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Biomedical subjects

R Aloni

Publications and source records attributed to R Aloni.

At least 19 recordsLinked to original sources
PubMed2006

Comparative anatomy of gall development on Gypsophila paniculata induced by bacteria with different mechanisms of pathogenicity.

Galls induced on Gypsophila paniculata by Pantoea agglomerans pv. gypsophilae (Pag) and Agrobacterium tumefaciens (At), bacteria with different mechanisms of pathogenicity, were compared morphologically and anatomically. The pathogenicity of Pag is dependent on the presence of an indigenous plasmid that harbors hrp gene cluster, genes encoding Hop virulence proteins and biosynthetic genes for auxin (IAA) and cytokinins (CKs), whereas that of At involves host transformation. The Pag-induced gall was rough, brittle and exhibited limited growth, in contrast to the smooth, firm appearance and continuous growth of the At-induced gall. Anatomical analysis revealed the presence of cells with enlarged nuclei and multiple nucleoli, giant cells and suberin deposition in Pag that were absent from At-induced galls. Although circular vessels were observed in both gall types, they were more numerous and the vascular system was more organized in At. An aerenchymal tissue was observed in the upper part of the galls. Ethylene emission from Pag galls, recorded 6 days after inoculation, was eight times as great as that from non-infected controls. In contrast, a significant decrease in ethylene production was observed in Gypsophila cuttings infected with Pag mutants deficient in IAA and CK production. The results presented are best accounted for by the two pathogens having distinct pathogenicity mechanisms that lead to their differential recognition by the host as non-self (Pag) and self (At).

Caryophyllaceae↗
PubMed2006

Role of cytokinin and auxin in shaping root architecture: regulating vascular differentiation, lateral root initiation, root apical dominance and root gravitropism.

BACKGROUND AND AIMS: Development and architecture of plant roots are regulated by phytohormones. Cytokinin (CK), synthesized in the root cap, promotes cytokinesis, vascular cambium sensitivity, vascular differentiation and root apical dominance. Auxin (indole-3-acetic acid, IAA), produced in young shoot organs, promotes root development and induces vascular differentiation. Both IAA and CK regulate root gravitropism. The aims of this study were to analyse the hormonal mechanisms that induce the root's primary vascular system, explain how differentiating-protoxylem vessels promote lateral root initiation, propose the concept of CK-dependent root apical dominance, and visualize the CK and IAA regulation of root gravitropiosm. KEY ISSUES: The hormonal analysis and proposed mechanisms yield new insights and extend previous concepts: how the radial pattern of the root protoxylem vs. protophloem strands is induced by alternating polar streams of high IAA vs. low IAA concentrations, respectively; how differentiating-protoxylem vessel elements stimulate lateral root initiation by auxin-ethylene-auxin signalling; and how root apical dominance is regulated by the root-cap-synthesized CK, which gives priority to the primary root in competition with its own lateral roots. CONCLUSIONS: CK and IAA are key hormones that regulate root development, its vascular differentiation and root gravitropism; these two hormones, together with ethylene, regulate lateral root initiation.

Cytokinins↗
PubMed2000

Vascularization is a general requirement for growth of plant and animal tumours.

Solid-tumour growth in animals as in humans depends on angiogenesis. Tumours that fail to induce the formation of new blood vessels do not enlarge beyond a few millimetres in diameter. Plant tumours induced by Agrobacterium tumefaciens can reach diameters of more than 100 mm, thus raising the question of how they are sufficiently supplied with nutrients and water. Until recently, these rapidly growing tumours were considered unorganized or partly organized masses. However, in analogy to animal and human tumours, growth of leaf and stem tumours depends on neovascularization. Plant tumour cells induce the formation of a sophisticated vascular network consisting of water-conducting vessels and assimilate-transporting sieve elements. Similar to animal and human tumours that overexpress angiogenic growth factors, plant tumours overexpress the T-DNA-encoded vascularization-promoting growth factors auxin and cytokinin upon AGROBACTERIUM: infection. High auxin levels induce ethylene emission from the tumours, which has a strong impact on tumour and host stem, as well as on root structure and function. Ethylene apparently stimulates abscisic acid synthesis in the leaves above the tumour, which reduces transpiration and thus protects the host plant from rapid wilting. Hence, for the elucidation of phytohormone-dependent vascular development in plants, such tumours are regarded as an excellent model system. The comparison of analogous requirement of neovascularization for tumour growth in plants, as in animals and humans, is discussed in terms of interdisciplinary strategies of possible prevention and therapy.

