Confidential inquiry into perinatal mortality in the Lower Rio Grande Valley, 1988

A review of 1985 neonatal death statistics in the Lower Rio Grande Valley of Texas revealed an excessive perinatal death rate among Hispanics compared to Anglos. In order to identify factors contributing to perinatal mortality in the region and to determine if existing perinatal services were adequate, a confidential inquiry into each 1988 perinatal death was performed.^ Medical risk factors in the mothers were infrequent. The most commonly noted pregnancy complication was polyhydramnios. This complication is often associated with anencephalus which was the most frequent birth anomaly detected in the region.^ The study results did not reveal an association between lay midwife deliveries in the region and excessive perinatal mortality nor did perinatal mortality appear to be associated with a lack of neonatal intensive care facilities. Lack of prenatal care was the most commonly encountered preventable factor associated with perinatal death. It was not possible to determine if the level of care for Anglos and Hispanics differed because of the low number of Anglo deaths although the socioeconomic level of deaths in each of the ethnic groups was the same. ^

RESPIRATORY COMPENSATION MECHANISMS IN THE UPPER AND LOWER RESPIRATORY TRACTS OF AN ANIMAL MODEL AFTER SUBCHRONIC INHALATION EXPOSURE TO FORMALDEHYDE: IMPLICATIONS FOR TOXICOLOGY RISK ASSESSMENT (DEPOSITION, DOSE RECEIVED, RESPONSE)

The potential for significant human populations to experience long-term inhalation of formaldehyde and reports of symptomatology due to this exposure has led to a considerable interest in the toxicologic assessment of risk from subchronic formaldehyde exposures using animal models. Since formaldehyde inhalation depresses certain respiratory parameters in addition to its other forms of toxicity, there is a potential for the alteration of the actual dose received by the exposed individual (and the resulting toxicity) due to this respiratory effect. The respiratory responses to formaldehyde inhalation and the subsequent pattern of deposition were therefore investigated in animals that had received subchronic exposure to the compound, and the potential for changes in the formaldehyde dose received due to long-term inhalation evaluated. Male Sprague-Dawley rats were exposed to either 0, 0.5, 3, or 15 ppm formaldehyde for 6 hours/day, 5 days/week for up to 6 months. The patterns of respiratory response, deposition and the compensation mechanisms involved were then determined in a series of formaldehyde test challenges to both the upper and to the lower respiratory tracts in separate groups of subchronically exposed animals and age-specific controls (four concentration groups, two time points). In both the control and pre-exposed animals, there was a characteristic recovery of respiratory parameters initially depressed by formaldehyde inhalation to at or approaching pre-exposure levels within 10 minutes of the initiation of exposure. Also, formaldehyde deposition was found to remain very high in the upper and lower tracts after long-term exposure. Therefore, there was probably little subsequent effect on the dose received by the exposed individual that was attributable to the repeated exposures. There was a diminished initial minute volume response in test challenges of both the upper and lower tracts of animals that had received at least 16 weeks of exposure to 15 ppm, with compensatory increases in tidal volume in the upper tract and respiratory rate in the lower tract. However, this dose-related effect was probably not relevant to human risk estimation because this formaldehyde dose is in excess of that experienced by human populations. ^

Mineral resources in Lower Brule Indian Reservation

On the Lower Brule Indian Reservation in South Dakota, about 3 million tons of metallic manganese are in low-grade deposits in the DeGrey Member of the Pierre Shale on the reservation. The geology and methods of mining and processing this sub-economic mineral resource have been studied extensively; technologically, extraction of manganese is possible. However, an efficient, economical method to separate manganese-bearing nodules from the shale host rocks has yet to be found. The manganiferous nodules occur in the Oacoma zone of the Sully shale member (De-Grey Member) which is a subdivision of the South Dakota Pierre Shale formation. These nodular deposits have an interesting similarity in stratigraphical position, lithology and manganese content to those of the Porcupine Mountain area in Manitoba.

Lower Cretaceous nannofossils of the northwestern Australian margin

Moderately to sparsely nannofossiliferous Neocomian siliciclastics and rich Aptian-Albian nannofossil chalks were cored at two Leg 123 sites on the abyssal plains off northwestern Australia. At Site 765, the basal 70 m of cored section yields questionable Tithonian and Berriasian to early Hauterivian assemblages of moderate diversity containing Cruelellipsis cuvillieri, Tegumentum striatum, Speetonia colligata, and Crucibiscutum salebrosum. The overlying Hauterivianlower Aptian is represented by 140 m of sediments barren of nannofossils. Above this, the remaining 80 m of the Lower Cretaceous section has been assigned to the Rhagodiscus angustus Zone (late Aptian-early Albian in age) and the Prediscosphaera columnata Zone (middle-late Albian in age). Common species include Rhagodiscus angustus, Prediscosphaera columnata, Eprolithus floralis, Eprolithus sp., Chiastozygus litterarius, Rucinolithus irregularis, and Flabellites biforaminis. At Site 766, the Neocomian, represented by 200 m of sediment, yields C. cuvillieri, T. striatum, S. colligata, and C. salebrosum. Within the overlying Aptian-Albian sequence of 80 m, the Rhagodiscus angustus, and P. columnata zones were recognized. The paleobiogeographic patterns and implications are discussed, with special emphasis paid to the bipolar high-latitude distribution pattern of C. salebrosum in the Valanginian-Hauterivian. Biostratigraphically important species are discussed and their occurrence in the Indian Ocean is compared with one from the Tethys and Boreal realms. Two new species, Serbiscutum gaultensis and Eprolithus bettenstaedtii, are described.

Lower Cretaceous planktonic foraminifer stratigraphy of sediments from ODP Leg 171B sites

During Ocean Drilling Program Leg 171B, an Aptian to Turonian sedimentary succession yielding exceptionally well-preserved planktonic foraminiferal faunas was recovered at Sites 1049, 1050, and 1052. Most of the standard Tethyan planktonic foraminiferal zones have been recognized within the mid-Cretaceous section, with the exception of two Albian zones not reached by any of the drilled holes. In addition, some emphasis is brought here on the current problems concerning the definition of the Aptian/Albian and Albian/Cenomanian boundaries.

(Table 1) Cation exchange capacity and other characteristics of soils common in Lower Saxony, Germany

The chemical and biochemical processes associated with the filtration of rainwater through soils, a step in groundwater recharge, were investigated. Under simulated climatic conditions in the laboratory, undisturbed soil columns of partly loamy sands, sandy soils and loess were run as lysimeters. A series of extraction procedures was carried out to determine solid matter in unaltered rock materials and in soil horizons. Drainage water and moisture movement in the columns were analysed and traced respectively. The behaviour of soluble humic substance was investigated by percolation and suspension experiments. The development of seepage-water in the unsaturated zone is closely associated with the soil genetic processes. Determining autonomous chemical and physical parameters are mineral composition and grain size distribution in the original unconsolidated host rock and prevailing climatic conditions. They influence biological activity and transport of solids, dissolved matter and gases in the unsaturated zone. Humic substances, either as amorphous solid matter or as soluble humic acids play a part in diverse sorption, solution and precipitation processes.