PubMed Health⌕ Search

Biomedical subjects

B Lyons

Publications and source records attributed to B Lyons.

At least 55 records · Page 3Linked to original sources
PubMed1991

'Solitary' necrotic nodules of the liver: an aetiology reaffirmed.

Morphological features of lesions conforming to the description of solitary necrotic nodules of the liver were compared with liver haemangiomata and necrotic tumour metastases in the liver. An origin in haemangiomata is confirmed for most of the lesions studied, although the necrotic nodule may represent the end stage of a variety of lesions. These lesions are usually benign, although necrotic nodules are often mistaken for liver metastases. A reticulin stain is useful in assessing the lesions.

Adult↗
PubMed1991

Hairpatches, a single gene mutation characterized by progressive renal disease and alopecia in the mouse. A potential model for a newly described heritable human disorder.

A new murine mutation, hairpatches (Hpt), is on chromosome 4, 18.1 recombination units distal to brown near the interferon alpha and beta chain structural gene complex. On the inbred HPT/Le strain background, Hpt is semi-dominant, and Hpt/Hpt mice die in utero by 6 to 8 days of gestation. Such death in utero is associated with abnormalities of embryonic ectodermal derivatives. However on the (C57BL/6J x C3HeB/FeJ-a/a) segregating hybrid background, Hpt is a fully dominant mutation. HPT/Le Hpt/+ mice can be recognized by 3 to 4 days of age by patches of lightly pigmented skin. These mice show reduced numbers of hair follicles, abnormalities in hair follicle structure, and patchy absence of hair throughout life. By 2 weeks of age, abnormal hair follicle development is accompanied by thickening of the epidermis, reduction in levels of subcutaneous fat, and dermal inflammation. Progressive glomerulosclerosis, resulting in chronic kidney failure, is accompanied by increases in glomerular mesangial matrix, deposition of immune complexes, and glomerular enlargement. Scanning electron microscopic studies revealed abnormalities of podocytes including disorganization, swelling, and fusion of the foot processes. Increase in serum blood urea nitrogen levels accompanies conspicuous renal histopathologic changes. Cardiovascular changes in Hpt/+ mice are evidenced by hypertrophy of the left heart ventricle. Increased systolic blood pressure in these animals was found by 3 months of age. Anemia occurs in Hpt/+ mice by 40 weeks. The Hpt/+ mutation provides a valuable new animal model for chronic kidney disease accompanied by skin abnormalities and ventricular hypertrophy. The pathologic changes caused by this mutation are similar to those reported in affected family members with a newly described autosomal dominant human disease.

Alopecia↗
PubMed1989

Triple jeopardy: rural, poor, and uninsured.

Current knowledge on health care for the rural poor and uninsured demonstrates little descriptive and empirical knowledge on this population. Policy strategies call for a better understanding of the gaps in insurance coverage and the special problems of rural residents, especially those with low incomes.

Adolescent↗
PubMed1988

IL-4 regulates differentiation and proliferation of human precursor B cells.

The mechanism by which precursor and pre-B cells undergo differentiation is unclear; however, it is known that growth factors play an important role in this maturation process. The lymphokine, IL-4 has been shown to increase expression of class II Ag on B cells and induce B cell proliferation. In the murine system, IL-4 induced differentiation of precursor B cells into pre-B cells. In order to analyze growth factors on B cell development we have established an in vitro culture system for human bone marrow cells. We found that in the presence of IL-4, normal human precursor and pre-B cells can be induced to differentiate in the absence of cell proliferation with four days of culture. Furthermore, IL-4 depressed proliferation induced by supernatant from a T cell line. The differentiation was measured by an increase in both the number of cytoplasmic mu and surface IgM-positive cells. The effect of IL-4 on precursor and pre-B cell differentiation was detected as soon as 14 h of exposure to the lymphokine in the absence of an adherent feeder layer. These data suggest that IL-4 directly affects the differentiation process of normal human precursor and pre-B cells, and may antagonistically affect cell proliferation.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1988

In situ hybridisation and S1 mapping show that the presence of infiltrating plasma cells is associated with poor prognosis in breast cancer.

In order to identify potential markers of prognosis in breast cancer, representative cDNA libraries were constructed using RNA isolated from primary breast tumour tissue associated with good and poor prognosis. Cross-screening of these libraries repeatedly identified cloned mRNA species associated with the immune system, in particular B-cells, in libraries derived from tumours of poor prognosis. We have used one of these a kappa IV light chain cDNA probe, in two complementary studies to investigate the relationship between immunoglobin gene expression and prognosis. The results obtained using a combination of S1 mapping, RNA blotting and in situ hybridisation demonstrate that the presence of plasma cells, as defined by infiltrating cells which express high levels of immunoglobulin kappa-chain mRNA, is associated with a poor prognosis.

Adult↗
PubMed1987

Health care for black Americans: the public sector role.

Most of the improvement--both absolute and relative--in the health status of black Americans over the past two decades can be traced to major gains in access to health care services. Public payment programs, most notably Medicaid and Medicare, have not only reduced financial barriers, but have also combatted those of racial discrimination. Other federal programs supporting targeted local services have been especially effective in reducing infant mortality. But the redistributive effects have been uneven and unequal across populations; many categorical gaps remain and increasing numbers are potentially without access to essential primary care services.

Black or African American↗
PubMed1986

Detection of diffuse glomerular lesions in rats: II. Comparison of indium-111 cationic small macromolecules with technetium-99m DTPA.

