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Biomedical subjects

L Nicholson

Publications and source records attributed to L Nicholson.

30 records · Page 2Linked to original sources
PubMed1988

Periventricular and subcortical hyperintensities on magnetic resonance imaging. 'Rims, caps, and unidentified bright objects'.

Magnetic resonance imaging hyper-intensities were classified as periventricular rim, caps, and unidentified bright objects (UBOs). These were quantitated in 100 acute stroke and 23 hemorrhage patients and 59 control subjects selected from 590 consecutive scans. The rims, caps, and ventricular size were rated on a scale from 0 to 3 for severity, and the UBOs were counted. The results indicated that the rim is also frequent in control subjects and increases with age. Unidentified bright objects, caps, and severe rims usually signify pathology, occurring much more frequently in patients with strokes and hemorrhages than in control subjects. Hypertension is a significant risk factor in UBOs and caps, but in rims, the incidence of diabetes is higher. The clinical and pathologic significance of these hyperintensities and their relationship to Binswanger's disease, lacunar state, and "état criblé" is discussed.

Acute Disease↗
PubMed1987

The sensitivity and specificity of MRI in stroke.

We compared MRI and CT in a study of 175 patients; 87 infarcts within a week, 40 from 1 to 40 weeks, 25 a year after onset, and 23 hemorrhages, 18 within 2 weeks and 5 in 4 to 8 weeks. Fifty-nine infarcts and eight hemorrhages had sequential scanning. MRI is more sensitive than CT in the early detection of cerebral infarcts. CT is the method of choice to rule out intracerebral bleeding, but MRI is more specific in later stages of hemorrhage. Periventricular hyperintensity is seen more frequently with diabetes than without. Hyperintense white matter patches are often unrelated to clinical events. MRI is useful in following the evolution of strokes and distinguishing acute and chronic infarcts without contrast agents.

Aged↗
PubMed1986

Regulation by calcium of parathyroid hormone mRNA in cultured parathyroid tissue.

We have examined the effect of changes in the concentration of extracellular calcium on parathyroid hormone mRNA in both short-term (hours) and long-term (days) cultures of bovine parathyroid tissue. Using a 32P-labeled PreProPTH cDNA probe, PTH mRNA was measured by gel blot hybridization of total RNA from tissue slices incubated for 4 h in low (0.5 mM) or high (5 mM) calcium concentrations and also by dot blot hybridization of cytoplasmic RNA extracted from aggregates of partially dispersed cells cultured up to 72 h in low (0.4 mM), normal (1 mM), or high (3 mM) calcium concentrations. PTH mRNA was unchanged over 4 h while high calcium had suppressed PTH secretion. However PTH mRNA did respond during long-term culture. By 24 h in high calcium there was a 50% suppression which was maintained for a further 48 h. PTH mRNA in normal calcium remained unchanged over 72 h while in low calcium it had increased slightly by 48 h. In contrast to the effect seen in cultured bovine parathyroid cells, PTH mRNA in human parathyroid adenoma cells cultured for 48 h in high calcium was decreased by only 10%.

Adenoma↗
PubMed1986

Vitamin D-dependent rickets type II: extreme end organ resistance to 1,25-dihydroxy vitamin D3 in a patient without alopecia.

Vitamin D-dependent rickets type II (VDDR II) is a rare syndrome resulting in severe rickets and is resistant to treatment with vitamin D and its derivatives. Patient with this disease, who are frequently the children of consanguinous marriages, present with elevated circulating concentrations of 1,25-dihydroxy vitamin D, the active metabolite of vitamin D, and in vitro studies have indicated a failure of intracellular binding of the hormone. Alopecia has been noted in many of these patients and it has been suggested that this feature may indicate a more marked resistance to treatment. However we describe a 3-year-old boy with this disease who, although having normal hair growth, displayed extreme resistance to treatment with active vitamin D metabolites. In vitro studies of skin fibroblasts disclosed not only an absence of hormone binding or 1,25(OH)2D3-induced 24-hydroxylase activity but reduced metabolism of 1,25(OH)2D3 itself. In this child, treatment with exogenous 1,25-dihydroxy vitamin D3 at doses of up to 24 micrograms/day, which increased the circulating concentration of the metabolite to greater than 100 times the normal adult mean, failed to alleviate his condition and he died at the age of 39 months. This would therefore suggest that absence of alopecia, in this condition, cannot be regarded as a constant predictive sign of a lesser resistance and of responsiveness to Vitamin D treatment.

Calcitriol↗
PubMedDate not supplied

A comparison of diagnostic tests to determine Helicobacter pylori infection.

Twenty-five Helicobacter pylori positive and 25 H. pylori negative subjects as defined by culture and phase contrast microscopy of antral biopsy specimens obtained from routine upper endoscopy were studied. Antral biopsies were examined by rapid urease test, phase contrast microscopy, culture and histology. Venous blood was tested for H. pylori specific IgG antibodies by an ELISA technique. Within 7 days of endoscopy the patients also had a [14C]-urea breath test. The sensitivity and specificity of the rapid urease test was 92%, the breath test 96% and 100%, histopathology 96% and 91% and serology 96% and 88%, respectively. The [14C]-urea breath test performed over 1 h with sampling of subjects at 0, 0.5 and 1 h was an accurate and reliable method. Results expressed as counts per minute of the expired 14CO2 proved to be a simple method of assessing H. pylori status. A significant correlation between severity of histological antral gastritis and the amount of 14CO2 expired was observed. This study has shown that the non-invasive 14C-urea breath test and serology are highly sensitive and specific for the diagnosis of H. pylori infection.

Breath Tests↗
PubMedDate not supplied

Helicobacter pylori prevalence in endoscopy and medical staff.

The epidemiology and mode of transmission of Helicobacter pylori is currently unclear; it is postulated that the human stomach is the natural reservoir and that spread occurs by faecal-oral or oral-oral transmission. The aim of this study was to assess the prevalence of H. pylori in gastroenterologists and gastroenterology nurses compared with internists, general nurses and the normal population. An enzyme-linked immunosorbent assay technique (sensitivity 96%, specificity 88%) was used to detect circulating H. pylori immunoglobulin G antibodies in 39 gastroenterologists, 107 gastroenterology nurses, 25 internists and 42 general nurses. These subjects were compared to an age- and sex-matched Caucasian population obtained by random sampling of an urban population area. The overall prevalence of H. pylori in gastroenterologists was 69% compared to 40% of internists (P < 0.01), 17% of gastroenterology nurses (P < 0.001), 19% of general nurses (P < 0.01) and 32% of controls (P < 0.01). There was no significant difference in H. pylori prevalence between the gastroenterology nurses and controls, general nurses and controls. The prevalence in gastroenterologists increased with years of practice to levels greater than age-matched controls. The prevalence in gastroenterology nurses increased with age and years of working and was similar to age-matched control subjects. These findings of an increased prevalence of H. pylori infection in gastroenterologists performing endoscopy support human-to-human transmission possibly from patients to medical staff.

Adult↗