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Biomedical subjects

L Weiss

Publications and source records attributed to L Weiss.

At least 721 records · Page 40Linked to original sources
PubMedDate not supplied

Leiomyoma of the adrenal gland in a patient with AIDS.

Leiomyoma of the adrenal gland is an exceptional localization. We report a case occurring in a young patient with AIDS. Diagnosis was a surprise on pathologic examination. On enhanced computed tomographic (CT) scan, the adrenal mass had a low central attenuation area and a thin enhancing peripheral ring. On magnetic resonance (MR) imaging the left adrenal mass was isointense with the liver on T1-(TR/TE = 500/300 ms) and T2-(TR/TE = 2030/60, 120 ms) weighted spin-echo images, except a central area with a lower signal on T1-weighted images and a higher signal on T2-weighted images. The mass was slightly enhanced after Gd-DOTA injection, but the central area remained unchanged.

Acquired Immunodeficiency Syndrome↗
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The relationship between lymphogenous and hematogenous metastasis in rats bearing the MT-100-TC mammary carcinoma.

Temporal and quantitative aspects of lymphogenous and hematogenous metastasis were examined using the rat MT-100-TC mammary carcinoma injected into the hind feet of syngeneic rats. Metastases first appeared in the draining popliteal nodes and then progressed in an invariable pattern to regional and then distal nodes: 'skipped' negative nodes within a chain of positive nodes were not observed. Metastatic progression in the lymphatic system occurred metachronously, with nodal metastases acting as 'generalizing' sites for 'downstream' nodes. Perturbation of lymph flow was apparent when nodes were involved with tumor, and resulted in retrograde seeding of contralateral nodes. Lung involvement was first observed by ectopic bioassay in 50 per cent of animals after 1 and 2 weeks of primary tumor growth; in contrast, all animals had popliteal involvement after 1 week. These results indicate that lymph nodes and lungs are not seeded synchronously, and the lungs are seeded after nodal metastases. Thus, a phase of metastasis has been identified, during which resection of the primary tumor and local nodes may well be curative in the 50 per cent of cases in which the disease is confined to these sites.

Animals↗
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Biomechanical destruction of cancer cells in skeletal muscle: a rate-regulator for hematogenous metastasis.

Following left ventricular injection into mice, B16 melanoma and Ehrlich ascites tumor cells are arrested in the microvasculature of the quadriceps femoris muscles. Within 5 min of delivery the effects of variation in surrounding tissue pressure on the survival of the arrested cells have been determined by bioassays of denervated (relaxed), non-contracting or contracting muscle. The results show that cancer cell survival is greatest in denervated, then non-contracting muscle, and least in electrically stimulated muscle. The results are in accord with the hypothesis that the rapid death of most cancer cells after delivery to at least some target organs is a consequence of their mechanical interactions within the microvasculature.

Animals↗
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Interactions between cancer cells and the microvasculature: a rate-regulator for metastasis.

Hematogenous metastasis is a major consideration in the staging, treatment and prognosis of patients with cancer. Key events affecting hematogeneous metastasis occur in the microvasculature. This is a brief, selective review of some interactions involving cancer cells and the microvasculature in pathologic sequence, specifically: (1) intravasation of cancer cells; (2) the arrest of circulating cancer cells in the microvasculature; (3) cancer cell trauma associated with arrest; (4) microvascular trauma; (5) the inflammatory; and (6) the hemostatic coagulative responses associated with arrest, and finally (7) angiogenesis, leading to tumor vascularization. The evidence shows that through a series of complex interactions with cancer cells, the microvasculature acts as a rate-regulator for the metastatic process, in addition to providing routes for cancer cell dissemination and arrest sites for cancer cell emboli.

Cell Adhesion↗
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Metastasis.

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Cell Adhesion↗
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Abnormalities of blood selenium and glutathione peroxidase activity in patients with acquired immunodeficiency syndrome and aids-related complex.

