Effect of hydroxyl group position and system parameters on the features of hydroxystearic Acid monolayers

The characteristic features of hydroxystearic acid monolayers OH-substituted in the mid position of the alkyl chain deviate considerably from those of the usual nonsubstituted stearic acid. The phase behavior, domain morphology, and two-dimensional lattice structure of 9-, 11-, and 12-hydroxystearic acids are studied, using pi-A isotherms, Brewster angle microscopy (BAM), and grazing incidence X-ray diffraction (GIXD), to obtain detailed information on the effect of the exact position of the OH-substitution. The pi-A isotherms of all three hydroxyoctadecanoic acids have an extended flat plateau region, the extension of which only slightly decreases with the increase of temperature. At the same temperature, the extension of the plateau region increases and the plateau pressure decreases from 9-hydroxyoctadecanoic acid to 12-hydroxyoctadecanoic acid. The absolute -DeltaH and -DeltaS values for the phase transition increase slightly from 9-hydroxyoctadecanoic acid to 12- hydroxyoctadecanoic acid and indicate differences in the ordering of the condensed phase under consideration of the special reorientation mechanism of these bipolar amphiphiles at the fluid/condensed phase transition. The morphology of the condensed phase domains formed in the fluid/condensed coexistence region is specific for the position of the OH-substitution of the alkyl chain, just as the lattice structures of the condensed monolayer phase. 11-hydroxyoctadecanoic acid monolayers form centered rectangular lattices with the chain tilt toward the NNN (next nearest neighbor) direction, and 12-hydroxyoctadecanoic acid monolayers have an oblique lattice over the entire pressure range. A special feature of 9-hydroxystearic acid monolayers is the phase transition between two condensed phases observed in the pi-A isotherm of 5 degrees C at approximately 18 mN/m, where the centered rectangular lattice shows a NNN/NN transition. The morphology of the condensed phase domains formed in the fluid/condensed coexistence region, just as the lattice structures of the condensed monolayer phase, reveal the high specifity of the monolayer feature of the bipolar hydroxystearic acids OH-substituted in the mid position.

Brushing Abrasion of Softened and Remineralised Dentin: An in situ Study

The aim of the present in situ study was to evaluate the effect of different periods of intra-oral remineralisation on the susceptibility of softened dentin to toothbrushing abrasion. Groups of 6 human dentin specimens (A-F) were recessed in the buccal aspects of intra-oral appliances which were worn for 21 days by 11 volunteers. The samples were demineralised twice a day extra-orally in the acidic beverage Sprite Light (pH 2.9) for 90 s. Subsequently, the dentin specimens were brushed at different times. Specimen A was brushed immediately after demineralisation. Specimens B-E were brushed after the intra-oral appliances had been worn for various periods in the mouth: specimen B for 10 min, C for 20 min, D for 30 min and E for 60 min. Specimen F was not brushed (control). After 21 days, dentin wear was measured with a profilometer. The following values (means +/- standard deviation) were recorded (microm): A, 23.6 +/- 16.7; B, 37.9 +/- 29.7; C, 31.8 +/- 26.5; D, 18.5 +/- 10.5; E, 15.3 +/- 11.6; F, 12.6 +/- 6.7. There was a statistically significantly increased dentin loss for groups A, B and C as compared to the controls (U test: p < 0.05). However, after intra-oral periods of 30 and 60 min, wear was not significantly higher than in unbrushed controls. It is concluded that for protection of dentin surfaces at least 30 min should elapse before toothbrushing after an erosive attack.

Effects of experimental hypogravity on peroxidase and cell wall constituents in the dwarf marigold

Dwarf Marigolds grown from seed under experimental hypogravity are modified in lignin content, hemicellulose composition, and peroxidase activity. The two conditions used, clinostats and flotation, induced changes differing in magnitude but qualitatively similar. Most responses on clinostats required corrections for vertical axis rotational effects, thus limiting the value of these instruments in free-fall simulation. These findings extend earlier observations suggesting that increased peroxidase and decreased lignin are characteristic of growth under experimental hypogravity.

