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Biomedical subjects

M Jacobson

Publications and source records attributed to M Jacobson.

At least 145 records · Page 8Linked to original sources
PubMed1978

Origin of the retina from both sides of the embryonic brain: a contribution to the problem of crossing at the optic chiasma.

Cells originating from one of the first two blastomeres of the frog embryo were labeled either by injecting them with horseradish peroxidase or by changing the ploidy of one blastomere. Both methods show the labeled cells confined to the same side of the brain as the labeled blastomere except for cells that have moved from the opposite side into the ventral diencephalon and ventral part of the retina. Reciprocal movement of cells from each side of the prospective forebrain into the prospective retina on the opposite side starts before the neural tube closes and results in the formation of an incipient optic chiasma which may provide the pathway for optic axons to grow from the retina to the opposite side of the brain.

Animals↗
PubMed1978

Effects of 5-bromodeoxyuridine on development of Mauthner's neuron and neural retina of Xenopus laevis embryos.

Bromodeoxyuridine (BrUdR) injected into Xenopus embryos at stages before, during or after the last period of DNA synthesis in Mauthner's neurons had no serious effect on differentiation of Mauthner's neurons. However, the BrUdR caused widespread cell degeneration in the central nervous system. The action of BrUdR on retinal neuronal differentiation depended on dose and stage of infection. At all doses (0.005-0.9 microgram per injection), and all stages (22-29), the main effect was retinal cell degeneration. The drug produced complete absence of differentiated retinal neurons only when given at early stages (22-24) and at the highest doses (0.5-0.9 microgram) that enabled the embryo to survive to stage 44. At stages 22-24 at lower doses (0.005 or 0.05 microgram per injection) and at stages 26-29 at all doses, some retinal neurons differentiated, although retinal cell degeneration was the main effect. In these two systems BrUdR did not selectively inhibit neuronal differentiation.

Age Factors↗
PubMed1977

Retinoblastoma-like neoplasm induced in C3H/BifB/Ki strain mice by human adenovirus serotype 12.

Eighty newborn C3H/BifB/Ki strain mice received a single intraocular inoculation of 0.002--0.003 ml of 10(8.0) TCID 50/0.1 ml human adenovirus 12 (AD 12), within 24 h after birth. Forty mice survived and in seven of these (17.5%) a solid retinoblastomalike neoplasm developed between 64 and 236 days. The tumors have been successfully cultured and also transplanted subcutaneously into syngeneic hosts. Morphologically, all tumors revealed characteristic features of retinoblastoma associated with the Homer Wright type of rosettes. Bizarre giant cells were commonly detectable. Ad 12-specific T-antigens were demonstrated in both the primary and cultured tumor cells using immunofluorescent techniques. Some giant cells also showed numerous T-positive filaments. Electron microscopy disclosed poorly differentiated unipolar cells possessing a large ovoid nucleus. Many tumor cells appeared to contain a well organized solitary cilium consisting of a typical ring of nine doublets with no axial (9 + 0) in close association with a pair of centrioles. Some multinucleated giant tumor cells also contained multiple cilia-centriole complexes within their broad syncytial cytoplasm. Occasional endogenous C particle-like virions unique to murine neuroblastomas were observed for the first time in virus-induced retinal tumors. This unprecedented tumor model in a pure strain mouse adds to the range of known animals sensitive to Ad 12 oncogenesis.

Adenoviruses, Human↗
PubMed1977

Mapping the developing retinotectal projection in frog tadpoles by a double label autoradiographic techinque.

Tadpoles of Xenopus at developmental stages 45-59 were given an intraocular injection of [3H]proline and an intraperitoneal injection of [3H]thymidine, killed either after a short (1-2 day) or long (16-37 day) survival period, and processed for autoradiography. In all cases, there was a regular pattern of labelling. In the retina, the proline-labelled cells were always central to the thymidine-labelled cell nuclei, and in the long survivors there was a sharp transition between the cells occupying the central labelled retina and the surrounding unlabelled cells at the retinal periphery. In the tectum, unlabelled optic axons were confined to a rostrolateral zone which was bordered caudomedially by a zone of labelled tectal cell nuclei, and in the long survivors there was a completely unlabelled zone at the caudomedial margin of the tectum. The size of the tectal zone of labelled axons was not significantly different in the long survivors from that in short survivors injected at the same stage of development. Labelled optic axons remained close to the tectal cells that were present before the time of injection and did not move later into the zone of cells added to the tectum in the survival period after the injections.

Animals↗
PubMed1977

Tocopherols in canned entrées and vended sandwiches.

