Tritiated thymidine autoradiographic study on the origin and renewal of argentaffin cells in the pyloric gland of hamsters

The origin and renewal of the argentaffin cells in the pyloric glands of hamsters were studied by flash, cumulative and pulse labelling autoradiography with 3H-thymidine. The argentaffin cells were identified by the Diazo Method using Fast Red B Salt. By flash labelling autoradiography, it was shown that the argentaffin cells located from the middle to the lower level of the pyloric mucosa were not labelled with 3H-thymidine, indicating that this cell type has no proliferative activity. On the 10th and the 20th day of cumulative labelling, 31% and 63% of the argentaffin cells in the gland were found to be labelled, respectively. The labelled argentaffin cells were concentrated in the upper part of the gland (around the region of the isthmus), and no label was found over nuclei of the cells at the lowermost level of the gland. These labelled cells were shown to undergo a downward migration in the days following pulse labelling. They were replaced by unlabelled (and weakly or very weakly labelled) cells which arose at the region of the isthmus. The argentaffin cells in the pyloric gland are thought to arise from epithelial precursor cells at the region of the isthmus. The labelled argentaffin cells in the gland were found to decrease in number almost exponentially after pulse labelling. This indicates that the life span of argentaffin cells is not fixed, but their renewal conforms to the "random loss system". The half time of turnover of this cell population was 15 days on average.

Enzymatic oxidation of isethionate to sulfoacetaldehyde in bacterial extract

Isethionate degradation in a bacterial extract was shown by the isolation of enzymes and by identification of an intermediate to take place in two steps; dehydrogenation to sulfoacetaldehyde and desulfonation leading to the formation of sulfite and acetate. The enzyme responsible for isethionate oxidation in the presence of FAD was particulate in nature and a solubilized preparation obtained by extraction with buffer of low ionic strength had oxidizing activities against only isethionate and n-butanol among compounds tested. The enzyme was inhibited by thiol and carbonyl reagents.

Interaction of alloxan and anomers of D-glucose on glucose-induced insulin secretion and biosynthesis in vitro

The direct effects of alloxan on glucose-induced insulin secretion and biosynthesis and the interaction of alloxan and D-glucose anomers were studied in vitro by use of isolated islets from rat pancreas. Islets were pretreated by incubation for five minutes in media containing alloxan (0.2 mg./ml.) alone or alloxan with either the alpha or beta anomer of D-glucose (3 mg./ml.). After washing, batches of five islets were incubated in the medium supplemented with glucose (1.8 mg./ml.) for 60 minutes to observe insulin secretion and for 90 minutes to observe insulin biosynthesis. Prior exposure to alloxan alone produced marked inhibition of subsequent glucose-induced insulin secretion and biosynthesis. A significantly greater protection against these inhibitory effects of alloxan was observed by using the alpha anomer of D-glucose than the beta anomer. The anomeric preference of D-glucose for protecting islet cells from the inhibitory effect of alloxan on glucose-induced insulin secretion and biosynthesis was similar to that for triggering insulin secretion. Possible mechanisms of the inhibitory effect of alloxan and the protective effect of D-glucose anomers in connection with those of other sugars are discussed. It is suggested that a glucoreceptor, stereospecific to the alpha anomer of D-glucose, may exist for both insulin secretion and biosynthesis.

Prefrontal unit activity and delayed response: relation to cue location versus direction of response

Two monkeys were trained to perform 3 kinds of spatial tasks (right-left DR, up-down DR, and conditional position discrimination with delay). In the conditional position task, the animal was required to respond to the right (left) choice key when the cue had been presented on the upper (lower) position. Single unit activity was recorded from the principalis area of the dorsolateral prefrontal cortex while the animal was performing the tasks. Once a differential delay unit (i.e., unit showing specificity during the delay period for two kinds of trials) was found in right-left DR (or up-down DR), the same unit was tested in the other tasks. A total of 32 differential delay units were investigated sufficiently to allow comparison of all 3 conditions. The results indicate that there are two types of differential delay units. The first type showed a clear dependence on the cue location, while the second type was related to the direction of the impending response. Activity of the second type of differential delay unit during the delay period served to predict the occurrence of errors, whereas this relation between unit discharge and correct or incorrect responses was not seen for the first type of differential delay unit.

