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Biomedical subjects

R Ryan

Publications and source records attributed to R Ryan.

At least 19 recordsLinked to original sources
PubMed1995

Stabilization of ribonuclease B activity by concentrated xylose solutions.

Ribonuclease B has become a paradigm as a simple example of an N-linked glycoprotein. We have found that certain affinity-purified preparations of this enzyme demonstrated a pronounced tendency to lose activity if stored as dilute aqueous solutions. Such inactivation is accelerated by the presence of NaCl, but can be counteracted by inclusion of high (1 mol/l) concentrations of xylose. Enzyme activity cannot be restored by addition of xylose after storage of the enzyme. In marked contrast to alpha-methyl-mannoside, xylose does not prevent ribonuclease B from binding to concanavalin A and so may be used to stabilize the enzyme during purification by lectin affinity chromatography.

Chromatography, Affinity↗
PubMed1995

A prospective randomised trial of the use of sodium bicarbonate and hydrogen peroxide ear drops to clear a blocked tympanostomy tube.

This randomised prospective trial compared the efficacy of sodium bicarbonate and hydrogen peroxide ear drops in clearing a blocked tympanostomy tube. Tympanostomy tubes, 110 in number, obstructed with blood or inspissated secretions were randomised into treatment and control groups. Details of the operative procedure were retrospectively collected from the patients notes. The patients were reviewed after 2 weeks for both clinical and tympanometric evidence of clearance of the tube and evidence of complications of the drops. There was no significant therapeutic advantage between the two drops (P > 0.9), but in both treatment arms there was a significant therapeutic advantage over a period of observation (P < 0.05 in both groups). Otorrhoea and pain on instilling the drops occurred with equal incidence in both treatment groups. As obstruction of tympanostomy tubes is a common occurrence which often prompts surgical reventilation, there is great potential for cost savings if conservative treatment can be used effectively. The treatments for obstructed tympanostomy tubes are reviewed and methods of prevention of this common occurrence are discussed.

Acoustic Impedance Tests↗
PubMed1995

Mastoidectomy audit: results of the Royal College of surgeons of England comparative audit of ENT surgery.

This paper presents the results of a national comparative audit of mastoid surgery, retrospectively analysing 611 operations by 55 consultants. Confidentiality for both patient and surgeon was assured. For cholesteatoma 80% of mastoidectomies performed were open cavity procedures and for other middle ear disease 58% used an intact canal wall technique. Thirty-two surgeons used only an open cavity mastoidectomy for cholesteatoma during the period of the audit. There was a statistically significantly greater number of wet ears with open cavities than with closed cavities, but the frequency of the operator did not correlate with the dry ear rate. Ten serious complications (facial palsy and dead ear) were recorded. All occurred in open cavity mastoidectomies. The post-operative hearing status was unknown in 40% of patients.

Cholesteatoma↗
PubMed1993

Cytokine indices in Alzheimer's temporal cortex: no changes in mature IL-1 beta or IL-1RA but increases in the associated acute phase proteins IL-6, alpha 2-macroglobulin and C-reactive protein.

Recent immunocytochemical data have demonstrated increases in interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6) and the IL-6-inducible acute phase protein, alpha 2-macroglobulin (alpha 2-M), in Alzheimer's disease (AD) brains. We investigated the levels of these proteins quantitatively using ELISA procedures and determined if increases in IL-1 beta were compensated for by a parallel increase in the endogenous interleukin-1 receptor antagonist (IL-1RA). Comparing control vs. Alzheimer's temporal cortex, we examined mature IL-1 beta, IL-1RA, IL-6, alpha 2-M and C-reactive protein (CRP). The specificities of the ELISA procedures were verified by serial dilutions of the samples; by chromatofocusing, and by Sephadex G-150 gel filtration. There were no differences in the levels of mature IL-1 beta or IL-1RA in AD and control brains. However, IL-6 levels were detectable in 14 of the 16 Alzheimer samples but only 2 of the 14 control samples. There were also significant increases seen in alpha 2-M and CRP levels in the Alzheimer's group compared to controls. These data support previous studies demonstrating a possible up-regulation of neuroimmune function in Alzheimer's cortex; however, we cannot determine, at this time, if this immune reaction is initiated by IL-1 beta.

