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Biomedical subjects

S M Ryan

Publications and source records attributed to S M Ryan.

At least 37 records · Page 2Linked to original sources
PubMed1986

Stressor controllability and the pituitary-adrenal system.

Stressor controllability can alter both behavior and pituitary-adrenal activity. Potential mediation of these behavioral effects by differential pituitary-adrenal output requires that the precise conditions that lead to differential behavioral consequences also produce differential pituitary-adrenal activity. Both plasma ACTH and corticosterone levels were measured at various times following escapable and yoked inescapable electric shock conditions known to produce differential behavioral outcomes. The escapable and inescapable shock procedures did not produce a detectable differential effect. Both shock conditions produced equivalent elevation of ACTH and corticosterone. Neither decay rates nor the ACTH and corticosterone response to shock reexposure differed among shocked groups.

Adrenocorticotropic Hormone↗
PubMed1985

Spinal pain suppression mechanisms may differ for phasic and tonic pain.

The dorsolateral funiculus (DLF) spinal pathway has previously been identified as a major pathway involved in descending modulation of pain. While bilateral lesions of the DLF attenuated systemic morphine analgesia as measured by the tail-flick test, they failed to attenuate analgesia as measured by the formalin test. These results suggest that phasic and tonic pain, modeled by the tail-flick and formalin tests, respectively, may utilize different pain suppression mechanisms.

Animals↗
PubMed1984

Opiate and non-opiate analgesia induced by inescapable tail-shock: effects of dorsolateral funiculus lesions and decerebration.

Previous studies have demonstrated that inescapable tail-shock can produce either non-opiate or opiate short-term analgesia, dependent on the number of shocks delivered. Additionally, extended exposure to inescapable tail shock can produce long-term, opiate analgesic effects. Several lines of investigation suggest that the psychological dimension of perceived controllability may powerfully influence these phenomena in that each form of opiate analgesia can only be produced following exposure to inescapable, rather than equal amounts and distribution of escapable, shock. This has suggested that these opiate analgesias result from the organism's learning that it has no control over shock. Although it has been assumed that the opiate and non-opiate analgesias induced by tail shock may be subserved by neural circuitry similar to that mediating morphine analgesia and other forms of environmentally induced analgesia, no direct evidence exists to support this assumption. The present study sought to provide an initial attempt at defining the neural circuitry involved in these phenomena by examining the effect of bilateral dorsolateral funiculus (DLF) lesions and decerebration. These experiments revealed that pathways within the spinal cord DLF are critical for the production of short-term non-opiate analgesia, short-term opiate analgesia, and long-term opiate analgesia since bilateral DLF lesions abolished all three pain inhibitory effects. Additionally, it was found that decerebration did not attenuate either the short-term non-opiate or short-term opiate analgesia induced by inescapable tail shock. Combining the observations that these non-opiate and opiate short-term effects are not reduced by decerebration yet are abolished by DLF lesions clearly delimits the source of descending pain inhibition as being within the caudal brainstem.

Animals↗
PubMed1984

Librium prevents the analgesia and shuttlebox escape deficit typically observed following inescapable shock.

Administration of a benzodiazepine, chlordiazepoxide (CDP), prior to exposure to inescapable shock prevented both the long-term analgesia and the shuttle-escape deficit typically observed following inescapable shock. If given only prior to testing, CDP had little effect. The protective effects of CDP were determined not to be a result of state dependency or a general facilitatory effect of the drug on escape performance. It is suggested that the induction of anxiety or fear by inescapable shock is critical in mobilizing endogenous changes such as transmitter depletion which are thought to be responsible for the deficits observed.

Analgesia↗
PubMed1984

The formalin test and the opioid nature of stress-induced analgesia.

Exposure to electric shock produces an analgesic reaction (SIA) that is reversed by opiate antagonists ("opioid" SIA) under some conditions but not under other conditions ("nonopioid" SIA). A number of studies using tail-flick to radiant heat as the measure of pain sensitivity have found that a small number of shocks lead to nonopioid SIA, while a large number of shocks produce opioid SIA. In contrast, a small number of shocks have been reported to produce opioid SIA when the Formalin test was used to measure pain reactivity. However, the Formalin test involves administering a chronic pain stimulus (injection of Formalin into the paw) for an extended period before the shocks. Here it is reported that this "preexperimental" stress is sufficient to convert the SIA after a small number of shocks measured by tail-flick to the opioid form.

