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Biomedical subjects

C S Goodman

Publications and source records attributed to C S Goodman.

196 records · Page 11Linked to original sources
PubMed1981

Embryonic development of identified neurons: origin and transformation of the H cell.

We describe the origin and the transformation of a single neuron, the H cell, which assumes two different roles during grasshopper embryogenesis. The H cell originates from the single cell division of midline precursor 3 (MP3). In the metathoracic (T3) segment, the H cell first appears as one of a pair of central pioneer fibers and later transforms into an unpaired identified neuron. During the course of its transformation, the H cell loses its original morphology and acquires new morphological and physiological properties. The H cell acquires many of the same phenotypes as the first progeny of the median neuroblast (MNB); the processes of the first MNB progeny contact the soma of the H cell and these cells are electrically coupled prior to the H cell transformation.

Animals↗
PubMed1980

Electrical excitability: a spectrum of properties in the progeny of a single embryonic neuroblast.

We have examined the range of some properties of the progeny of a single embryonic precursor cell in the grasshopper. The approximately 100 progeny of this single neuroblast share certain features such as their transmitter and some aspects of their morphology; at the same time, however, they demonstrate a broad spectrum of electrical properties, from spiking to non-spiking neurons. The first-born progeny are spiking neurons with peripheral axons. Many of the progeny, including all of the last-born, do not generate action potentials. The nonspiking progeny are local intraganglionic neurons and appear to compose a major proportion of the progeny of this neuroblast. All of the nonspiking neurons have calcium inward current channels and can make action potentials when outward current channels are blocked. We propose a model for grasshopper neurogenesis based on cell lineage such that (i) certain features (e.g., transmitter) are shared by the progeny of all cell divisions from a single neuroblast, and (ii) other features (e.g., electrical properties) are shared by the progeny of a given birth position (e.g., first versus last born) from all of the neuroblasts. According to this model, the first-born progeny from all neuroblasts are spiking neurons, whereas the last-born are nonspiking.

Action Potentials↗
PubMed1979

Embryonic development of identified neurones: differentiation from neuroblast to neurone.

Individually identified neurones are sufficiently large and accessible in grasshopper embryos to permit visualisation and impalement with intracellular microelectrodes from the time of their birth to their maturation. In this article part of the temporal pattern of differentiation from an identified neuroblast (precursor cell) to a group of identified neurones is described.

Acetylcholine↗
PubMed1979

Embryonic development of identified neurons: temporal pattern of morphological and biochemical differentiation.

Individually identified neurons can be recognized in grasshopper embryos, and are accessible to examination by morphological, physiological, and biochemical techniques from their birth to their maturation. Only after the axon of an identified neuron reaches its postsynaptic target does the neurotransmitter accumulate, the soma rapidly enlarge, and the central arborizations greatly expand.

Animals↗
PubMed1978

Isogenic grasshoppers: genetic variability in the morphology of identified neurons.

Although identified neurons are defined as constant and unique from animal to animal within the same species, we might expect to find phenotype variability in the number, morphology, and physiology of identified neurons if we examined them in enough sexually reproduced animals of the same species. Morphological variability and axonal abnormalities were previously encountered in a study of the large ocellar interneurons in 50 grasshoppers. Both the somata and arborizations in the brain of the ocellar interneurons from one or more ocelli can be stained easily and repeatedly with cobalt, so that one can routinely examine the morphology of large numbers of cells in large numbers of animals. In the present study, the large ocellar interneurons were examined in three types of animals: (i) animals from two different breeding populations and their offspring, (ii) the offspring within clutches from single mated pairs of known phenotypes, and (iii) isogenic animals from the parthenogenetic clones of single unmated females. The soma location, axonal pathway, location of arborizations, and fine branching patterns of 14 of the large ocellar interneurons were examined in 430 grasshoppers. The large ocellar interneurons were examined in 11 clones raised in nearly constant and identical conditions. In most of the clones, the morphology of interneurons L5L and L5R was normal; all of the 82 animals examined from clones 4, 7, 9, 10, 12, 13, 16, and 17 were normal. Clones 8 and 2 had high percentages of animals with axonal abnormalities of interneuron L5: 16 out of 24 animals (66%) in clone 8 and 37 out of 42 animals (88%) in clone 2. All of the ocellar interneurons except for L5 were normal in all of these animals. Thus, the abnormal development of at least one identified interneuron, L5, can occur with a high degree of genetic control and a high degree of specificity. The axonal abnormality of interneuron L5 was not the same in each of the 37 animals from clone 2, although common mistakes and patterns were detected.