Uptake of radioactive D-glucose anomers by pancreatic islets

Isolated rat islets were incubated in media containing either the alpha or beta anomer of D-[1-3H]glucose for 5 min at 37 degrees. The amounts of the two anomers incorporated were determined using L-[1-14C]glucose as an extracellular space marker. The incorporation of beta-D-glucose was about twice that of alpha-D-glucose. Our previous and present results suggest that the two anomers of D-glucose each have a preferential function in pancreatic beta cells; alpha-D-glucose stimulates insulin secretion, and beta-D-glucose is transported into the cells.

Hydroxyl Radical Concentrations Measured in Ambient Air

Diurnal variations in the hydroxyl radical concentration of ambient air were measured for the first time by the technique of laser-induced fluorescence.

Neurotological studies on the role of the sympathetic nervous system in the formation of traumatic vertigo of cervical origin

To test the validity of the hypothesis that irritation of the cervical sympathetic nerves is a cause of hypertonicity of the cervical soft supporting tissues, especially the deep nuchal muscles, and that this hypertonicity is a cause of traumatic vertigo of cervical origin, we examined 44 vertigo cases with whiplash injury by testing equilibrium function and EMG discharges from the neck before and after administration of drugs affecting the sympathetic receptors. The results obtained were as follows: 1. Administration of iso-proterenol (beta-receptor stimulant) caused a significant increase in the EMG's from the injured neck muscles, in parallel with increased impairment of the righting reflex. The blindfolded vertical writing test showed the appearance or intensification of ataxia or deviation in writing when this drug was given. In contrast, administration of propranolol (beta-receptor depressor) had the opposite effects on the EMG's, the righting reflex and blindfolded vertical writing. Furthermore, the resulting changes in the EMG's and equilibrium functions were parallel with alterations in subjects' complaints, i.e., increase or decrease in neck pain and vertigo. 2. Administration of drugs affecting the alpha receptors, such as noradrenaline (alpha-receptor stimulant) and phentolamine (alpha-receptor depressor) had no appreciable effect on the EMG's, equilibrium function or the subjects' complaints. These results show that in vertigo due to whiplash injury hypertonicity of the cervical erector muscles can be induced sympathetically, and that this hypertonicity is based on over-excitement of beta receptors in the injured neck muscles, which results in vertigo of cervical origin.

Insulin secretion by anomers of d-glucose

Isolated rat islets were incubated for 5 minutes in the media containing either the alpha or beta anomer of D-glucose (2 milligrams per milliliter). The amounts of secreted insulin and changes of anomers ratio were concomitantly determined. In spite of rapid mutarotation, significantly greater stimulation of insulin secretion was observed by alpha-D-glucose as compared with beta-D-glucose.

Reaction Kinetics Involving O and N Compounds

Experimental work performed during the past 4 years is reviewed briefly for aeronomically interesting reactions involving ground electronic states of O and N compounds.

Carbon monoxide balance in nature

Consideration of the steady-state equations for stable carbon monoxide and for radioactive carbon monoxide in the troposphere leads to the conclusion that carbon monoxide is produced at a rate of 5x10(15) grams per year, a value some 25 times greater than the rate of carbon monoxide production from combustion. The concomitant residence time for carbon monoxide is 0.1 year, in agreement with a previous estimate of Weinstock. Hydroxyl radicals are shown to account for both the production of this large amount of carbon monoxide by methane oxidation and for its removal by carbon monoxide oxidation. The average concentration of hydroxyl radicals in the troposphere required to achieve this effect is 2.3x10(6) molecules per cubic centimeter, with a daytime concentration of twice that. Levy and McConnell, McElroy, and Wofsy have deduced concentrations of hydroxyl radicals in the troposphere of the same magnitude from purely photochemical considerations, in support of this model.

Serotonin and the plasma amino acid reduction caused by a single injection of growth hormone

An acute reduction in the concentration of plasma free amino acids was observed in normal, hypophysectomized, pancreatectomized, and doubly operated (Houssay) dogs following a single injection of bovine growth hormone (NIH, lots B8, B12, and B13, 1–5 mg/kg). The reduction obtained with administered growth hormone in diabetic animals was abolished by dihydroergotamine (2 mg) or 2-brom-d-lysergic acid diethylamide (BOL-148, 1 mg). Pharmacological blockade of the adrenergic and serotonergic systems partially counteracted the growth hormone effect in normal and hypophysectomized dogs; complete suppression was achieved only in combination with puromycin (200 mg). These results indicate that the reduction in the concentration of plasma free amino acids following a single injection of growth hormone has at least two components. It is suggested that one is protein anabolic in nature and the other involves hepatic gluconeogenesis caused chiefly by serotonin.