PubMed Health⌕ Search

Biomedical subjects

J Ayers

Publications and source records attributed to J Ayers.

14 recordsLinked to original sources
PubMed1991

Gross, microscopic and ultrastructural lesions of protoporphyria in Limousin calves.

The gross, microscopic and ultrastructural lesions associated with the genetic disease, protoporphyria, in Limousin cattle were studied in detail. The clinical signs and lesions were most severe in young animals. In the liver, the lesions consisted of portal fibroplasia, bile ductule hyperplasia, parenchymal cell swelling, and pigment accumulation. Maltese cross-like crystals were evident under polarized light. Ultrastructurally, there were large secondary lysosomes comprised of electron-dense granules associated with lipid droplets in hepatocytes. Phagocytic cells in the dermis also contained large heterogeneous secondary lysosomes.

Animals↗
PubMed1989

Steroid secretion by a virilizing lipoid cell ovarian tumor: origins of dehydroepiandrosterone sulfate.

A 78-year-old woman had a 3-year history of severe virilization caused by a lipoid cell ovarian tumor localized by pelvic ultrasound examination and NP-59 scan. Steroid secretion was evaluated by the following: 1) peripheral plasma levels before and after hormonal stimulation with ACTH or hCG, 2) venous catheterization and measurement of steroid levels in the left and right ovarian veins during surgery, 3) measurements of enzymatic activities in the tumor tissue compared with those in normal ovarian tissue, and 4) steroid secretion studies in vitro of the tumor tissue, surrounding tissue, and contralateral ovarian tissue. The tumor tissue secreted both delta 5 and delta 4 androgens, including dehydroepiandrosterone sulfate. Dehydroepiandrosterone sulfate was also secreted by the surrounding and contralateral ovarian tissue.

Aged↗
PubMed1987

Plasticity of fin command system function following spinal transection in larval sea lamprey.

The descending control of dorsal fin posture by a reidentifiable reticulospinal command neuron (I1), was examined in the sea lamprey, Petromyzon marinus. Intracellular stimulation of I1 controls the posture of both dorsal fins. Spinal transection between the fins results not only in loss of control of posterior dorsal fin posture, but after 2 h, the control of the anterior dorsal fin as well. Anterior dorsal fin responses remained absent at 4, 5 and 6 days after transection. Stimulation of I1 could control anterior dorsal fin posture in specimens which had recovered the ability to right during swimming (77 and 100 days after transection), although higher than normal stimulus frequencies were required. I1 control of posterior dorsal fin posture did not recover.

Animals↗
PubMed1984

The relationship of I-131 6 beta-iodomethyl-19-norcholesterol (NP-59) adrenal cortical uptake to indices of androgen secretion in women with hyperandrogenism.

Dexamethasone suppression (DS) adrenal cortical scintigraphy has been shown to be useful in the detection of the adrenal pathology in women with hyperandrogenism. However, a relationship between adrenal cortical uptake of I-131 6 beta-iodomethylnorcholesterol (NP-59) and the level of adrenal androgen secretion has not been established. A retrospective analysis of DS adrenal scintiscans has been performed on 39 women with hirsutism and hyperandrogenism. In 14 patients with normal patterns of imaging, in vivo adrenal gland iodocholesterol uptake, calculated using a semi-operator-independent-computer algorithm, did not correlate with the excretion of urinary 17-ketosteroids (17-KS). In contrast, in 20 patients demonstrating abnormal bilateral early imaging patterns, adrenal gland NP-59 uptake correlated significantly with the level of urinary 17-KS excretion (r = 0.65, P less than 0.05). To date seven of these 20 patients have had confirmatory procedures documenting the adrenal glands as contributing sites of androgen secretion. A similar correlation with urinary 17-KS excretion was seen in five other patients with unilateral imaging patterns (r = 0.94, P less than 0.005), due to androgen-secreting adrenal cortical adenomas. No correlation between adrenal NP-59 uptake and plasma testosterone or dehydroepiandrosterone sulphate levels was observed in any of the groups. Thus, adrenal gland uptake of NP-59 under DS reflects a measure of androgen secretion in women with androgen excess.

17-Hydroxycorticosteroids↗
PubMed1984

Synaptic perturbation and entrainment of gastric mill rhythm of the spiny lobster.

