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Biomedical subjects

K O'Driscoll

Publications and source records attributed to K O'Driscoll.

At least 19 recordsLinked to original sources
PubMed2006

Effects of mixing on drinking and competitive behavior of dairy calves.

Group housing provides increased access to space and social interactions for calves while reducing labor costs for producers. However, group housing necessarily requires that calves be mixed and no research to date has addressed the effects of mixing on behavior of milk-fed dairy calves. The objective of this study was to monitor the feeding and competitive behavior of individual dairy calves (n = 8) after introduction into an established group of older calves fed ad libitum by a computer-controlled milk feeder. Milk feeding was monitored for 2 d before introduction into the new group and both milk feeding and competitive behaviors were monitored for 4 d after mixing. Mean (+/- SE) milk consumption before mixing was 9.7 +/- 0.7 kg/d, dropped slightly on the day of mixing to 8.6 +/- 0.6 kg/d, but increased on d 1 to 3 after mixing to 11.1 +/- 0.3 kg/d. Calves visited the feeder less frequently on the day of mixing (6.0 +/- 1.8 visits/d) than on either the days before mixing (20.3 +/- 2.5 visits/d) or the days after mixing (25.3 +/- 6.9 visits/ d). The mean duration of feeder visits and mean milk consumption per visit increased from 4 min 15 s +/- 21 s and 0.53 +/- 0.06 kg per visit before mixing to 8 min 17 s +/- 1 min 28 s and 1.87 +/- 0.51 kg per visit on the day of mixing. Competitive displacements from the milk-feeding stall were rare. In summary, feeding behavior of young calves is altered on the day of mixing, but calves are able to maintain milk intake when using a milk feeder fitted with a stall that prevents calves from displacing one another.

Aggression↗
PubMed2003

Spatial localization and properties of pacemaker potentials in the canine rectoanal region.

The present study investigated the spatial organization of electrical activity in the canine rectoanal region and its relationship to motility patterns. Contraction and resting membrane potential (E(m)) were measured from strips of circular muscle isolated 0.5-8 cm from the anal verge. Rapid frequency [25 cycles/min (cpm)] E(m) oscillations (MPOs, 12 mV amplitude) were present across the thickness of the internal anal sphincter (IAS; 0.5 cm) and E(m) was constant (-52 mV). Between the IAS and the proximal rectum an 18 mV gradient in E(m) developed across the muscle thickness with the submucosal edge at -70 mV and MPOs were replaced with slow waves (20 mV amplitude, 6 cpm). Slow waves were of greatest amplitude at the submucosal edge. Nifedipine (1 micro M) abolished MPOs but not slow waves. Contractile frequency changes were commensurate with the changes in pacemaker frequency. Our results suggest that changing motility patterns in the rectoanal region are associated with differences in the characteristics of pacemaker potentials as well as differences in the sites from which these potentials emanate.

Anal Canal↗
PubMed2003

Direct lung delivery of para-aminosalicylic acid by aerosol particles.

Para-aminosalicylic acid (PAS), a tuberculostatic agent, was formulated into large porous particles for direct delivery into the lungs via inhalation. These particles possess optimized physical properties for deposition throughout the respiratory tract, a drug loading of 95% by weight and physical stability over 4 weeks at elevated temperatures. Upon insufflation in rats, PAS concentrations were measured in plasma, lung lining fluid and homogenized whole lung tissue. Systemic drug concentrations peaked at 15 min, with a maximum plasma concentration of 11+/-1 microg/ml. The concentration in the lung lining fluid was 148+/-62 microg/ml at 15 min. Tissue concentrations were 65+/-20 microg/ml at 15 min and 3.2+/-0.2 microg/ml at 3h. PAS was cleared within 3 h from the lung lining fluid and plasma but was still present at therapeutic concentrations in the lung tissue. These results suggest that inhalation delivery of PAS can potentially allow for a reduction in total dose delivered while providing for higher local and similar peak systemic drug concentrations as compared to those obtained upon oral PAS dosing. Similar particles could potentially be used for the delivery of additional anti-tuberculosis agents such as rifampicin, aminoglucosides or fluoroquinolones.

Administration, Inhalation↗
PubMed2002

Electrical activity induced by nitric oxide in canine colonic circular muscle.