Severe protein-calorie malnutrition is common in patients with AIDS and could contribute to the progressive deterioration characteristic of that disease. Selenium deficiency could also have a negative impact on immune function and other organ functions vital for recovery from infectious diseases. Therefore, to assess any role for selenium in AIDS we determined plasma and erythrocyte selenium levels and glutathione peroxidase activity in 13 patients with AIDS compared to 8 patients with AIDS-related complex (ARC) and 14 healthy controls. Plasma selenium levels were significantly reduced in AIDS patients compared to controls (p less than .0001) and to ARC (p less than .02). Erythrocyte selenium levels in both AIDS and ARC were also reduced compared to controls (p less than .02), but not to each other. Glutathione peroxidase activity in AIDS was 28.9 +/- 1.4 U/g Hb vs 38.4 +/- 6.9 in ARC (p = NS) and 52.3 +/- 1.7 in controls (p less than .0001 vs AIDS; p less than .02 vs ARC). When all groups were combined, there were significant correlations between total lymphocyte count and both plasma selenium (r = .53; p less than .002) and erythrocyte glutathione peroxidase activity (r = .65; p less than .0001). In addition, strong correlations were noted between plasma selenium and serum albumin (r = .68; p less than .0001), plasma selenium and glutathione peroxidase (r = .77; p less than .0001), and glutathione peroxidase and hematocrit (r = .66; p less than .0001). In AIDS or ARC, no correlations between selenium with disease duration or weight loss were present. We conclude that, in comparison to normals, patients manifesting infection with human immunodeficiency virus have evidence of selenium deficiency as determined by diminished plasma and erythrocyte levels and glutathione peroxidase activity. These abnormalities are most marked in patients with AIDS, but are also present in patients with AIDS-related complex. Selenium deficiency has important implications for the progression and pathogenesis of clinical disease in AIDS.

AIDS-Related Complex↗
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Failure of cyclosporine to induce graft-vs-host disease or graft-vs-leukemia after syngeneic bone marrow transplantation in mice.

Cyclosporine administration can result in graft-vs-host disease (GVHD) after syngeneic or autologous bone marrow transplantation (BMT). However, data on its anti-tumor effects are limited. We have tried to produce cyclosporine-induced GVHD or graft-vs-leukemia (GVL) against two Ia-bearing murine leukemias. BALB/c mice undergoing syngeneic BMT after total-body irradiation received 1 mg/kg or 10 mg/kg cyclosporine or dextrose intraperitoneally for 30 days post-transplant, followed by 5 x 10(3) BCL1 murine leukemia cells 1 or 3 weeks after stopping cyclosporine. Similarly, SJL/J mice undergoing syngeneic BMT received 10 mg/kg cyclosporine or dextrose intraperitoneally for 30 days post-transplant, and were inoculated with 5 x 10(3) or 10(5) murine acute myeloid leukemia (mAML) cells 3 weeks after stopping cyclosporine. No clinical or histological evidence of GVHD was seen, and leukemia-free and overall survival was similar with cyclosporine and dextrose. We conclude that under the experimental conditions used, it is not possible to induce syngeneic GVHD with cyclosporine in BALB/c or SJL/J mice. In the absence of GVHD, this approach is also not associated with any GVL effect against murine leukemias BCL1 and mAML.

Animals↗
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The hepatitis B virus transactivator HBx causes elevation of diacylglycerol and activation of protein kinase C.

Chronic infection with hepatitis B virus (HBV) is accompanied by an increasing risk of developing hepatocellular carcinoma. There are indications that the HBx protein of HBV is involved in the process of tumour formation. HBx also transactivates several transcription factor binding sites. Recently, we reported that HBx can use a tumour promotor pathway for transactivation. In particular, we found that transactivation of the binding motif for transcription factor AP-1 (JUN/FOS) by HBx is dependent on functional protein kinase C (PKC), as indicated by abolition of the transcriptional stimulation following downregulation or inhibition of the enzyme. Moreover, HBx activates PKC, probably via increasing the endogenous PKC activator sn-1,2-diacylglycerol (DAG). Here we extend these data and report on the time course of PKC activation. We found that activation of PKC by HBx is transient and differs from activation of PKC by the ras oncogene product or phorbol ester in that it does not lead to rapid downregulation of the enzyme subsequent to the activation. Moreover, we provide evidence that an increase in cellular DAG is observable not only as an early event in response to HBx but also in cell lines transformed after transfection with HBV DNA and stably expressing HBx. Besides its important role in the regulation of cellular genes, PKC is also the intracellular receptor for tumour-promoting agents and an activator of proto-oncogenes, suggesting that our observations might provide an explanation for the oncogenic properties of HBx.

