PubMed Health⌕ Search

Biomedical subjects

B E Morton

Publications and source records attributed to B E Morton.

At least 19 recordsLinked to original sources
PubMed1982

Inexpensive fiber optic two-dimensional densitometer for the high-resolution quantitation of autoradiogram grain densities.

The design and construction of a simple, low cost high performance fiber optic 2-dimensional microdensitometer is described. With this instrument the film to be quantitated is placed upon a back-lit frosted glass bench and scanned with an optic fiber probe attached to a transparent micromanipulator. The emerging light is transported by the fiber to the photocell of a direct reading spectrophotometer. The resulting numerical data can either be transcribed, portrayed on a recorder or entered into the memory of a microdata processor for further analysis and comparisons. The instrument was sensitive to very small differences in optical density and could resolve lines 100 but not 30 micrometers apart. It was precise, reliable and easy to build. With the use of this equipment many previously undetected, significant local brain glucose utilization differences were quantitated in groups of unrestrained rodents, maintained in several behavioral states.

Animals↗
PubMed1981

Quantitation of sperm population migration: capillary scanning assay.

Bulk sperm migration through capillaries containing experimental media was quantitated by use of a recording spectrophotometer equipped with a linear transport. The method was applied to human semen and caudal epididymal sperm samples from hamster, rat, rabbit, and bull. The rate of migration of a given sperm population was approximately 1/10 that of the velocities previously reported for individual sperm of that species. This matched theoretical approximations based upon assumptions of random orientation and multiple, direction-changing collisions for individual cells. The rate of migration for undiluted caudal epididymal sperm populations into Tyrode's solution for all species tested showed an initial burst followed by a slower, more linear rate. Predilution or prewashing the sperm samples eliminated the initial burst in hamster and rabbit sperm but elevated migratory rates in bull sperm. Human sperm populations diluted by ejaculation also exhibited no initial burst but maintained a strong linear rate down the capillaries.

Animals↗
PubMed1981

Migration of hamster sperm within capillaries: effect of agents elevating cyclic AMP.

Semiautomated capillary scanning was used to quantitate the migratory rate of hamster caudal epididymal (HCE) sperm populations from undiluted exudates into various defined media. The populations migrated through calcium-containing Tyrode's solution four times more rapidly than they did through buffered-glucose fortified saline or isotonic sucrose. This difference was partially eliminated by the addition to the saline or sucrose of the motility inducers, calcium ion or cyclic adenosine monophosphate (cAMP), and completely eliminated by the additional presence of the motility amplifiers, caffeine or spermine. The addition of the motility amplifiers, caffeine or spermine, alone to either calcium-saline or Tyrode's solution greatly stimulated the microscopically judged vigor of motility. However, this increase in flagellar activity was not coupled to increased forward velocity. Instead, as in the case of capacitated HCE sperm, the activation of motility resulted in significantly reduced forward velocities. Thus, it appears that under certain conditions caffeine, spermine, or capacitation can elevate sperm cAMP concentrations above those optimal for maximal forward progression.

Animals↗
PubMed1979

Scotophobin A causes several responses in goldfish if the pineal gland is present.

Rat scotophobin A increased dark avoidance in goldfish in dark and light avoidance shuttlebox experiments, controlled for general and light cycling-induced swimming activity. A possible site of action for scotophobin was suggested by the reports that dark avoidance was also increased in goldfish by pinealectomy, a treatment which increased shock sensitivity as well. It was found that scotophobin alone decreased the voltage required to induce tail-flip contractures in goldfish. The pineal gland was further implicated in the mode of action of scotophobin when it was found that this peptide suppressed the norepinephrine-induced aggregation of goldfish chromatophores whose state is in part controlled by pineal melatonin. Pinealectomized goldfish became insensitive to the effects of scotophobin upon both light-dark preference and chromatophore aggregation state. There observations strongly suggest that the pineal gland is required for the action of scotophobin.

Animals↗
PubMed1979

Scotophobin A causes dark avoidance in goldfish by elevating pineal N-acetylserotonin.

We had shown that synthetic rat scotophobin A caused several effects upon goldfish, apparently mediated by the pineal gland. Here we report that norepinephrine decreased goldfish dark avoidance in a manner that was blocked by scotophobin or pinealectomy. Increased dark avoidance was caused by either propranolol or scotophobin alone. Certain components of the pineal melatonin pathway also affected goldfish light-dark preference: serotonin, and especially N-acetylserotonin, increased dark avoidance, as did the hydroxyindole-O-methyl-transferase (HIOMT) product inhibitor, S-adenosyl-homocysteine. Melatonin and S-adenosyl-methionine were without effect in this regard. Pinealectomy prevented the dark avoidance increase caused by serotonin and N-acetylserotonin. These data suggested that increased dark avoidance behavior in goldfish was correlated with N-acetylserotonin buildup in the pineal, and that scotophobin could cause this, if it were to inhibit pineal HIOMT. To test this hypothesis the effect of various agents upon pineal melatonin levels was determined. Scotophobin was found to both reduce pineal melatonin and to block the melatonin-increasing effect of N-acetylserotonin. This led to the discovery that, indeed, scotophobin was an effective inhibitor (KI50, 6 x 10(-7) M) of purified bovine HIOMT.

