Search PubMed⌕ Search

Biomedical subjects

N A Harrison

Publications and source records attributed to N A Harrison.

At least 19 recordsLinked to original sources
PubMed2004

Late recurrences of Sydenham's chorea are not associated with anti-basal ganglia antibodies.

Anti-basal ganglia antibodies (ABGA) have been associated with 100% of acute cases and 69% of persistent cases of Sydenham's chorea. We describe two cases of late recurrences of Sydenham's chorea with absence of ABGA. Both patients had several childhood episodes of Sydenham's chorea. MRI imaging of the basal ganglia and exhaustive investigations for other causes of chorea were normal or negative. The absence of ABGA may be evidence against an autoimmune pathology in late and some persistent recurrences. We suggest the likely pathophysiology to be dopamine hypersensitivity of chronically damaged basal ganglia neurones possibly following induction of an autoimmune antibody response in childhood.

Aged↗
PubMed2003

Atypical herpes type 2 encephalitis associated with normal MRI imaging.

We describe a case of chronic atypical herpes simplex type 2 encephalitis in an immunocompromised 68 year old man presenting with headache and cognitive changes without focal neurological or MRI findings. To our knowledge this is the first described case of herpes simplex encephalitis associated with normal MRI brain imaging and non-focal neurological examination. This further expands the range of clinical presentations that may be associated with herpes simplex encephalitis and emphasises the value of PCR for herpes simplex virus in the investigation of encephalitis regardless of imaging findings.

Aged↗
PubMed2001

Evaluation of the accuracy of seizure descriptions by the relatives of patients with epilepsy.

The descriptions of seizures by witnesses are important in the diagnosis and classification of epileptic seizures. The aim of the study was to evaluate the accuracy of this information obtained from relatives of patients with epileptic and non-epileptic attacks. Thirty patients with epileptic or non-epileptic attacks had seizures videorecorded whilst inpatients at the Assessment and Treatment Centre of the National Society for Epilepsy and the National Hospital for Neurology and Neurosurgery, Chalfont, Buckinghamshire, UK. A relative or close friend of each patient viewed the recording and subsequently completed a structured questionnaire, testing recall of 15 separate elements of the episode. This account was compared to a definitive evaluation completed by medical staff. An accuracy of describing seizures was therefore obtained. Our results showed that there was a wide variation in the accuracy of recall with convulsive episodes described less well than non-convulsive (median accuracies 44.5 and 70%, respectively, P<0.05). Attacks in which the diagnosis had been changed, following admission, from the one obtained on history alone were particularly inaccurately described (median accuracy 26%). Elements of the questionnaire that were most inaccurately recalled were description of limb movement and post-ictal behaviour. Those most accurately described were facial appearance and vocalization. Features only present in non-epileptic attacks included reactivity to eyelash stimulation, opisthotonic posturing, flailing or protective limb movements. In conclusion, our results confirm that inaccuracy exists when witnesses describe attacks and that this may lead to errors in diagnosis and subsequent treatment.

Adolescent↗
PubMed1996

Genomic diversity and differentiation among phytoplasma strains in 16S rRNA groups I (aster yellows and related phytoplasmas) and III (X-disease and related phytoplasmas).

