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Biomedical subjects

G S Allen

Publications and source records attributed to G S Allen.

At least 37 records · Page 2Linked to original sources
PubMed1991

Heart-specific autoantibodies can be eluted from the hearts of Coxsackievirus B3-infected mice.

This study was undertaken to determine if immunoglobulin G (IgG) antibodies could be eluted from the hearts of mice with Coxsackievirus B3-induced autoimmune myocarditis and to characterize the immunoreactivity of any elutable autoantibodies. Susceptible (A/J) and resistant (B10.A) mice were administered the virus or the control treatment and killed at various times after treatment. Acid eluates from pooled heart tissue from each treatment group and each time were tested for IgG reactivity with normal heart tissue by immunohistochemistry and with normal heart extracts by Western immunostaining. Eluates from infected A/J mice reacted strongly with syngeneic heart and modestly with syngeneic skeletal muscle tissue. Eluates from infected B10.A or control mice of either strain exhibited little reactivity with either tissue. Tissue reactivity was similar when allogeneic tissue was used as the substrate. Eluates from infected A/J mice recognized the heavy chain of cardiac myosin and several other cardiac antigens by Western immunostaining while eluates from the other treatment groups exhibited little or no reactivity with any normal heart constituents. These results indicate that in vivo IgG deposition occurs in the hearts of mice with post-infectious autoimmune myocarditis and that the specificity of these antibodies is similar to that reported for serum from animals with this disease. The mechanism(s) leading to myocardial IgG deposition and its possible role in pathogenesis remain to be elucidated.

Animals↗
PubMed1990

Combined chylothorax, chylopericardium, and cranial vena cava syndrome in a dog with thymoma.

A dog was examined because of anorexia and development of submandibular, sternal, and forelimb edema. Physical examination revealed engorged jugular veins and engorged blood vessels of the conjunctivae and nictitating membranes. Thoracic radiography revealed pleural and pericardial effusions, later identified as chyle. Contrast angiography revealed an intravascular mass, later identified as thymoma, in the cranial vena cava.

Animals↗
PubMed1990

Alterations in prealbumin concentration after adrenal autotransplantation for Parkinson's disease.

The cerebrospinal fluid of eight patients with Parkinson's disease who underwent adrenal medullary autotransplantation was analyzed using SDS-polyacrylamide gel electrophoresis. A protein, subsequently identified as prealbumin, was noted to change in concentration over the intraoperative to 18-month postoperative time course. The qualitative changes observed on visual inspection were confirmed and quantified using laser densitometry. The concentration of prealbumin increased by an average of 90% when the intraoperative and 12-month samples were compared. This increase persisted at 18 months. The ratio of prealbumin to albumin also increased from intraoperative to 12 months by an average of 56%. This suggests that the increases in PA are the result of choroid plexus activation rather than a nonspecific breakdown of the blood-brain barrier. Given the association of prealbumin with other nervous system diseases, as well as its known ability to bind multiple substances, these findings may have important implications. Alterations in prealbumin may be responsible for the improvement seen in some patients who receive adrenal medullary autotransplants. Alternatively, prealbumin may be implicated in the pathophysiology of Parkinson's disease.

Adrenal Medulla↗
PubMed1989

Alteration of kainic acid and quinolinic acid toxicity by neostriatal transplants in vitro.

Mature (greater than 21 days in vitro) organotypic corticostriatal cultures prepared from newborn rat brain were incubated in either kainic acid (KA) 10(-3) M or quinolinic acid (QUIN) 10(-3) M for up to 48 h. Other identical cultures were similarly incubated immediately after they had received one or two additional explants of neonatal striatal tissue placed beside each corticostriatal culture. The cultures incubated with either KA or QUIN in the presence of the neonatal striatal tissue showed better preservation than cultures incubated with KA or QUIN alone. Results suggest that the neonatal striatal explants or 'transplants' afford some protective effect against the toxicity or either KA or QUIN.

Animals↗
PubMed1989

Adrenal medullary transplantation to the caudate nucleus in Parkinson's disease. Initial clinical results in 18 patients.

