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Biomedical subjects

B Benson

Publications and source records attributed to B Benson.

At least 91 records · Page 5Linked to original sources
PubMed1978

Location by paper chromatography of compensatory ovarian hypertrophy (COH) inhibiting activity in acetic acid extracts from bovine pineals.

Acetic acid extracts of bovine pineals and cerebral cortex were separated on Sephadex G-25 columns. Subsequently two low molecular weight fractions, F2 and F3, were ultrafiltered through the membranes UM2 and UM05. The UM05 residues were gel filtered on Sephadex G-15 columns or chromatographed on Dowex W50-X4 columns. Fractions from these columns were tested and those which showed COH-inhibiting activity were separated by preparative paper chromatography in different solvents. The absorption spectra of those fractions were recorded and tested for COH-inhibiting activity were separated by preparative paper chromatography in different solvents. The absorption spectra of those fractions were recorded and tested for COH-inhibition. By these methods, a COH-inhibitor was localized in three different solvents. Some active paper chromatography fractions were studied in high pressure, reverse phase, liquid chromatography. This latter method showed that the active fractions obtained by paper chromatography contain several orthophthlaldehyde (OPT) positive compounds. Key words: acetic acid, bovine pineal extracts, compensatory ovarian hypertrophy (COH), paper chromatography, high pressure, reverse phase, liquid chromatography.

Acetates↗
PubMed1978

Pineal peptides.

In pineal extracts several activities have been observed which cannot be explained on the basis of their content of melatonin or other pineal indoles to which an antigonadotropic activity is ascribed. The significance of structurally identified and unidentified substances is not fully understood. The list includes a neurohypophysial peptide, vasotocin (AVT), hypothalamic releasing factors and certain unidentified substances including the antigonadotropin under investigation in our laboratory. Our initial experiments demonstrated the presence of a non-melatonin antigonadotropin (PAG) in partially purified extracts of bovine, ovine, rat and human pineals. Purification by ion exchange chromatography and amino acid analyses have shown that this substance is not AVT. Recent purification studies include paper chromatography and high performance chromatography as final steps. It is concluded that if the active principle in a peptide, or contains a peptide moiety important for the biological activity, it may be present only in minute amounts in the puriest fractions derived and the quantities of recoverable material may be similar to those amounts of releasing factors recoverable from hypothalamic tissue. It is anticipated that large scale preparative methods will be required for structural determination. High performance chromatography may prove to be extremely useful in future studies.

Animals↗
PubMed1977

Circadian rhythm in the number of granulated vesicles in the pinealocytes of mice. Effects of sympathectomy and melatonin treatment.

Adult, Charles River CD-1, male mice were housed in an environmental control chamber under strict conditions of controlled light (12D/12L) and temperature. The mice were sacrificed at various times throughout the twenty-four hour clock and their pineals prepared routinely for electron microscopy. The number of dense-cored or granulated vesicles present in the polar terminals of pinealocytes were quantitated in thin cross sections through pericapillary areas. A distinct circadian rhythm was observed in the number of granulated vesicles with a three- to four-fold difference between late photoperiod maximum and late dark period minimum. The rhythm was abolished by bilateral superior cervical ganglionectomy. These results are consistent with the hypothesis that the granulated vesicles are synthesized and stored in the pinealocytic cytoplasm during the photoperiod under the tropic influence of norepinephrine, and are released during the dark period when melatonin synthesis is greatest. Melatonin, administered as daily intraperitoneal doses of 50 microgram over a period of five days, was observed to increase markedly the number of pinealocytic granulated vesicles during the light period, but led during the dark period to a decrease in their numbers to levels below that of diluent-treated controls. It may be that melatonin stimulates the synthesis and/or release of granulated vesicles which represent the packaged form of a major secretory product.

Animals↗
PubMed1977

Effects of blinding on the ultrastructure of mouse pinealocytes with particular emphasis on the dense-cored vesicles.

The mammalian pineal is thought to produce an antigonadotropic principle under conditions of reduced photoperiod, constant darkness or blinding by optic enucleation. A number of previous studies on mammalina pineals have suggested that the dense-corde vesicles present in pinealocytes may represent morphological evidence of secretory activity. In the present study the ultrastructure of pinealocytes was studied in adult Charles River CD-1 mice blinded by optical enucleation. By one month following optic enucleation the mean number of dense-corde vesicles in the cytoplasm of pinealocytes adjacent to pericapillary spaces had significantly decreased by 55% when compared with intact controls, and remained at this low level at two months and six months. A relative increase in the proportion of large agranular vesicles and an increased number of large, irregular vacuoles was observed also in the pinealocytic polar processes of blinded mice. When compared to control mice the pinealocytic Golgi regions appeared to be hypertrophied in blinded mice. The apparent stimulation of pinealocytic organelles coupled with the observed decrease in dense-corde vesicles suggest an increased synthesis and release of secretory product.

Animals↗
PubMed1976

Quantitation of ultrastructural changes in the mouse pineal in response to continuous illumination.

Adult male mice were exposed to either alternating illumination or constant illumination for 70 days. Light and dark pinealocytes were compared as to distribution within the gland and ultrastructure. Quantitative studies with the electron microscope revealed a significant reduction in pinealocyte size and Golgi complex size in constant light treatment, as well as a marked but nonsignificant reduction in the concentration of lipid droplets and irregular vacuoles. Under constant light treatment the cross-sectional area of pinealocyte pericapillary terminals and the number of granulated vesicles per terminal decreased significantly. A greater number of mitochondria appeared swollen, with rarified matrix and reduced numbers of cristae, with constant light treatment. These results provide ultrastructural correlation with the known reduction of pineal weight, protein synthesis and antigonadotrophic activity that is seen with constant light treatment. The marked decrease in concentration of pinealocyte granulated vesicles in constant light treatment gives morphological support to the theory that these vesicles contain antigonadotrophic secretory material.

Animals↗