Early Middle Ordovician evidence for land plants in Argentina (eastern Gondwana).

• The advent of embryophytes (land plants) is among the most important evolutionary breakthroughs in Earth history. It irreversibly changed climates and biogeochemical processes on a global scale; it allowed all eukaryotic terrestrial life to evolve and to invade nearly all continental environments. Before this work, the earliest unequivocal embryophyte traces were late Darriwilian (late Middle Ordovician; c. 463-461 million yr ago (Ma)) cryptospores from Saudi Arabia and from the Czech Republic (western Gondwana). • Here, we processed Dapingian (early Middle Ordovician, c. 473-471 Ma) palynological samples from Argentina (eastern Gondwana). • We discovered a diverse cryptospore assemblage, including naked and envelope-enclosed monads and tetrads, representing five genera. • Our discovery reinforces the earlier suggestion that embryophytes first evolved in Gondwana. It indicates that the terrestrialization of plants might have begun in the eastern part of Gondwana. The diversity of the Dapingian assemblage implies an earlier, Early Ordovician or even Cambrian, origin of embryophytes. Dapingian to Aeronian (Early Silurian) cryptospore assemblages are similar, suggesting that the rate of embryophyte evolution was extremely slow during the first c. 35-45 million yr of their diversification. The Argentinean cryptospores predate other cryptospore occurrences by c. 8-12 million yr, and are currently the earliest evidence of plants on land.

Photoluminescence of as-grown silicon nanocrystals embedded in silicon nitride: influence of atomic hydrogen abundance.

Silicon nanocrystals embedded in silicon nitride films were grown by direct plasma enhanced chemical vapor deposition at 300 degrees C, using mixtures of SiH2Cl2/NH3/H2/Ar. The films composition and chemical stability was tested by Fourier Transform Infrared Spectroscopy and Rutherford Backscattering Spectroscopy. The influence of hydrogen abundance during the deposition process on the photoluminescence of as-grown samples was studied as a function of the radiofrequency power and hydrogen dilution flow rate. In situ Optical Emission Spectroscopy allowed the diagnostic of the species in the plasma region and their general trends as a function of the radiofrequency power. The changes in the hydrogen content and silicon incorporation to the film as a function of the radiofrequency power were discussed in terms of silicon nanocrystals formation and growth in the silicon nitride matrix. The photoluminescence emission from the as-grown samples was found to red-shift with increasing hydrogen abundance. This observation is consistent with the increase in silicon content associated to nc-Si of larger size. On the other hand, the photoluminescence intensity was observed to decrease for very high radiofrequency powers and hydrogen dilutions. High Resolution Transmission Electron Microscopy confirmed the presence of silicon nanocrystals embedded in the amorphous silicon nitride matrix and allowed the correlation between the nanocrystals size and the photoluminescence emission energy using the quantum confinement model.

[Clinical and laboratory characteristics of patients with pathologic chronic gastroesophageal reflux]. / Características clínicas y de laboratorio de pacientes con reflujo gastroesofágico crónico patológico.

BACKGROUND: Sixty percent of adults has typical symptoms of gastroesophageal reflux in Chile. AIM: To report the clinical and laboratory features of patients with gastroesophageal reflux. PATIENTS AND METHODS: Five hundred thirty-four patients (255 male) with gastroesophageal reflux were included in a prospective protocol that included clinical analysis, manometry and endoscopy in all patients, barium swallow in 427, scintigraphy in 195, acid reflux test in 359, 24 h pH in 175, and differential potential of gastroesophageal mucosa in 73 patients. RESULTS: There was no correlation between the severity of symptoms and the endoscopical severity. Patients with Barret esophagus were 12 years older, were male in a greater proportion and had a higher proportion of manometrically incompetent sphincters than patients with esophageal reflux but without esophagitis or with erosive esophagitis. Severity of acid reflux, measured with 24 h pH monitoring was proportional to the endoscopical damage of the mucosa. There was a close relationship between the mucosal change limit determined with differential potentials and with endoscopy. No short esophagi were found. CONCLUSIONS: Patients with symptoms of gastroesophageal reflux must be assessed using several objective measures to determine the severity of their pathological alterations.

'Carditis': an objective histological marker for pathologic gastroesophageal reflux disease.

In a prospective endoscopic and bioptic study, 141 control subjects and 359 patients with symptoms of gastroesophageal reflux (GER) were included to determine the prevalence of cardial epithelium inflammation or 'carditis' and to determine the prevalence of Helicobacter pylori in this area. Two biopsies at the antrum, four distal to the squamous-columnar junction and two proximal in the esophageal mucosa, were taken. Patients with gastroesophageal reflux were divided into four groups, according to the severity of endoscopic findings: patients without esophagitis, patients with erosive esophagitis, patients with short-segment and long-segment Barrett's esophagus (BE). Control subjects had normal histological findings at the cardia in 90% of cases, fundic mucosa being present twice as cardial epithelium. Carditis was present in 8% of cases and intestinal metaplasia (IM) in 2%. On the contrary, patients with GER had carditis in nearly 50% of cases. Intestinal metaplasia was present in 12% of cases with GER without esophagitis or erosive esophagitis, in 35% of cases with short-segment BE and in 65% of the cases with long-segment BE. IM at the antrum was present in only 5% of cases. Helicobacter pylori at the squamous-columnar junction was present in 13% of control subjects and in 30% of the patients with GER. It is concluded that carditis is an easy and objective marker for the presence of chronic gastroesophageal reflux and the presence of Helicobacter pylori at this region must be carefully evaluated in order to determine some pathogenic role for the development of Barrett's esophagus.