Results from a pilot study of adrenal medullary autotransplantation for Parkinson's disease are presented. Eighteen patients were studied; 12 were followed up for 1 year, and 6 were followed up for 6 months. Four of 12 patients showed distinct improvement in the signs and symptoms of their disease, as assessed using the Columbia Rating Scale, at 1 year; none showed distinct deterioration. The 6 patients who were followed up for only 6 months were an average of 20 years older and generally more severely affected. None distinctly improved. Morbidity was considered to be minor and transient among the first 12 patients, while 4 of the last 6 patients experienced alteration in mental status lasting as long as several months. This problem has led us to conclude that older patients with preexisting cognitive impairment should not be included in future studies until the benefits are more clearly established. However, we believe that the distinct and persistent improvement seen in some of the younger patients warrants the initiation of a well-designed, randomized, and controlled trial of adrenal medullary autotransplantation for the purpose of confirming these results and assessing the effect of the procedure on the natural progression of Parkinson's disease.

Adrenal Medulla↗
PubMed1988

Striatal grafts provide sustained protection from kainic and quinolinic acid-induced damage.

Grafts of neonatal striatal tissue were placed into the striata of adult rats. When challenged immediately with intrastriatal injections of either kainic or quinolinic acid, excitotoxic damage was prevented. Thirty days later these same graft recipients received another injection of excitotoxin. The intrastriatal grafts continued to mitigate toxin-induced damage. It is hypothesized that the grafted cells not only survive, but that they may continue to elaborate some substance or substances that prevent excitotoxin-induced injury for at least 30 days. Previous investigations indicated that grafts of neonatal striatal tissue can protect the recipient striatum from kainic acid toxicity. In the following study it is demonstrated that such grafts also protect the striatum from quinolinic acid, an endogenous excitotoxin which induces kainate-like neuronal degeneration and has been implicated in the pathogenesis of Huntington's disease. It is postulated that the salutary effect of striatal grafting may be sufficiently long lasting to mitigate a chronic toxic insult. Such grafting may therefore represent a therapy for Huntington's disease and other neurodegenerative disorders in which an endogenous or exogenous toxin has been implicated as the pathogenetic agent.

Animals↗
PubMed1986

Neonatal striatal grafts prevent lethal syndrome produced by bilateral intrastriatal injection of kainic acid.

It is reported that unilateral grafts of neonatal striatal tissue protect the recipient from the lethal aphagia and adipsia produced by bilateral intrastriatal injection of 10 nmol of kainic acid in rats. It is shown that neither adult striatum nor neonatal tissue from other sites have the same lifesaving effect and that the salutary effect of the graft is dependent upon graft survival. Grafts from a histoincompatible donor are apparently rejected, leading to the death of the recipient. Cyclosporine inhibits rejection thereby enabling recipient survival. It is postulated that the graft exerts a neurohumoral influence that protects the striatum from the toxic effect of kainate.

Animals↗
PubMed1986

Pituitary transplantation: cyclosporine enables transplantation across a minor histocompatibility barrier.

Pituitary glands from neonatal donors were transplanted to the median eminence of hypophysectomized adult rats. Rats with transplants were then treated for 2 weeks with the immunosuppressive drug cyclosporine. For 5 weeks thereafter, blood was drawn at regular intervals for determination of serum thyroxine, prolactin, and luteinizing hormone. Cyclosporine-treated recipients of grafts with minor histocompatibility differences had normal levels of thyroxine and prolactin, whereas untreated animals did not. In addition, the treated animals responded to oophorectomy with a marked elevation in serum luteinizing hormone. This evidence indicates that cyclosporine enables successful transplantation across a minor histocompatibility barrier. It also suggests that these grafts interact with the hypothalamus. Transplantation across a major histocompatibility barrier was unsuccessful even in the presence of cyclosporine.

Animals↗
PubMed1986

Canine basilar artery contractions mediated by 5-hydroxytryptamine1A receptors.