Acetylserotonin O-Methyltransferase↗
PubMed1979

Studies on factors in hamster caudal epididymal plasma and other sources which inhibit sperm dilution damage.

We observed that hamster caudal epididymal (HCE) plasma could inhibit dilution damage in HCE sperm. Here it is shown that in the absence of HCE plasma survival factors (SF), dilution of HCE sperm led to apparently simultaneous lysis and loss of motility. However, in the presence of HCE plasma, lysis did not occur when HCE sperm motility was blocked by palytoxin. Using a newly developed microassay for SF, significant amounts of SF activity were detected in dog and bovine caudal epididymal plasma, hamster testes exudate, HCE sperm cytosol, human seminal plasma, hamster and bovine adrenal extracts, hen's egg, and human serum. The SF activity of HCE plasma could tolerate restricted periods of boiling or pH extremes but was destroyed by trypsin and protease. Unlike human serum, HCE plasma did not significantly alter HCE sperm respiration or ATP content.

Adenosine Triphosphate↗
PubMed1979

Inhibition of sperm dilution damage by purified factors from hamster caudal epididymal plasma and by defined diluents.

Sperm dilution damage can be prevented by diluting hamster caudal epididymal (HCE) sperm in HCE plasma, a fluid which had been shown to contain sperm survival factors (SF). Dialysis and ultrafiltration studies demonstrated that SF consisted of both small-molecule and large-molecule components. Several known macromolecules and small molecules could substitute for these factors. Chemically defined diluents were designed that were able to substitute for HCE plasma in the prevention of sperm dilution damage under certain conditions. When the HCE plasma large-molecule component were fractionated by Sephadex G-100 chromatography, three bands of SF activity eluted. One appeared in the void volume ( is greater than 100,000 daltons), one with bovine serum albumin (67,000 daltons), and one at about 35,000 daltons. Two HCE plasma small-molecule components of less than 500 daltons eluted from both Sephadex G-25 and G-15 columns. Proteolysis studies suggested that both the small-molecule and the large-molecule components of HCE plasma may possess peptide bonds.

Animals↗
PubMed1979

Initiation of hamster sperm motility from quiescence: effect of conditions upon flagellation and respiration.

The point within the male reproductive tract where sperm motility originates varies with mammalian species. Premotile sperm from hamster, a species whose sperm are still quiescent in the epididymis, were used here to investigate further the parameters involved in the initiation of sperm motility. Two types of motility were produced: (1) partial, weak flagellation by simple dilution; (2) strong, complete motility by inducers (calcium, cyclic adenosine 3':5'-monophosphate) in the presence of amplifiers (caffeine, spermine). Expansion of initiation conditions to test tube volumes revealed that, at high sperm dilutions, bicarbonate could also induce motility. The respiratory consequences of sperm motility induction were measured. A Large, short-term burst of oxygen consumption occurred at a time paralleling the previously reported shifts in nucleotide levels associated with this event.

Animals↗
PubMed1978

Sperm motility within the mammalian epididymis: species variation and correlation with free calcium levels in epididymal plasma.

The region within the epididymis where spontaneous sperm motility first appeared and the extent of later motility within that organ, as shown by microscopic observation of undiluted samples, varied with the species. In the rat, mouse, and hamster, little sperm motility was present. In other species, spontaneously motile sperm were obtained from the caput (rabbit) and corpus (bull and man) regions of the epididymis. Samples from the cauda region of the epididymis were found to contain many motile sperm in the rabbit, bull, and especially man, where most of the sperm were intensely motile. There was a correlation between the amount of free calcium surrounding the sperm within the cauda epididymidis of a given species and the level of sperm motility therein. An inverse relationship was also found between the free calcium concentration in the cauda epididymal plasma of a species and the later inducibility of motility in diluted sperm from that species by calcium ion.

Animals↗
PubMed1975

Palytoxin: effects on contractility and 45Ca2+ uptake in isolated ventricle strips.

Palytoxin (PTX) inhibited phasic tension production and initiated tonic contracture in isolated paced ventricle strips at concentrations greater than 10(-10) M. PTX-induced contracture was associated with increased 45Ca2+ uptake. PTX-induced additional 45Ca2+ uptake was completely blocked by 2 mM La3+. All observed PTX effects were enhanced by elevation of [Ca2+] o from 1.9 to 6 mM and this threefold increase in [Ca2+] o resulted in a threefold increase in isotope-determined Ca2+ uptake in presence of 10(-8) M PTX. It is concluded that the observed effects of PTX could be mediated by an increase in calcium permeability of myocardial cells.

Acrylamides↗