

Oxytocin secretion and human parturition: pulse frequency and duration increase during spontaneous labor in women

The secretory pattern of oxytocin was determined in blood samples taken at 1-minute intervals for 30 minutes from 32 parturient women. The samples were collected in a manner that minimized degradation by plasma oxytocinase, and a highly specific antibody was used for the radioimmunoassay. The results indicated that oxytocin is secreted in discrete pulses of short duration. The frequency of the pulses was significantly higher during spontaneous labor than before the onset of labor. The mean pulse frequencies per 30 minutes were 1.2 +/- 0.54 before labor, 4.2 +/- 0.45 during the first stage, and 6.7 +/- 0.49 during the second and third stages of labor. The mean pulse durations in these three groups were 1.2 +/- 0.20, 1.9 +/- 0.28, and 2.0 +/- 0.26 minutes, respectively. The amplitude of the pulses was variable with no significant differences between the groups, the majority being around 1.0 microU/ml. The spontaneous pulses were of similar magnitude as those measured in 18 women after intravenous injections of 4 to 16 mU of oxytocin, which doses stimulated uterine contractions. We therefore conclude that the pulses of oxytocin observed at increasing frequency during spontaneous labor are of physiologic significance and provide evidence for the participation of oxytocin in the onset and maintenance of spontaneous labor.

Neutrophil attractant/activating peptide-1/interleukin-8 in term and preterm parturition

The neutrophil is the leukocyte most frequently recruited into the amniotic fluid in cases of microbial invasion of the amniotic cavity. Neutrophil attractant/activating peptide-1/interleukin-8 is a newly identified cytokine that is capable of inducing selective neutrophil chemotaxis and activation. The purpose of this study was to examine the relationship between amniotic fluid concentrations of neutrophil attractant/activating peptide-1/interleukin-8, microbial invasion of the amniotic cavity, and parturition (term and preterm). Amniotic fluid neutrophil attractant/activating peptide-1/interleukin-8 was measured with an immunoassay validated for human amniotic fluid (sensitivity 0.3 ng/ml). Fluid was obtained from women in the following groups: midtrimester (n = 38), term not in labor (n = 38), term in active labor (n = 67), and preterm labor with intact membranes (n = 62). Fluid was cultured for aerobic and anaerobic bacterial and Mycoplasma. Sterile amniotic fluid from most women in the midtrimester of pregnancy and women at term not in labor did not contain immunoreactive neutrophil attractant/activating peptide-1/interleukin-8. Microbial invasion of the amniotic cavity was associated with increased concentrations of neutrophil attractant/activating peptide-1/interleukin-8. The amniotic fluid of women with preterm labor and sterile amniotic fluid who had preterm delivery contained higher neutrophil attractant/activating peptide-1/interleukin-8 levels than did the amniotic fluid of women who responded to tocolysis and had delivery at term. Term parturition is associated with increased concentrations of neutrophil attractant/activating peptide-1/interleukin-8 in the amniotic fluid. We conclude that neutrophil attractant/activating peptide-1/interleukin-8 is part of the host response to microbial invasion of the amniotic cavity and that increased amniotic fluid availability of this cytokine occurs in term and preterm parturition.