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D Rivers

Publications and source records attributed to D Rivers.

7 recordsLinked to original sources
PubMed2001

Anti-SLIP1-reactive proteins exist on human spermatozoa and are involved in zona pellucida binding.

Sulpholipid immobilizing protein 1 (SLIP1) is an evolutionarily conserved 68 kDa plasma membrane protein, present selectively in germ cells. We have previously shown that mouse sperm SLIP1 is involved in sperm-zona pellucida (ZP) binding. In this report, we extended our study to the human system. Immunoblotting demonstrated that anti-SLIP1-reactive proteins (mol. wt 68 and 48 kDa) could be extracted from human spermatozoa by an ATP-containing solution, a result that is consistent with observations in other species. Direct immunofluorescence, using Cy3-conjugated anti-SLIP1 IgG, revealed SLIP1 staining over the acrosomal region, with higher intensity at the posterior area. Using the human sperm-ZP binding assay, we demonstrated that pretreatment of human spermatozoa from three donors with anti-SLIP1 IgG revealed lower numbers of zona-bound spermatozoa, as compared to the corresponding control spermatozoa treated with normal rabbit serum IgG. This decrease in zona pellucida binding was not from an antibody-induced decline in sperm motility or an increase in the premature acrosome reaction. The results strongly suggest that anti-SLIP-reactive proteins on human spermatozoa play an important role in ZP binding.

Acrosome↗
PubMed1997

Caste formation in the polyembryonic wasp Copidosoma floridanum (Hymenoptera: Encyrtidae): in vivo and in vitro analysis.

The polyembryonic wasp Copidosoma floridanum produces two morphologically distinct types of larvae in its host Trichoplusia ni. Reproductive larvae consume the host, pupate, and form adult wasps, whereas precocious larvae manipulate the sex ratios of the reproductive caste and defend the brood against interspecific competitors. The previous study indicated that morphogenesis of the reproductive caste was associated with a 9-day competency period, and that ecdysteroids of host origin were required for completion of embryogenesis. Here we investigated whether factors associated with the host environment mediate morphogenesis of precocious larvae and caste determination. Embryogenesis of precocious larvae was found to be synchronized with specific stages of the host first-fourth instars. However, development of precocious larvae did not depend on environmental factors specifically associated with these host stages. Elevation of the host juvenoid titer using the analogue methoprene induced T. ni to undergo a supernumerary sixth instar, but did not alter the proportion of wasp embryos that developed into precocious and reproductive larvae. In contrast, embryos competent to initiate morphogenesis developed into precocious larvae when transplanted into novel host stages such as pupae. Development of precocious larvae was arrested by ablation of the host's source of ecdysteroids, but could be rescued dose-dependently by injection of 20-hydroxyecdysone. In vitro rearing studies confirmed that completion of embryogenesis of the precocious caste required an exogenous pulse of 20-hydroxyecdysone. Combined with previous studies, our results indicate that embryos forming precocious and reproductive larvae acquire the competence to undergo morphogenesis at different times. However, we find no evidence to suggest that caste determination is mediated by environmental factors associated with a specific stage of the host.

Journal Article↗
PubMed1991

Functional domains of Bacillus thuringiensis insecticidal crystal proteins. Refinement of Heliothis virescens and Trichoplusia ni specificity domains on CryIA(c).

Insecticidal crystal proteins (delta-endotoxins), CryIA(a) and CryIA(c), from Bacillus thuringiensis are 82% homologous. Despite this homology, CryIA(c) was determined to have 10-fold more insecticidal activity toward Heliothis virescens and Trichoplusia ni than CryIA(a). Reciprocal recombinations between these two genes were performed by the homolog-scanning technique. The resultant mutants had different segments of their primary sequences exchanged. Bioassays with toxin proteins from these mutants revealed that amino acids 335-450 on CryIA(c) are associated with the activity against T. ni, whereas amino acids 335-615 on the same toxin are required to exchange full H. virescens specificity. One chimeric protein toxin, involving residues 450-612 from CryIA(c), demonstrated 30 times more activity against H. virescens than the native parental toxin, indicating that this region plays an important role in H. virescens specificity. The structural integrity of mutant toxin proteins was assessed by treatment with bovine trypsin. All actively toxic proteins formed a 65-kDA trypsin-resistant active toxic core, similar to the parental CryIA(c) toxin, indicating that toxin protein structure was not altered significantly. Contrarily, certain inactive mutant proteins were susceptible to complete protease hydrolysis, indicating that their lack of toxicity may have been due to structural alterations.

Bacillus thuringiensis↗
PubMedDate not supplied

Microcomputer-assisted transmission of disaster data by cellular telephone.

Voice communication of information during disasters is often inadequate. In particular, simultaneous transmission by multiple callers on the same frequency can result in blocked transmissions and miscommunications. In contrast, nonvoice transmission of data requires less time than does voice communication of the same data, and may be more accurate. We conducted a pilot study to test the feasibility of a microcomputer assisted communication (MAC) network linking the disaster scene and the command hospital. The radio chosen to transmit data from the field disaster site to the command hospital was a cellular telephone connected to the microcomputer by modem. Typed communications between the microcomputer operators enabled dialogue between the disaster site and the hospitals. A computer program using commercially available software (Symphony by Lotus, Inc.) was written to allow for data entry, data transmission, and reports. Patient data, including age, sex, severity of injury, identification number, major injuries, and hospital destination were successfully transmitted from the disaster site command post to the command hospital. This pilot test demonstrated the potential applicability of MAC for facilitating transmission of patient data during a disaster.

Computer Communication Networks↗
PubMedDate not supplied

Mainframe computer use and residency cohort data.

This paper describes a computer based method that was developed to prepare a profile of the patient care experiences of a cohort in a three-year, university based family practice residency. Sample pages from the report produced by this method and a description of the computer program are presented. This method of presenting patient encounter information may be particularly useful for program-level evaluation and for monitoring resident training.

Chicago↗