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Biomedical subjects

C A Anderson

Publications and source records attributed to C A Anderson.

15 recordsLinked to original sources
PubMed1992

Glutamate in the inferior colliculus plays a critical role in audiogenic seizure initiation.

Alterations of excitant amino acid (EAA) action are implicated in seizure susceptibility in the genetically epilepsy-prone rat (GEPR). The inferior colliculus (IC) is critical for audiogenic seizure (AGS) initiation in the GEPR. The present study observed that bilateral microinjection into the IC of L-canaline, a glutamate synthesis inhibitor, decreased AGS severity in the GEPR and also decreased potassium-evoked release of glutamate from IC slices. Bilateral microinjection of NMDA receptor antagonists, 2-amino-7-phosphonoheptanoate (AP7) or 3-((+/-)-2-carboxypiperazin-4-yl)-propyl-1-phosphonate (CPP) into IC blocked AGS, and an antagonist at non-NMDA EAA receptors, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), also blocked AGS. NMDA receptor antagonists were 5-200 times more effective than CNQX. Microinjection of a non-competitive NMDA receptor antagonist, dizocilpine (MK-801), into IC had little effect except with very high doses. Microinjection of CPP or AP7 into the IC blocked AGS at considerably lower doses as compared to pontine reticular formation (PRF). However, MK-801 attenuated AGS when microinjected into PRF at doses that were ineffective in IC. Systemically administered CPP blocked AGS and significantly reduced IC neuronal firing in the behaving GEPR, suggesting an important action of systemically administered NMDA receptor antagonists on brainstem auditory nuclei critical to AGS. The present results support a critical role for glutamate acting, in part, through NMDA receptors in IC in initiation of AGS.

Acoustic Stimulation↗
PubMed1992

Takayasu arteritis.

Takayasu Arteritis is a vasculitis of the giant cell type which affects young people. Complications of this disease can include myocardial infarction, stroke, limb loss, renal failure, and mesenteric ischemia. A case study demonstrates some of the complexities of diagnosis and treatment for this condition. Nursing care should be directed toward the alteration in tissue perfusion, prevention of infection in a patient on immunosuppressive therapy, and a variety of potential problems with coping.

Adult↗
PubMed1991

Reversible effects of triamcinolone and lack of effects with aspirin or L-656,224 on external genitalia of male Sprague-Dawley rats exposed in utero.

Inhibitors of the arachidonic acid cascade were given to pregnant rats during the critical period for morphogenesis of the external genitalia. Groups treated subcutaneously (s.c.) with 0.1 or 0.25 mg/kg/day of triamcinolone acetonide (TA) on gestational days (GD) 14-19 had male fetuses on GD 20 with moderate decreases in absolute anogenital distance (AGD), but gross and histological examinations revealed no alterations to the genital tubercle (i.e., no hypospadias). The s.c. coadministration of arachidonic acid at 100 mg/kg/day had minimal to no effect on AGD in the TA-exposed groups. No effect on AGD was observed in male fetuses from groups administered aspirin orally at 150 mg/kg/day, and only a 6% decrease was observed in the 300-mg/kg/day group. Neither TA nor aspirin adversely affected AGD of female fetuses. In another study, TA was administered on GD 11-19 at dose levels of 0.05 and 0.1 mg/kg/day, and dams were allowed to deliver. High-dose male offspring examined on postcoitum day (PCD) 23, had moderate decreases in AGD. In both studies with TA, there were also significant decreases in offspring weights. The contribution of the decreased weight to the decrease in absolute AGD was examined by a variety of methods (ratio of AGD to cube root of weight or biparietal distance, comparison to weight-matched controls, and covariance analysis). We conclude that TA caused a specific decrease in AGD on GD 20 that was largely reversed by PCD 23. When examined as adults (8 weeks old), the external genitalia of TA-exposed offspring were normal. Thus, the TA-induced decreases in AGD on GD 20 did not predict irreversible malformation. TA also caused other effects, which included a somewhat flattened genital tubercle and apparently thinned and glossy skin between the tubercle and the anus in both sexes on GD 20 and PCD 23, but not as adults. In addition, there were high pup mortality and high incidences of micrognathia and omphalocele (in the 0.25-mg/kg/day group only). Aspirin at 75 or 150 mg/kg/day and a specific lipoxygenase inhibitor (L-656,224) at 1,000 or 2,000 mg/kg/day were also administered from GD 14 to 19, and no offspring effects were observed. Thus, of the three agents that potentially inhibit the arachidonic acid cascade, only triamcinolone produced moderate effects on rat external genitalia that were largely reversible.(ABSTRACT TRUNCATED AT 400 WORDS)

