Neoarchean carbonate-associated sulfate records positive Δ³³S anomalies

Mass-independent fractionation of sulfur isotopes (reported as Δ(33)S) recorded in Archean sedimentary rocks helps to constrain the composition of Earth's early atmosphere and the timing of the rise of oxygen ~2.4 billion years ago. Although current hypotheses predict uniformly negative Δ(33)S for Archean seawater sulfate, this remains untested through the vast majority of Archean time. We applied x-ray absorption spectroscopy to investigate the low sulfate content of particularly well-preserved Neoarchean carbonates and mass spectrometry to measure their Δ(33)S signatures. We report unexpected, large, widespread positive Δ(33)S values from stratigraphic sections capturing over 70 million years and diverse depositional environments. Combined with the pyrite record, these results show that sulfate does not carry the expected negative Δ(33)S from sulfur mass-independent fractionation in the Neoarchean atmosphere.

Evoked pressure curves from the external anal sphincter following transcranial magnetic stimulation in healthy volunteers and patients with faecal incontinence

AIM

The hypothesis was tested that evoked pressure curves (EPCs) after transcranial magnetic stimulation (TMS) would provide additional neuropathophysiological information on the descending pathways to the external anal sphincter (EAS) in patients with faecal incontinence (FI).

METHOD

Twenty-five healthy subjects and 69 patients with FI were investigated. TMS was applied to the vertex, and EPCs were recorded with a probe placed through the EAS. TMS was performed with the EAS at rest and during contraction (facilitated responses). At least three responses were recorded for each modality. Clinical data and anorectal manometric, electrophysiological perineal and transanal ultrasound recordings were compared with respect to the EPC results.

RESULTS

There was no statistically significant difference between the EPCs of healthy subjects and FI patients. Twenty-three per cent of the FI patients had abnormal EPC latencies, with significantly lower voluntary contraction amplitudes (P = 0.03) and significantly higher rectal sensation (P = 0.04) than the other group. We found no significant difference between FI patients with and without abnormal EPC latencies in terms of clinical characteristics and electrophysiological and endoanal ultrasound parameters. There was no difference in the identified causes of the FI between the two groups.

CONCLUSION

As abnormal EPC latencies were found in 23% of FI patients with no known central neurological disease, abnormal EPC latencies might reveal undetected lesions of descending pathways in patients with FI.

Clinical screening of oropharyngeal dysphagia in patients with ALS

OBJECTIVE

It is a major issue to diagnose and detect oropharyngeal dysphagia in the early stage of ALS in order to avoid pulmonary and nutritional complications. The aim of this study was to validate a simple clinical test, the Volume-Viscosity Swallow Test (V-VST), to detect oropharyngeal dysphagia in this population.

PATIENTS AND METHODS

Twenty patients were included in this study (mean age: 66.1 ± 8.13, six women). All patients had their swallowing function assessed by videofluoroscopy and V-VST.

RESULTS

Among these 20 patients, 15 presented oropharyngeal dysphagia, diagnosed by videofluoroscopy, and five had normal swallowing. Norris score was lower in patients with oropharyngeal dysphagia compared to the patients with normal swallowing (27 ± 6 versus 36 ± 2; P=0.003). Among the 15 patients with oropharyngeal dysphagia, 14 had abnormal V-VST, and only one had normal V-VST. The sensibility of V-VST to detect oropharyngeal dysphagia in these patients with ALS was of 93%, and the specificity was of 80% (P=0.007). There was no significant difference between the two populations for ALSFRS score (22 ± 6 versus 20 ± 6) and body mass index (BMI) (26 ± 6 versus 26 ± 6 kg/m(2)).

CONCLUSION

The V-VST presented good sensibility and specificity. It may be interesting to use it systematically for the detection of oropharyngeal dysphagia in ALS, after confirming these results on a wider patient sample.

