G-11 staining in Turner's syndrome with mos 45,X/46,X,r(?)

Mos 45,X/46,X,r(?) in 4 patients with Turner's syndrome and no signs of virilization, and in one pair of monozygotic twins, one of them with clitoral hypertrophy, was studied using combined cytogenetic techniques and specially G-11 staining for the characterization of the X or Y origin of the rings. In all 6 patients the ring was G-11 positive, attesting its Y origin. Both twins were operated and bilateral streak gonads with a bilateral nodule of testicular tissue were found. Similar small rings were also studied in one patient with mos 46,XX/46,X,r(X) and in one nonvirilized Turner's syndrome patient with a larger ring; in these two cases the ring was G-11 negative. It seems that the small rings occasionally found in Turner's syndrome are more frequently from Y origin and therefore prophylactic gonadectomy should be considered.     

Neuronal origin of a cerebral amyloid: neurofibrillary tangles of Alzheimer''s disease contain the same protein as the amyloid of plaque cores and blood vessels.

The protein component of Alzheimer's disease amyloid [neurofibrillary tangles (NFT), amyloid plaque core and congophilic angiopathy] is an aggregated polypeptide with a subunit mass of 4 kd (the A4 monomer). Based on the degree of N-terminal heterogeneity, the amyloid is first deposited in the neuron, and later in the extracellular space. Using antisera raised against synthetic peptides, we show that the N terminus of A4 (residues 1-11) contains an epitope for neurofibrillary tangles, and the inner region of the molecule (residues 11-23) contains an epitope for plaque cores and vascular amyloid. The non-protein component of the amyloid (aluminum silicate) may form the basis for the deposition or amplification (possible self-replication) of the aggregated amyloid protein. The amyloid of Alzheimer's disease is similar in subunit size, composition but not sequence to the scrapie-associated fibril and its constituent polypeptides. The sequence and composition of NFT are not homologous to those of any of the known components of normal neurofilaments.     

Fecal Microflora in Healthy Persons in a Preindustrial Region

Procedures for quantitating the fecal microflora of man were described. Special attention was given to criteria for characterizing the culturable aerobic, Micro-aerophilic, and anaerobic bacteria. Three groups of healthy persons were studied: wholly breast-fed infants (2 to 4 month-olds), weanlings (1 to 2 year-olds), and adults. In breast-fed children, bifidobacteria predominate and outnumber by one or several logs all other culturable bacteria. The fecal flora of wholly breast-fed infants is "simpler" and more numerous [10(11) to 10(12) per g (wet weight) of feces than that of the adult 10(2) to 10(11) per g]. In the adult, gram-negative anaerobic bacilli (bacteroides) outnumber all other groups by a factor of 1 log or more. Weanlings receiving an adult-type diet, but still breast-fed, showed a flora intermediate between that of the wholly breast-fed infant and that of the adult, but more similar to the latter. Anaerobes always constitute the predominant component of the culturable flora of children and adults and are always found in large numbers under conditions of health. The aerobes are significantly less numerous, and vary widely in their number and in the frequency with which they appear in feces.     

Gummivory and gut morphology in two sympatric callitrichids (Callithrix emiliae and Saguinus fuscicollis weddelli) from western Brazilian Amazonia.

A comparative analysis of the gastrointestinal tracts of wild-caught marmosets, Callithrix emiliae, and tamarins, Saguinus fuscicollis weddelli, was undertaken in order to evaluate the degree of specialisation for digestion of plant exudates. Compared to S.f. weddelli, C. emiliae exhibits a reduced small intestine and a relatively large, compartmentalised caecum in which gum is probably fermented. The apparent specialisation of the digestive tract in C. emiliae correlates with that of its dentition, which is adapted for gouging the bark of gum-producing plants. A similar degree of specialisation of the caecum is predicted for other marmosets (Callithrix spp. and Cebuella pygmaea).     

Detection of virulence factors in culturable Escherichia coli isolates from water samples by DNA probes and recovery of toxin-bearing strains in minimal o-nitrophenol-beta-D-galactopyranoside-4-methylumbelliferyl-beta-D-g luc uronide media.

A total of 449 Escherichia coli isolates in treated and raw water sources were submitted to DNA-DNA hybridization using seven different DNA probes to detect homology to sequences that code for Shiga-like toxins I and II; heat-stabile and heat-labile toxins, adherence factors EAF and eae, and the fimbrial antigen of entero-hemorrhagic E. coli. Fifty-nine (13%) of the isolates demonstrated homology with one or more specific DNA probes. More than 50% of the isolates in treated water were not recovered in MMO-4-methylumbelliferyl-beta-D-glucuronide media designed for detection of this indicator.     