Animals↗
PubMed1999

A review of the effect of traumatic brain injury on the human sexual response.

A human sexual response format was used to describe possible sexual dysfunctions after TBI. Additional material was also included to qualify the information drawn from the above format. A number of possible conclusions were drawn, indicating that the causes and effects of sexual functioning after TBI are very confusing and that the literature does not clarify this confusion. One cannot accurately differentiate between primary and secondary sexual problems and, therefore, cannot evaluate the contribution of each problem to the presented sexual dysfunction.

Adult↗
PubMed1999

Sexual dysfunction of persons after traumatic brain injury: perceptions of professionals.

The purpose of this paper was to study the perceptions of professionals in the field of rehabilitation in Israel concerning sexual dysfunction of persons after traumatic brain injury. Thirty professionals filled out an open-ended questionnaire that focused on problems of sexual functioning, dyadic and social relationships, and suggestions for the most appropriate interventions for these problems. The results indicated that for persons with TBI, the physical changes were not identified as the primary obstacle preventing persons after TBI from achieving sexual satisfaction, but rather the cognitive and emotional sequelae of TBI. A number of possible intervention techniques were also suggested.

Brain Injuries↗
PubMed1999

p53 tumor suppressor gene expression in the mouse ovary during an artificially induced ovulatory cycle.

OBJECTIVE: To evaluate the expression of p53 in the mouse ovary during an artificially induced ovulatory cycle. STUDY DESIGN: Ovulation induction was performed using pregnant mares' serum gonadotropin/human chorionic gonadotropin (PMSG/hCG). First, a p53 promoter-chloramphenicol acetyl transferase (CAT) transgenic mouse model was used. Protein samples from ovaries of transgenic mice were assayed for CAT activity as evidence of p53 promoter activation. Next, RNA extracted from CD-1 mouse ovaries was used for reverse transcription/polymerase chain reaction (PCR) and northern blot analysis using a p53-specific probe. RESULTS: Increased CAT activity was noted in transgenic mice treated with PMSG/hCG as compared with controls. PCR studies on transgenic mice using primers for CAT and on CD-1 mice using primers for wild type p53 substantiated this observation. Furthermore, CAT assay and northern analysis, performed on samples obtained at serial time intervals from induction, indicated that maximal p53 expression occurs around the time of ovulation, beginning 48 hours after PMSG and peaking 6-12 hours after hCG administration. CONCLUSION: The temporal expression of p53 in the ovary during a PMSG/hCG artificially induced ovulatory cycle may indicate a role for p53 in processes of differentiation of granulosa cells into luteal cells.

Animals↗
PubMed1998

The never ripe mutant provides evidence that tumor-induced ethylene controls the morphogenesis of agrobacterium tumefaciens-induced crown galls on tomato stems

We confirm the hypothesis that Agrobacterium tumefaciens-induced galls produce ethylene that controls vessel differentiation in the host stem of tomato (Lycopersicon esculentum Mill.). Using an ethylene-insensitive mutant, Never ripe (Nr), and its isogenic wild-type parent we show that infection by A. tumefaciens results in high rates of ethylene evolution from the developing crown galls. Ethylene evolution from isolated internodes carrying galls was up to 50-fold greater than from isolated internodes of control plants when measured 21 and 28 d after infection. Tumor-induced ethylene substantially decreased vessel diameter in the host tissues beside the tumor in wild-type stems but had a very limited effect in the Nr stems. Ethylene promoted the typical unorganized callus shape of the gall, which maximized the tumor surface in wild-type stems, whereas the galls on the Nr stems had a smooth surface. The combination of decreased vessel diameter in the host and increased tumor surface ensured water-supply priority to the growing gall over the host shoot. These results indicate that in addition to the well-defined roles of auxin and cytokinin, there is a critical role for ethylene in determining crown-gall morphogenesis.

Journal Article↗
PubMed1994

Continued weight loss in the newborn during the third day of life as an indicator of early weaning.

Little information is available about continued weight loss (CWL) of the newborn during the third day of life as an additional factor in early weaning. The purpose of the present study was to establish the value of CWL as an indicator of early weaning. The study group comprised 54 normal newborns of non-smoking healthy mothers. Newborns with CWL were compared with those whose weight remained stable or increased (controls). Follow-up was conducted by telephone interview at 10 days, 6 weeks, and 3 months after birth. It was found that mothers in the control group breastfed for a much longer period than those in the study group (P = 0.014); at age 3 months 66.7% of the controls vs. 46.3% of the study group continued to breastfeed. CWL and/or absence of or inadequate breastfeeding guidance for the mother places infants at high risk of early weaning. These mothers require very early and strong support in order to avoid early weaning of their infants.