Determination was made of alpha-, beta-plus-gamma-, and delta-tocopherol contents of brand-name canned entrées from a supermarket and from vending machines on a college campus, of several home-prepared entrées, and of sandwiches from vending machines in Spokane, Washington. Amounts of total tocopherols in canned entrées were small, ranging from none detected to 0.66 mg. per 100 gm. food. Similar home-prepared entrées, however, contained 0.41 mg. to 1.55 mg. Tocopherols in vended sandwiches ranged from 0.05 mg. to 1.86 mg. per 100 gm. sandwich. Results are also expressed as total tocopherols per serving (I.U.). These convenience foods contribute only a small amount to the day's intake of vitamin E.

Food Analysis↗
PubMed1976

2-Phenylethanol, a presumed sexual stimulant produced by the male cabbage looper moth, Trichoplusia ni.

A sex pheromone produced by male cabbage looper moths, Trichoplusia ni (Hübner), has been isolated from the genital scent brushes and identified as 2-phenylethanol. It is shown conclusively to elicit specific behavioural responses in the female (such as wing vibration and abdominal elevation), as determined by a novel behavioural laboratory bioassay. This is taken as further evidence that the male pheromone of T. ni acts as a sexual stimulant (aphrodisiac) prior to mating. 2-Phenylethanol represents the first identification of a genital scent brush pheromone in the family Noctuidae, and of a male pheromone in the subfamily Plusiinae.

Action Potentials↗
PubMed1976

Premature specification of the retina in embryonic Xenopus eyes treated with ionophore X537A.

Eyes excised from Xenopus embryos at stages 24 to 25 were cultured for 4 to 6 hours in a medium containing the ionophore X537A or in a control medium. The eyes were implanted either upside down or normally in host embryos at stages 28 to 30, and their retinotectal projections were mapped after metamorphosis. Treatment with X537A prevented realignment of retinal axes in eyes implanted into hosts that were capable of producing retinal axial alignment in all control eyes.

Animals↗
PubMed1976

Clinical uses of frozen-thawed erythrocytes in pediatrics.

Frozen red cells have a definite place in the mangement of a transfusion service even if one does not include its originally intended use -- inventory control. Undoubtedly, the benefits achieved from frozen red cells can be accomplished in less expensive ways. However the growth in transsplantion and intensive chemotherapy with its concommiatant uses of granulocyte and platelet support predict a greater upsurge in the use of frozen red cells in the very near future.

Anemia, Aplastic↗
PubMed1975

Evaluation of gossyplure, compared with hexalure, for monitoring pink bollworm infestations in cotton fields of Israel.

Gossyplure used to bait field traps at a dose of 50 micrograms admixed with 4-16 milligrams of an antioxidant attracted and captured male pink bollworm moths early in the cotton-growing season (early May) in Israel, whereas 20 milligrams of hexalure plus antioxidant was completely inactive under identical conditions. Although gossyplure without antioxidant was inactivated through decomposition within ten days, the mixtures remained attractive for at least two months; the antioxidant also increased moth catches 2.5 fold. Monitoring data obtained with 3000 gossyplure-baited traps, at one trap per 50 dunams, in cotton fields in the Beth-Shann region proved that capture thresholds of 5 moths/trap/night to the end of July and 8 moths/trap/night afterward were completely satisfactory for maintaining a low 2.8% average boll infestation for which only 5.8 insecticidal treatments were required during the entire growing season; results were even better in other areas of the country.

Animals↗
PubMed1975

Improvement of the attractiveness of spodoptera littoralis sex pheromone, and its possible use in safety belts around cultivated areas to control the pest in Israel.

A comparison of the field attractiveness of five samples of American-synthesized and one sample of Japanese-synthesized (Z,E)-9,11-tetradecadien-1-01 acetate (9,11-TDDA), the sex pheromone of Spodoptera littoralis Boisd. and S. litura (F.), showed that traps baited with one of the American-produced samples and the Japanese product were equally effective in attracting and capturing S. littoralis males in cotton and alfalfa fields of Israel. Optimum captures were obtained for periods up to three months with 4800 mug of 9,11-TDDA plus 8 mg of an antioxidant; higher doses were not advantageous. Paper squares were superior to two types of rubber septa and to closed polyethylene vials as dispensers for the pheromone; the polyethylene vials were least effective. In terms of numbers of moths captured, open polyethylene vials were as effective as paper dispensers when both were baited with 9-11-TDDA plus antioxidant. Admixture of (Z,E)-9,12-tetradecadien-1-o1 acetate (9,12-TDDA) with 9,11-TDDA was antagonistic at ratios of 1:20 and 1:50, but ratios from 1:500 to 1:1600 were synergistic, increasing moth catches up to 2.5-fold. Pheromone traps placed in Caesarea sand dunes located at least 3 km from the nearest host area captured larger numbers of males than traps placed in cultivated areas. It is therefore recommended that safety belts of pheromone traps, about 500 m apart, be used around cultivated areas to prevent invasion of the pest from outside and to attract males present inside such areas, thus reducing both the male population and mating through mass trapping and disruption of sex communication.

Animals↗