Stopped-flow mechanistic study of bromide substitution by an organonitrile at an iron(II) phosphinic centre; a π-electron driven process

The kinetics of the displacement reactions of the bromide ligands of trans-[FeBr₂(depe)₂] (depe = Et₂PCH₂CH₂PEt₂) by the organonitrile NCCH₂C₆H₄OMe-4, in tetrahydrofuran (either in the absence or in the presence of added Br⁻), to give the corresponding mono- and dinitrile complexes trans-[FeBr(NCCH₂C₆H₄OMe-4)(depe)₂]⁺ and trans-[Fe(NCCH₂C₆H₄OMe-4)₂(depe)₂]²⁺, have been investigated by stopped-flow spectrophotometry. The substitution reaction occurs by a mechanism involving rate-limiting dissociation of bromo ligands to form the unsaturated intermediates [FeBr(depe)₂]⁺ (k₁ = 1.52 ± 0.02 s⁻¹) and [Fe(NCR)(depe)₂]²⁺ (k₃ = 0.063 ± 0.008 s⁻¹) which add the nitrile ligand to form those nitrile complexes. The competition between the nitrile and Br⁻ for such metal centres has also been investigated and a stronger inhibiting effect of added Br⁻ is observed for the substitution of the second bromo ligand relative to the first one. The kinetic data are rationalized in terms of π-electronic effects of these unsaturated metal centres and of the bromide and nitrile ligands.     

Measurement of nutrient spiralling during a period of continuous surface flow in a Mediterranean temporary stream (Arroyo de La Montesina, Spain)

Uptake rate of calcium, potassium, nitrate-N and phosphorus were measured in a second order Mediterranean temporary stream, in February and March 1992. This study analyzed a period of continuous surface flow between two hydrologic disturbance events (flood and drought) of an annual hydrological cycle (1991–92).The lowest values of uptake length were recorded for nitrate-N in February 92 and calcium in March 92. Nitrate had the highest uptake rate in both release performances, and potassium showed the lowest uptake rate values. The increase of calcium and nitrate uptake rate between February 92 and March 92 suggested a higher ecosystem efficiency in nutrient retention with a higher temperature and light intensity and slower water velocity, discharge and water depth. These results obtained were similar to those reported in permanent streams, indicating that in periods of continuous surface flow (without extreme hydrologic disturbance), abiotic factors can influence nutrient retention in temporary streams.     

The Jurassic succession in west-central Argentina: stratal patterns, sequences and paleogeographic evolution

Jurassic rocks in west-central Argentina are predominantly marine and marginal-marine siliciclastics, associated with prominent but volumetrically subordinate carbonates and evaporites. Facies developments were ruled by paleogeographic persistence within the southern-infratropical latitude belt (within 40–50°S) and by siliciclastic derivation from the Patagonian hinterland to the southwest. Minor volcanic and volcaniclastic supply arrived from the west, out of a magmatic belt related to Circum-Pacific convergence. Timing of the main marine-flooding events and general correspondence with the high-rank stratal packaging recorded in western North America, suggest that global eustasy was also a factor in controlling the local stratigraphic record. Early Jurassic sedimentation occurred within a series of semi-isolated depocentres linked to fault-bounded Triassic troughs. The Sinemurian-Toarcian deposits record depocentre expansion and coalescence. These trends were coeval with progressively more widespread marine invasions from the northwest and west, leading to an elongate marine seaway which connected central Patagonia with the Pacific domain. During the Aalenian-Bajocian the region was subject to a more subdued tectonism and the foreland side of the basin became fringed by an extensive clastic embankment. Bathonian and Early Callovian were times when coarse clastics prograded into the basin, while the marine embayment shrank as a result of stepwise forced regressions. During Late Callovian to Oxfordian globally rising sea-level, the depocentre witnessed the appearance of cosmopolitan invertebrates and a stratal pattern of basin widening and depositional underbalance, that promoted cratonward onlap and inception of widespread carbonate deposition. Ooidal-coralline carbonate development was terminated after a relatively sudden (Messinian-style) event that desiccated a large tract of the Andean basin, and favored massive precipitation of anhydrite. In the course of the Kimmeridgian the evaporite basin was largely flooded by siliciclastics and turned into a broad and featureless mudflat-salina complex, linked to a widespread erg and to an ephemeral drainage system. By the Tithonian, at a period of peak oceanic stand, marine connection was reinstated and recorded as the most widespread Jurassic transgression across the Neuquén-Aconcagua embayment. Shelfal deposition consisted of molluscs and ooid-dominated carbonate terraces that grew in pulses tuned to eustatic fluctuations. Like in other prolific petroleum provinces around the world the Tithonian basinal strata involve widespread euxinic deposits featuring unusually high organic content.