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Biomedical subjects

P McKenna

Publications and source records attributed to P McKenna.

At least 19 recordsLinked to original sources
PubMed1995

A functional neuroanatomy of hallucinations in schizophrenia.

Hallucinations, perceptions in the absence of external stimuli, are prominent among the core symptoms of schizophrenia. The neural correlates of these brief, involuntary experiences are not well understood, and have not been imaged selectively. We have used new positron emission tomography (PET) methods to study the brain state associated with the occurrence of hallucinations in six schizophrenic patients. Here we present a group study of five patients with classic auditory verbal hallucinations despite medication, demonstrating activations in subcortical nuclei (thalamic, striatal), limbic structures (especially hippocampus), and paralimbic regions (parahippocampal and cingulate gyri, as well as orbitofrontal cortex). We also present a case study of a unique, drug-naive patient with visual as well as auditory verbal hallucinations, demonstrating activations in visual and auditory/linguistic association cortices as part of a distributed cortical-subcortical network. Activity in deep brain structures, identified with group analysis, may generate or modulate hallucinations, and the particular neocortical regions entrained in individual patients may affect their specific perceptual content. The interaction of these distributed neural systems provides a biological basis for the bizarre reports of schizophrenic patients.

Adult↗
PubMed1995

Differential antiviral activity of derivatized dextrans.

The antiviral activity of water-soluble dextrans derivatized with varying percentages of carboxymethyl, benzylamide, and sulfonate groups was evaluated. Several of the polymers exhibited potent antiviral activity against a variety of enveloped viruses, but not against non-enveloped viruses, and only when present during virus adsorption. The mechanism of activity against retroviruses [i.e. human immunodeficiency virus (HIV)] and herpes viruses (i.e. human cytomegalovirus) could be ascribed to inhibition of virus binding to the cells. An absolute requirement for anti-HSV activity appeared to be a sufficiently high percentage of benzylamide and benzylamide sulfonate groups. This did not, however, apply for human cytomegalovirus, respiratory syncytial virus, and HIV. The sensitivity of the latter viruses appeared to be influenced by factors other than the global chemical composition, which leads us to assume that physical factors such as the distribution and sequence of the substituents on the sugar backbone play an important role in the antiviral activity of the derivatized dextrans.

Antiviral Agents↗
PubMed1995

Canine Lyme disease in Belgium.

Lyme borreliosis is a multisystem disease caused by the tick-borne spirochaete Borrelia burgdorferi. In addition to causing human illness, borreliosis has been recorded in many species of mammals, including domestic animals which come into contact with the infected tick vector. This paper describes the first two cases to the authors' knowledge of Lyme borreliosis in dogs in Belgium. Both animals suffered recurrent lameness and general prostration. In addition, one of the dogs had recurrent paralysis of nerves V, VII, IX and X, leading to dysphagia and total bilateral paralysis of the mandibular muscles. This complication of Lyme borreliosis has been well documented in human pathology, but has not previously been recorded in the veterinary literature.

Animals↗
PubMed1995

Epidemiology and laboratory diagnosis of hantavirus (HTV) infections.

Hantavirus (HTV) is recently discovered "hemorrhagic fever virus" belonging to the Bunyaviridae family, which is spread throughout the world by wild rodents and/or laboratory rats. During an epidemic in the Belgian-French Ardennes in 1993, more than 200 acute cases were recorded of the milder European form of HTV-illness, otherwise known as Nephropathia epidemica (NE). This variant may be recognized by the sudden onset of fever, acute renal failure, thrombocytopenia and sometimes by ophthalmologic complications. The symptomatology is rather aspecific and diagnosis can only be confirmed by serologic tests, of which the best option nowadays seems to be: screening by IgG EIA, followed by IgM confirmation with a mu-capture EIA test. Some of the tests described allow an evaluation of the causative serotype or even the moment of infection. Next to the "classic" serologic assays for detection of specific viral antibodies, we describe briefly our own experience with newer tests such as "high density particle agglutination" and "line immuno assay". Polymerase chain reaction for viral RNA genome typing and immunohistochemical colouring of the viral antigen in tissues seem to offer promising alternatives for the immediate future.

Belgium↗
PubMed1995

[Epidemic of hantavirus disease in Entre-Sambre-et-Meuse: year 1992-1993. Clinical and biological aspects].

A multihospital study allowed us to follow a total of 62 serologically proven cases of Nephropathia epidemica (NE) in the Belgian region between Sambre and Meuse during the 1992-1993 period. The clinical picture consisted of sudden high fever (100% of the cases), headache (71%), abdominal or lumbar pains (80%) and, as a less frequent but very specific sign, acute myopia (24%). Non-specific respiratory symptoms such as a non-productive cough and an abnormal lung auscultation were found in 1 case out of 4. Frequent laboratory anomalies were thrombocytopenia (69%), left-shift leucocytosis (77%), abnormal LDH (69%) and an inflammatory syndrome (86%) with levels of C-reactive protein (CRP) elevated up to a mean of 102 mg/L, often accompanied by a marked fall of total serum cholesterol and a rise of triglycerides. Impaired kidney function is the rule (84%), nevertheless serum creatinine levels remain inferior to 150 mumol/L (1.7 mg%) in 25% of the patients. As for neurological signs, 1 case of encephalitis and 1 syndrome of Guillain-Barré were observed. Relative bradycardia (< 90 bpm) was noted in 50% of the cases with fever, whereas Doppler-echocardiography detected pericarditis in 1 case, and transient impairment of the left ventricle function in 3 cases. Frequent elevation of liver enzymes (46%) confirms the observation that from now on, Hantavirus infections should be considered in the differential diagnosis of viral hepatitis. One severe case was observed with shock, diffuse intravascular coagulation and adult respiratory distress syndrome (ARDS), followed by 5 other patients presenting with marked degrees of hypoxemia and hypocapnia. We conclude that not only the causative Hantaviral serotype, but also the degree of "systemic inflammatory response syndrome" (SIRS) seems to determine the clinical picture in Hantavirus infections.