The gastric mill rhythm of the lobster stomatogastric ganglion was perturbed with short trains of synaptic input from the inferior ventricular nerve (IVN) through fibers. The stimulus was delivered randomly for phase-response curve analysis or repetitively to examine entrainment. The responses depend on the phase of the stimulus in the endogenous rhythm. The stimulus may alter the internal coordination of the motor pattern. Stimuli that occur during a lateral gastric nerve-anterior lateral nerve-E-neuron (LG-GM-E) burst perturb the burst internally and produce a prolonged LG-GM-E burst, while those that occur during the silent interval between LG-GM-E bursts may evoke a triggered LG-GM-E burst. Spontaneous, prolonged, and triggered LG-GM-E bursts differ in their internal structure as well as the order of burst onsets and offsets. The intercalated triggered LG-GM-E burst delays the occurrence of the subsequent spontaneous LG-GM-E burst, thus strongly resetting the rhythm. These resetting effects have been formalized by phase-response curve analysis. Over limited constraints, cyclic IVN stimuli can entrain the rhythm. Repetitively delivered IVN stimuli have parametric effects on the rhythm that mask the predictive value of phase-response curve analysis for the determination of the phase relations during entrainment.

Animals↗
PubMed1983

Regeneration of locomotor command systems in the sea lamprey.

Ammocoete larvae of the sea lamprey were allowed to recover from a complete transection of the spinal cord posterior to the last gill arch. Specimens were then prepared for focal extracellular stimulation of the brainstem in the region known to contain the command systems for swimming. In 4 preparations where behavioral recovery had occurred, stimulation in this region would initiate swimming, indicating that the command function of this 'locomotor' region had recovered.

Animals↗
PubMed1983

Which behavior does the lamprey central motor program mediate?

The isolated lamprey spinal cord, when bathed in 2 millimolar D-glutamic acid, will generate a pattern of motor neuron discharge that has generally been assumed to represent the central motor program for swimming. Motion pictures of behaving lampreys were analyzed by a computer algorithm to estimate undulatory movement parameters that could be directly compared with those generated during D-glutamate--induced undulations. The D-glutamate--induced movement parameters were significantly different from those observed during normal behaviors, including swimming, but accurately predicted the undulations produced by spinally transected adult lampreys.

Animals↗
PubMed1977

[Walking in Crustacea: motor program and peripheral regulation (author's transl)].

1. Rock lobsters can walk in all directions. In the present study, we report the organization of the motor output of the three muscles which control the mero-carpopodite joint (M-C): the extensor E, the flexor F and the accuracy flexor FA, during unrestrained locomotion (fig. 1). 2. During lateral walking, movements of the M-C joint provide most of the propulsive force, whereas during forward and backward walking this joint function more as a strut (fig. 2). Corresponding differences are observed in the motor discharge in the different walking modes. During lateral walking, discharge in the M-C extensor and M-C flexor alternates, whereas during forward and backward walking these antagonists are coactivated (fig. 3 and 4). 3. We have also examined the effects of alterations of proprioceptive feedback: the FA tendon has been cut to eliminate MCO afferents during walking. This ablation does not modify the burst period and the temporal structure of the output pattern is largely unaffected (fig. 5, 6 and 7). MCO may influence the motor output of a given muscle depending upon whether it participates in the return stroke or the power stroke.

Action Potentials↗
PubMed1976

Alcoholism, cigarette smoking, coffee drinking and extraversion.

Alcoholic patients smoked significantly more cigarettes and drank more cups of coffee than nonalcoholic psychiatric patients even when the higher extraversion scores of the alcoholics, as measured by the Eysenck Personality Inventory, were statistically controlled.

Adult↗
PubMed1975

The MMPI in the differential diagnosis of organicity vs. schizophrenia: empirical findings and a somewhat different perspective.

Watson's MMPI Scale for differentiating organicity from schizophrenia was found to correlate significantly with the MMPI Schizophrenia Scale and was found not to differentiate significantly better than the Schizophrenia Scale for the two patient groups under consideration. Watson's general approach of using personality measures for such differential diagnosis was lauded, although doubt that his scale is superior to other methods of diagnosing schizophrenia was expressed.

Brain Damage, Chronic↗