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Biomedical subjects

K Ritchie

Publications and source records attributed to K Ritchie.

98 records · Page 6Linked to original sources
PubMed1979

Prematurity.

Perinatal epidemiologists no longer speak much of "prematurity". Instead the World Health Organization recommends that infants born before 37 completed weeks of gestation should be designated "preterm" and those of birthweight less than 2500 g "low birthweight". Both definitions have obvious drawbacks--the former because menstrual dates are often unknown or unreliable, the latter because it does not separate preterm from small-for-gestational-age infants. Whatever the classification of these small infants there is no dispute about their high mortality and morbidity; in the United Kingdom they account for over two-thirds of first-week deaths.

Female↗
PubMed1977

A typology of parasuicide.

Parasuicide is not a single syndrome. Subtypes at present recognized are based largely on clinically derived stereotypes. When considering a series of patients, the clinician is unable to handle more than a few attributes at a time. This paper describes the application of three very different clustering algorithms to a material of 350 treated parasuicide patients. Mathematically, three types emerge. Clinically, two of these are interpretable and make sense. The types established are: I (n = 107) a group not characterized by any of the variables we examined; this group is a puzzle, mainly because the reasons for the parasuicidal act are not clear. II (n = 132) a depressed, alienated group with high life-endangerment. III (n = III) a group whose act was highly operant: they felt alienated and were angry with others. These groups did not differ significantly on demographic variables. The usefulness of this typology, particularly for management, after-care and prevention, has now to be assessed.

Anger↗
PubMedDate not supplied

Identification of amyloid beta protein in the brain of the small, short-lived lemurian primate Microcebus murinus.

The deposition of amyloid beta (A beta) protein in the brain has been demonstrated immunocytochemically in the small Lemurian primate Microcebus murinus. Both meningocerebral vascular deposits and cortical parenchymal deposits occur. All eight aged (> 8 years old) Microcebus examined showed vascular amyloid deposits, whereas only four exhibited parenchymal plaques. The vascular amyloid infiltrated the tunica media of the leptomeningeal and cortical arteries and arterioles and was also found in capillaries. A beta was observed to be deposited in three general forms in the cortical neuropil: round or elliptical plaques that were thioflavin-negative but sometimes showed a central concentration of A beta immunoreactivity; round plaques with a densely immunoreactive core that was thioflavin-positive; extensive ribbon-like infiltrations enclosing multiple cortical blood vessels. These observations, taken together with previous descriptions of age-related neurodegenerative changes in Microcebus, indicate that this species undergoes a beta-amyloid-associated neuropathology highly similar to that seen in Alzheimer's disease. We conclude that this lemurian primate of small size and relatively short life expectancy, provides a compelling animal model of some principal features of Alzheimer's disease.

Aging↗
PubMedDate not supplied

Subclinical cognitive impairment: epidemiology and clinical characteristics.

Subclinical cognitive impairment is commonly reported in elderly populations, but its clinical significance is largely undetermined. It is commonly perceived as a normal feature of the aging process or a separate nosological entity. The clinical status of this disorder is explored herein by reference to longitudinal observations. It is concluded that persons with subclinical cognitive impairment constitute a highly heterogeneous group. There is an elevated risk in this group for senile dementia, with an estimated 18% incidence rate over 3 years, but in the majority of cases, this problem is more commonly associated with depressive symptomatology and physical illness. Only 13% of persons with recent observable change in cognitive functioning appear to have a totally benign and transient syndrome. Caution should be exercised in applying single unifying nosological entities such as age-associated memory impairment to this group of the elderly.

Aged↗
PubMedDate not supplied

Novel technique for the combined recovery, extraction and clean-up of forensic organic and inorganic trace explosives samples.

This paper describes a simple processing and analysis scheme for explosives trace swab samples which deals both with organic and inorganic materials. Swabs, wetted with ethanol or ethanol/water mixture, were extracted with ethanol/water mixture. The extract was passed directly through a simple column containing an acrylonitrile/styrene copolymer adsorbent. The adsorbent retained common organic explosives, which were recovered with an efficiency of 30-50% as a relatively clean ethyl acetate solution. The concentrated ethyl acetate eluate was analysed using gas chromatography with chemiluminescence or mass spectrometric detection. The unretained inorganic ions and sugars, which were recovered with generally high efficiency as an ethanol/water solution, could be directly analysed using ion chromatography and/or capillary electrophoresis. Minor difficulties encountered in the analysis of sugars, fluoride and phosphate were examined.

Chromatography, Gas↗
PubMedDate not supplied

The relationship between apolipoprotein E4 and lipid metabolism is impaired in Alzheimer's disease.

BACKGROUND: Human apolipoprotein (Apo) E4 (ApoE4) is an important determinant of lipid metabolism and cell-to-cell cholesterol transport. It is also a major genetic risk factor for both vascular disease and familial and sporadic late-onset Alzheimer's disease (AD). Since vascular pathology could dramatically reduce neuronal reserve capacity, a biological chain of events between ApoE4, hypercholesterolemia and AD has been postulated. The aim of the present study is to explore the relationship between lipid metabolism and ApoE isoforms in a large series of elderly subjects in relation to the presence or absence of AD. METHODS: Of 332 referrals to a neurology clinic specializing in memory disorders, 146 were given a diagnosis of AD (age, mean +/- SD 76 +/- 13.1 years, 64.4% women) according to DSM-IIIR criteria. One hundred and seventy-six subjects were included as controls (age 80 +/- 5.6 years, 58% women). The ApoE phenotype was determined by the isoelectrofocalization method, cholesterol, triglycerides, phospholipids, ApoA and ApoB were determined by routine chemistry. FINDINGS: A significant association was observed between the E4 allele and AD (chi2 = 13, p < 0.001) only below age 80. In the control group, cholesterol levels were found to be significantly higher in men but not in women with an E4 allele (6.35 +/- 1.3 mmol/l) as opposed to those without (5.8 +/- 1.2 mmol/l). ApoB levels were also found to be higher in the presence of ApoE4, with no gender effect. Within the AD group no significant relationship was found between ApoE4 and cholesterol levels (mean 6.05 +/- 0.9 mmol/l in E4-AD subjects versus 5.8 +/- 1.21 mmol/l in non-E4-AD subjects). Similar observations were made in relation to triglycerides and phospholipids. INTERPRETATION: Our results demonstrate the disappearance of the ApoE4-raising effect on serum cholesterol, triglyceride and phospholipid levels in AD suggesting a more complex relationship between AD and lipid metabolism than has previously been supposed. This lipid abnormality may further contribute to the progression of AD.

Aged↗