Conserved gene sequences, including 16S rRNA and ribosomal protein gene sequences, were used to evaluate genetic variations in phytoplasma strains belonging to 16S rRNA groups I (aster yellows and related phytoplasmas) and III (X-disease and related phytoplasmas). We used PCR to amplify the sequences of the 16S ribosomal DNA and a segment of the ribosomal protein gene operon (encoding the 3' region of rps19, all of rp122, and rps3) from diverse phytoplasma group I and III strains. Additional chromosomal gene sequences of group I strains were also amplified. The PCR products amplified from members of each group of phytoplasmas were compared by performing restriction fragment length polymorphism (RFLP) analyses. On the basis of the RFLP patterns observed and similarity coefficients derived from combined RFLP analyses, the phytoplasma strains belonging to groups I and III were placed in distinct 16S rRNA, ribosomal protein, and 16S rRNA-ribosomal protein subgroups. Analyses of two or more conserved gene sequences revealed that members of the two groups were more diverse than previously thought. Subgroup differentiation on the basis of our combined analyses of 16S rRNA and ribosomal protein gene sequences seemed to adequately reflect the levels of chromosomal homology determined by DNA-DNA hybridization assays. On the basis of unique RFLP profiles, we identified new, previously unclassified group I phytoplasma strains, including the organisms that are associated with Ipomoea obscura witches'-broom [subgroup 16SrI-F(rr-rp)], maize bushy stunt [subgroup 16SrI-I(rr-rp)], and Mexican periwinkle virescence [subgroup 16SrI-J(rr-rp)], and new, previously unclassified group III phytoplasma strains, including the organism that is associated with pecan bunch [subgroup 16SrIII-H(rr-rp)]. On the basis of the results of our analyses of 16S rRNA and ribosomal protein conserved gene sequences, we recognized 9 group I subgroups and eight group III subgroups. We propose that phytoplasma strains belonging to each group I and III subgroup should be distinguished taxonomically at a level equivalent to the subspecies level.

Base Sequence↗
PubMed1996

Phytoplasma-specific PCR primers based on sequences of the 16S-23S rRNA spacer region.

In order to develop a diagnostic tool to identify phytoplasmas and classify them according to their phylogenetic group, we took advantage of the sequence diversity of the 16S-23S intergenic spacer regions (SRs) of phytoplasmas. Ten PCR primers were developed from the SR sequences and were shown to amplify in a group-specific fashion. For some groups of phytoplasmas, such as elm yellows, ash yellows, and pear decline, the SR primer was paired with a specific primer from within the 16S rRNA gene. Each of these primer pairs was specific for a specific phytoplasma group, and they did not produce PCR products of the correct size from any other phytoplasma group. One primer was designed to anneal within the conserved tRNA(Ile) and, when paired with a universal primer, amplified all phytoplasmas tested. None of the primers produced PCR amplification products of the correct size from healthy plant DNA. These primers can serve as effective tools for identifying particular phytoplasmas in field samples.

Base Sequence↗
PubMed1991

Renal failure in adult onset hypophosphatemic osteomalacia with Fanconi syndrome: a family study and review of the literature.

Follow-up of a previously reported family with dominantly inherited adult onset hypophosphatemic osteomalacia with Fanconi syndrome and diabetes mellitus has shown that both the proposita and her affected sister have developed renal glomerular failure. We describe the evolution of renal failure in this family and discuss the possible mechanisms involved. The development of renal tubular acidosis in this condition further impairs renal function and we suggest that correction of systemic acidosis might improve renal function and prevent further decline in these patients.

Acidosis, Renal Tubular↗
PubMed1990

Neopterin and beta-2 microglobulin levels in asymptomatic HIV infection: the predictive value of combining markers.

The concentrations of neopterin, beta-2 microglobulin, p24 antigen, anti-p24 antibody, and alpha-interferon were determined in the sera of 25 asymptomatic anti-HIV positive patients (CDC stages II and III) over a 50 month period (38 months retrospectively and 12 months prospectively). Evaluation of the data allowed the derivation of a threshold of abnormality for both neopterin and beta-2 microglobulin. Pre-AIDS (CDC groups IVa, IVc2, IVe) developed in 6 of the 26 patients within 18 months of the first abnormal value of beta-2 microglobulin, and within 12 months of the first abnormal value of neopterin. Combining the abnormal results of neopterin, beta-2 microglobulin, p24 antigen, and alpha-interferon allows prediction of progression to pre-AIDS within 18 months for most asymptomatic patients.

Acquired Immunodeficiency Syndrome↗
PubMed1989

C-reactive protein in acute renal failure.