Long-term results of classic antireflux surgery in 152 patients with Barrett's esophagus: clinical, radiologic, endoscopic, manometric, and acid reflux test analysis before and late after operation.

BACKGROUND: The classic surgical procedure for patients with Barrett's esophagus (BE) has been either Nissen fundoplication or posterior gastropexy with calibration of the cardia. METHODS: The purpose of our study was to determine late subjective and objective results of these classic surgical techniques in a large number of patients with BE. A total of 152 patients were included in this prospective protocol. RESULTS: There was 1 death (0.7%) after operation. The late follow-up of 100 months demonstrated a high percentage of failures among patients with noncomplicated BE (54%) and an even higher figure in patients with complicated BE (64%). In 15 patients low grade dysplasia appeared at 8 years of follow-up and an adenocarcinoma in 4 patients. Twenty-four-hour pH monitoring demonstrated a decrease in acid reflux into the esophagus, and Bilitec studies also demonstrated a decrease of duodenoesophageal reflux, but in all cases with a higher value than the normal limit. CONCLUSIONS: Classic antireflux surgery in patients with BE results in a high percentage of failures at very late follow-up because it cannot completely avoid acid and duodenal reflux into the esophagus.

Correlation of serum fructosamine activity in type I diabetic children.

The serum fructosamine assay is a new commercially available test designed to measure serum glycated protein as an index of glycemic control in diabetes. The test relies on the ability of glucose bound to protein with a ketamine linkage (fructosamine) to act as a reducing agent in alkaline solution. Serum fructosamine activity was studied in 61 Type I diabetic patients attending a 2-week American Diabetes Association sponsored diabetic camp for children. The initial fructosamine level was found to correlate well with the initial HgA1C value (r = .82, p less than .001). To assess if mean blood glucose correlated with these objective parameters, the authors performed capillary blood glucoses preprandially and at bedtime on all 61 diabetic campers during the 2-week period of observation and reassessed serum fructosamine activity and HgA1C on day 14 of camp. We found the HgA1C and fructosamine correlated well with the mean daily blood glucose obtained during the preceding week (r = .45, p less than .01 and r = .58, p less than .01) respectively. Our data suggest that the serum fructosamine is as effective as the HgA1C in correlating to mean blood glucose control in this cross-sectional study of Type I diabetic patients.

Post-traumatic stress disorder in Hispanic Vietnam veterans. Clinical phenomenology and sociocultural characteristics.

The complex symptomatology of Hispanic Vietnam veterans receiving treatment for post-traumatic stress disorders (PTSD) was explored with the National Institute of Mental Health Diagnostic Interview Schedule, a structured diagnostic interview that yields current and lifetime operational diagnoses (e.g., DSM-III). Social networks and level of acculturation of these veterans were also examined and compared to those of a "control" group and a sample of veterans with DSM-III schizophrenic disorder (both samples included only Hispanic veterans from the Vietnam and post-Vietnam eras). All subjects reported heavy combat stress and met DSM-III criteria for PTSD. Most were very symptomatic and had significant social impairment. PTSD was rarely seen as a discrete entity but appeared instead mixed with symptom clusters cutting across various DSM-III diagnoses. Social networks of PTSD veterans were intermediate in size, frequency of contact with network members, and network density to those of the comparison groups. A distinctive feature of the PTSD group was the high proportion of negative relationships with close family members, especially spouses. "Highly" symptomatic PTSD veterans reported significantly smaller networks, fewer contacts outside the close family circle, and more negative emotionality directed toward family members than "minimally" symptomatic veterans. While all Hispanic groups studied were not significantly different in level of acculturation, PTSD veterans appeared more alienated from their cultural heritage than the other groups. The severe and polymorphous psychopathology found among these veterans suggests that "rap" groups alone may not constitute an adequate therapeutic approach and that more formal psychiatric therapies should be additionally considered in the management of Vietnam-linked PTSD.

[Somatic preoccupations and their effect on the colon]. / Preoccupazioni somatiche e loro effetti sul colon.

The psychic reevocation of disturbance of the colon or disturbances of other body districts not felt by the patient at the time facilitates the accentuation of colon motility or tone, leading to the exacerbation of the pathogenetic premises of the disturbances complained of. The colonmetrographic findings are instructive in this respect. Direct functional disturbance of various districts is also suggested, and the pathology of such forms in psychosomatically oriented patients is described. Such orientation takes the form of a ready translation of ideas into rather diffuse somatic changes that are partly aspecific, due to the predominance of response mechanisms that are more physiological than psychological. The picture is one of a primordial reaction to difficulties and problems, coupled with increased stress, sometimes to the points of vegetative or motor storms, in the expectation of help from outside, such help being represented in the past by intervention on the part of the mother.