Animals↗
PubMed1977

Neuron duplications and deletions in locust clones and clutches.

Duplications and deletions of identified neurons can occur with a high degree of genetic control and specificity, as shown by examining the ocellar interneurons of locusts from different breeding populations, clutches from single mated pairs, and isogenic animals from parthenogenetic clones.

Animals↗
PubMed1976

Anatomy of the ocellar interneurons of acridid grasshoppers. I. The large interneurons.

The anatomy of the large ocellar interneurons in the brain of five species of acridid grasshoppers of two different subfamilies (Schistocerca vaga, S. gregaria, Gastrimargus africanus, Trimerotropis pallidipennis, and Arphia conspersa) was revealed by cobalt-filling of the three ocellar nerves and subsequent reconstructions from silver-intensified (Timm's method) serial sections. Conflicts in the literature are reviewed (Tables 1, 2) and differences in the number of cells, anatomical descriptions of these cells, and nomenclature are resolved by demonstration of an identical number of large ocellar identical number of large ocellar interneurons in all five species examined (Fig. 1). There are 17 large 1st-order ocellar interneurons (Figs. 2, 3). Each of the three ocellar nerves contains the axons of seven large interneurons; four of these interneurons have axons in two ocellar nerves. The anatomy of three pairs of 2nd-order ocellar interneurons (with branches in the ocellar tracts within the brain and axons in the circum-esophageal connectives) is reconsidered in light of recent conflicts in the literature. Previous accounts by Williams (1975) of interneurons O2, O3, and PI(2):5 are corroborated and new details added (Fig. 7) by the use of a cobalt method that appears to stain these 2nd-order interneurons transsynaptically (Fig. 6).

Animals↗
PubMed1976

Anatomy of the ocellar interneurons of acridid grasshoppers. II. The small interneurons.

The anatomy of the small ocellar interneurons in the brain of the acridid grasshopper Schistocerca vaga was revealed by cobalt-filling the three ocellar nerves and subsequent reconstructions from silver-intensified (Timm's method) serial sections. In total, 61 small ocellar interneurons were repeatedly identified with arborizations in many areas of the brain and optic lobe, including in particular the posterior neuropil, ocellar tracts, protocerebral bridge, lobula, ventral bridge and tritocerebral crotch, calyces, and antenno-glomerular tracts. Each ocellar nerve contains the axons of small cells that arborize in the other two ocellar tracts; these tracts are sites of ocellar integration. Direct interactions between the ocelli and compound eyes are suggested by the projections of small ocellar interneurons into the proximal lobula. Small cell arborizations from all three ocelli are distributed actoss much of the protocerebral bridge, implying a role for the bridge as an ocellar neuropil within the brain. Four of the small interneurons could be seen in whole-mount preparations and are demonstrated to be identical in five species of acridid grasshoppers of two different subfamilies: Schistocera vaga, S. gregaria, Gastrimargus africanus, Trimerotropis pallidipennis, and Arphia conspersa.

Animals↗
PubMedDate not supplied

Cell determination and regulation during development of neuroblasts and neurones in grasshopper embryo.

The embryonic development of the central nervous system (CNS) involves the generation of an enormous diversity of cellular types arranged and interconnected in a remarkably precise pattern. In each hemisegment of the grasshopper embryo, the ectoderm generates a stereotyped pattern of 30 neuronal precursor cells, called neuroblasts (Fig. 1). Each of these stem cells makes a stereotyped contribution of 6-100 progeny to the approximately 1,000 different neurones, each cell identifiable according to its unique morphology, physiology and biochemistry. What are the contributions of cell interactions and cell lineage to the generation of this diversity and specificity of identified neurones in the grasshopper CNS? Here we report on cell ablations with a laser microbeam at different stages of development. Our results suggest the importance of cell-cell interactions in the determination of ectodermal cells to become identified neuroblasts. However, once a neuroblast begins to divide, then cell lineage appears to play an important role in the determination of its stereotyped family of neuronal progeny. Furthermore, cell-specific interactions continue to play an important role as neurones, according to their mitotic ancestry, recognize and interact with other differentiating neurones in their environment.

