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Biomedical subjects

L Weiss

Publications and source records attributed to L Weiss.

At least 523 records · Page 29Linked to original sources
PubMed1977

The macrophage electrophoretic mobility test: Results on carcinoma of the colon and rectum.

The macrophage electrophoretic mobility (MEM) test was performed on guinea-pig macrophages treated with the interaction products of encephalitogenic protein and peripheral lymphocytes from 44 patients with colorectal cancer and 33 "healthy" controls. In 54/60 tests involving patients, statistically significant reductions in electrophoretic mobilities were observed, compared with 12/33 in controls. Our overall results on the reductions in macrophage mobilities by lymphocyte products are in accord with the work of some other workers, but not all. In contrast to many other studies, the standard procedures used here to express the results should permit an exchange of data on an international basis and allow a more rapid, general appraisal of the MEM test.

Adult↗
PubMed1977

Colloidal iron hydroxide-binding to the surfaces of chick embryo fibroblasts transformed by wild-type and a temperature-sensitive mutant of Rous sarcoma virus.

The densities of colloidal iron hydroxide (CIH) particles binding to the surfaces of chick embryo fibroblasts were determined before and after transformation with wild type Rous sarcoma virus and a temperature sensitive (ts) mutant of this virus. On the basis of in vitro behavior, cells transformed by the ts virus manifest a malignant phenotype at 36 degrees C (permissive temperature) and appear normal at 41 degrees C (non-permissive temperature). At the permissive temperatures there is a significant increase in CIH particle-binding to spaces of cell surface between microvilli on the wild type and ts transformed cells. At the non-permissive temperature this significant increase in binding is only observed on the wild type transformant, while the density found on the ts transformant is not significantly different from the untransformed state. Therefore, in vitro characteristics of normalcy and malignancy are reflected in changes in the CIH binding properties of the cell surface spaces between microvilli. The CIH densities observed on the microvilli are significantly different from the density on the spaces between them for each of the classes of cells studied at either temperature. The microvilli are found to bind a lower density of particles in five of the six cases. No correlations between microvilli particle density and transformation to in vitro malignant characteristics were observed.

Animals↗
PubMed1977

Mechanisms of spontaneous hypertension in rats.

Studies on the Kyoto (SHR) and the New Zealand (GHR) strains of genetically predisposed hypertensive rats have shown that in the SHR neurogenic influences, primarily of higher central origin, play an important role in the initiation of hypertension. Studies on human essential hypertension indicate that this may also be true for man, although it is far from being the sole explanation. Brookhaven hypertension-prone rats illustrate the interaction between genetic and exogenous factors since they require an overload of salt for the development of high blood pressure. The Milan hypertensive rats (MHS), on the other hand, illustrate a genetic deviation of renal function with imbalance between glomerular filtration and tubular resorption of sodium and water, which may simulate at least some variants of the relatively mild forms of low renin hypertension in man. Structural adaptive vascular changes have been demonstrated in SHR and GHR and in nongenetic renal hypertension in rats, and there are several indications of their presence in MHS. Thus, regardless of the nature of the initiating factors, these secondary but rapidly established changes occur and greatly contribute to the maintenance and acceleration of the hypertensive state. The vascular changes can even be regarded as a common denominator for chronic hypertension and serve as an element which, in fact, reinforces the initiating mechanisms. The progress of the vascular changes can be interfered with by reducing the pressure load. Lowering the blood pressure by pharmacologic treatment is most effective when the treatment is initiated as such an early age when the cardiovascular structural adaptation is still minimal. Treatment in later phases is less successful since the adaptive increases in cardiac and vessel wall thickness can then no longer be fully normalized by pressure reduction because of increased amounts of collagen and other connective tissue elements in the vessel wall, which regress poorly. An increased wall thickness of the resistance vessels implies a vascular hyperreactivity to constricting influences which, in turn, rapidly brings the blood pressure back to supranormal levels as soon as therapy is stopped.

Animals↗
PubMed1977

The antigen-induced degranulation of basophil leukocytes from atopic subjects studied by electron microscopy.

