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Biomedical subjects

B Williams

Publications and source records attributed to B Williams.

At least 487 records · Page 27Linked to original sources
PubMed1980

Ionic transport through bis-glycidyl methacrylate films.

Specific ion meter studies have shown that ionic transport through bis-GMA fissure sealant films is selective and that dissolved fluoride ions disappear from the solution around tooth sections at a more rapid rate than do calcium and chloride ions. This would indicate that topical fluoridation of pits and fissures can still be effected after placement of a fissure sealant. A causative mechanism for this phenomenon has been postulated. Calcium exchange studies indicate that calcium is removed from the enamel and that the microsolubility of fissure sealed teeth in CaCl2 solution is increased by the preparative and sealing procedure used for the enamel.

Acrylates↗
PubMed1980

Microporosity in bis-glycidyl methacrylate films.

The existence of hitherto unsuspected micropores in fissure sealant films (bis-glycidyl methacrylate resin films) has been demonstrated by means of scanning electron microscopy. Immersion of specimens in various ionic solutions showed that the defects in the surface of the resin film tended to become filled with the passage of time.

Acrylates↗
PubMed1980

Risk of breast cancer in women with benign breast disease.

A group of 1,489 white women were treated in a private surgery practice from 1940 through 1975 for biopsy-proved benign breast disease, and 1,441 were followed through 1976 for the development of breast cancer. Average duration of follow-up was 12.9 years for a total of 18,617 person-years of observation. Information was collected from a set of questions devised in 1941 and asked of all subjects at the time of their initial office visit, follow-up interview conducted in 1976, and a standardized histology review of the slides from the initial benign lesions and the subsequent cancers. The current pathology review indicated that 66 of the women developed breast cancer. The incidence rate was 3.55 per 1,000 person-years, which is 2.10 times that of the general population. When multiple disease types and other variables were controlled for, excess risk of breast cancer was related to the presence of fibrocystic disease. In women with fibrocystic disease, excess risk was particularly related to the presence of epithelial hyperplasia and/or papias not related to the presence of fibroadenoma alone, but it was related to the presence of fibroadenoma in women with concomitant fibrocystic disease. The excess risk was also directly related to the estimated size of the initial benign mass and was greater for women with bilateral than with unilateral benign lesions.

Adult↗
PubMed1979

Responses to stimulation of marginal fibers in the teleostean optic tectum.

The marginal fibers (mf) constitute a major fiber component of the teleostean optic tectum, and this report deals with the physiological properties of these fibers and their postsynaptic elements. The mf are unmyelinated axons which originate at the torus longitudinalis and run lateralwards, parallel to one another, along the tectum's most superficial layer (stratum marginale). Here they synapse upon the dendritic arborizations of the pyramidal (p) neurons. These arborizations originate from a single apical dendritic shaft which, near the soma, receives retinofugal axon terminals. The p-neurons also have a basal dendritic shaft and a descending axon, both of which branch out horizontally at the stratum griseum centrale (SGC). The mf were stimulated through surface microelectrodes, and field potentials were recorded on-beam throughout the tectal thickness by means of micropipettes. The mf action potential (M-spike) may show two negative subpeaks which propagate at 0.20 and 0.16 m/s. Its refractory period is followed by a period of increased amplitude and decreased latency. The M-spike is followed by a series of slow waves, namely: (a) The S-wave, which probably represents the monosynaptic depolarization of the p-neuron's apical arbor; (b) The N-wave which possibly represents an active current sink at the point where these dendritic arborizations merge into the apical dendritic shaft; (c) The D-wave, recorded at the SGC, which possibly represents the activation of the p-neuron's axon and terminals (and perhpas also basal dendritic shaft and branches); and (d) the L-wave, which might represent a later depolarization of the p-neuron's apical arborizations. Morphologically and electrophysiologically, there are several similarities between the tectal mf/p-neuron system and the cerebellar parallel fiber/Purkinje cell system.

Animals↗
PubMed1979

An antineuronal antibody cross-reacting with erythrocytes and lymphocytes in systemic lupus erythematosus.

