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P Nicolaides

Publications and source records attributed to P Nicolaides.

12 recordsLinked to original sources
PubMed1998

Non-disjunction of chromosome 18.

A sample of 100 trisomy 18 conceptuses analysed separately and together with a published sample of 61 conceptuses confirms that an error in maternal meiosis II (MII) is the most frequent cause of non-disjunction for chromosome 18. This is unlike all other human trisomies that have been studied, which show a higher frequency in maternal meiosis I (MI). Maternal MI trisomy 18 shows a low frequency of recombination in proximal p and medial q, but not the reduction in proximal q observed in chromosome 21 MI non-disjunction. Maternal MII non-disjunction does not fit the entanglement model that predicts increased recombination, especially near the centromere. Whereas recent data on MII trisomy 21 show the predicted increase in recombination proximally, maternal MII trisomy 18 has non-significantly reduced recombination. Therefore, chromosome-specific factors must complicate the simple model of susceptible chiasma distributions interacting with age-dependent deterioration of the meiotic mechanism. For chromosome 18, 30% of tetrads are nullichiasmate in maternal MI non-disjunction, but nullichiasmates are not observed in maternal MII non-disjunction. Chiasma distributions from normal chromosome 18 meioses provide no evidence for normal disjunction from nullichiasmate tetrads. We extend this study to examine the remaining autosomes and find no evidence for normal disjunction from nullichiasmate tetrads generally.

Age Factors↗
PubMed1996

Stroke in children.

Explore the source record for details and available documents.

Cerebrovascular Disorders↗
PubMed1996

Cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS): a new syndrome.

There are a large number of well recognised syndromes comprising cerebellar ataxia in association with other neurological features. We report three family members who presented with a relapsing, early onset cerebellar ataxia, associated with progressive optic atrophy and sensorineural deafness. All three patients have areflexia (in the absence of a peripheral neuropathy), a pes cavus deformity, and show varying degrees of severity. Extensive neurological investigations have been normal, and the aetiology and pathophysiology of this disorder remain unclear. This may represent a separate syndrome of early onset cerebellar ataxia with associated features ("cerebellar ataxia plus"), which is likely to either have an autosomal dominant or maternal mitochondrial pattern of inheritance. The recognition of this association under the acronym of CAPOS (cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural deafness) may help in the delineation of a new syndrome.

Abnormalities, Multiple↗
PubMed1995

Primary malignant melanoma of meninges: atypical presentation of subacute meningitis.

Primary malignant melanoma of the meninges is described in a 5-year-old boy who presented with a 3-month history suggestive of subacute meningitis. Clinically the diagnosis of tuberculous meningitis was made and antituberculous treatment was begun. Despite this treatment, the patient's condition continued to deteriorate. Through cytologic examination of the cerebrospinal fluid malignant melanoma cells were identified, emphasizing the importance of this investigation in children with atypical meningitis. The diagnosis of malignant melanoma of the meninges was confirmed on brain biopsy.

Biopsy↗
PubMed1995

Immunoglobulin therapy in Guillain-Barré syndrome in children.

Four children with evolving Guillain-Barré syndrome were treated with a five-day course of intravenous immunoglobulin. No patient showed further progression of the condition and all made a rapid and complete recovery with no evidence of relapse over a six- to 24-month follow-up period. The early use of immunoglobulin in this disorder may prevent further progression of the disease and accelerate short-term recovery, with resulting medical, social and financial implications.

Adolescent↗
PubMed1995

EEG requests in paediatrics: an audit.

An audit of 165 requests for electroencephalography (EEG) was undertaken before and after the introduction of guidelines and recommendations, 12 months apart. Inadequate clinical information was provided in requests in both surveys; 40% of requests were considered to be unnecessary, and approximately 50% of clinicians felt that EEG could diagnose epilepsy.

Adolescent↗
PubMed1992

Midpregnancy plasma zinc in normal and growth retarded fetuses--a preliminary study.

OBJECTIVE: To determine plasma zinc concentrations in normally and abnormally growing fetuses. DESIGN: Prospective observational study. SETTING: Fetal Medicine Unit, Queen Charlotte's Maternity Hospital. SUBJECTS: 53 pregnant women attending for fetal blood sampling at between 18 and 40 weeks gestation. 27 fetuses were normal (central group), 11 fetuses were growth retarded and 15 were malformed. MAIN OUTCOME MEASURES: Plasma zinc concentrations in maternal and fetal blood at time of fetal blood sampling. RESULTS: In normally growing fetuses, between 18 and 40 weeks gestation, there was no fall in maternal plasma zinc concentration; the fetal level fell by 36%. In 10 fetuses with symmetrical growth retardation, plasma zinc concentration tended to be low, but was not significantly different from that in the normal control fetuses. CONCLUSION: The results suggest that (i) placental transfer of zinc is an uphill secretory process and that it is a rate-limiting step in the accumulation of zinc by the fetus and (ii) in fetuses with symmetrical intrauterine growth retardation, a low plasma zinc is probably a parallel phenomenon and not necessarily an aetiological factor.

Female↗
PubMed1979

A statistical description of the human tracheobronchial tree geometry.

Most physiological studies which made use of lung geometry have utilized average deterministic models of the tracheobronchial tree geometry, such as Weibel's Model A (1963). However, as shown by morphometric studies, it is well known that there are significant inter-subject and intra-subject variabilities in the structural components of the human lung. Hence, inherent inaccuracies exist when deterministic dimensions for lung geometry are used. In this paper, a statistical description of the lung geometry is presented. Using Weibel's Model A as the underlying average model, probability distributions for the lengths and the diameters of airways and for the number and volume of alveoli are proposed based on morphometric data. As a check for consistency, the probability distribution of the functional residual capacity is derived from those associated with airways and alveoli and it is compared with reported data. Results of this comparison are favorable, suggesting that the statistical description presented herein represents a self-consistent model for lung geometry which can be used for studies of problems related to pulmonary physiology.

Bronchi↗
PubMed1979

Effect of random airway sizes on aerosol deposition.

A previously developed deposition model is used to determine the total and regional deposition of inhaled aerosols in a population of human lungs by taking into account variability in airway dimensions. The results for particle sizes ranging from 0.1 micron to 8 micron aerodynamic diameter agree favorably with experimental data, thus suggesting that observed intersubject deposition variability is caused primarily by difference in airway dimensions.

Aerosols↗