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Biomedical subjects

L Hanna

Publications and source records attributed to L Hanna.

At least 73 records · Page 4Linked to original sources
PubMed1994

[Triplet and quadruplet pregnancy: management and perinatal outcome].

The frequency of multiple pregnancies with more than two fetuses has increased considerably since the introduction of methods of ovulation induction, in vitro fertilization, and embryo transfer. We have analyzed the evolution, complications, delivery and perinatal outcome of 23 triplet and 3 quadruplet pregnancies occurred during a four-year period in one medical center. The most frequent complication was preterm labor (62%). The mean gestational age at delivery was 32.5 weeks for the quadruplets and 31.5 weeks for the triplets and the mean birth weight was 1461 and 1526 for quadruplets and triplets, respectively. Perinatal mortality for the whole group was 148/1000.

Embryo Transfer↗
PubMed1993

Development and maintenance of a simple reflex circuit in small-patch mosaics of Drosophila: effects of altered neuronal function and developmental arrest.

A combined genetic, anatomical, and behavioral approach has been undertaken to study the developmental and functional plasticity of identified bristle mechanosensory neurons in Drosophila. A stereotyped grooming reflex in decapitated flies enabled simple but reliable assessments of the functional output of individual bristle sensory cells to correlate with their axonal projections and terminal arbors revealed by the cobalt backfill technique. Construction of small-patch mosaics that contain only a single mutant bristle allowed functional perturbation of individual neurons within an otherwise normal environment. Mutations that affect nerve excitability and membrane recycling have been used to examine their effects on neuronal pathfinding, arborization, and the initiation and maintenance of functional connections. Previous studies (Burg and Wu, 1986, J. Neurosci. 6:2968-2976; 1989, Dev. Biol. 131:505-514) have demonstrated that para(ts)nap(ts) double-mutant sensory neurons, in which action potentials are unconditionally blocked by defects in sodium currents, and eag Sh double-mutant sensory cells, in which membrane excitability is increased by alterations in potassium currents, can establish and maintain central projections that are indistinguishable from their functionally normal counterparts. Mutations of the shi(ts) gene cause a temperature-sensitive, reversible block of the membrane recycling process, resulting in arrest of neuronal growth in culture (Kim and Wu, 1987, J. Neurosci. 7:3245-3255) and depletion of synaptic vesicles that leads to transmission blockade at established synapses (Ikeda, Ozawa, and Hagiwara, 1976, Nature 259:489-491; Koenig and Ikeda, 1983, J. Neurobiol. 14:411-419; 1989, J. Neurosci. 9:3844-3860). Prolonged heat treatments (up to 16% of total development time) of small-patch shi(ts) mosaics at different pupal stages did not prevent the establishment of central projections characteristic of the various sensory cell types. However, none of the shi(ts) sensory neurons heat-pulsed during the initial or the final 16% of pupal development were able to initiate the reflex behavior, although a proportion of those treated in other periods apparently established functional contacts with appropriate targets to support the characteristic cleaning reflex. The possibility exists that the membrane recycling process blocked in shi(ts) cells provides a crucial mechanism for cell-cell interactions taking place during initial differentiation and final synaptic stabilization, and possibly competition, in the developing sensory neuron. Heat treatments of adult shi(ts) mosaics blocked the reflex initiated by the mutant (but not the surrounding normal) bristles, as expected from the effect of synaptic block.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1982

Immune responses to chlamydial antigens in humans.

