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Biomedical subjects

J Lewis

Publications and source records attributed to J Lewis.

At least 307 records · Page 17Linked to original sources
PubMed1989

Cancellous bone material properties in osteoarthritic and rheumatoid total knee patients.

One hundred and thirty-four cancellous bone biopsy specimens were taken from the proximal tibias and distal femurs of 55 patients undergoing total knee replacement for analysis of their area fraction and mechanical testing to determine their strength and stiffness. The purpose of the study was to measure the material properties of cancellous bone taken from arthritic patients and compare these with bone from normal subjects. The results showed a wide variation of strength (0.5-18.1 MPa, mean 5.6 MPa) and stiffness (11-504 MPa, mean 152 MPa). These values are in the same range or less than those reported for bone from normal tibias.

Aged↗
PubMed1989

Rigidity of initial fixation with uncemented tibial knee implants.

This study quantifies the in vitro motion occurring between bone and cemented and noncemented tibial components. Liquid metal strain gauges were used to measure the motion between the tibial component and bone at four locations in eight cadaver tibia at near-point cyclic loads ranging from 10 to 2,000 N. Two types of motion were observed: inducible displacement, which is reversible, followed the oscillating load and occurred in both cemented and uncemented tests, and liftoff or separation of the component and bone, which occurred only for the noncemented cases and remained even after removal of the load. For both motion types, noncemented tests exhibited significant (P less than .05) and dramatic increased interface motion compared to the cemented cases for all load types. The results suggest that the magnitudes of implant-bone interface separation at loads in the low physiologic range for noncemented implants can be sufficiently large to inhibit bony ingrowth into a prosthesis with an average pore size of 300 microns.

Adult↗
PubMed1989

Noncontraceptive estrogen use and epithelial ovarian cancer.

The relation of noncontraceptive estrogen use to epithelial ovarian cancer was evaluated in a case-control study conducted in hospitals mainly in the northeastern United States. There were 377 cases diagnosed within the year before hospital admission and 2,030 hospital controls; data were collected by interview in the hospital. Compared with women who never took noncontraceptive estrogens, the overall relative risk estimate for women whose estrogen use lasted at least one year and was not combined with progestogens or testosterone was 1.2 (95% confidence interval (CI) 0.8-1.9), after taking into account risk factors for ovarian cancer. There were 55 cases of the endometrioid, clear cell, or malignant mixed mesodermal cell type; the corresponding relative risk estimate was 0.9 (95% CI 0.3-3.0). There were 26 cases of undifferentiated cell type, with a relative risk estimate of 3.6 (95% CI 1.2-11). Relative risk estimates were similar in a subset of the cases (57%) for which pathology slides were reviewed. For estrogen use of long duration, use of high-dose preparations, or use in the distant past, the relative risk estimates were not significantly different from 1.0. The estimates were elevated for some categories of use, but not consistently--for example, for an interval of 5-9 years since estrogen use began (relative risk (RR) = 2.7), but not after shorter or longer intervals, and for use of conjugated estrogens with a dose of 0.3 mg (RR = 3.2) or 1.25 mg (RR = 2.4), but not for doses of 0.625 mg or 2.5 mg. The relative risk estimate was also elevated for use by nulliparous women (RR = 2.4). The results suggest that, overall, noncontraceptive estrogen use is not associated with the risk of epithelial ovarian cancer. Furthermore, our data do not support the hypothesis that estrogens increase the risk of endometrioid ovarian cancer. The elevated estimates could be due to multiple stratification of the data, but they should be explored in further studies, given the lethality of ovarian cancer and the common use of estrogens by postmenopausal women.

Adult↗
PubMed1989

Anterior tumour of the corpus callosum with atypical depression.

We report a patient with an anteriorly placed tumour of the corpus callosum presenting with primarily depressive symptoms, without any associated neurological abnormality. It is important to be alert to the possibility of an organic cause to depression.

Brain Neoplasms↗
PubMed1989

Cutaneous nerves of the embryonic chick wing do not develop in regions denuded of ectoderm.

