Search PubMed⌕ Search

Biomedical subjects

J Williams

Publications and source records attributed to J Williams.

At least 973 records · Page 54Linked to original sources
PubMed1984

Direct and indirect determination of tibial natural frequency--a comparison of frequency domain analysis and fast Fourier transform.

The natural frequency of in vivo mechanical systems has been derived in the past by signal conditioning techniques. For the living tibia the accuracy of this derived method was not validated. In addition the use of Fast Fourier Transform is time consuming, tedious and expensive. Direct measurement yields results which are more accurate, more easily obtained, and more clinically applicable.

Biomechanical Phenomena↗
PubMed1984

Vibration analysis of human tibia: the effect of soft tissue on the output from skin-mounted accelerometers.

The vibration response of bone can be recorded from a skin-mounted accelerometer, but only if it is sufficiently preloaded to overcome the damping effect of the interposed soft tissue. Excessive preload results in distortion of the recorded signal by a high-frequency component which probably originates in the supporting apparatus of the accelerometer. The required preload is proportional to the soft tissue thickness, but for any given soft tissue thickness, the range of allowable preload is fairly wide.

Acceleration↗
PubMed1984

Natural frequency of fracture fragments in the assessment of tibial fracture healing.

The natural frequency of fracture fragments has been measured at various times in the course of healing of 11 midshaft tibial fractures. The major fragments manifest different frequencies which are themselves distinct from that of the intact bone. It has been shown that the difference in frequency between the major fragments falls with time, so that the separate frequencies approach a common value which corresponds with the healed state. The results have been used to construct a model healing curve, against which other tibial fractures can be compared.

Adolescent↗
PubMed1984

Examination of some fragrance substances for mutagenic activity.

We tested 64 perfumes and aftershaves for mutagenicity in Salmonella typhimurium strains TA98 and TA100; most were tested both with and without metabolic activation. None of the test compounds gave a positive mutagenic response. The available amounts of some test samples were very small, however, and the possibility that larger samples might have produced positive results cannot be altogether discounted. Some tests indicated the presence of cytotoxic substances which require chemical analysis.

2-Acetylaminofluorene↗
PubMed1984

Influence of the method of re-expansion of atelectatic lung upon the development of pulmonary edema in dogs.

An endobronchial tube was used to separately ventilate each lung in anesthetized dogs, and absorption atelectasis was then induced in the left lung and maintained for 3 1/2 h. The left lung was partially re-expanded by ventilation at normal tidal volumes for 10 min, and then completely re-expanded by manual hyperinflation. This delayed re-expansion was associated with an extravascular water content significantly greater than that of the right lung. A previous study demonstrated no increase in the ratio of left to right lung water content after 3 h of atelectasis alone and a significant increase after immediate hyperinflation. Delayed re-expansion produces significantly different results, and it is therefore concluded that the method of lung re-expansion influences the development of pulmonary edema after atelectasis.

Animals↗
PubMed1984

Accuracy and precision of gas-liquid chromatographic, high-pressure liquid chromatographic, and enzyme immunoassay techniques for the measurement of theophylline concentrations in serum: a comparison based on external quality assurance measurements.

The accuracy and precision of gas-liquid chromatography with and without derivatization (GLC + D, GLC-ND), high-pressure liquid chromatography (HPLC), and enzyme multiplied immunoassay (EMIT) for the measurement of serum levels of theophylline were compared below, within, and above the therapeutic range (55-110 mumol/L) using data from 63 samples from the Heathcontrol quality assurance scheme. Within the therapeutic range, the methods did not differ in either precision or accuracy. Coefficients of variation (CV) of measurements were between 12 and 16%, and measurements did not differ from spiked values. Below the therapeutic range, the methods differed significantly. The GLC methods had the lowest precision (CV 23-25%), while the CV for HPLC was 19% and for EMIT 14%. GLC + D and HPLC also overestimated drug level by 11 and 8%, respectively. Above the therapeutic range, the precision of the methods did not differ (CV 10-13%), although both EMIT and HPLC underestimated theophylline level by 5-6%. In a comparison of individual laboratories based on a ranking of overall precision, laboratories employing GLC commonly exhibited less precise rank positions than laboratories using EMIT. Laboratories making HPLC measurements showed a bimodal distribution but no methodological differences were identified to explain this difference in precision.