A series of 11 agents was analyzed at both 5-hydroxytryptamine1A (5-HT1A) sites labeled by [3H]-8-hydroxy-2-(N,N-dipropylamino)tetralin and total 5-HT1 binding sites labeled by [3H]-5-HT in rat brain membranes. Three distinct patterns of relative inhibition were noted. First, drugs such as 8-hydroxy-2-(N,N-dipropylamino)tetralin n-(3-acetylaminophenyl)piperazine hydrochloride, 2-[4-[4-(2-pyrimidinyl)-1-piperazinyl]-1,2-benziso-thiazol-3 -(2H)one-1,1-dioxidehydrochloride] and buspirone display 1.0 to 15 nM potency for the 5-HT1A subpopulation of 5-HT1 binding sites but are more than two orders of magnitude less potent at total 5-HT1 sites. Secondly, 5-methoxy-N,N-dimethyltryptamine and methysergide are approximately one order of magnitude more potent at 5-HT1A than total 5-HT1 sites. In the third group, 5-HT, d-lysergic acid diethylamide, 1-(m-trifluoromethylphenyl)piperazine, 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyrimidinyl) 1H indole, quipazine and pirenperone are essentially equipotent at both 5-HT1A and 5-HT1 sites. Thus, the 5-HT1A binding site has a pharmacological profile which, depending on the agents studied, could be significantly different from the pharmacological profile derived from total 5-HT1 binding. Drug interactions were also analyzed with canine basilar artery segments using 5-HT, 10 putative serotonergic agonists and a selective 5-HT2 antagonist, pirenperone. The maximal contraction was obtained using 5-HT (Cmax = 6.6 +/- 0.6 g). However, each of the 10 other putative 5-HT agonists elicited a less forceful contraction of the canine basilar artery.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1985

Role of calcium antagonists in cerebral arterial spasm.

Spasm of the large cerebral arteries at the base of the brain causes delayed ischemic neurologic deficits in approximately 30% of patients after a subarachnoid hemorrhage from an intracranial aneurysm. In vitro chamber studies have shown that both dog and human large cerebral artery segments contract to a variety of vasoactive agents, and the dog and human segments are remarkedly similar in their responses. The source of calcium necessary to initiate contraction was found to be extracellular for large cerebral arteries. In contrast, systemic arteries such as the femoral artery use a bound intracellular pool of calcium for contraction. The calcium antagonists nifedipine and nimodipine were found to selectively inhibit the contractions of large cerebral arteries but not the femoral artery. In vivo experiments demonstrated that both nifedipine and nimodipine, given sublingually, would prevent and reverse cerebral arterial spasm in the dog after a subarachnoid hemorrhage. Nimodipine was found to be more potent, both in the chamber and in the live dog experiments. Nimodipine significantly decreased the occurrence of severe neurologic deficits from spasm alone in a multi-institutional, prospective, double-blind, randomized, placebo-controlled trial.

Animals↗
PubMed1985

Calcium channel antagonism by pizotifen.

Pizotifen is a clinically effective anti-migraine agent with potent anti-serotonin and anti-histamine properties. Pizotifen is equipotent in blocking contractions of the canine basilar artery induced by serotonin, norepinephrine or calcium chloride. As a result, the primary action of pizotifen in the canine basilar artery system appears to be calcium channel blockade and not selective antagonism of serotonin or norepinephrine. Calcium channel blocking ability may be related to the clinical efficacy of pizotifen in the treatment of migraine.

Animals↗
PubMed1985

Pituitary transplantation: Part 1. Successful reconstitution of pituitary-dependent hormone levels.

Neonatal or adult pituitary glands were transplanted to the median eminence of adult rats of the same or a histoincompatible inbred strain. The hormonal status of 39 transplanted rats and of control animals was evaluated by serial determination of serum prolactin and thyroxine. Grafts of neonatal tissue to adults of the same strain resulted in normal postoperative hormone levels. This indicates not only that pituitary grafts had survived, but also that the transplants were under hypothalamic control. Grafts of adult tissue were less successful. The prolactin value was lower, but still within the normal range, whereas the thyroxine value was lower than normal, suggesting that viable pituitary tissue had survived but was not under hypothalamic control. Transplantation across a histocompatibility barrier was uniformly unsuccessful. Postoperative prolactin levels were low and thyroxine levels were not significantly different from those in hypophysectomized controls.

Age Factors↗
PubMed1985

Visual function following optic canal decompression via craniotomy.

Visual function was assessed in 15 eyes of 11 patients who underwent unilateral (seven patients) or bilateral (four patients) optic canal decompression for presumed compressive optic neuropathies. Both immediate and long-term postoperative vision was evaluated in all eyes. Over 90% of the eyes that had undergone nerve decompression had either the same or improved visual acuity and visual field immediately following surgery. In this group of patients there were no deaths and there was only one postoperative complication, a transient dysphasia caused by an epidural hematoma that was evacuated. Long-term follow-up evaluations revealed that most of the eyes retained their immediate postoperative visual function or showed gradual visual improvement with time. The results of this series as well as a review of the available literature indicate that optic canal decompression via craniotomy can be a safe procedure and that it appears to have lasting visual benefit in many patients.

Adolescent↗