The role of cholecystokinin in conditional compensatory responding and morphine tolerance in rats

As elaborated in the conditioning analysis of tolerance, cues present at the time of drug administration become associated with the drug effect. A particularly salient cue that may become associated with the drug effect is the pharmacological drug-onset cue inherent to drug administration. Drug-associated cues contribute to tolerance by eliciting a conditional compensatory response that attenuates the drug effect. For example, the early drug effect, having been paired with the subsequent larger drug effect, may elicit the release of antiopioid peptides that counter opioid effects. The role of a putative antiopioid peptide, cholecystokinin-8 (CCK), in the associative mechanisms of opiate tolerance was evaluated. The results of these experiments suggest that a CCK2 receptor antagonist attenuates both the expression of opiate tolerance and the conditional compensatory response hypothesized to mediate such tolerance.

Sacral nerve stimulation in patients with chronic intractable pelvic pain

PURPOSE

Transforamenal sacral nerve stimulation with an implantable neuroprosthetic device has been shown to benefit patients with chronic voiding dysfunction. In this study we measured the effectiveness of sacral nerve stimulation in 10 patients with chronic intractable pelvic pain.

MATERIALS AND METHODS

After successful percutaneous trial stimulation, a neuroprosthetic sacral nerve stimulation device was surgically implanted in 10 patients with chronic intractable pelvic pain. Leads were placed in the S3 and S4 foramen in 8 and 2 cases, respectively. Patients were evaluated throughout the study using a patient pain assessment questionnaire on a scale of 0-absent to 5-excruciating pain. Pain was assessed at baseline, during test stimulation, and 1, 3 and 6 months after surgical lead implantation. An additional long-term assessment was done at a median followup of 19 months.

RESULTS

Of the 10 patients with the implant 9 had a decrease in the severity of the worst pain compared to baseline at a median followup of 19 months. The number of hours of pain decreased from 13.1 to 6.9 at the same followup interval. There was also an average decrease in the rate of pain from 9.7 at baseline to 4.4 on a scale of 10-always to 0-never having pain. At a median of 19 months 6 of 10 patients reported significant improvement in pelvic pain symptomology.

CONCLUSIONS

These data imply that transforamenal sacral nerve stimulation can have beneficial effects on the severity and frequency of chronic intractable pelvic pain. Future clinical studies are necessary to determine the long-term effectiveness of this therapy.

Computerized neurocognitive scanning: II. The profile of schizophrenia

Cognitive dysfunction in schizophrenia is well established with neuropsychological batteries, which have assessed multiple domains indicating diffuse deficits especially in processing related to frontotemporal systems. Two studies are reported examining the feasibility of the computerized neurocognitive scan to assess differential deficits in schizophrenia. In Study 1, we tested 53 patients and 71 controls with the traditional and computerized assessments counterbalanced in order. Both showed comparable generalized impairment in schizophrenia with differential deficits in executive functions and memory. The profile was replicated in Study 2 in a new sample of 68 patients and 37 controls, receiving only the computerized scan. The combined sample showed robust correlations between performance on both speed and accuracy measures of the neurocognitive scan and clinical variables, including premorbid adjustment, onset age, illness duration, quality of life, and severity of negative symptoms. These correlations were higher and more prevalent in women than men, who showed correlations predominantly for speed rather than accuracy. Neuroleptic exposure was associated with poorer performance only for speed of memory processing, and in men, this association was seen only for typical neuroleptics. We conclude that the computerized neurocognitive scan can be applied reliably in people with schizophrenia, yielding data that support its construct and criterion validity.

Urinary retention after tension-free vaginal tape procedure: incidence and treatment

OBJECTIVES

To review our experience with persistent urinary retention after the tension-free vaginal tape (TVT) procedure and report our treatment results. Ulmsten recently introduced the TVT procedure for female stress urinary incontinence. Although the morbidity is minimal, no surgical procedure is without risks, and experience will better define the morbidity of the TVT procedure.