Antibody titer, lymphocyte stimulation and leukocyte migration inhibition with chlamydial antigens were determined repeatedly over many months on human subjects. The volunteers were retrospectively placed into four groups on the basis of clinical, laboratory and epidemiologic criteria. Group A consisted of persons with proven or probable chlamydial infection, including an illness confirmed by chlamydial isolation or seroconversion, or a clinically compatible illness with positive serologic results. Group B were sexual partners or close contacts of group A individuals. Group C were laboratory workers with prolonged exposure to viable chlamydiae or their antigens. Group D included persons of comparable age as those in groups A and B, but lacking a history of symptomatic chlamydial infection or of contact with chlamydiae. Individual cases illustrated the rise of antibody and some cell mediated immunity reactions (CMI) with active chlamydial infection. By contrast, laboratory exposure resulted in elevation of CMI but not of antibody. Statistical analysis of the results in 46 volunteers tested repeatedly indicated a strong association of specific antibody with lymphocyte stimulation, but not with leukocyte migration inhibition. Regression analysis suggested that the type of exposure markedly influenced the relationship between antibody and lymphocyte stimulation. Measurement of immunotype-specific antibody titer by microimmunofluorescence (or an equally sensitive method) remains the best laboratory indicator of past chlamydial infection. Neither antibody nor CMI can, as yet, be definitely related to resistance to re-infection in humans.

Acute Disease↗
PubMed1982

Long-term clinical, microbiological, and immunological observations of a volunteer repeatedly infected with Chlamydia trachomatis.

A blind volunteer was inoculated in one eye with an isolate of Chlamydia trachomatis in 1961 and followed for 20 years. During this time, many observations were made of his clinical responses to the first inoculation and several subsequent inoculations with the same and other strains, chlamydial shedding, and antibody and cell-mediated immune responses. Evidence is presented that partial resistance to chlamydial eye infection developed during repeated infections and that antibodies, cell-mediated immune reactions, and specific antigen in conjunctival cells persisted for many years after the last infection. The antibody response was directed mainly against the original infecting immunotype, regardless of whether the response was restimulated by infection with the same immunotype or with other immunotypes. The lymphocyte stimulation response appeared to be species specific.

Antibody Formation↗
PubMed1981

Cell-mediated and humoral immune responses to chlamydial antigens in guinea pigs infected ocularly with the agent of guinea pig inclusion conjunctivitis.

Cell-mediated immune response and humoral response to chlamydial antigens were investigated in guinea pigs infected with the agent of guinea pig inclusion conjunctivitis (GPIC). Pronounced cell-mediated immune response to the homologous antigen, as well as to two other chlamydial antigens, 6BC (Chlamydia psittaci) and LB-1 (C. trachomatis), occurred in all infected animals. Cell-mediated immune response to GPIC, and to a lesser extent to 6BC and LB-1 as well, was enhanced with time after infection even without the re-inoculation of the infectious agent. Extensive cross-reactions among the three chlamydial antigens during the cell-mediated immune response appeared to be due to shared species-specific and group-reactive antigens. Serum antibody response was pronounced and uniform to GPIC; it was less marked to 6BC and LB-1, with fewer cross-reactions than seen in tests for cell-mediated immunity.

Animals↗
PubMed1980

Cell-mediated immune responses to chlamydial antigens in guinea pigs injected with inactivated chlamydiae.

Cell-mediated immunity (CMI) to chlamydial antigens was readily induced in guinea pigs by a single injection of Betaprone-inactivated chlamydiae in complete Freund adjuvant. The CMI was measured in vivo by delayed hypersensitivity skin tests, and in vitro by inhibition of migration of peritoneal exudate cells and by proliferation of lymph node lymphocytes. There was an overall correlation between in vivo and in vitro responses. Of the in vitro assays, migration inhibition reflected the state of sensitization, as judged by skin tests, more uniformly than lymphocyte stimulation. Extensive inter- and intra-species cross-reactivity was noted between LB-1, a strain of C. trachomatis, and three strains of C. psittaci, 6BC, GPIC, and 562F. Cross-reactivity between LB-1 and 6BC was one-way only, by all three parameters: LB-1 elicited strong cross-reactions in 6BC-immunized animals but not vice versa. Antichlamydial antibodies could not be demonstrated in any of the animals by microimmunofluorescence.

Animals↗