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Biomedical subjects

S Connor

Publications and source records attributed to S Connor.

At least 55 records · Page 3Linked to original sources
PubMed1999

Conversion of multiple solid testicular teratoma metastases to fatty and cystic liver masses following chemotherapy: CT evidence of "maturation".

Testicular germ cell tumour metastases may undergo "retroconversion" to mature differentiated teratoma following chemotherapy or irradiation. We report a patient with testicular germ cell liver metastases in whom computed tomography (CT) scans following chemotherapy demonstrated a reduction in CT attenuation of the liver lesions to that of cystic and fatty density. This is believed to represent CT evidence of liver metastasis "retroconversion", which offers the potential for non-invasive monitoring of histological progression.

Adult↗
PubMed1998

Niche overlap among three species of pinworm parasitic in the hindgut of the American cockroach, Periplaneta americana.

Individual American cockroaches, Periplaneta americana, often harbor 3 species of pinworm (Oxyurida: Nematoda) Thelastoma bulhoesi, Leidynema appendiculatum, and Hammerschmidtiella diesingi, simultaneously. We looked for evidence of trophic niche segregation based on differences in size preference among the 3 species. Fluorescent beads of 1, 3, 6, and 10 microm diameter were mixed in agar and fed to individual hosts. Adult female worms of each species were removed from hosts, and the number of each size of bead in each worm was assessed. Horn's R0 and Hurlbert's L indices of niche overlap were calculated for infracommunities containing at least 1 of each species. Hurlbert's index extends the information given by Horn's index to include the effects of proportional availability of each resource. Both indices indicated a lack of trophic segregation based on particle size among the 3 species. Species did, however, differ in consumption rate: L. appendiculatum ate more than T. bulhoesi, which ate more than H. diesingi.

Animals↗
PubMed1997

Separation of extracts from biological tissues into polycyclic aromatic hydrocarbon, polychlorinated biphenyl and polychlorinated dibenzo-p-dioxin/polychlorinated dibenzofuran fractions prior to analysis.

A low-pressure liquid chromatography method is presented for separating polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDDs/PCDFs) from biological tissue extracts. After removing lipid from extracts, the PAHs are separated from PCBs and PCDDs/PCDFs on a deactivated 13-24 microns silica gel column. The PCBs are subsequently separated from PCDDs/PCDFs by collecting the first fraction from an automated three column cleanup procedure for PCDDs/PCDFs. The complete method has been used to obtain high recoveries of the three compound classes for analysis by GC-electron capture detection (PCBs) or GC-MS (PAHs and PCDDs/PCDFs).

Animals↗
PubMed1996

Geographical perspectives on bednet use and malaria transmission in The Gambia, West Africa.

Insecticide-impregnated bednets are now widely accepted as an important tool in reducing malaria-related deaths in children in Africa. Defining the circumstances in which net treatment programmes are likely to be effective is essential to a rational development of this control strategy. In The Gambia a National Impregnated Bednet Programme was introduced into the primary health care system in 1992. Prior to its introduction baseline epidemiological and entomological studies were conducted throughout the country. These studies showed that in areas where mosquito biting nuisance was high, people protected themselves with bednets and that where mosquito densities (and therefore bednet usage) was low malaria prevalence rates were relatively high. Since the national programme is designed to assist only those people who already own a bednet (by providing the insecticide) an understanding of the factors which determine bednet ownership is needed to help evaluate the programme's effectiveness and provide guidelines for increasing bednet usage. Village scale bednet usage rates and malaria prevalence rates obtained from the baseline survey were correlated with certain geographical variables: dominant ethnic group, area, habitat, distance from the River Gambia and distance from the 'bluffline' (the interface between the sandstone soils and alluvial soils which border the river system). In a multiple regression analysis, bednet usage was independently associated with area (P < 0.001), ethnic group (P = 0.010), habitat (P = 0.006) and distance from the river (P = 0.013). A negative association of bednet usage with malaria prevalence persisted after allowing for the other variables. Malaria prevalence was not independently associated with area, ethnic group, habitat or distance from the river. Our analysis showed that the impregnated bednet programme is likely to be most effective in villages which are sited near to or on the alluvial soils in the middle and lower river zones. These villages, which were originally settled for easy access to the river (for transport) and its swampy margins (for rice production) are within the flight distance of mosquitoes that have their breeding sites on the poorly drained alluvial soils. Variation in malaria prevalence rates (after bednet usage has been taken into account) may be related to factors such as poverty and access to health care, and/or to localized differences in the ecology of The Gambia, which determine the duration and intensity of transmission. If the National Bednet Programme is to be effective throughout The Gambia it is vital to develop promotional activities which will encourage bednet usage in areas where nuisance biting by mosquitoes is low.

Animals↗
PubMed1993

Thermally-induced cutaneous vasodilatation in aging.

A decrease in heat-induced cutaneous vasodilatation has been implicated as the cause of increased heat stress in the elderly. We used laser Doppler techniques to study the skin blood flow response to local heat in 82 healthy volunteers. There were 39 young volunteers, mean age 29 +/- 1, and 43 elderly volunteers, mean age 76 +/- 1. There was minimal difference in skin blood flow at 35 degrees C between the two groups. In contrast, skin blood flow at 44 degrees C was significantly lower in the older subjects at nutritively perfused sites, such as the knee and elbow. However, there was no difference between the young and old groups in skin blood flow at the finger or toe pulp, sites with primarily arteriovenous anastomotic (AVA) flow. In the older subjects, the two components of skin blood flow, microvascular volume (VOL) and red blood cell velocity (VEL), were both decreased at 44 degrees C at nutritive sites, but not at AVA sites. Regression analysis demonstrated a linear fall in blood flow, VOL, and VEL with advancing age at nutritive sites at 44 degrees C. We conclude that thermally-induced cutaneous blood flow is reduced in older persons at nutritive capillary sites, but not at AVA sites.

Adult↗
PubMed1993

Quality assurance: a prescription for success.

Provides a theoretical and practical overview of one organization's total quality management initiative. Concentrates particularly on the pursuit and achievement of registration against the quality assurance standard BS 5750/ISO 9002. The organization is a public sector trading agency providing a financial internal audit service to a range of clients within the NHS.

England↗
PubMed1992

Current perception thresholds in ageing.

We studied 40 healthy elderly and 31 healthy young volunteers and 25 elderly diabetic and 37 young diabetic patients. All subjects received detailed neurological examinations focusing particularly on sensory symptom and physical evaluations. Standardized assessment of symptoms and physical testing of light touch, pain, vibratory and thermal sensation were performed at the hand, wrist, elbow, foot, ankle and knee. The total symptom score (SS) and the total physical score (PS) were defined by summing test scores at each site. Current perception threshold (CPT) testing using constant current sine wave alternating current was completed at the same anatomical sites. CPT findings did not differ significantly between young and old healthy subjects. Older diabetic patients had higher CPTs than younger diabetic patients, but the severity of clinical diabetic neuropathy was greater in the older group. CPTs correlated with the degree of clinical diabetic neuropathy (r = 0.47 with SS and r = 0.60 with PS) rather than with age (r = 0.12). We conclude that current perception does not decline with age. Nor does ageing by itself worsen CPT values in patients with neuropathy. CPT testing is easily performed, clinically applicable and the first objective sensory measure not affected by the process of ageing.

Adult↗