METHODS

Since November 1998, we have collectively performed 600 TVT procedures. Of these, 17 patients (2.8%) developed urinary retention or symptoms consistent with obstruction (including hesitancy, straining to void, or feeling of incomplete emptying) lasting more than 1 week from the date of the procedure. We reviewed the operative record, noting the operative time, estimated blood loss, presence of bladder penetration, and any reported complications. All 17 patients subsequently underwent transvaginal release on an outpatient basis.

RESULTS

Seventeen patients (mean age 56 years, range 38 to 81) underwent sling release a mean of 64 days (range 6 to 228) after the TVT procedure. All patients voided to completion within 24 hours of release and reported no further subjective complaints of outlet obstruction. None of the subjects reported de novo urge incontinence or urgency. In each patient, the estimated blood loss was minimal; the operative time averaged 15 minutes. One urethral injury occurred and was managed intraoperatively without sequelae. Sixteen patients who underwent sling release have remained dry; the remaining patient, in whom a urethral injury was repaired, redeveloped stress incontinence and underwent an uncomplicated successful transvaginal sling procedure.

CONCLUSIONS

Outlet obstruction is a risk of the TVT procedure and occurred with an incidence of 2.8% in our experience. The TVT mesh can be released by a simple vaginal incision under local anesthesia with rapid return to normal voiding. Although the number of patients studied was small, stress incontinence did not recur after uncomplicated release in our series.

Computerized neurocognitive scanning: I. Methodology and validation in healthy people

Neuropsychological testing batteries are applied in neurobehavioral evaluations of brain disorders, including neuropsychiatric populations. They are lengthy, require expert administrators and professional scorers, and are prone to data handling errors. We describe a brief computerized neurocognitive "scan" that assesses similar domains with adequate reliability. The scan and a traditional battery were administered to a sample of 92 healthy individuals (44 men, 48 women) in a counterbalanced order. Both approaches showed a significant "sex-typical" gradient, with women outperforming men in verbal memory relative to spatial tasks. Both methods also yielded similar profiles of sex differences, with the additional computerized measure of face memory showing better performance in women. Age effects were evident for both methods, but the computerized scan isolated the effects to speed rather than accuracy. Therefore, the computerized scan has favorable reliability and construct validity and can be applied efficiently to study healthy variability related to age and gender.

Collagen implant for treating stress urinary incontinence in women with urethral hypermobility

PURPOSE

We evaluated the use of collagen in women with stress urinary incontinence and urethral hypermobility.

MATERIALS AND METHODS

We treated 90 patients with stress urinary incontinence and urethral hypermobility with 1 to 3 injections of Contigen implant (C. R. Bard, Inc., Covington, Georgia) between June 1996 and October 1998. Observations at 3, 6 and 12 months included continence grade, 7-day voiding diaries and quality of life questionnaires. Abdominal leak point pressure was determined at baseline and 12 months.

RESULTS

At the 6-month followup 68 patients remained in the study, of whom 30 (44%) were dry and 24 (35%) were improved. Of the 58 patients who reached the 12-month followup 19 (33%) were dry and 19 (33%) were improved. Considering all patients entered into the study at 6 months 30 (33%) were dry and 24 (27%) were improved. Of the original 90 patients 19 (21%) were dry and 19 (21%) were improved at 12 months. The probability of maintaining initial improvement for 12 months was 44%. The success of bulking agent therapy was not predicted by the initial incontinence grade. Improved continence grade correlated with improved leak point pressure.

CONCLUSIONS

This therapy is appropriate in women with urethral hypermobility who wish to avoid surgical risks and in those in whom surgery is ill advised.