Chromatography, Gas↗
PubMed1984

Haemopexin in sheep, mouflon and goat: genetic polymorphism, heterogeneity and partial characterization.

Benzidine staining of starch gels after electrophoresis of sera to which haematin was added revealed polymorphism of haemopexin in sheep, mouflon and goat. In sheep three phenotypes were observed, Hpx A, Hpx AB and Hpx B. Pedigree data support the hypothesis of codominant inheritance from a single locus by two alleles, HpxA and HpxB. Neuraminidase treatment of haemopexin preparations showed that Hpx B covered two variants, B1 and B2, thus indicating genetic control by three alleles (HpxA, HpxB1 and HpxB2). In sheep populations the frequency of HpxB is low. In mouflon, in addition to the two variants that are like those of sheep, absence of haemopexin was observed in some animals, by using starch gel electrophoresis as well as immunoelectrophoresis. In goat, three phenotypes were detected, Hpx A, Hpx AB and Hpx B, differing in migration from those of sheep. Haemopexins of the studied species are heterogeneous. Sialic acid is responsible for electrophoretic heterogeneity of sheep haemopexin. Chemical composition (amino acid and carbohydrate), molecular weight (56 060) and N-terminal sequence (Leu-Pro-Pro-) of sheep haemopexin were also determined.

Alleles↗
PubMed1984

Deep posterior compartment pressure in the evaluation of venous insufficiency of the lower extremity--a preliminary report.

A new method of assessing the extent of venous insufficiency in the lower extremity at the tissue level was tested on thirteen limbs with various degrees of venous insufficiency as evidenced by clinical signs and descending venography. Deep posterior compartment pressures in standing patients correlated well with standing venous pressures in these same limbs. Eighty-three percent of those limbs with deep posterior compartment pressures above 30 mmHg had objective clinical signs of venous insufficiency, namely edema, stasis dermatitis and/or stasis ulcer. Descending venography results were compared in six of these limbs, however, no correlation with compartment pressures could be found from this small sample. With further study, deep posterior compartment pressures using the slit catheter technique may prove to be a valuable aid in the diagnosis of venous insufficiency.

Adult↗
PubMed1984

Studies of Jungian typology: III. Personality and marriage.

Jung's theory of psychological types provided the conceptual framework for a study of personality characteristics implicated in marital relationships. Partners in 20 couples completed the Myers-Briggs Type Indicator and a series of open-ended questions describing their marital relationships. As predicted, (a) type similarity was more characteristic than type dissimilarity, particularly on sensation-intuition and thinking-feeling preferences, (b) sensation-intuition preferences were reflected in perceptions of qualities valued in self and spouse, (c) thinking-feeling preferences were significantly related to reported satisfaction in marriage, and (d) intuitives were more open to changes in the relationship than were sensing types. Marital problems were highly diverse, and were not related in any clear way to type patterns in individuals or dyads.

Journal Article↗
PubMed1984

Radical removal of lipomas of the conus and cauda equina with laser microneurosurgery.

Ten patients with ages ranging from 4 weeks to 21 years presented with a subcutaneous lumbosacral mass noted at birth. After spinal high resolution ultrasonography or computed tomography to determine the extent of neural involvement and the length of the tumor mass in the spinal canal, the patients underwent operation. Rectal electromyographic continuous monitoring was used in all for assessment of the S-2 and S-3 function during dissection. Carbon dioxide laser microneurosurgery was used in all operations. Radiating energy was used for the subcutaneous mass removal (40 to 60 W), the intracanalicular dissection (1 to 5 W), and the intraconus dissection (1 to 3 W). A radical removal was obtained in all. Postoperative cerebrospinal fluid fistula occurred in 1 patient and was successfully treated. Wound dehiscence that healed with secondary closure occurred in 2 patients. Would infection that required treatment with systemic antibiotics and topical therapy occurred in 1 patient. Paraplegia occurred in 1 patient. This was the single very significant complication of this series. It was thought to have occurred because of the polymer used to seal the tenuous dura mater at the time of closure. We conclude that, with carbon dioxide laser microneurosurgery, the lipomatous tumors can be removed safely from the neural structures of the conus and cauda.

