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Biomedical subjects

L Weiss

Publications and source records attributed to L Weiss.

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

Organ vascularity and metastatic frequency.

The "hemodynamic" or "mechanical" theory proposes that the frequency of metastases in different organs is primarily determined by the numbers of cancer cells delivered to them in their arterial blood. This theory has not yet been adequately tested in man because reproducible, noninvasive measurements of organ blood flow have only recently become available. Correlation between these data and the metastatic frequency in 10 organs, in groups of patients with primary cancers in 15 anatomic sites, has therefore been sought. No correlation was obtained between metastatic frequency and organ weights, blood volumes, blood volumes per gram, "transit times," or blood flow. However, correlations significant at the 4-8% level were obtained between organ blood flow per gram and metastatic frequency in 4 of 5 groups of primary cancers with initial venous drainage into the portal system, compared with 1 of 10 draining into the caval system. At present, no definitive explanation can be offered for the apparent compliance of one set of primary cancers with the "hemodynamic" theory of metastasis, but not the others.

Female↗
PubMed1980

Results of postoperative clinical examination of inguinal hernia after three years.

Of 285 consecutively operated inguinal hernias in 274 patients 87.4% were clinically examined after three years by two independent investigators. The operations were performed by several surgeons in a small community hospital. All patients were adults. The total reucrrence rate was 10.4%, but if only symptomatic recurrences were included, the recurrence rate was 5.2%. No recurrences were seen in women. Total recurrence rates were in men for lateral hernias 7.7%, medial hernias 11.8% and for recurrent hernia 18.4%. When only symptomatic recurrences in men were taken into account the corresponding figures were 2.4%, 7.8% and 13.2% respectively. Simultaneous bilateral operation seemed to increase the risk of recurrence, while bilateral hernia disease per se did not increase the recurrence rate. The total complication rate was 2.4% and there was no mortality.

Adult↗
PubMed1979

Contribution of macrophages to interactions between tumor cells and other tissues assessed in an in vitro system.

The modification of the tissues surrounding solid tumors is usually attributed exclusively to interactions between the normal tissues and the cancer cells in the tumor, in spite of the fact that tumors contain many different types of non-cancer cells including macrophages. As an experimental model for some facets of the cellular interactions between tumor and normal tissues, we have assessed the individual contributions of macrophages and cancer cells to the differential inhibition of neural retina (NR) cell aggregation by co-culturing NR cells with small numbers of macrophages or cancer cells alone, as well as with both natural (ascites tumors) and artificial mixtures. Cells from human colonic adenocarcinoma inhibited NR aggregation to a greater extent than normal colon mucosa. Aggregation of NR cells was inhibited by macrophages from mice and rats, and to a greater extent by cancer cell suspensions of mouse Ehrlich and rat Walker 256 lines from spinner culture or in the ascites form. Combinations of macrophages and cancer cells indicated that their inhibitory effects were neither additive nor synergistic. Cell-free media from macrophages and cancer cell cultures were equally effective inhibitors of aggregation. The results suggest that the interaction between a malignant tumor and the surrounding normal tissue can be modified by cancer cells, tumor macrophages and their products.

Adenocarcinoma↗
PubMed1979

Ring chromosome 6: case report and review of literature.

A ring chromosome 6 has been identified by GTG-banding in a male with microcephaly, growth retardation, seizures, epicanthus, hypertelorism, micrognathia, and other congenital anomalies. Cytogenetic studies indicate the instability of the ring chromosome. The most common findings in subjects with ring 6 include: profound to moderate mental retardation, microcephaly, prenatal growth failure, retarded bone age, epicanthal folds, flat nasal bridge, short neck, ears low-set or malformed, microphthalmia, and micrognathia. Linkage studies, including HLA, are consistent with reported maps of chromosome 6.

Child, Preschool↗
PubMed1979

On the mechanism of binding of human lymphocyte products to guinea pig macrophages.