Performance evaluation of the microPET P4: a PET system dedicated to animal imaging

The microPET Primate 4-ring system (P4) is an animal PET tomograph with a 7.8 cm axial extent, a 19 cm diameter transaxial field of view (FOV) and a 22 cm animal port. The system is composed of 168 detector modules, each with an 8 x 8 array of 2.2 x 2.2 x 10 mm3 lutetium oxyorthosilicate crystals, arranged as 32 crystal rings 26 cm in diameter. The detector crystals are coupled to a Hamamatsu R5900-C8 PS-PMT via a 10 cm long optical fibre bundle. The detectors have a timing resolution of 3.2 ns, an average energy resolution of 26%, and an average intrinsic spatial resolution of 1.75 mm. The system operates in 3D mode without inter-plane septa, acquiring data in list mode. The reconstructed image spatial resolution ranges from 1.8 mm at the centre to 3 mm at 4 cm radial offset. The tomograph has a peak system sensitivity of 2.25% at the centre of the FOV with a 250-750 keV energy window. The noise equivalent count rate peaks at 100-290 kcps for representative object sizes. Images from two phantoms and three different types of laboratory animal demonstrate the advantage of the P4 system over the original prototype microPET. including its threefold improvement in sensitivity and a large axial FOV sufficient to image an entire mouse in a single bed position.

The role of cholecystokinin in conditional compensatory responding and morphine tolerance in rats

As elaborated in the conditioning analysis of tolerance, cues present at the time of drug administration become associated with the drug effect. A particularly salient cue that may become associated with the drug effect is the pharmacological drug-onset cue inherent to drug administration. Drug-associated cues contribute to tolerance by eliciting a conditional compensatory response that attenuates the drug effect. For example, the early drug effect, having been paired with the subsequent larger drug effect, may elicit the release of antiopioid peptides that counter opioid effects. The role of a putative antiopioid peptide, cholecystokinin-8 (CCK), in the associative mechanisms of opiate tolerance was evaluated. The results of these experiments suggest that a CCK2 receptor antagonist attenuates both the expression of opiate tolerance and the conditional compensatory response hypothesized to mediate such tolerance.

Self-administration cues as signals: drug self-administration and tolerance

There is evidence that drug-associated exteroceptive cues elicit compensatory conditional responses (CCRs) that contribute to tolerance. The authors evaluated whether interoceptive, self-administration cues (SACs) similarly contribute to tolerance. In Experiments 1 and 2, the ataxic effect of ethanol was measured in rats that self-administered (SA) ethanol--by either oral consumption or intragastric infusion--and in rats that were yoked (Y) to these self-administrators. In both experiments, the ataxic effect of ethanol was more pronounced in Y than in SA rats. In addition, SA rats failed to display usual levels of tolerance when ethanol was administered in the absence of SACs and displayed a CCR of hypertaxia in response to SACs not followed by ethanol. The results of Experiment 3 indicate that the ataxic effect of intravenous heroin also was greater in Y than in SA rats. The findings suggest that SACs contribute to drug tolerance.

Pesticide exposures in children with non-Hodgkin lymphoma

BACKGROUND

The association between pesticide exposure and non-Hodgkin lymphoma (NHL) in adults has been the subject of numerous case-control and cohort studies. However, to the authors' knowledge, data regarding pesticide exposures in children diagnosed with NHL have been lacking.

METHODS

The Children's Cancer Group conducted a study comparing 268 children who developed NHL or leukemia with bulk disease with a group of matched, randomly selected regional population controls. The telephone interviews of both the case and control mothers included selected questions regarding occupational and home exposures to pesticides around the time of the index pregnancy and exposure of the child.

RESULTS

A significant association was found between risk of NHL and increased frequency of reported pesticide use in the home (odds ratio [OR] = 7.3 for use most days; trend P = 0.05), professional exterminations within the home (OR = 3.0; P = 0.002), and postnatal exposure (OR = 2.4; P = 0.001). Elevated risks were found for T-cell and B-cell lymphomas; for lymphoblastic, large cell, and Burkitt morphologies; and in both young (age < 6 years) and older children. There was an increased risk of NHL with occupational exposure to pesticides (OR = 1.7) that was not significant overall, but that was significant for Burkitt lymphoma (OR = 9.6; P < 0.05).

CONCLUSIONS

The results of the current study provide further evidence linking pesticide exposure to the risk of NHL, but the authors were unable to implicate any specific agent.