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Biomedical subjects

M Williams

Publications and source records attributed to M Williams.

At least 487 records · Page 27Linked to original sources
PubMed1990

How many tests are required in the diagnosis of palpable breast abnormalities?

Palpable breast nodules in 143 patients attending our primary diagnosis breast clinics were assessed by clinical examination, needle cytology, mammography, ultrasonography and magnetic resonance imaging (MRI). The diagnostic accuracy of all test combinations was compared with the final diagnosis of malignant or benign disease. Two-test combinations increased the sensitivity of diagnosis over that of the individual tests to between 93% and 100% except for MRI/mammography and MRI/cytology. The combinations of three or more tests increased the sensitivity further, but at the expense of an increased false-positive rate. MRI does not appear to have an important role in the primary diagnosis of breast cancer. Mammography is necessary because of the possibility of occult or multifocal disease. Clinical examination was associated with a high false-positive rate. The combination of cytology and ultrasound was best at correctly diagnosing malignancy, but in this series only 42% of patients underwent ultrasound examination. The role of breast ultrasound together with needle aspiration cytology for the diagnosis of malignancy in palpable breast nodules deserves further evaluation.

Adult↗
PubMed1990

The ventricular-brain ratio (VBR) in functional psychoses: the relationship of lateral ventricular and total intracranial area.

CT scans were performed on 72 consecutive patients with a functional psychosis, and compared with 50 community controls. There was a specific difference in lateral ventricular area between these two groups but it accounted for only 11% of the variance in this measure. In contrast, racial and sexual differences in the ventricular-brain ratio (VBR) related to differences in intracranial area. It is argued that analysis of variance, using lateral ventricular area and intra-cranial area, is more informative than VBR in examining these structural changes in functional psychoses.

Adolescent↗
PubMed1990

2-(Arylalkylamino)adenosin-5'-uronamides: a new class of highly selective adenosine A2 receptor ligands.

The synthesis and receptor-binding profiles at adenosine receptor subtypes for a series of 2-(arylalkylamino)-adenosin-5'-uronamides is described. Halogenated 2-phenethylamino analogues such as 3e show greater than 200-fold selectivity for the A2 receptor subtype on the basis of rat brain receptor binding. The general structure-activity relationship of this series of compounds is discussed both in terms of potency at A2 receptors as well as receptor subtype selectivity. It is possible to introduce a hydrophilic carboxyalkyl substituent to this series such as in CGS 21680A (3h) and still retain good potency and selectivity for A2 receptors. In addition, functional data in a perfused working rat heart model shows that these compounds possess full agonist properties at A2 receptors with 3h having a greater than 1500-fold separation between A2 (coronary vasodilatory) and A1 (negative chronotropic) receptor mediated events.

Adenosine↗
PubMed1990

The value of computed tomographic (CT) scan surveillance in the detection and management of brain metastases in patients with small cell lung cancer.

One hundred and twenty-seven consecutive patients presenting with small cell lung cancer were entered into a whole-brain CT scan surveillance study, starting at presentation and repeating at 3-monthly intervals for 2 years as an alternative to prophylactic cranial irradiation (PCI). The aim of the study was to detect CNS metastases at an early asymptomatic stage in the hope that prompt CNS radiotherapy could achieve long-term control; at the same time unnecessary PCI with its potential long-term morbidity could be avoided. CNS metastases were found in 56 patients (44%) including 16 (13%) at diagnosis and 40 at a median of 4 months (range 1-27 months) after completing chemotherapy. No patient developed CNS disease while on chemotherapy. Thirty-six patients were asymptomatic at diagnosis (group A) but 20 developed clinical CNS relapse between scans (group B) (interval relapse). Despite prompt radiotherapy 56% of patients in group A and 60% of patients in group B died with active CNS disease. Likewise, there was no survival difference between patients in group A, group B or those who never developed CNS disease. Regular 3-month CT scan surveillance is therefore not an effective substitute for PCI.

Brain Neoplasms↗
PubMed1990

An evaluation with piglets of bovine milk, hydrolyzed bovine milk, and isolated soybean proteins included in infant milk formulas. I. Effect on organ development, digestive enzyme activities, and amino acid digestibility.

A study, using the piglet as a model for the human infant, was undertaken to determine the effect of the protein source of a milk formula on organ development, the activity of digestive enzymes, and the absorption of amino acids as measured at the terminal ileum and over the entire digestive tract. Three isocaloric liquid milk formulas containing equal amounts of either intact bovine milk, hydrolyzed bovine milk, or isolated soybean protein as the sole source of this nutrient and with equal levels of fat and carbohydrate were each given to six 14-day-old piglets over a 19-day period in a manner that mimicked human infant feeding practice. Following a 6-day metabolism study, the piglets were killed, their organs removed, and samples of digesta collected. The protein source of the milk-based formula did not affect (p greater than 0.05) the weight/unit body weight of the small intestine, large intestine, liver, or pancreas, but the relative weight of the kidneys was lower (p less than 0.05) for animals fed the intact bovine milk-based formula and that of the stomach was higher (p less than 0.01) for piglets receiving the isolated soybean formula. The activities of pepsin, intestinal trypsin and chymotrypsin and pancreatic chymotrypsin were not influenced (p greater than 0.05) by protein source, but piglets receiving the bovine milk-based formula had a lower level of activity (p less than 0.01) for pancreatic trypsin. The apparent ileal and fecal absorption of nitrogen was similar for the three milk-based formulas, the overall mean ileal absorption of nitrogen (+/- SE) being 89.0% (+/- 1.44). Excluding cystine, where ileal absorption was relatively lower (p less than 0.05) with the isolated soybean formula (86.7%) compared with the intact bovine milk (91.5%), protein source had little effect on the apparent absorption of essential amino acids. It was concluded that the replacement of intact cow's milk protein in human infant formulas by either hydrolyzed cow's milk or isolated soybean protein is unlikely to cause any major disturbance in the digestive process.