An antibody with erythrocyte and lymphocyte activity, present in the sera of patients with systemic lupus erythematosus (SLE), demonstrated additional reactivity with neurons. The neuronal reactivity was greater with cortical neurons than with cerebellar and caudate nucleus neurons, was predominantly IgG, and was immunologically specific. Selected sera from 22 patients with active SLE were tested for the presence of antineuronal antibody. Eleven of 12 sera obtained from patients with neuropsychiatric disease demonstrated definite neuron reactivity, in contrast to only 2 of 10 sera obtained from patients without evidence of neuropsychiatric involvement (P less than 0.005). Five of 21 sera from patients with rheumatoid arthritis, but no sera from 5 other disease control groups, contained antineuronal antibody. Serial studies of 2 SLE patients with transient psychotic episodes demonstrated a close association between antibody titer and the appearance of psychosis in one. These observations suggest that the detection of antineuronal antibodies in patients with SLE may be of value in the diagnosis and management of neuropsychiatric complications.

Absorption↗
PubMed1979

Subarachnoid pouches of the posterior fossa with syringomyelia.

Three men are presented, all of whom were born with difficulty and later developed severe syringomyelia with collapsing cords on air myelography. Each had hydrocephalus and a sizable subarachnoid pouch in the posterior fossa. The clinical features and investigations are presented with a discussion of the aetiology and possible mechanisms concerned in pathogenesis and treatment. All three men had posterior fossa exploration over fifty years after birth, and the first two were also treated by valved ventriculo-atrial shunts. Each patient has improved a little since operation, but no certainty that this was due to surgery has been proved in any case; none has progressed since the last operation.

Cerebrospinal Fluid Shunts↗
PubMed1979

Errors in velocity measurement by the Pitot principle in fluids with slowly propagated pressure waves.

An attempt has been made to develop a velocity probe using the Pitot principle for the measurement of fluid velocities in cerebrospinal fluid. Pressures were measured using conventional transducers and amplifiers and the pressure difference signal has the predicted relationship to the square of fluid velocity in the steady state. However, in the clinical situation where slowly propagated pressure waves accompany cerebrospinal fluid movement the pressure difference incorporates an indeterminate term unrelated to velocity, and this imposes severe limitations on the technique. Measurements and discussion are presented.

Amplifiers, Electronic↗
PubMed1979

The measurement of cerebrospinal fluid flow.

A technique for the measurement of cerebrospinal fluid (CSF) velocity-flow is described. It enables the flow of CSF in response to pressure pulses to be measured whilst allowing the simultaneous measurement of pressure through a lumber puncture needle. The physical principles which govern the operation of the flow probe are presented together with practical forms of the probe. The application of the technique is demonstrated by experiments on dog.

Animals↗
PubMed1979

The Valved-Y-Cardiff Connector (V.Y.C. Con).

A disposable Y-connector for use when two infusions are connected to the same channula has been tested. The connector incorporates a valved tap in one limb which prevents retrograde flow into the infusion connected to that limb.

Infusions, Parenteral↗
PubMed1979

Possible factors in the adhesion of fissure sealants to enamel.

The type of aqueous solution used to wash the enamel surface immediately after etching with orthophosphoric acid affected the tensile bond strength obtained. Washing with a 1% potassium chloride solution was found to effect an improved bond strength, but no difference was observed when different types of water were employed for this purpose. A similar finding of no difference in bond strength was obtained when the possible influence of electrostatic forces was eliminated.

Acid Etching, Dental↗
PubMed1979

Orthopaedic features in the presentation of syringomyelia.

The orthopaedic surgeon is often the first consultant to whom a patient with syringomyelia is referred. The disease is not as rare as he may suppose, but its early presenting features are very variable; if he relies solely on such familiar features as pes cavus and scoliosis, he may well miss the diagnosis. The commonest presenting symptom is pain in the head, neck, trunk or limbs; headache or neckache made worse by straining is particularly significant. A history of birth injury also may suggest the possibility of syringomyelia, especially if any spasticity subsequently worsens. Neurological features which may be diagnostic include nystagmus, dissociated sensory loss, muscle wasting, spasticity of the lower limbs or Charcot's joints. Radiographic features include erosion of the bodies of cervical vertebrae and widening of the spinal canal; if, at C5, the size of the canal exceeds that of the body by 6 millimetres in the adult, pathological dilatation is present. The presence of basilar invagination or other abnormalities of the foramen magnum, of spina bifida occulta and of scoliosis are further pointers. Thermography is a useful way of showing asymmetrical sympathetic involvement in early cases. A greater awareness of the prevalence of syringomyelia may lead to earlier diagnosis and to early operation, which appears to hold out the best hope of arresting what is all too commonly a severely disabling and progressive condition.

Adolescent↗