Adolescent↗
PubMed1984

Adjuvant-free immunological manipulation of livestock.

Mice and sheep were immunised to growth hormone release inhibiting hormone (GHRIH) using a number of systems which avoided conventional adjuvants. GHRIH was linked directly, or via a horse IgG carrier, to algin or purified protein derivative of tuberculin. A conjugate of GHRIH and flagella from Salmonella dublin was also prepared. Complexes were administered with or without lipopolysaccharide from S typhosa 0901 in a two-injection schedule. Animals receiving conjugates containing purified protein derivative or flagella were preimmunised with live Bacille Calmette-Guérin (BCG) or live S dublin vaccines respectively. Antibody titres to GHRIH, horse IgG and flagella were determined by radioimmunoassay. The system based on tuberculin yielded anti-GHRIH titres in both species which were equivalent to those obtained using Freund's complete adjuvant, while the system based on S dublin produced similar results but only in mice. These data suggest that carrier proteins of bacterial origin may be useful in the development of adjuvant-free autoimmunisation schedules for the practical manipulation of endocrine systems.

Alginates↗
PubMed1984

Sonographic demonstration of the progression of meconium peritonitis.

A case of meconium peritonitis that was diagnosed ultrasonographically in the early third trimester in a patient with acute polyhydramnios is presented. The pathophysiologic progression of this condition is demonstrated by serial ultrasound examinations. Neonatal radiologic confirmation of the diagnosis is also presented. The obstetric and neonatal implications of meconium peritonitis and the importance of serial ultrasonography in those pregnancies in which this diagnosis is made are discussed.

Adult↗
PubMed1984

Resistance to Haemonchus contortus transferred between genetically histocompatible sheep by immune lymphocytes.

The pattern of faecal egg counts after infection with 10,000 Haemonchus contortus larvae was similar within but not between, four pairs of monozygous twin sheep. Transfer of whole lymph or washed lymph cells from three immune donor sheep to their identical co-twin recipients reduced the susceptibility of the recipients to challenge with 10,000 larvae as measured by faecal egg counts. Cells from a nonimmune donor did not have this effect. In a final experiment, washed cells from an immune triplet sheep, which was actively responding to a repeated challenge infection, transferred a secondary local IgA response to a second recipient triplet and resulted in a marked reduction in worm count when compared with that of a third infectivity control triplet.

Animals↗
PubMed1983

Maintenance of DNA integrity during murine erythroleukemia cell differentiation induced by ethionine and other hypomethylation agents.

The extent of single-strand nicks in DNA from murine erythroleukemia cells induced to differentiate to hemoglobin synthesis in the presence of the hypomethylating agent ethionine was estimated and compared to those levels in uninduced cells and from cells induced to differentiate upon exposure to dimethylsulfoxide or butyrate ion. Although ethionine has been shown to cause more extensive hypomethylation in the DNA of induced cells than that caused by dimethylsulfoxide or butyrate ion, the frequency of detected single-strand breaks in the DNA of uninduced, control cells was not significantly different from that of cells exposed to any of these inducing chemicals. This data indicates that no correlation exists between DNA hypomethylation and DNA single-strand breaks and that unmethylated CpG loci likely do not operate as specific endonuclease recognition sites or as potential origins of transcription in these mammalian cells.

5-Methylcytosine↗
PubMed1983

Drug treatment of primary hyperparathyroidism: use of clodronate disodium.

Clodronate disodium (dichloromethylene diphosphonate), a specific inhibitor of bone resorption, was given by mouth (1.0-3.2 g daily) to nine patients with primary hyperparathyroidism for two to 32 weeks so that its clinical and metabolic effects could be evaluated. Bone resorption decreased in all patients as judged by a fall in the fasting urinary calcium to creatinine and hydroxyproline to creatinine ratios. Serum calcium concentration was increased in all patients before treatment and fell in response to treatment to values near the upper end of the normal range. Hypercalcaemia and hypercalciuria recurred when treatment was stopped. In three patients treated for longer than 19 weeks clodronate failed to sustain the reduction in serum calcium concentration but the concentration remained below pretreatment values. These results suggest that clodronate may be of use in the medical management of primary hyperparathyroidism, particularly in patients in whom suppression of bone disease is desirable before surgery or in whom surgery is contraindicated.

Aged↗