Management of neurogenic bowel dysfunction

There are several modalities for treating neurogenic bowel dysfunction (NBD), including conservative treatments (diet, medications, biofeedback, transanal irrigation, massage, electrical stimulation, anal plug). When conservative treatments fail, clinicians can choose from a variety of therapeutic options, including colostomies, Malone anterograde continence enemas, sacral anterior root stimulator implantations, graciloplasties, and artificial bowel sphincters. We reviewed the various treatments for constipation and/or fecal incontinence in patients with NBD and propose over-reaching stepwise algorithms for the management of NBD. Our review included English language articles, randomized controlled studies, cohort studies, case-control studies, and retrospective studies (if necessary) that assessed the management of NBD. Our literature search identified 577 articles, of which 79 met our inclusion criteria. There is little evidence for the success of conservative but non-pharmacological treatments. There is strong evidence for the success of pharmacological interventions (i.e., prokinetic agents) in the treatment of chronic constipation. While surgical interventions may be considered, there is little evidence of their effectiveness. Bowel management programs for patients with neurologic diseases require a multi-faceted approach. While a range of medical and surgical treatments are available, there is little evidence for their effectiveness, with the exception of pharmacological interventions.

[High resolution sonography of the dorsal radiocarpal and intercarpal ligaments: findings in healthy subjects with anatomic correlation to cadaveric wrists]

PURPOSE

To assess the value of ultrasound (US) imaging of the dorsal radiocarpal and intercarpal ligaments of the wrist, after characterization of their imaging features on cadaveric specimen.

MATERIALS AND METHODS

Two wrist dissections of fresh cadaver were performed. The orientations and the osseous insertions of the ligaments were clarified, allowing development of an US examination protocol. Then, forty wrists of asymptomatic volunteers were analyzed prospectively with US. The visibility and thickness of both ligaments were estimated at their midpoint and at their osseous insertions.

RESULTS

The dorsal radiocarpal and intercarpal ligaments were visualized as thin, hyperechoic and fibrillar structures, extending between their respective osseous insertions. The mid portions of the ligaments were visible at all volunteers. The osseous insertions were completely or partially visible in 90% of cases, except for the radial insertion of the dorsal radiocarpal ligament, visible in 77.5% of cases.

CONCLUSION

US, based on good anatomical knowledge and a standardized protocol, which we describe in this work, enables evaluation of the dorsal radiocarpal and intercarpal ligaments of the wrist.

Sildenafil increases ocular perfusion

PURPOSE

Our goal was to determine whether visual system responses to sildenafil accompany shifts in ocular perfusion. The human choroid, which supports the metabolic function of the outer retina, is an erectile tissue, analogous in many respects to the corpus cavenosum.

METHODS

Right eyes of 12 normal adults were evaluated before and 2 h after 50 mg oral dose of sildenafil. Pulsatile ocular blood flow (POBF), intraocular pressure (IOP), Heidelberg retinal flowmetry (HRT), 4.26 cpd, 7.5 Hz temporally-modulated contrast sensitivity (CS), full-threshold C-20 frequency doubling technology (FDT) perimetry, and blood pressure (BP) were measured.

RESULTS

POBF (+29.4%; p > 0.016) and CS (+33.6%; p > 0.014%) increased within 110 (+/-7.7) minutes after sildenafil administration. No subject demonstrated decreases in either variable. HRF flow values increase among 7 of the 9 eyes producing stable scans (+8.2%; p > 0.1). FDT values did not change significantly, nor did systemic pulse amplitude or mean IOP.

CONCLUSIONS

Since IOP and systemic pulse amplitude both remained stable after sildenafil administration, while POBF values increased to a level nearly one third greater than baseline. It appears sildenafil can induce intrinsic change in the choroidal vasculature, with an apparently positive impact on pericentral contrast sensitivity. This effect may be of clinical utility.

Probing molecular function of trypanosomal sialidases: single point mutations can change substrate specificity and increase hydrolytic activity

Sialidases are present on the surface of several trypanosomatid protozoan parasites. They are highly specific for sialic acid linked in alpha-(2,3) to a terminal beta-galactose and include the strictly hydrolytic enzymes and trans-sialidases (sialyl-transferases). Based on the structural comparison of the sialidase from Trypanosoma rangeli and the trans-sialidase from T. cruzi (the agent of Chagas' disease in humans), we have explored the role of specific amino acid residues sought to be important for substrate specificity. The substitution of a conserved tryptophanyl residue in the two enzymes, Trp312/313-Ala, changed substrate specificity, rendering the point mutants capable to hydrolyze both alpha-(2,3)- and alpha-(2,6)-linked sialoconjugates. The same mutation abolished sialyl-transferase activity, indicating that transfer (but not hydrolysis) requires a precise orientation of the bound substrate. The exchange substitution of another residue that modulates oligosaccharide binding, Gln284-Pro, was found to significantly increase the hydrolytic activity of sialidase, and residue Tyr119 was confirmed to be part of a second binding site for the acceptor substrate in trans-sialidase. Together with the structural information, these results provide a consistent framework to account for the unique enzymatic properties of trypanosome trans-sialidases.