Peripheral nerves travel to their targets along precise routes, and it is likely that different cues provide guidance at different stages of the journey. In a developing chick limb, the cutaneous nerve fibres follow at first deep mixed nerve trunks, in company with motor axons; they branch from these trunks at predictable points and approach the skin; they then ramify profusely to form a plexus at a precisely defined depth beneath the ectoderm, at exactly the same level as the blood vascular plexus. To analyse the role of signals from the target patch of skin in regulating cutaneous nerve development, we have ablated patches of dorsal wing ectoderm using short-wave ultraviolet irradiation at E4 (embryonic day 4), approximately one day before nerves grow into the limb bud. The irradiated patches remain denuded of ectoderm for more than a week, by which time the cutaneous nerve plexus on the contralateral control side is well developed and can be revealed by whole-mount silver staining. Where the ectoderm has been ablated, no cutaneous nerve plexus forms, and the nerve branches that normally would have diverged from the neighbouring mixed nerve trunk to innervate the missing patch of skin are absent - ab initio, apparently. The routes of the mixed nerve trunks are not affected. Partial ablation of the territory of a cutaneous nerve branch often leads to loss of the whole nerve branch; the intact skin territory thus left vacant is invaded by ramifications from the remaining cutaneous branches, as expected if the normal extent of a cutaneous nerve's territory is regulated by competition. Where there is an ectodermal lesion, cutaneous innervation stops precisely at its boundary, even though the vascular plexus extends for some distance beyond this margin, beneath the denuded surface. The data suggest that the embryonic skin is required firstly to trigger divergence of cutaneous nerve branches from the mixed nerve trunks, and secondly, once the nerve fibres have reached the skin, to supply a trophic cue (probably NGF) encouraging growth of a plexus; at the same time, the embryonic skin generates a signal inhibiting nerves from approaching closer than about 70 microns to the surface.

Animals↗
PubMed1989

Superparamagnetic iron oxide: pharmacokinetics and toxicity.

The pharmacokinetics (distribution, metabolism, bioavailability, excretion) and toxicity (acute and subacute toxicity, mutagenicity) of a superparamagnetic iron oxide preparation (AMI-25), currently used in clinical trials, were evaluated by 59Fe radiotracer studies, measurements of relaxation times, the ability to reverse iron deficiency anemia, histologic examination, and laboratory parameters. One hour after administration of AMI-25 to rats (18 mumol Fe/kg; 1 mg Fe/kg), 82.6 +/- 0.3% of the administered dose was sequestered in the liver and 6.2 +/- 7.6% in the spleen. Peak concentrations of 59Fe were found in liver after 2 hr and in the spleen after 4 hr. 59Fe slowly cleared from liver (half-life, 3 days) and spleen (half-life, 4 days) and was incorporated into hemoglobin of erythrocytes in a time-dependent fashion. The half-time of the T2 effect on liver and spleen (24-48 hr) was shorter than the 59Fe clearance, indicating metabolism of AMI-25 into other forms of iron. IV administration of AMI-25 (30 mg Fe/kg) corrected iron-deficiency anemia and showed bioavailability similar to that of commercially available IV iron preparations within 7 days. No acute or subacute toxic effects were detected by histologic or serologic studies in rats or beagle dogs who received a total of 3000 mumol Fe/kg, 150 times the dose proposed for MR imaging of the liver. Our results indicate that AMI-25 is a fully biocompatible potential contrast agent for MR.

Animals↗
PubMed1989

Origins of the neurovascular bundle: interactions between developing nerves and blood vessels in embryonic chick skin.

Growth cones of nerves and endothelial cells of blood vessels are closely analogous in their migratory behavior, and they are both set a similar task during the early development of a limb. Both must invade the mesenchyme to form ramifying networks of large nerves and vessels. Both systems must densely pervade certain regions of the developing limb, such as muscle rudiments, and both form dense cutaneous plexuses at precisely the same depth beneath the epidermis. Moreover, adult tissues show many examples of neurovascular bundles in which nerves and blood vessels run closely parallel and branch in a correlated fashion, suggesting some interdependence during development. We have examined the interrelationship between developing nerves and blood vessels in chick wing skin because it allows a particularly convenient two-dimensional analysis of the two systems which can be revealed simultaneously in the same preparation by injection of Indian ink combined with silver-staining. We show that nerves do not use blood vessels as pathways along which to crawl, but that there are two other ways in which neurovascular associations arise: in some situations nerves and blood vessels follow the same route because they are responding independently to the same mesenchymal cues; and in some situations nerves induce blood vessels to remodel around them.

Animals↗
PubMed1988

The detection of at-risk drinking in a teaching hospital.

We studied a sample of 302 inpatients from all medical and surgical wards of Westmead Hospital. Twenty-six per cent of patients (47% of men and 4% of women) were identified as past or current "at-risk" drinkers. Current drinkers preponderantly were male and were more likely to be admitted to hospital with trauma. Apart from trauma, alcohol-related disease was not diagnosed commonly, and most drinkers were admitted to hospital with diagnoses that were not related clearly to alcohol abuse. Hospital medical staff members appeared reluctant to address alcohol abuse; a low rate of alcohol problems was identified, and alcohol-related diseases appeared to be underdiagnosed.