Afferent Pathways↗
PubMed1983

Coping and immunosuppression: inescapable but not escapable shock suppresses lymphocyte proliferation.

Rats were given series of escapable shocks, identical inescapable shocks, or no shock. The subjects were reexposed to a small amount of shock 24 hours later, after which an in vitro measure of the cellular immune response was examined. Lymphocyte proliferation in response to the mitogens phytohemagglutinin and concanavalin A was suppressed in the inescapable shock group but not in the escapable shock group. This suggests that the controllability of stressors is critical in modulating immune functioning.

Animals↗
PubMed1982

Further evaluation by ultrasound of mammographically determined breast dysplasia.

Evaluation of 135 consecutive patients was made for breast masses by the same surgeon and the patients were subsequently referred for ultrasound mammography of the breast after xeromammography revealed a "dysplastic" (DY) pattern only, with no evidence of malignancy. Three patients had carcinoma of the breast detected by ultrasound mammography that had been missed by xeromammography. Two of the three cancers were similarly diagnosed by fine-needle aspiration cytology. All patients with a normal ultrasound examination have now been followed for a minimum of 15 months without evidence of developing breast cancer. This study confirms the importance of using additional diagnostic modalities for evaluating patients with dysplastic breasts and strongly suggests the value of ultrasound mammography in this group of patients.

Adult↗
PubMed1981

Enkephalin-like immunoreactivity in vocal control regions of the zebra finch brain.

Singing in passerine birds is an androgen-dependent behavior typical of males, and in many species is learned during an early critical period. Brain regions which control song form a rather discrete, interconnected series of nuclei which have been described in the canary and zebra finch. These regions include the caudal nucleus of the hyperstriatum ventrale (HVc), the robust nucleus of the archistriatum (RA), the magnocellular nucleus of the neostriatum (MAN), area X of the lobus parolfactorius, nucleus interface (NIF), intercollicular nucleus (ICo), and the tracheosyringeal portion of the hypoglossal motor nucleus (nXIIts). In the present report, we describe cell bodies and terminals in these brain regions which contain enkephalin-like immunoreactivity (ELI). This study is the third in a series investigating the histochemical characteristics of the vocal control system in zebra finches.

Animals↗
PubMed1981

Evidence for cholinergic participation in the control of bird song; acetylcholinesterase distribution and muscarinic receptor autoradiography in the zebra finch brain.

Brain regions thought to be involved in the control of song in the zebra finch (Poephila guttata), were examined histochemically using the Karnovsky and Roots direct-coloring method for the detection of acetylcholinesterase (AChE) and the autoradiographic method for the localization of muscarinic cholinergic receptors following injection of tritiated quinuclidinyl benzilate (3H QNB). All presently identified vocal control nuclei in both males and females contain AChE. These nuclei include Area X, magnocellular nucleus of the anterior neostriatum (MAN), nucleus interface (NIF), caudal nucleus of the hyperstriatum ventrale (HVc), intercollicular nucleus (ICo), nucleus uva, robust nucleus of the archistriatum (RA), and tracheosyringeal portion of the hypoglossal nerve nucleus (nXIIts). All nuclei except Area X contain mostly AChE-synthesizing cell bodies. All of these nuclei contain some AChE in the neuropil, with particularly intense staining in Area X, the surrounding LPO, and the dorsomedial portion of ICo. In agreement with this description are very high concentrations of 3H QNB in both Area X and the dorsomedial ICo. HVc also appears specifically labeled. Evidence from these two histological technique suggests that efferent projections of most vocal control area may utilize acetylcholine, and that several of the vocal control nuclei may themselves receive muscarinic cholinergic projection. In Area X, there are sex differences of AChE neuropil staining. This evidence suggesting that sexually dimorphic projections to or within Area X are cholinergic or cholinoceptive.

Acetylcholinesterase↗
PubMed1981

Evidence for a catecholaminergic projection to area X in the zebra finch.