Abnormalities, Drug-Induced↗
PubMed1991

Loss of intensity-induced inhibition in inferior colliculus neurons leads to audiogenic seizure susceptibility in behaving genetically epilepsy-prone rats.

The genetically epilepsy-prone rat (GEPR) exhibits elevated seizure sensitivity and audiogenic seizures (AGS). The inferior colliculus (IC) is the most critical brain region for AGS initiation. The present study evaluated IC neuronal firing and convulsive behavior simultaneously in freely moving GEPRs. High intensity acoustic stimulation produces neuronal firing reductions (intensity-induced inhibition) in about 50% of IC neurons in normal rats. However, in GEPR IC neurons, intensity-induced inhibition is significantly less effective than normal. Offset inhibition is also reduced in GEPR IC neurons, which leads to a greater than normal incidence of offset (afterdischarge) responses at high stimulus intensities. At AGS onset most IC neurons exhibit burst firing and reductions of acoustically evoked neuronal responses. Responsiveness to acoustic stimuli returns following AGS. This change in IC neuronal firing pattern suggests that the network that governs IC neuronal firing has temporarily changed from the auditory system to the network that mediates seizure propagation. GABA is strongly implicated in intensity-induced, binaural, and offset inhibition in IC neurons. The diminished efficacy of these forms of GABA-mediated acoustically evoked inhibition in the GEPR IC extends previous results, showing reduced effectiveness of exogenously applied GABA and benzodiazepine in GEPR IC neurons. This reduced effectiveness of GABA-mediated inhibition along with excess excitant amino acids in GEPR IC, previously reported, appear to be vital neurotransmitter mechanisms, subserving the exaggerated output of IC neurons at high acoustic intensities. This exaggerated IC firing may be instrumental in seizure initiation in this epilepsy model.

Acoustic Stimulation↗
PubMed1991

Implementing continuous quality improvement (CQI) in hospitals: lessons learned from the International Quality Study.

Continuous Quality Improvement is in the process of being implemented in hospitals around the world. In an attempt to gain a better understanding of the "best management practices" the International Quality Study is being conducted in four countries--Canada, Germany, Japan and the United States--and across four industries--Health Care, Banking, Automotive and Computers. Information collected through a survey process will be analysed through causal modeling to determine correlations between management practices and achievement of quality objectives. Given both the complexity of the models and the number of key concepts involved, 400 hospitals have been invited to participate. The preliminary results show direct correlations between cultural influences and the concept of quality. The perceived definition of quality by the various countries varies and therefore the application of "quality concepts" differs. Once complete, this database of "best management practices" will serve as a worldwide benchmark for quality progress.

Canada↗
PubMed1990

External genitalia of the rat: normal development and the histogenesis of 5 alpha-reductase inhibitor-induced abnormalities.