Acute-Phase Proteins↗
PubMed1992

NMDA-, but not kainate- or quisqualate-dependent increases in cerebellar cGMP are dependent upon monoaminergic innervation.

As previously reported, intracerebellar injections of D-serine, quisqualate and kainate elevated mouse cerebellar cGMP levels. Similarly, activation of endogenous excitatory amino acid utilizing neurons with harmaline or pentylenetetrazole also increased cerebellar cGMP. We previously have demonstrated that the harmaline- and pentylenetetrazol-dependent cGMP increases are NMDA receptor mediated. In this report we further demonstrate that NMDA-dependent increases in cGMP are dependent upon monoaminergic innervation of the cerebellum, while kainate- and quisqualate-dependent cGMP increases are independent of such innervation.

Animals↗
PubMed1992

Excitatory amino acid signal transduction in the hippocampus: role of noradrenergic afferents and nitric oxide in cGMP increases in vivo.

Previous studies have demonstrated that excitatory amino acid (EAA)-dependent increases in cerebellar cGMP are dependent upon the prior activation of nitric oxide (NO) synthase. Additionally, the actions of NMDA, but not kainate or quisqualate, in elevating cerebellar cGMP have been shown to be dependent upon intact noradrenergic innervation of the cerebellum. In the current study we extended these observations to the hippocampus and again found that EAA-dependent increases in hippocampal cGMP also involve prior formation of NO. And as in the case of the cerebellum, NMDA-dependent increases in hippocampal cGMP involve prior release of norepinephrine which in turn apparently activates an alpha 1-adrenergic receptor to elicit cGMP increases. In toto, these data suggest that a key role of NMDA receptors in these brain regions is to presynaptically regulate the release of norepinephrine, thereby modulating the tone of this monoaminergic system. This may be a general principle which needs experimentation in other terminal fields of noradrenergic pathways.

Analysis of Variance↗
PubMed1992

The morbidity from nasal splints in 105 patients.

The results of a randomized prospective trial investigating the morbidity from intranasal splints in 105 patients, were analysed. Intranasal splints are associated with considerable morbidity (significantly greater post-operative pain and a higher incidence of septal perforation and vestibulitis) and although they significantly reduce the likelihood of developing intranasal adhesions, a similar benefit can be obtained by careful nasal toilet at one week.

Adult↗
PubMed1992

Babesiosis: an underdiagnosed disease of children.

Babesiosis is a malaria-like illness caused by the intraerythrocytic parasite Babesia microti and is transmitted by the same tick that transmits Borrelia burgdorferi, the causative agent of Lyme disease. Babesiosis is well recognized in adult residents of southern New England and New York but has been described in only five children. To determine whether children are infected with B microti less often than are adults, a prospective serosurvey was carried out on Block Island, RI, where babesiosis is endemic. Randomly recruited subjects completed a questionnaire and provided a blood sample. Antibodies against B microti and B burgdorferi were measured using a standard indirect immunofluorescence assay and enzyme-linked immunosorbent assay, respectively. Of 574 subjects, 9% tested positive for B microti, including 12% of the 52 children (7 months through 16 years) and 8% of the 522 adults (not significant, P less than .6). Although babesiosis had not been diagnosed in any of the Babesia-seropositive subjects, 25% of the children and 20% of the adults reported symptoms compatible with this infection during the previous year. Of the 6 children and 45 adults seropositive for B burgdorferi, 17% and 14%, respectively, were also seropositive for B microti. It is concluded that children are infected with B microti no less frequently than are adults and that this infection is underdiagnosed in all age groups. Physicians who practice where Lyme disease is endemic should become familiar with the clinical presentation and diagnosis of babesiosis, both in adults and children.