Animals↗
PubMedDate not supplied

From grasshopper to Drosophila: a common plan for neuronal development.

Little is known about the mechanisms that generate neuronal specificity during development. Whereas the grasshopper embryo has been an ideal system for a cellular analysis of neuronal development, the Drosophila embryo has obvious attributes for a molecular genetic analysis. Here we show that the early Drosophila embryo is a miniature replica of the grasshopper embryo in terms of its identified neurones, their growth cones and their selective fasciculation choices, thus opening the way for a combined cellular and molecular genetic analysis of cell recognition during neuronal development in Drosophila.

Animals↗
PubMedDate not supplied

Transient expression of a surface antigen on a small subset of neurones during embryonic development.

During development, neurones find and interconnect with their targets in a remarkably precise way. The unfolding of neuronal specificity involves a series of highly specific recognition events which are likely to be coordinated by the spatial and temporal expression of many different surface molecules. At early stages of development, neuronal recognition occurs most dramatically at the tips of growing axons, at growth cones and their filopodia. Previous studies on the grasshopper embryo suggest that specific filopodial contacts lead to the stereotyped patterns of selective axonal fasciculation; these results support the 'labelled pathways' hypothesis which predicts that the different neighbouring axon fascicles in the embryonic neuropil within filopodial grasp are differentially labelled. To uncover the molecular labels on fasciculating embryonic axons, we screened 2,000 monoclonal antibodies generated against the embryonic neuroepithelium. Here we describe three antibodies which reveal surface antigens whose temporal and spatial expression during embryogenesis correlate with the predictions of the model. In particular, the Mes-2 antibody recognizes an antigen which is transiently expressed on the surface of only 4 out of approximately 1,000 neurones in each metathoracic hemisegment during a short period of embryogenesis. The growth cones of two of these neurones fasciculate in the periphery and innervate the same target. Moreover, they transiently express the Mes-2 surface antigen while doing so.

Animals↗
PubMedDate not supplied

Emergency medical services equipment hygiene practices.

OBJECTIVE: To determine whether emergency medical services (EMS) systems adhere to accepted equipment hygiene standards. METHODS: Mail surveys were sent to the physician medical directors of the EMS systems of the 125 most populous cities in the United States. RESULTS: Eighty-five surveys (68%) were returned. Seventy-three (86%) of the responding services have a policy addressing equipment decontamination, and 32 of these (44%) have an accompanying quality assurance program. Seventy-nine (93%) utilize either alcohol or a commercial disinfectant (A/CD) on noncritical items when visibly contaminated with blood. However, only 32 of those agencies (41%) use soap and water in addition to A/CD. Another nine (11%) exchange contaminated items at the hospital, one (1%) uses other methods, and two (2%) respondents did not know. Seventy-six (89%) of the responding agencies perform endotracheal intubation. Of the 54 that decontaminate their own blades, 20 (37%) use soap and water in addition to A/CD, 32 (59%) use A/CD alone, and two (4%) use soap and water alone. CONCLUSION: Adherence to accepted hygiene standards among EMS systems in our most populous cities is poor. Many systems do not use soap and water prior to A/CD. Failure to do so may minimize the effectiveness of disinfection. Several systems use A/CD or soap and water alone, neither of which meets current standards for high-level disinfection recommended for items that will come in contact with mucous membranes, such as laryngoscope blades.

Disinfection↗
PubMedDate not supplied

Outcomes and effectiveness research in the private sector.

Private-sector health care organizations increasingly tout the use of outcomes and effectiveness research in activities ranging from pharmaceutical research to insurance coverage determinations. The rapid development of this research raises important questions about the role of the Agency for Health Care Policy and Research (AHCPR) as the producer, funder, and champion of outcomes and effectiveness research. To address this issue, we reviewed the activities of pharmaceutical companies, insurers, managed care organizations, health information technology companies, and other private-sector actors in outcomes and effectiveness research. We found that it is being used in a focused way to promote business goals and other organizational objectives, particularly in the pharmaceutical, insurance, and managed care industries. We also found significant gaps in its application to important public health issues and virtually no overlap with prior federal activities in this area.

Health Services Research↗