The normal histogenesis of the rat genital tubercle and the effect of exposure in utero to the 5 alpha-reductase inhibitor finasteride (L-652,931; MK-0906; Proscar) on that process were studied. In normal males and females, the genital tubercle was first seen on Day 14.25 of gestation. It contained a urethral plate which extended from the cloaca (and after Day 15.25, from the urogenital sinus) to the tip of the tubercle. On Day 18.25 the glans lamellae, which would separate the glans penis or the clitoris from the prepuce, began to develop in both sexes. Also on Day 18.25 a dense, midline plate of mesenchymal cells was first evident between the urogenital sinus and the rectum in normal males. This plate acted as a wedge, first increasing the separation between the rectum and the urogenital sinus, and subsequently separating the urethral plate from the surface epithelium in the genital tubercle. As a result, by Day 21.25 the urethra in males followed an "S"-shaped course, extending from the pelvis through the center of the glans penis to an orifice near the tip of the genital tubercle. In females, in which a mesenchymal plate did not develop, the urethral orifice remained at the base of the tubercle, and the clitoris contained the remnants of the urethral plate, extending as an open groove from the urethral orifice to the tip of the tubercle. Finasteride did not affect development of the genital tubercle in females. However, in males exposed to finasteride in utero, there was variable failure of the mesenchymal wedge to develop. As a result, the urethral plate remained in contact with the surface epithelium and eventually opened to form a groove on the ventral surface of the glans penis (hypospadias). Also, the persistence of the urethral plate along the ventral midline in finasteride-treated male fetuses and its subsequent opening as a groove interfered with development of the glans lamellae, causing displacement of the frenulum distally on the glans penis and the development of a cleft in the prepuce.

Androstenes↗
PubMed1990

Army trauma research: tapping the potential.

Trauma management is the primary mission of military surgeons. Since the Vietnam War, however, military surgeons have relinquished leadership in clinical trauma care to the civilian sector, particularly to urban university surgeons. In this paper we explore whether the Army's contribution to trauma research has also diminished. Using standard bibliometric analysis of publication counts, we have shown that few recent publications related to trauma have originated from U.S. Army Medical Centers, compared with adjacent civilian universities. In 1988, 16 papers originating from the eight Army Medical Centers had key words related to trauma. In contrast, eight universities adjacent to the Army's medical centers published 139 articles on trauma. Problems including lack of clinical exposure to trauma patients, lack of funding, and inadequate emphasis on staff research training have contributed to this decline. We review these factors and describe solutions that could reverse this trend.

Humans↗
PubMed1979

Ambient temperature and the occurrence of collective violence: a new analysis.

Prevalent folklore suggests that riots tend to occur during periods of very hot weather. Baron and Ransberger examined 102 major riots in the United States between 1967 and 1971 and concluded that the frequency of collective violence and ambient temperature are curvilinearly related. The present article points out that the Baron and Ransberger analysis did not take account of the different number of days in different temperature ranges. The artifact is eliminated, and the probability of a riot, conditional upon temperature, is estimated. When this is done, the evidence strongly suggests that the conditional probability of a riot increases monotonically with temperature. Some general implications of such data analyses are discussed.

Humans↗
PubMed1978

Femorofemoral grafts: the role of concomitant extended profundaplasty.

Twenty-one femorofemoral grafts were placed in high risk patients with symptomatic, unilateral, iliofemoral, arterial occlusive disease. There was 100 per cent immediate postoperative relief of ischemia or improvement in claudication. Three late below-knee amputations have been performed. All other living patients had healed extremities and were ambulatory at last follow-up. Cumulative graft patency determined by the life table method was 95 per cent at twenty-four months. The physiologic "steal" created by a femorofemoral bypass with donor limb and/or outflow stenosis must be considered to prevent clinical donor limb functional impairment. A gradient of 10 mm Hg or less between the radial artery mean pressure and the donor femoral artery ensured adequate donor artery flow without regard to angiographic a-pearance of the donor artery. The crucial technical problem in patients operated on for ischemia was reconstruction of adequate outflow. All but one patient required at least minimal profunda endarterectomy, and nine of seventeen (53 per cent) required concomitant extended profundaplasty procedures.

Age Factors↗
PubMed1978

Death and dying.

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Attitude of Health Personnel↗