In the zebra finch (Poephila guttata), horseradish peroxidase injected into or near Area X of the lobus parolfactorius (LPO) is transported to cell bodies in ipsilateral hyperstriatum ventrale pars caudale (HVc), area ventralis of Tsai (AVT), and nucleus tegmenti pedunculo-pontinus, pars compacta (TPc). Area X, LPO, and paleostriatum augmentatum (PA) all contain a dense network of catacholamine-containing axons and nerve terminals, as determined in histofluorescence studies. Cell bodies in AVT and TPc contain catacholamines; lesions of TPc greatly reduce or abolish catacholamine fluorescence in PA, and a lesion of AVT eliminates histofluorescence in LPO, icluding Area X. The anatomical location and catecholaminergic projection from AVT suggest that LPO-Area X may be the avian homolog of the mammalian nucleus accumbens, olfactory tubercle, and/or rostromedial caudate.

Animals↗
PubMed1980

The value of aspiration cytology in the evaluation of dysplastic breasts.

Sixteen consecutive patients who had carcinoma of the breast and who had preoperative xeromammography were evaluated and classified according to Wolfe's classification. Five of the patients had correct preoperative evaluation by mammography, and 11 had false negatives. Eight of these were in patients who had Wolfe's classification "DY", suggesting that this is an extremely difficult group to diagnose by mammography alone. The value of aspiration cytology in this group and in all patients having breast masses is discussed. Aspiration cytology as a cellular technique for diagnosing the group with dysplastic breast is strongly recommended.

Adult↗
PubMed1978

Effect of the dopamine agonist, lergotrile mesylate, on circulating anterior pituitary hormones in man.

The effects of the ergoline derivative, lergotrile mesylate, on the serum levels of PRL, GH, TSH, LH, FSH, cortisol, and blood sugar were studied in six normal males. The effects of lergotrile mesylate on the serum levels of GH and PRL were also studied in eight patients with acromegaly and in two with idiopathic hyperprolactinemia. In the normal subjects, 2 mg oral lergotrile lowered basal PRL levels after 90 min and markedly impaired the PRL response to TRH (200 micrograms iv); the mean peak value +/- SE was 8.3 +/- 1.1 micrograms/liter, compared to the control value of 66.6 /+- 11.3 micrograms/liter. Lergotrile raised serum GH levels in five of the six subjects to peaks of 8-49 micrograms/liter, compared to 2-8 micrograms/liter after placebo. In three subjects, the GH response to lergotrile was attenuated by the prior administration of the dopamine antagonist, metoclopramide (10 mg orally). Lergotrile had no effect on FSH and LH levels under basal conditions or after the gonadotrophin-releasing hormone (GnRH; 100 micrograms iv). Circulating TSH levels were unaltered basally but impaired after TRH. Blood sugar levels were unaltered; serum cortisol was elevated in five of six subjects; there was a brief depression of diastolic blood pressure, but no change in pulse rate. The side effects after lergotrile were variable, with drowsiness as a consistent feature. These actions are similar to those of bromocriptine (an ergot derivative treatment of hyperprolactinemia and acromegaly, to suppress PRL and GH secretion, and in parkinsonism. Therefore, it may be expected that lergotrile could fulfill these clinical uses; however, in the studies comparing the effects of single oral doses of lergotrile (2 mg) and bromocriptine (2.5 mg) on GH and PRL secretion in patients with acromegaly and hyperprolactinemia, lergotrile in the dose used has been found to have an earlier onset and shorter duration of action.

Acromegaly↗
PubMed1975

RNA-dependent DNA-polymerase activity in human milk.

A simple method is described for testing milk specimens from nursing mothers for the presence of RNA-dependent DNA-polymerase activity. Positive results were obtained in five of 137 women (3.6%) without a family history of breast cancer, and in six of 31 women (19.3%) with a family history of breast cancer.

Breast Feeding↗
PubMed1971

Perception.

Explore the source record for details and available documents.

Afterimage↗
PubMed1969

Graduate program in biomedical communication.

The need for harnessing the achievements of communication technology to the burgeoning mass of biomedical information is critical. Recognizing this problem and aware of the short supply of professionals with the skills necessary for the job, a group of leaders from the fields of medicine and communications formed a consortium in 1967 and have developed a twelve month graduate program in biomedical communication. Designed to ground the advanced student in the development and administration of biomedical communication programs, the curriculum focuses on the principles and practice of communication and the development of communications media. Courses are given in the control and communication of information; the printed and spoken word; visual media of photographic arts, television, and motion pictures; computer science; and administration and systems analysis.

Communication↗