Female↗
PubMed1992

An open trial of vacuum penile tumescence: constriction therapy for neurological impotence.

Sexual dysfunction is a frequent result of traumatic and non traumatic neurological disorders, including spinal cord injury, stroke, traumatic brain injury and autonomic neuropathy (for example, as may be seen in patients with diabetes mellitus). Although many methods have been suggested for the treatment of some of these problems in male patients, most are invasive and have a substantial morbidity. This is the report of a pilot trial of vacuum tumescence constriction therapy for 30 patients with chronic neurological impotence. Seventeen of these patients, following sexual counselling and training, decided to purchase such a device. At follow up, a mean of 21 months, over 50% of those who had purchased the device were still actively using it. The frequency of coitus increased from 0.3/wk to 1.5/wk (t = -5.7; p less than 0.0001). No significant morbidity was reported by patients. Vacuum tumescence constriction therapy shows promise as a noninvasive method for the treatment of neurological impotence.

Adult↗
PubMed1992

Noninvasive treatment for erectile dysfunction in the neurogenically disabled population.

Erectile dysfunction is the most prevalent sexual dysfunction in neurogenically disabled men. Studies of rehabilitation patients indicate that the restoration of sexual functioning is considered an important priority. This article reports on a pilot study of vacuum tumescence constriction therapy as a noninvasive method for use by a population with traumatic or nontraumatic neurologic disorders such as spinal cord injury, stroke, multiple sclerosis, and diabetes mellitus. Of the 30 patients who participated in the study, 17 purchased the device and over 50% of them reported using the device on a long-term basis. Frequency of coitus increased from 0.3/wk to 1.5/wk. Included in the study are methods used by patients to integrate the device into their sex life, the role of the patient's partner in the decision to purchase the device, and the rate of partner satisfaction. There were no reports of substantial morbidity. Thus, this method shows promise as a noninvasive treatment for men who are moderately to severely neurogenically disabled.

Equipment and Supplies↗
PubMed1992

Selective translational control and nonspecific posttranscriptional regulation of ribosomal protein gene expression during development and regeneration of rat liver.

Mammalian liver development is accompanied by a transition from rapid growth in the fetus to a quiescent state in the adult. However, extensive proliferation can be induced in the adult liver by partial hepatectomy. In this study, we examined the regulation of ribosomal protein (rp) gene expression in the developing and regenerating rat liver. Our results indicate that the translation of rp mRNAs is selectively repressed by about 70% upon development from fetal to adult life, as illustrated by the decrease in ribosomal loading. In addition, the relative abundance of these mRNAs, like that of several other, but not all, housekeeping mRNAs, declines during development through a posttranscriptional mechanism. When liver cells commence growth following partial hepatectomy, translation of rp mRNAs is resumed to near-maximal capacity, as judged by their very efficient recruitment into polysomes. The concomitant increase in the abundance rp mRNAs under these circumstances is achieved by a posttranscriptional mechanism. The apparent fluctuations in the translation efficiency of rp mRNAs are accompanied by parallel changes in the expression of the genes encoding the initiation factors eIF-4E and eIF-4A. Our results indicate that selective translational control of rp mRNAs in mammals is not confined to manipulated cells in culture but constitutes an important regulatory mechanism operating in vivo in the course of liver development and regeneration.

Animals↗
PubMed1990

The role of cytokinin in sieve tube regeneration and callose production in wounded coleus internodes.

Cytokinin proved to be a controlling factor in sieve tube regeneration around wounded collateral bundles in an in vivo system in which the endogenous cytokinin level had been minimized. Both kinetin and zeatin were applied in aqueous solution to the bases of excised, mature internodes of Coleus blumei Benth. that had an active vascular cambium. Each internode also received indoleacetic acid (IAA) in lanolin at its apical end. Under either low (0.1% w/w) or high (1.0% w/w) auxin concentrations, the control internodes (without exogenous cytokinin) exhibited small amounts of sieve tube regeneration. At appropriate concentrations, both kinetin and zeatin induced a significant increase in sieve tube regeneration around the wound. However, the highest concentration of kinetin tested (50 mug/mL) completely inhibited this process. Kinetin was the most effective with high auxin (1.0% IAA), while zeatin was the most effective with low auxin level (0.1% IAA). Kinetin and zeatin showed the strongest promotive effect at 10 mug/mL and 20 mug/mL, respectively. Both cytokinins also induced supplementary phloem regeneration further from the wound surface. In addition to their effects on vascular tissue regeneration, both cytokinins promoted callose production. This was most evident on the sieve plates of the regenerated sieve tube members and on the walls of the parenchyma cells around the wound. The largest deposits of callose were found in both regenerated sieve tube members and parenchyma cells at the highest cytokinin concentration tested (50 mug/mL). The possible role of cytokinin in controlling callose accumulation in the sieve tubes during autumn is discussed.