Alcohol Drinking↗
PubMed1988

Cytotoxic T lymphocyte recognition of novel allodeterminants expressed on in vitro selected H-2Kb mutants.

In the present study, in vitro derived H-2Kb mutants have been examined by alloreactive CTL. Two mutants, R8.24 and R8.246, have been shown to express novel determinants detected by CTL generated against some but not all in vivo derived Kb mutants. BDF1 anti-bm3, anti-bm11, anti-bm19, anti-bm23, and anti-bm6 CTL populations lyse the two R8 variants. The novel determinants expressed on the R8 mutants detected by the bm3 and bm23-specific CTL appear to differ from the determinant recognized by the bm6-specific CTL. No new serologically defined determinants were detected on any of 18 independent R8 variants. However, these results do not rule out the existence of new determinants which could be recognized by antibodies. Finally, the relationship between the T cell recognition of the in vivo and in vitro derived mutants and their use in understanding the structure/function relationships between the immune response and class I Ag based on recent crystallographic analyses is discussed.

Animals↗
PubMed1988

AIDS policy.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Juvenile galactosialidosis in a white male: a new variant.

We describe a 19-year-old white male with juvenile galactosialidosis. He presented with hip arthralgia and was found to have facial "coarseness," corneal clouding, mitral and aortic insufficiency, and hepatosplenomegaly. Ultrastructural studies of skin biopsy and peripheral blood lymphocytes showed membrane-bound inclusions containing sparse fibrillogranular material. Biochemical analysis showed elevated urinary sialyloligosaccharides and no free sialic acid. Fibroblast enzyme analysis showed low activities of both alpha-neuraminidase and beta-galactosidase. To date, most patients with juvenile galactosialidosis have been Japanese. However, unlike those patients, our patient did not have macular cherry-red spots, neurologic abnormalities, or mental retardation. We speculate that this young man represents a new subtype of juvenile galactosialidosis with a potentially different molecular defect from that of the Japanese variant.

Adult↗
PubMed1988

Flatulence--causes, relation to diet and remedies.

In addition to causing embarrassment and unease, flatulence is linked to a variety of symptoms, some of which may be distressing. This review describes the origins of intestinal gas, its composition and methods which have been developed for its analysis. Emphasis is placed upon the effects of legumes in the diet in producing excessive intestinal gas and, particularly, on the role of raffinose-type oligosaccharides, containing alpha-galactosidic groupings. Suggestions for overcoming the problem are presented, including drug treatment, enzyme treatment, food processing and plant breeding. It is emphasised that removal of all raffinose-oligosaccharides from beans does not remove the problem of flatulence in animals and man; the compounds responsible--though assumed to be polysaccharides (or polysaccharide-derived oligomers formed by processing or cooking)--have yet to be characterised.

Animals↗
PubMed1988

Clear cell ("mesonephroid") adenocarcinoma of the vulva arising in endometriosis: a case report.

A very unusual case of an apparent primary clear cell adenocarcinoma of the vulva in a 57-year-old female is presented. The carcinoma arose in an area of endometriosis within the canal of Nuck in the superior aspect of the right labium majus. Smooth muscle fibers presumably representing remnants of the extrapelvic round ligament were found associated with the endometriosis. Of interest is the fact that the patient underwent right herniorrhaphy 9 years earlier. Although several cases of primary adenocarcinoma arising within the vulva have been reported, none has arisen in areas of endometriosis within the canal of Nuck. No case in the literature of a primary clear cell adenocarcinoma arising from endometriosis in the canal of Nuck and in association with the extrapelvic portion of the round ligament could be found.

Adenocarcinoma↗
PubMed1988

The use of serum methadone levels in patients receiving methadone maintenance.

Trough serum methadone concentration was measured in 43 patients under treatment for heroin addiction and complaining of withdrawal symptoms. Low serum levels were noted only in patients taking very low doses and in 10 patients who were concomitantly using enzyme-inducing drugs. The 27 patients in the maintenance program who had trough levels greater than 100 ng/ml were given no dose increase and were followed up prospectively. Alternate explanations for the patient's symptoms were well accepted in almost all cases, and subsequent performance in the treatment program appeared to be independent of serum level. We conclude that a trough serum level of 100 ng/ml is adequate for effective methadone maintenance. Measurement of serum levels can be a valuable intervention in patients with difficulties.

Dose-Response Relationship, Drug↗