Nitric oxide generates slow electrical oscillations (SEOs) in cells near the myenteric edge of the circular muscle layer, which resemble slow waves generated by interstitial cells of Cajal (ICCs) at the submucosal edge of this muscle. The properties of SEOs were studied to determine whether these events are similar to slow waves. Rapid frequency membrane potential oscillations (MPOs; 16 +/- 1 cycles/min and 9.6 +/- 0.2 mV) were recorded from control muscles near the myenteric edge. Sodium nitroprusside (0.3 microM) reduced MPOs and initiated SEOs (1.3 +/- 0.3 cycles/min and 13.4 +/- 1.4 mV amplitude). SEOs were abolished by the guanylate cyclase inhibitor 1H-[1,2,4]-oxadiazolo-[4,3-a]-quinoxaline-1-one (10 microM). MPOs were abolished by nifedipine (1 microM), whereas SEO frequency increased and the amount of depolarization decreased. BAY K 8644 (1 microM) prolonged SEOs and reduced their frequency. SEOs were abolished by Ni(2+) (0.5 mM), low Ca(2+) solution (0.1 mM Ca(2+)), cyclopiazonic acid (10 microM), and the mitochondrial uncouplers antimycin (10 microM) and carbonyl cyanide p-trifluoromethoxyphenylhydrazone (1 microM). Oligomycin (10 microM) was without effect. These effects are similar to those described for colonic slow waves. Our results suggest that nitric oxide-induced SEOs are similar in mechanism to slow waves, an activity not previously thought to be generated by myenteric pacemakers.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2000

Significance of white matter abnormalities in patients with closed head injury.

Neuroimaging in patients with closed head injury (CHI) may frequently reveal abnormalities of white matter. Because white matter abnormalities may be seen in patients aged over 40 years even without CHI, the significance of these abnormalities in patients with CHI is questionable and needs to be assessed in the context of relevance to clinical outcome. The aims of this study were to determine the relative incidence of white matter abnormalities in a group of patients with CHI, and to assess the impact (if any) of these abnormalities on clinical outcome. Sixty-three patients with CHI underwent neuroimaging with magnetic resonance imaging (MRI) and regional cerebral blood flow (rCBF) single photon emission tomography (SPET) approximately 6 months after trauma. Seven patients had white matter abnormalities on MRI scanning. There are no rCBF SPET criteria for defining abnormal perfusion to the white matter. The SPET scans ranged from normal (one patient) and abnormal perfusion to frontal, temporal or parietal lobes in these patients (n = 6). Patients were assessed for outcome after undergoing appropriate rehabilitation programmes with indices of reintegration into the community, activities of daily living, disability, and their cognitive ability to perform tasks. This assessment was conducted 2 years after initial trauma. Of these seven patients with abnormal MRI of the white matter, one performed poorly and six had moderate to good clinical outcome. When individual lobar perfusion is considered, abnormal perfusion to the frontal or temporal lobes was significantly associated with poorer outcome (P < 0.005). In conclusion, white matter abnormalities detected by MRI are frequently associated with cortical perfusion defects identified by SPET (6/7 or 86%). However, when these white matter abnormalities were accompanied by perfusion defects in the frontal and temporal lobes, these were statistically significant in predicting poorer outcome.

Activities of Daily Living↗
PubMed1999

Acute inspiratory stridor: a presentation of myasthenia gravis.

We present a rare presentation of myasthenia gravis as acute inspiratory stridor in a 16-year-old girl. Prompt diagnosis and medical treatment avoided the need for tracheostomy. Although an uncommon cause, myasthenia gravis should be included in the differential diagnosis of stridor.

Acute Disease↗
PubMed1994

The utility of nasal bone radiographs in nasal trauma.

A prospective study was performed to assess the value of nasal bone radiographs taken in the accident and emergency department. The study population consisted of 100 consecutive patients who had nasal bone radiographs in our accident and emergency (A&E) department following trauma. We looked at the casualty officers', radiologists' and ENT surgeons' assessment of the cases. Thirty months later we reviewed the patients' notes to identify the number who sought medico-legal reports on their injury in that interval. We found sporting injuries to be the commonest mechanism of injury, followed closely by accidental falls. The remaining third was made up predominantly of cases of personal assault and road traffic accidents. Only two patients had a naso-pharyngeal history recorded on their visit to A&E. Thirty-five patients were referred to ENT out-patients, only 24 kept their appointment. Thirty-one of the 35 ENT referrals were felt to have a fracture demonstrated on their radiographs. However, 19 of those discharged were also thought to have an X-ray-proven fracture. Thirty months later only two patients had requested a medico-legal report. We demonstrate that the decisions regarding treatment of nasal trauma are based on clinical findings and that nasal bone radiography has no place in the decision making process and should therefore be abandoned.