Adolescent↗
PubMed1991

The miscarriage clinic: an audit of the first year.

We preview the results of the first year in a Miscarriage Clinic set up in 1989 in an effort to improve the support and counselling of women who have a miscarriage. Of 381 patients referred, 79% attended. The only statistically significant difference between the women who attended and those who did not attend was in the proportion of women who had planned their pregnancies (65% versus 33%, P less than 0.01). Of the 300 patients who attended, 4% reported no grief reaction; 75% experienced a reaction which had resolved within one month and 21% experienced a reaction which had not resolved. No factor was identified which could predict the duration of the grief reaction. This audit demonstrates that there is a strong demand and need for this service for couples who experience a miscarriage.

Abortion, Spontaneous↗
PubMed1991

Geographical and temporal distribution of babesial infection in Connecticut.

Human babesiosis was first recognized in Connecticut in 1989, nearly 15 years after Lyme disease, a similarly transmitted spirochetosis, was detected in the state. To determine the seroprevalence for the babesial pathogen and whether it was recently introduced, we used an indirect immunofluorescence assay to test for Babesia microti antibody in 1,285 Connecticut residents. Four groups were studied: I, people seropositive for Lyme disease, tested from 1986 to 1989; II, randomly selected outpatients tested in 1989; III, college students residing in Connecticut, tested from 1959 to 1989; and IV, healthy people without tick exposure or Lyme disease, tested in 1989. Babesia seropositivity was significantly higher in group I (9.5%; n = 735) than in groups II (2.6%; n = 304, P less than 0.0001) and III (1.0%; n = 206, P less than 0.0001) but not group IV (2.5%, n = 40). Babesia seropositivity for group I ranged from 9.2 to 10.2% between 1986 and 1989, and Babesia seropositivity for group III ranged from 0% between 1959 and 1985 to 2.9% between 1986 and 1989. There is a considerable risk of babesial infection among residents of the Connecticut mainland who are seropositive for Lyme disease, a risk that appears to have remained constant over the past 5 years.

Animals↗
PubMed1989

Spinal epidural abscess. An infectious emergency. Case report and review.

Spinal epidural abscess is an unusual disease in the pediatric age group, requires early diagnosis and prompt surgical drainage to insure a good clinical outcome. Back pain and fever are usually the only presenting symptoms occurring before precipitous neurologic deterioration. The causative organism is most often Staphylococcus aureus, which presumably is spread to the epidural space hematogenously. Diagnosis is facilitated by computed tomography (CT) scan, but the entire spine must be imaged by either myelography or magnetic resonance imaging (MRI) to assess for skip lesions.

Abscess↗
PubMed1988

Recurrent tonsillitis and growth in children.

Anecdotal observations suggest an association between tonsil disease and growth retardation. This study compared height, weight and skinfold thickness measurements between a group of children (44) suffering from recurrent tonsillitis for a mean duration of 4 years, and a control group (34). No important differences were observed between the groups. Recurrent tonsil infection does not appear to retard the growth of children.

Body Height↗
PubMed1987

The effect of swimming in chlorinated water on middle ear pressure.

This study evaluated whether an important fall in middle ear pressure (MEP) was recordable several hours after swimming. MEPs were measured in 52 normal school children on an average of four occasions immediately before swimming and "control" exercise sessions, and were repeated four hours after the activity. Twenty-nine children swam in a high chlorine concentration, with a mean free chlorine level of 2.3 parts per million, and 23 children swam in a low chlorine environment, with a mean concentration of 0.4 parts per million. For the former there was an average decrease of 0.5 daPa after swimming and an increase of 34.7 daPa after exercise; for the latter there were increases of 13.3 and 15.6 daPa after swimming and exercise respectively. It is concluded that swimming does not adversely affect middle ear function. Exercise induces an increase in MEP, and exposure to high chlorine levels appears to cause a small reduction in middle ear pressure.

Child↗