Amino Acids↗
PubMed1990

Relationships between N1, P300, and contingent negative variation recorded at age 15 and criminal behavior at age 24.

Recent event-related potential (ERP) studies indicate that antisocial and psychopathic behavior is in some circumstances characterized by heightened attentional processes. This prospective study assesses whether ERP measures of attention recorded in adolescence are capable of predicting criminality status in adulthood. N1, P300, and contingent negative variation (CNV) were recorded during a CNV paradigm in a representative sample of 101 male schoolchildren at age 15, and related to criminality status at age 24. Criminals-to-be were characterized by larger N1 amplitudes and faster P300 latencies to the warning stimulus. Psychopathic personality within the criminal group was associated with larger N1 and CNV amplitudes. A discriminant function analysis using N1 and P300 measures correctly classified 74% of cases. It is concluded that enhanced early attentional processing may be of etiological significance in the development of criminality and that ERP measures may be of value in the early prediction of criminal behavior.

Adolescent↗
PubMed1990

Surfactant maturation and preterm premature membrane rupture: a case study.

Preterm premature membrane rupture (PPROM) is known to accelerate fetal lung surfactant maturation. The mechanism for this is unclear. We report a case of prolonged PPROM, where the maturation of fetal surfactant was studied in detail by the serial analysis of surfactant phospholipids in the drained liquor.

Adult↗
PubMed1990

The adenosine/neutrophil paradox resolved: human neutrophils possess both A1 and A2 receptors that promote chemotaxis and inhibit O2 generation, respectively.

Occupancy of specific receptors on neutrophils by adenosine or its analogues diminishes the stimulated release of toxic oxygen metabolites from neutrophils, while paradoxically promoting chemotaxis. We now report evidence that two distinct adenosine receptors are found on neutrophils (presumably the A1 and A2 receptors of other cell types). These adenosine receptors modulate chemotaxis and O2- generation, respectively. N6-Cyclopentyladenosine (CPA), a selective A1 agonist, promoted neutrophil chemotaxis to the chemoattractant FMLP as well as or better than 5'N-ethylcarboxamidoadenosine (NECA). In contrast, CPA did not inhibit O2- generation stimulated by FMLP. Pertussis toxin completely abolished promotion of chemotaxis by CPA but enhanced inhibition by NECA of O2- generation. Disruption of microtubules by colchicine or vinblastine also abrogated the enhancement by NECA of chemotaxis whereas these agents did not markedly interfere with inhibition by NECA of O2- generation. FMLP receptors, once they have bound ligand, shift to a high affinity state and become associated with the cytoskeleton. NECA significantly increased association of [3H]FMLP with cytoskeletal preparations as it inhibited O2-. Disruption of microtubules did not prevent NECA from increasing association of [3H]FMLP with cytoskeletal preparations. Additionally, CPA (A1 agonist) did not increase binding of [3H]FMLP to the cytoskeleton as well as NECA (A2 agonist). These studies indicate that occupancy of one class of adenosine receptors (A1) promotes chemotaxis by a mechanism requiring intact microtubules and G proteins whereas engagement of a second class of receptors (A2) inhibits O2- generation. Signalling via A2 receptors is independent of microtubules, insensitive to pertussis toxin and is associated with binding of [3H]FMLP to cytoskeletal preparations.

Adenosine↗
PubMed1990

Autonomic orienting responses in 15-year-old male subjects and criminal behavior at age 24.

This prospective study analyzed relationships between skin conductance and heart rate measures of orienting in a noninstitutionalized sample of 101 15-year-old male subjects and criminal behavior as assessed at age 24 years. Subjects with a criminal record at age 24 (N = 17) had significantly smaller skin conductance responses and smaller heart rate deceleratory and acceleratory responses than the other subjects (N = 84). Lack of any skin conductance response was significantly more prevalent in subjects with a criminal record (31%) than in the control subjects (10%). These results implicate deficits in orienting with the later development of criminal behavior. The authors hypothesize that the genetic predisposition to criminal behavior may find its expression in part through smaller autonomic orienting.

Adolescent↗
PubMed1990

The functional psychoses in Afro-Caribbeans.

When 54 Afro-Caribbean and 49 white British consecutive psychotic in-patients were prospectively studied for clinical differences in course of illness and pattern of symptoms, no major differences were found. This does not support the hypothesis that misdiagnosis within the psychoses can explain the higher admission rates of schizophrenia calculated for Afro-Caribbean populations.

Acculturation↗
PubMed1990

An electrical network model of inertially induced bone-conducted sound.

A model for the description of inertially induced bone-conducted sound has been developed and a discussion of the appropriate techniques for its representation as an electrical network is described. Predictions are made for the sound pressure produced in the meatus in the cases of normal ears and pathological ears resulting from vibration applied to the skull. Evidence from this modelling suggests that the technique may provide improved discriminability over conventional immitance measurements for some types of pathology.

Acoustics↗