When lymphocytes from a majority of patients with cancer are incubated with encephalitogenic factor, a lymphocyte product is released that reduces the anodic electrophoretic mobilities of guinea pig macrophages and fixed, tanned sheep erythrocytes. Although these reactions are not specific for cancer, it is distinctly possible that in patients with cancer, products from stimulated lymphocytes are capable of altering the surfaces of the patients' own macrophages, thereby modifying the course of their disease. In this paper, we attempt to elucidate some mechanisms for the binding of lymphocyte products to macrophages, such as occurs in the macrophage electrophoretic mobility (MEM) test, since this may be of general interest. Binding of lymphocyte product to macrophages has been monitored by measurements of their electrophoretic mobilities and by electron microscopic determination of the density of binding of electron-dense, cationic colloidal iron hydroxide particles to their surfaces. The results show that the lymphocyte products reduce the net surface negativity of the macrophages by (coulombic) binding of this net positively charged material to sialic acids at the macrophage surface. Product-binding can be prevented by prior treatment of the macrophages with neuraminidase. It appears that only a minority of sialic acids are involved in the binding process, which occurs without demonstrable blocking of adjacent sialic acids or redistribution of such sites over the macrophage surface. Parallel experiments with fixed tanned erythrocytes also suggest that binding of lymphocyte product is not solely determined by surface sialic acids, although it cannot occur without them.

Animals↗
PubMed1979

Cardiovascular design after 'reversal' of long-standing renal hypertension in rats.

1. After 4.5 months of renal hypertension in rats renal artery 'declipping' was performed. Eight weeks afterwards paired hindquarter perfusions were performed on the declipped rats and normotensive control rats, exploring the relationships between mean arterial pressure and flow, from maximal vasodilatation to maximal vasoconstriction, induced by graded noradrenaline infusions. Left ventricular weights were measured. 2. Declipping caused a fall in mean arterial pressure from 180 to 135 mmHg, though still after 8 weeks the mean pressure was 19% higher than in normotensive control rats. 3. All parameters reflecting design and reactivity of the resistance vessels and left ventricular weight decreased significantly, but not as much as mean arterial pressure, and were still significantly increased compared with those of control rats. 4. This neither mean arterial pressure nor cardiovascular design was normalized 8 weeks after 'reversal' of long-standing renal hypertension, in contrast to short-standing renal hypertension where both are completely normalized 3 weeks after declipping.

Animals↗
PubMed1979

Women's attitudes toward gynecologic practices.

Seventy-five female students and faculty members at a community college completed a questionnaire exploring their attitudes toward gynecologic procedures, their physicians, and the discussion of sexual concerns. Eighty-five percent reported negative feelings toward the pelvic examination (anxiety, vulnerability-humiliation, and dehumanization). Forty-one percent expressed negative feelings toward their physician's behavior, while 43% reported positive feelings. Seventy-two percent would not discuss sexual concerns with their physicians. A large percentage of recommendations (87%) addressed themselves to the doctor-patient relationship rather than to procedural matters (29%). These findings recommend serious self-scrutiny and behavior change on the part of physicians. Specific recommendations to alleviate the current situation are provided by the authors, and suggestions are made for incorporating the findings into educational environments.

Attitude↗
PubMed1979

Pyruvate dehydrogenase and ATP citrate (pro-3S)-lyase activities in adipose tissue and liver of the young lean and the older obese rat.

Pyruvate dehydrogenase and ATP citrate lyase, two lipogenic enzymes, were measured in young, lean and older, obese rats. While no significant differences were observed between the livers of the two groups, both enzymes were greatly reduced in epididymal adipose tissue of older rats. A similar decrease was found in adipose tissue from the perirenal, but not from the interscapular region. Prolonged meal-feeding over a one-year period did not prevent the loss of pyruvate dehydrogenase activity in epididymal fat pads. In short term experiments of two weeks' duration this feeding regimen elevated the activities of both enzymes in adipose tissue of young but not of older rats. It is concluded that the state of activity of adipose tissue pyruvate dehydrogenase and ATP citrate lyase is at least in part responsible for the augmented lipogenesis observed in meal-fed rats and for the reduced lopogenic capacity and insulin sensitivity seen in old obese rats.

ATP Citrate (pro-S)-Lyase↗
PubMed1979

ATP citrate (pro-3S)-lyase in the rat; two-step purification procedure, properties, organ distribution.