This paper demonstrates the utility of C-reactive protein (CRP) in the diagnosis of infection in patients with acute renal failure. C-reactive protein can be assayed using plasma as effectively as using serum, thus avoiding the problems of microclots in serum, which can occur in samples from a heparinised patient. Plasma concentrations of C-reactive protein are unaffected by the process of haemodialysis. In the complicated setting of the severely ill patient with acute renal failure, infection remains the most common cause of death and its detection is often difficult. The use of C-reactive protein assay in this setting is illustrated by data from 20 patients, and two representative cases are described in detail. It is recommended that C-reactive protein be assayed daily to aid in the detection of infection in patients with acute renal failure.

Acute Kidney Injury↗
PubMed1989

Proteinuria--what value is the dipstick?

The value of the urinary dipstick in the assessment of proteinuria was investigated in a study correlating laboratory measurements of protein and albumin against the dipstick protein in the same samples of urine; 94 patients (100 admissions) were studied at the Royal Air Force Renal Unit, each patient collecting two 24-h urine samples. Along with each 24-h sample, 10-ml aliquots of urine were obtained at 3 designated times during the day for both ward dipstick testing and laboratory assay; + or more on the dipstick correlated with abnormal proteinuria (greater than or equal to 150 mg/24 h) in 88% of cases, whilst trace values straddled the level of significant proteinuria. Further differentiation of trace was possible by repeat testing during the day. The subsequent presence of a dipstick negative during that day correlated with normality in all but 5% of cases. In order to ensure detection of renal disease presenting as isolated orthostatic proteinuria, assay of the mid-morning sample is recommended.

Adolescent↗
PubMed1988

Acute acalculous cholecystitis in acute renal failure.

Acute acalculous cholecystitis developed in 16 of 92 patients with acute renal failure who had no prior or coincidental biliary tract disease. The cause of this complication is considered to be multifactorial. Risk factors include sepsis, previous surgery, trauma, total parential nutrition, intermittent positive pressure ventilation, opiate sedation, multiple transfusions and hypotension. One patient had 5 risk factors, 15 had 6 or more. Diagnosis was based on clinical suspicion, serial ultrasound scanning and serial estimations of white cell count, liver function and C-reactive protein. Four patients were treated conservatively with antibiotics and ultrasound observation, 10 underwent cholecystotomy and 2 patients had cholecystectomy. Eleven patients survived (69% survival). No patient treated by cholecystotomy required further surgery to the biliary tract. Acute acalculous cholecystitis has become a significant complication in our "high risk" acute renal failure population as intensive care has advanced and patients are surviving longer. Prompt and appropriate treatment will prevent it contributing significantly to the already high mortality of acute renal failure. Anticipation is the watchword.

Acute Disease↗
PubMed1980

'Missed beats' in a fetus. A case report.

The unique documentation by ultrasonography of a cardiac conduction abnormality in a fetus resulting in 'missed beats' is presented. Whereas cardiac arrythmias in the neonate are well described, the aetiology in the fetus remains obscure.

Adult↗
PubMed1980

Pregnancy following conization of the cervix: complications related to cone size.

A retrospective study of 88 pregnancies occurring in 77 patients after cervical conization was undertaken to compare pregnancy outcome with cone size. Cone specimens were divided into two groups. Those measuring less than 2 cm in height or less than 4 cc in volume were considered to be "small cones" and those greater than 2 cm in height or 4 cc in volume were regarded as "large cones." The over-all normal term vaginal delivery rate was 46.6%, and was found to be inversely proportional to the size of the cone. The incidence of both spontaneous midtrimester abortion and prematurity increased in direct proportion to cone size. Cervical stenosis necessitating cesarean section was, however, noted to be a complication associated with small rather than large cones. It was concluded from this study that all postcone pregnancies should be regarded as high risk, preterm complications being particularly related to large cones.

Abortion, Spontaneous↗