Adolescent↗
PubMed1994

Serological evidence of Hantavirus disease in Northern Ireland.

Since, to our knowledge, no clinically documented cases of haemorrhagic fever with renal syndrome (HFRS) have been reported in Northern Ireland, a sero-epidemiological study was carried out to assess the degree of Hantavirus immunity in a group of 627 Northern Irish patients presenting with symptoms suggestive of HFRS and 100 healthy controls. IFA screening for IgG Hantavirus specific antibodies was carried out with a panel of up to 9 different Hantaviral antigens. IgM screening was performed using a commercially available mu-capture ELISA based upon two recombinant Hantaviral nucleocapsid antigens. A seropositivity of 2.1% (15/727) was recorded, with an almost exclusive reaction against a rat-derived R22VP30 strain of the Seoul serotype. Sole reliance upon non-rat-derived classic screening antigens Hantaan (HTN 76-118) and Puumala (CG 18-20) would have resulted in the detection of only 2/15 (13.3%) of cases in IgG IFA, and 8/14 (57.1%) of the cases in IgG ELISA. The findings indicate that for the first time in Europe, and more specifically in N. Ireland, non-laboratory outbreaks of HFRS may be caused by wild rats acting as a reservoir for a Seoul-like Hantavirus. Conventional Hantavirus serology using Hantaan and Puumala as screening antigens does not appear sufficient for the detection of such cases of HFRS. Hence, we propose the addition of a rat derived Hantaviral antigen to the antigen screening panel as a means of improving the specificity of the detection methods.

Animals↗
PubMed1994

Pharmacological management of schizophrenia in older patients.

Although antipsychotic drugs are the mainstay of treatment in older patients with schizophrenia, much of the theoretical work underpinning their use is based on evidence gained from younger patients. With respect to dosages, there has been little work comparing plasma concentrations of antipsychotics in older patients with those of younger patients. However, there are well documented changes in the pharmacokinetics of these drugs in the elderly, particularly in their hepatic metabolism and renal excretion. There is also evidence that older patients experience more adverse effects from antipsychotics than younger patients. Such effects include extrapyramidal symptoms, postural hypotension and falls. For these reasons it is recommended that starting doses of antipsychotic drugs in older patients should be in the region of 25 to 50% of that recommended for younger patients, and should be slowly increased. Selection of a particular antipsychotic agent is best made on the basis of individual patient characteristics and the adverse effect profiles of particular drugs.

Aged↗
PubMed1992

Teenage girls attending a Dublin sexually transmitted disease clinic: a socio-sexual and diagnostic profile.

Over a 12 month period, 32 teenage girls attended the sexually transmitted disease clinic in the Mater Misericordiae Hospital, Dublin for the first time, accounting for 17.8% of all first visits. Their mean age was 18.2 years (range 15-19 years). Twenty-four (75%) were from social class V. Five (15.6%) were abusing drugs. The mean age of first coitus was 16.1 years (range 13-19 years). The mean number of sexual partners was 1.8 (range 1-5). Four (12.5%) had been sexually abused in the past. Fourteen (43.8%) had never used contraception. Twenty-three (71.9%) were nulligravidae: 2 were diagnosed as being pregnant in the clinic. Twelve (37.5%) were unaware of cervical cytology screening. Of 29 having intercourse without condoms, none considered themselves to be at risk of contracting HIV from their present partner. A total of 26 diagnoses were made in 23 patients (71.9%). The most common diagnosis was ano-genital condylomata acuminata (6, 18.8%); Chlamydia trachomatis was located in 2 patients and Neisseria gonorrhoea in one. Mild to moderate dyskaryosis was reported in 4 cervical smears (12.5%). This data highlights the need for priority targeting of this high risk group.

Adolescent↗
PubMed1992

Eradication of hantavirus infection among laboratory rats by application of caesarian section and a foster mother technique.

Hantavirus antibodies were demonstrated by the indirect immunofluorescent antibody assay, in the serum of inbred strains of laboratory rats, during the period 1973-1982, at the Unit of Experimental Immunology in the Catholic University of Louvain, Brussels, Belgium. LOU rats, as well as immunocytomas, which were requested by laboratories in the U.K. and The Netherlands, were supplied at a time when the infection was unknown and unsuspected in Europe. Hantavirus-infected laboratory rats were rendered free of virus through re-derivation by caesarian section and suckling by virus-free foster mothers. Immunocytomas were tested for the presence of hantaviruses by implantation into seronegative laboratory rats. The strain of hantavirus causing the laboratory infection was clearly different from the one circulating in free-living bankvoles in Belgium. The exchange of laboratory rats and rat tumours in relation to the potential risk of laboratory-acquired hantavirus infection, is discussed.

Animals↗