A simple two-step procedure is described for the purification of rat liver ATP citrate lyase with an overall yield of upt to 70%. In binding experiments on Blue Sepharose CL-6B (an affinity gel for nucleotide-specific enzymes) it is observed that ATP citrate lyase recognizes ATP and CoA as well as ADP, 3'-AMP, and NADP, but not 5'-AMP, NAD, or adenosine. It is further demonstrated that ATP citrate lyase is activated by various anions including chloride, hydrogen carbonate, and acetate. The highest specific activity of the enzyme is found in adipose tissue of various origins. Activities are also present in the adrenals, in liver, and intestine, in brain, and in lung. No measurable enzyme activity is found in heart, skeletal muscle, and in the kidneys.

ATP Citrate (pro-S)-Lyase↗
PubMed1979

Dynamic aspects of cancer cell populations in metastasis.

Consideration of the entire metastatic process reveals it to be very inefficient in terms of cancer cells. Of the millions of cells released from primary cancers, relatively few metastases result. This disparity implies that in some way the process is selective. Some evidence will be reviewed that indicates that cancer cells in metastases are in some way different from those in the primary cancer from which they arose. Primary cancers and their metastases, then, should possibly be regarded as distinct entities when one is considering therapy or seeking an understanding of the fundamental aspects of metastasis. In this presentation some nonexclusive mechanisms will be discussed that could be responsible for differences between primary and secondary cancers. These include: 1) Random (statistical) selection of metastasis-forming cells; 2) The existence of genotypic metastatic subpopulations; 3) The existence of transient metastatic "compartments" within primary cancer; 4) Site-induced changes (modulation) occurring in the metastasizing cells after they arrive in the target organ; 5) A combination of the above.

Animals↗
PubMed1978

Initial tumor cell arrest in animals of defined coagulative status.

Experiments were made to evaluate the potential role played by thrombogenic factors on the hematogenous arrest of circulating tumor cells in mice with demonstrable coagulopathies associated with the presence of a primary tumor, by administration of "therapeutic" doses of anticoagulants. The effects of warfarin, aspirin and heparin administration on the early arrest patterns of 125IdUrd-labelled TA3 carcinoma and Gardner lymphosarcoma cells injected intravenously into tumor-bearing mice were examined. Several hematologic parameters of carcinoma- and lymphosarcoma-bearing animals were measured prior to anticoagulation experiments and the results indicated that mice had coagulopathies similar to those found in cancer patients with disseminated intravascular coagulation syndrome, i.e., thrombocytopenia and elevated fibrinogen levels. Despite the presence of coagulation abnormalities and effective anticoagulation in recipient animals, all three agents were without effect on localization patterns of both tumor types. It was concluded that the proposed involvement of thrombogenesis in metastasis was probably not due to any role played by those clotting factors inhibited by aspirin, warfarin and heparin in early intravascular tumor cell arrest.

Animals↗
PubMed1978

Comparison between the macrophage electrophoretic mobility (MEM) and the fixed tanned erythrocyte electrophoretic mobility (FTEEM) tests in the detection of cancer.

When peripheral lymphocytes from patients with a history of cancer are incubated with encephalitogenic factor (EF), in 90% of cases the resulting products reduce the net surface negativity of guinea-pig macrophages, used as detector cells, as revealed in the macrophage electrophoretic mobility (MEM) test. The MEM test is positive in 36% of people with no history of cancer. Formaldehyde-fixed tanned sheep erythrocytes have been used as detector cells in place of guinea-pig macrophages, in a fixed tanned erythrocyte electrophoretic mobility (FTEEM) test, with lymphocyte products identical to those used in MEM tests. In patients with a history of cancer, positive results were obtained in 28/42 cases with the FTEEM test compared with 32/42 in the MEM test. In people with no history of cancer, negative results were obtained in 16/18 cases with the FTEEM test, compared with 12/18 in the MEM test in the present series, and 51/69 in a more extensive series. These differences are not significant. Cases in which discrepancies are revealed between the two tests are discussed in terms of individual case histories.

Animals↗