Adolescent↗
PubMed1993

The regulatory domain of protein kinase C beta 1 contains phosphatidylserine- and phorbol ester-dependent calcium binding activity.

Certain isoforms of protein kinase C (PKC) require both Ca2+ and phospholipid for optimum activity. However, little is known about the nature of the interaction between PKC and Ca2+. The present study demonstrates that the isolated regulatory domain of PKC beta 1, when synthesized as a fusion protein in Escherichia coli, binds 45Ca2+ with high affinity, but only in the presence of phosphatidylserine or 12-O-tetradecanoyl-phorbol-13-acetate. This binding is highly selective for Ca2+ since it is preferentially inhibited by excess non-radioactive Ca2+ when compared with the cations Mg2+, Mn2+, Na+, or K+. It appears, therefore, that the binding of Ca2+ to PKC requires a complex tertiary structure in the regulatory domain.

Base Sequence↗
PubMed1993

Cloning genes from an inner ear cDNA library.

A rat inner ear complementary DNA (cDNA) library containing 1.9 x 10(6) recombinants was constructed and evaluated. Inserts averaged 2.0 (+/- 2.1) kilobases in length. A subset of inserts was screened for site of expression. Two cDNA transcripts were isolated based on cochlear expression restricted to the spiral ganglion. One transcript showed a high degree of homology to several long interspersed DNA elements, neuron-specific nuclear transcripts thought to be involved in gene regulation. The second transcript showed no homology to known sequences and appears to encode a neuron-specific protein of about 248 amino acids. The library can be used to identify proteins important for inner ear function and disease.

Animals↗
PubMed1993

An audit of the E.N.T. casualty service at the Royal Victoria Eye and Ear Hospital.

The only specialised Accident and Emergency unit for ENT in Ireland is at The Royal Victoria Eye and Ear Hospital, Dublin. This provides a service for the entire Republic, operating on a 9 am to 5 pm, Monday to Friday, basis. The aim of the present study was to define the role of this specialised unit. A prospective study of the service over a one month period was conducted. During this time 779 patients were seen of which 350 (45%) were new patients and 429 (55%) were return patients. Fifty two per cent were self referred, 35% were referred by their General Practitioners, 8% by other hospitals and 5% from other sources. The most common diagnosis was otitis externa (21% of new patients and 63% of returns), followed by ear wax (15% of new patients), and epistaxis (9% of new patients). Five per cent of patients required removal of foreign bodies from their ear, nose or oesophagus, and 3% received treatment for trauma to these regions. Of note during this period six new cases of head and neck cancer were detected. From these figures it is the authors' opinion that many of the problems seen could have been dealt with by General Practitioners or as non-emergency referrals to the out-patient department. This indicates the need for further training for primary care physicians and expansion of the present outpatients services. The specialised casualty service should continue to exist to provide a genuine emergency service and valuable training in the speciality.

Accidents↗
PubMed1993

Depression following laryngectomy. A pilot study.

When a group of 10 patients who had received surgery for carcinoma of the larynx were compared with 10 control patients who had received radiotherapy for carcinoma of the larynx, four of the former but none of the latter were found to be suffering from depression, a statistically significant difference. Depression was associated with poor communication skills and geographical isolation. Psychiatric intervention is recommended for patients undergoing mutilating forms of surgery.

Aged↗
PubMed1992

Protein kinase C isozymes epsilon and alpha in murine erythroleukemia cells.

Protein kinase C (PKC) has a role in signal transduction during hexamethylene bisacetamide (HMBA)-induced differentiation of murine erythroleukemia cells (MELC). Separation of MELC PKC isozymes by hydroxylapatite chromatography yields a major peak (III) and a minor peak (II) of PKC activity, previously reported to contain the PKC alpha and beta isozymes, respectively. In the present study, we confirm that peak III activity is PKC alpha but show that peak II contains PKC epsilon and little or no PKC beta. Immunoblot analysis with isozyme-specific anti-alpha and anti-epsilon PKC antibodies detected PKC alpha in peak III and PKC epsilon in peak II. Peak III activity was markedly enhanced (up to 20-fold) by phosphatidylserine, diolein, and Ca2+, whereas addition of these cofactors to the reaction mixture stimulated peak II activity only 2- to 4-fold. RNase protection analysis of MELC RNA showed that PKC alpha and PKC epsilon RNAs were in a ratio of approximately 2:1, but PKC beta RNA was barely detectable. Taken together, these data indicate that MELC contain PKC alpha and PKC epsilon but little or no PKC beta.

Animals↗