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Biomedical subjects

A M Hirsch

Publications and source records attributed to A M Hirsch.

42 records · Page 3Linked to original sources
PubMed1983

Ultrastructural analysis of ineffective alfalfa nodules formed by nif::Tn5 mutants of Rhizobium meliloti.

Ineffective alfalfa nodules formed by Rhizobium meliloti nif::Tn5 mutants were examined by light and electron microscopy. R. meliloti nifH::Tn5 mutants formed nodules that were similar in structure to wild-type nodules except that nifH- bacteroids accumulated a compact, electron-dense body. In contrast to nodules induced by wild type and nifH mutants, nifDK- R. meliloti mutants induced nodules which contained numerous starch grains and prematurely senescent bacteroids. In addition, meristematic activity in nifDK- nodules ceased significantly earlier than in nifH- nodules. All mutant nodules exhibited elevated levels of rough endoplasmic reticulum and Golgi membranes compared to wild-type nodule cells. These elevated levels may reflect either a response to nitrogen starvation in the ineffective nodules or an abnormal synthesis and export of nodule-specific proteins during later developmental stages.

Histocytochemistry↗
PubMed1982

Structural studies of alfalfa roots infected with nodulation mutants of Rhizobium meliloti.

Alfalfa roots infected with four nodulation defective (Nod-) mutants of Rhizobium meliloti which were generated by transposon Tn5 mutagenesis were examined by light and electron microscopy. In one class of Nod- mutants, which we can nonreactive, the bacteria did not induce root hair curling or penetrate host cells. In a second class of Nod- mutants, which we call reactive, the bacteria induced some root hair curling and entered root epidermal cells, although no infection threads were formed. In addition, reactive Nod- mutants induced extensive root hair proliferation and hypertrophied roots. This study presents the details of the phenotype of the association between each mutant strain and alfalfa roots.

Medicago sativa↗
PubMed1975

The effect of sucrose on the differentiation of excised fern leaf tissue into either gametophytes of sporophytes.

Excised juvenile leaves of Microgramma vacciniifolia (Polypodiaceae) develop sporophytic regenerants when grown on mineral agar with sucrose. The ratio of sporophytes to gametophytes produced from the leaf tissue increases with higher percentages of sucrose such that at 4% sucrose, the induction of aposporous gametophytes is a rare occurrence. Experiments varying the osmotic potential with sorbitol and those holding the osmotic potential of the culture medium constant while varying the sucrose level indicate that the effect of sucrose on the differentiation of fern leaf tissue into either gametophyte or sporophyte is nutritional rather than osmotic. A significant effect of sucrose in altering the differentiation of fern leaf tissue is the increased rate of senescence promoted by high sucrose concentrations.

Journal Article↗
PubMedDate not supplied

The effect of infertility on marriage and self-concept.

Two groups of subjects (couples seeking medical treatment for infertility and couples not yet attempting to conceive) completed questionnaires assessing the impact of infertility on their marriages and self-concept. Infertile individuals experienced greater dissatisfaction with themselves and their marriages. Females experienced greater discontent over time and had greater emotional investment than males. Infertile couples, labeled noncommunicators, were found to be affected even more by infertility. Nurses can play vital roles in counseling infertile couples.

Adult↗
PubMedDate not supplied

The long-term psychosocial effects of infertility.

OBJECTIVE: To explore the psychosocial effects of infertility and the role that social support plays over time. The major hypothesis was that although infertile persons report less contentment, lower levels of marital and sexual satisfaction, and lower self-esteem over time, those with higher levels of social support will be less affected. DESIGN/SETTING: Four questionnaires were completed in subjects' own homes, one every 9 months. PARTICIPANTS: Subjects, all of whom perceived themselves as infertile, were recruited through the national newsletter for an infertility support group. Ninety-four subjects entered the study, and 41% of the sample completed it. MAIN OUTCOME MEASURES: Contentment, marital satisfaction, sexual satisfaction, self-esteem, sex-role identity, press (the measure of perceived internal and external pressures), and social support. RESULTS: Perceived support (F[3, 111] = 4.77, p < 0.004), as well as contentment and self-esteem, significantly increased over time (F[3, 111] = 12.03, p < 0.0001, and F[3, 111] = 5.378, p < 0.002, respectively). Social support was positively correlated with all dependent measures. CONCLUSIONS: Contrary to what was hypothesized, infertile persons experienced increased social support and greater contentment over time. As hypothesized, there was a significant positive relationship between social support and all dependent measures. The positive impact of social support, counseling, and the adoption of strategies to deal with the stress of infertility lends credence to the crucial role nurses can play in helping infertile couples cope.

Adaptation, Psychological↗