Physical and Kinetic Evidence for an Association between Sucrose-Phosphate Synthase and Sucrose-Phosphate Phosphatase

The possible formation of a multienzyme complex between sucrose (Suc)-phosphate synthase (SPS) and Suc-phosphate phosphatase (SPP) was examined by measuring the rates of Suc-6-phosphate (Suc-6-P) synthesis and hydrolysis in mixing experiments with partially purified enzymes from spinach (Spinacia oleracea) and rice (Oryza sativa) leaves. The addition of SPP to SPS stimulated the rate of Suc-6-P synthesis. SPS inhibited the hydrolysis of exogenous Suc-6-P by SPP when added in the absence of its substrate (i.e. UDP-glucose) but stimulated SPP activity when the SPS substrates were present and used to generate Suc-6-P directly in the reaction. Results from isotope-dilution experiments suggest that Suc-6-P was channeled between SPS and SPP. A portion of the SPS activity comigrated with SPP during native polyacrylamide gel electrophoresis, providing physical evidence for an enzyme-enzyme interaction. Taken together, these results strongly suggest that SPS and SPP associate to form a multienzyme complex.

Randomised comparison of amoxycillin and erythromycin in treatment of genital chlamydial infection in pregnancy

Erythromycin, the standard treatment for chlamydial infection in pregnant women, commonly causes side-effects, which limits its efficacy. In a randomised, double-blind study, we compared amoxycillin with erythromycin in this setting. 210 pregnant women with Chlamydia trachomatis infection were randomly assigned 7 days' treatment with amoxycillin (500 mg three times daily) or erythromycin (500 mg four times daily). Control cultures were obtained 21 days after treatment, during late pregnancy, and from the infant within a week of birth. Treatment was judged a failure if any post-treatment culture was positive or if the patient had to stop therapy because of severe side-effects. 11 women (5.2%) were lost to follow-up. 1 (of 100) amoxycillin-treated women had to stop treatment because of severe side-effects compared with 12 (of 99) erythromycin-treated women (p = 0.002). 1 woman in the amoxycillin group had a positive culture at the third-trimester examination. No positive post-treatment culture was found in the erythromycin group. Severe gastrointestinal side-effects were more common in women who received erythromycin (31 vs 6%, p < 0.001). The overall failure rate was therefore 2% in the amoxycillin group and 12% in the erythromycin group (p = 0.005). These results suggest that amoxycillin is an acceptable alternative to erythromycin for C trachomatis infection in pregnant women.

[The mother and infant with Steinert's myotonic dystrophy]

Pregnancy and delivery present a number of risks for the mother suffering from myotonic dystrophy, and for her infant. Most of the time, she does not even know that she is affected by the disease and a carrier of the gene. We review the complications of pregnancy and delivery in myotonic patients, and propose a simple management with specific items for each gestational period. The child of a dystrophic mother has a 50% risk of inheriting the abnormal gene. He may also exhibit a developmental and malformation syndrome called "congenital myotonic dystrophy". From the beginning, he may show respiratory distress, thereafter inability to swallow and severely hypotonia. Later, he may demonstrate mental retardation. Some of the most obvious signs found in neonates in our practice are illustrated. We also add a few tests to the list of those already recommended for these children.

alpha-Glycerophosphate dehydrogenase activities in liver and brain mitochondria from neonatal rats treated with L-thyroxine

Liver alpha-GPD undergoes a dramatic increase in newborn rats treated with large doses of L-thyroxine, indicating the elevated exposure of peripheral tissues to the hormone. In contrast, brain enzyme remains unchanged in the two mitochondria populations, free and synaptic.

Use of dextran gradient for the study of the development of mitochondria and glyoxysomes during the germination of pine seeds

An isotonic gradient of dextran-sucrose was used for the separation of glyoxysomes and mitochondria. By this method, these organelles were easily separated from pine seeds on the first day of germination, with densities of 1.110 and 1.175 g/ml for mitochondria and glyoxysomes, respectively. Nevertheless, these sedimented closely at a density of 1.075 g/ml when coming from 30-day stratified seeds; and both organelles highly increased their densities as germination proceeded. A mild treatment of the organelles from 30 days stratified seeds with SDS modified their sedimentation pattern, being similar after this treatment to that of the particles from the seeds on the first day of germination.