3T3 Cells↗
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Do high-flux dialysis membranes affect renal dyslipidemia?

High-flux hemodialysis has been reported to attenuate renal dyslipidemia. To evaluate the contribution of dialysis membrane composition per se, we compared the impact on the lipoprotein profile of hemodialysis (HD) with a conventional cellulose dialysis membrane with that of a synthetic high-flux dialysis membrane in standard hemodialysis mode. Forty-two patients (24 men, 18 women; mean age, 69 years; range, 39-85 years) on maintenance HD with cellulosic dialysis membranes were randomized and stratified for diabetes mellitus to 12 weeks of HD treatment with either a cellulose acetate (CA; n = 23) or polyacrylonitrile (AN69; n = 19) membrane. HD was performed in a conventional low-flux standard HD mode 4-6 hours/session. Plasma levels of lipids (TC, TG), apolipoproteins (A-I, B, C-III, E), lipoprotein (a) (Ip(a)), and individual apoA and apoB containing lipoproteins (LP-A-I, LP-A-I:A-II, LP-B, LP-Bc) were determined. At baseline, the AN69 group had slightly higher plasma concentrations of apoC-III and C-III/HS, but there were no other differences at entry in study variables between the treatment groups. Twelve week treatment with an AN69 membrane did not result in any significant changes in lipoprotein profile compared with treatment with a cellulose acetate membrane. HD with AN69 dialysis membranes in the conventional low-flux standard hemodialysis mode does not affect the lipoprotein profile.

Adult↗
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Mesodermal induction defect as a possible cause of ear malformations.

Deafness due to inner ear anomalies is rarely associated with malformations of the auricles. We describe two brothers with profound congenital sensorineural deafness, abnormal vestibular function, normal ossicles, and delayed motor development. Since the external and inner ear originate from distinctly separate structures, the embryogenesis of this malformation association is less clear than in the more common association of external and middle anomalies, where the latter two structures are derived from the first and second branchial arches. The combination of auricular and inner ear anomalies, with sparing of the middle ear structures, can be explained on the assumption that mesodermal induction is responsible for normal differentiation of both the otocyst and of the branchial arch ectoderm. A recessive mutant gene may lead to a deficiency of a mesodermal inducer substance of a target tissue receptor site. A similar mechanism may be involved in other multiple malformation syndromes, whereby a mutant gene acting during a specific period of organogenesis causes disruption of the normal induction-competence relationship.

Cell Differentiation↗
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Selenium deficiency in the acquired immunodeficiency syndrome.

Severe protein-calorie malnutrition is common in patients with AIDS (acquired immunodeficiency syndrome). These nutritional deficits are likely to further impair immune responses and other organ functions vital for recovery from serious infectious diseases. Since selenium deficiency is known to be associated with oral candidiasis and abnormal phagocytic function in animals and depressed helper T-cell numbers in man, we evaluated both selenium status and other nutritional parameters in 12 patients with AIDS compared to 27 healthy controls. Selenium was measured by a spectrofluorometric method. The mean (+/- SD) plasma selenium level in AIDS was 0.043 +/- 0.01 microgram/ml vs 0.095 +/- 0.016 microgram/ml in controls (p less than 0.001). Whole blood selenium and red blood cell selenium levels were also significantly reduced in AIDS (p less than 0.005). The mean weight loss in AIDS patients was 35.5 +/- 21.2 pounds. Serum albumin was significantly (p less than 0.01) lower in AIDS patients compared to controls. A good correlation between serum albumin and plasma selenium was noted (r = 0.77; p less than 0.001). We conclude that selenium deficiency is a common component of the malnutrition seen in AIDS patients. Therefore, aggressive nutritional support, including attention to selenium status, should be considered an integral part of the therapy of AIDS patients.

Acquired Immunodeficiency Syndrome↗