Dextrans with average molecular weights of 5,000, 10,000, and 17,500 and inulin were rendered cationic by amination with 2-bromoethylamine hydrobromide. After limited coupling with DTPA cyclic dianhydride, they were labeled with 111In. A good correlation was found between their early renal uptake quantitated by camera-computer techniques and their renal clearance from multiple plasma samples in rats with glomerular damage induced by puromycin aminonucleoside and controls. However, there was poor correlation between the early renal uptake of these agents and the clearance of simultaneously injected [99mTc]DTPA. The 2-hr organ distribution and urinary excretion of these agents were compared with the corresponding values of DTPA. The differences in clearance between rats with glomerular damage and controls were greater with aminated dextran (mol wt 5,000) than with DTPA, confirming previous work with infusions of nonradioactive charged dextrans and neutral inulin. The cationic dextrans appear to reflect the presence or absence of the normal anionic charge of the glomerular membrane as well as changes in filtration rate. Aminated inulin did not differentiate between controls and rats with glomerular disease any better than DTPA, probably because the number of amino groups conjugated was insufficient to produce the charge effect.

Animals↗
PubMed1986

Detection of diffuse glomerular lesions in rats: I. Comparisons of conventional radioactive agents.

Conventional renal diagnostic agents, [131I]hippuran, [99mTc]glucoheptonate (GHA), and [99mTc] dimercaptosuccinate (DMS) were compared with [99mTc] or [111In] diethylenetriaminepentaacetic (DTPA) for the detection of glomerular damage in rats compared with controls. The glomerular lesions were induced by the i.v. injection of puromycin aminonucleoside (PA) 9 days before the radionuclide studies, a model of spontaneous "minimal change" glomerulonephritis in humans. Computer-generated early renal uptake of [99mTc]DTPA or GHA correlated with the glomerular filtration rate (GFR) quantitated by biexponential plasma clearance of DTPA administered by single i.v. injection. The early renal uptake of hippuran and DMS correlated poorly with GFR as assessed by DTPA clearance. However, the 2-hr renal retention of DMS correlated well with the DTPA clearance. None of the parameters measured with [131I]hippuran correlated well with DTPA clearance, probably because of decreased protein plasma binding of hippuran secondary to hypoproteinemia in this experimental model. It was concluded that none of these agents was superior to labeled DTPA for the detection of glomerular damage in this experimental model.

Animals↗
PubMed1985

Technetium-99m DADS complexes as renal function and imaging agents: II. Biological comparison with iodine-131 hippuran.

To find a 99mTc agent with a high renal extraction efficiency similar to [131]hippuran, 21 analogs of DADS were labeled and evaluated. Preliminary screening by serial gamma camera imaging in rabbits showed that most analogs had a higher liver uptake and/or slower renal clearance, than hippuran. Three agents (P-DADS, AP-DADS, and CAP-DADS), exhibiting a relatively rapid blood clearance and lower liver uptake in the rabbit, were studied in greater detail in comparison with hippuran and CO2-DADS-A, the best analog to date. In the rat, the plasma clearance of the four DADS analogs was slower than that of hippuran. In rats with tubular damage induced by cisplatin, the difference in renal retention at 1 hr compared to controls was much greater with hippuran than with the DADS compounds. In the dog, there was marked hepatic retention of the four DADS compounds. In volunteers, serial posterior images obtained with these [99mTc]DADS complexes showed significant hepatic as well as renal activity. The 1-hr plasma clearance and urinary excretion were much lower than with simultaneously injected hippuran. Although these 99mTc agents are satisfactory for imaging the kidneys, they closely mimic the biodistribution of hippuran only in the rabbit, and not in the rat, dog, or man.

Animals↗
PubMed1982

High-resolution ultrasound evaluation of experimental brain abscess evolution: comparison with computed tomography and neuropathology.

Computed tomographic (CT) and high-resolution ultrasound (HRUS) imaging of experimental brain abscess were correlated with neuropathologic findings in nine mongrel dogs. The HRUS scan was more sensitive to different histologic features than the CT scan but both accurately delineated the evolution of the experimental brain abscess. All stages of abscess evolution were characterized by an appearance of an echogenic rim with a hypoechoic center. In the early stages the echogenicity of the abscess was related primarily to marked cellular infiltration, while in the late stages extensive collagen deposition correlated closely with the echo pattern. The size of the abscess in the cerebritis stages appeared smaller on the HRUS scan than on the CT scan because the latter modality detected the extensive cerebritis around the developing necrotic center whereas the HRUS scan did not. This discrepancy disappeared in the capsule stages. The HRUS scan provided a more accurate depiction of the neuropathologic characteristics of the necrotic than did the CT scan. Healing of the abscess, indicated by a decrease in size of the hypoechoic center, was accurately detected by the HRUS scan.

Animals↗
PubMed1982

The effect of short-term corticosteroid treatment on the CT appearance of experimental brain abscesses.

The effect of short-term corticosteroid treatment on contrast enhancement was investigated in an experimental brain abscess model. The degree of enhancement was reduced in the cerebritis stage, unaffected in the capsule stage, and intermediate in the transitional stage. The area and pattern of enhancement were also altered in the cerebritis stage. Although the magnitude of the entire cerebritis time-density curve (extended for 60 minutes) was decreased by the steroids, its configuration was unchanged. Prior to steroid administration, the 10- and 60-minute components of the curve discriminated between cerebritis and capsule stages, with the latter exhibiting a far lower 60-minute value. Implications for treatment of brain abscesses are discussed.

Animals↗