Journal Article↗
PubMed1990

The Role of Auxin and Gibberellin in Controlling Lignin Formation in Primary Phloem Fibers and in Xylem of Coleus blumei Stems.

The hypothesis that auxin (IAA) and gibberellic acid (GA(3)) control the formation of lignin is confirmed for the primary phloem fibers and for the secondary xylem in the stem of Coleus blumel Benth. Indoleacetic acid alone, or a combination of high IAA/low GA(3) (w/w), induced short phloem fibers with thick secondary walls, that contained lignin rich in syringyl units (high ratio of syringyl/guaiacyl). On the other hand, a combination of high GA(3)/low IAA (w/w), which promoted the differentiation of long phloem fibers with thin walls, decreased the relative content of the syringyl units (low syringyl/guaiacyl ratio). In the secondary xylem, these hormonal treatments yielded only slight changes in the noncondensed monomeric guaiacyl units, confirming the relative stability of the guaiacyl lignification pattern in this tissue. In the xylem, indoleacetic acid alone, or a combination of high IAA/low GA(3) induced lignin poor in syringyl units (low syringyl/guaiacyl ratio). A combination of high GA(3)/low IAA promoted a relatively slight increase in syringyl yield, indicating greater responsiveness of the syringyl lignification pattern to growth regulators. The possible functional and technological significance of our results is discussed.

Journal Article↗
PubMed1990

The mammalian genome contains a high proportion of processed pseudogenes corresponding to ribosomal protein L19.

The mammalian genome contains multiple copies of ribosomal protein (rp) L19-related sequences. Screening of mouse and rat genomic libraries with cloned rpL19 cDNA yielded seventeen independent lambda Charon 4A recombinant phages containing twelve and five genes for mouse and rat rpL19, respectively. Structural analysis indicated that all of these rpL19 genes contain the entire coding sequence (approx. 700 bp) but lack introns. The nucleotide sequence of a mouse gene (rpL19-17), exhibiting the highest homology with the mouse rpL19 cDNA, revealed genetic lesions which would preclude the translation of an intact protein, from a putative transcript. Based on these features we propose that these clones represent processed genes of which most, if not all, are pseudogenes.

Animals↗
PubMed1984

Regulatory effect of cytokinin on secondary xylem fiber formation in an in vivo system.

The regulatory effect of cytokinin on the formation of secondary xylem fibers was studied in the hypocotyl of young Helianthus annuus L. plants. Positive correlation was found between the kinetin supplied (0.25-0.5 micrograms/gram) to the growth medium and the rate of fiber formation within and between the vascular bundles. Reducing the root originated cytokinin supply, either by root removal or by lowering the transpiration rate, diminished the number of newly formed secondary xylem fibers. This decrease was considerably reversed in the presence of 0.5 microgram/gram kinetin. Early pulse exposure of kinetin had a temporary promoting effect on fiber differentiation at low concentrations and a permanent inhibitory effect at high concentration.

Journal Article↗
PubMed1982

Role of cytokinin in differentiation of secondary xylem fibers.

The differentiation of secondary xylem fibers was studied in cultured hypocotyl segments of Helianthus annuus L. It is shown that cytokinin is both a limiting and controlling factor in the early stages of fiber differentiation. In the absence of kinetin or zeatin, there was no fiber differentiation. However, cytokinin could induce fiber differentiation only in the presence of indoleacetic and gibberellic acids. First fibers were observed in the tissue after 12 days in culture, and their number increased linearly during the following 2 weeks. At low cytokinin levels, there was a positive correlation between cytokinin concentration in the medium and the number of fibers formed in the explants. A similar correlation was also found at low gibberellic acid concentrations. At high concentration, zeatin was more effective than kinetin. It seems that later stages of fiber differentiation can occur in the absence of cytokinin. It is proposed that the mechanism which controls and determines the early stages of fiber differentiation is based on an interaction of three major hormonal signals: indoleacetic acid plus gibberellic acid from the leaves with zeatin from the root apices.

Journal Article↗