Suspensions of washed leukocytes were prepared from the blood of atopic subjects and incubated with diluent, ragweed antigen E or rye grass group I antigen. Histamine release into the suspending medium was measured and directly correlated with changes in the ultrastructure of basophil leukocytes from the same tubes. Incubation of leukocytes with either diluent or an antigen to which the donor was not hypersensitive caused no significant histamine release and the morphology of the basophils was unaltered. By contrast, incubation of leukocytes with an intigen to which the donor was hypersensitive caused substantial histamine release and characteristic morphologic changes in the basophils, many of which underwent exocytotic degranulation. Degranulated human basophils showed the following features: (1) an irregular surface, to which platelets and leukocytes were often adherent; (2) reduction in the number of basophilic granules; (3) residual granular material, both in exocytotic cavities and at the cell surface; (4) coated vesicles and cisternae of smooth endoplasmic reticulum, frequently related to the plasma membrane at sites of exocytosis; (5) thin membrane-bounded granules appeared unaltered; (6) no consistent change was observed in centrioles, microtubules, 90 A filaments, mitochondria, or multivesicular bodies, and degranulated basophils appeared ultrastructurally viable; (7) in reaction cell suspensions, nondegranulated basophils often showed a more active contour than control cells; both reacting but nondegranulated basophils and degranulated basophils sometimes showed localized filamentous webs at their periphery.

Antigens↗
PubMed1977

The origin and behavior of two isodicentric bisatellited chromosomes.

Karyotyping revealed three cell lines in a boy with mental retardation and few other abnormalities. Thirty cells exhibited a normal karyotype, and 54 had an extra acrocentric chromosome of E group size with satellites on the long and short arms. The remaining 20 cells each had, in addition to the first marker (M1), a second tiny bisatellited chromosome (M2). C-banding demonstrated that both markers were dicentric. G-, C-, and Q-banding and satellite association data were consistent with the markers having originated from chromosome 15 material. We propose that M1 was formed from a meiotic breakage and a chromatid fusion in the proximal long arms of an acrocentric pair. This would have produced a symmetrical isodicentric chromosomes, plus one or two acentric fragments. M2 then could have resulted from a dicentric bridge-break-synthesis-reunion phenomenon. This model of abnormal meiotic exchange can be generalized to encompass the formation of other dicentric isochromosome cases of isochromosome X.

Azure Stains↗
PubMed1976

The immunospecificity of altered initial arrest patterns of circulating cancer cells in tumor-bearing mice.

The early arrest patterns of a methylcholanthrene-induced fibrosarcoma were determined after injection of 125IUdR-labelled cells into the systemic circulation of mice bearing transplanted lymphosarcomas, and of normal animals. Similar experiments were performed using radiolabelled lymphosarcoma cells and normal or fibrosarcoma-bearing mice. The results showed that shifts in normal distribution patterns previously observed in tumor-bearing animals injected with cells of the same type as that borne by the animal, were not detectable when cells of a different tumor type were injected. Peritoneal exudate cell migration inhibition assays showed little immunologic cross-reactivity between the two tumors and, together with the results of the distribution studies, indicated that alterations of early arrest patterns in mice sensitized to their tumor is an immunologically specific phenomenon.

Animals↗
PubMed1976

Frontometaphyseal Dysplasia. Evidence for dominant inheritance.

A 10-year-old boy with mixed bilateral hearing loss and unusual facies was found to have frontometaphyseal dysplasia. He has prominent supraorbital ridges, height-span disproportion, dental abnormalities, thick clavicles, pectus excavatum, winged scapulae, joint contractures, and generalized muscular underdevelopment. Roentgenograms show supraorbital hyperostosis, antegonial notching of the mandible, flared ilia, contraction of the midpelvis, flattened vertebrae, deformities of the ribs posteriorly, flared metaphyses of the long tubular bones, and greatly widened and elongated metacarpals, metatarsals, and phalanges. His mother has prominent supraorbital ridges, distinct scoliosis, contractures of the fifth fingers, and conductive hearing loss. She also has many of the roentgenographic features of frontometaphyseal dysplasia. Frontometaphyseal dysplasia in a mother and son strongly suggests a dominant mode of inheritance.

Adult↗
PubMed1976

The hematopoietic microenvironment of the bone marrow: an ultrastructural study of the stroma in rats.

The bone marrow contains branching vascular sinuses lying in a fibroblastic stroma which supports hematopoiesis. This paper describes the stroma and vascular sinuses by scanning and transmission electron microscopy and in freeze-fracture etch replicas in normal fat femoral marrow and in rats made eosinophilic by larvae of trichinella spiralis. The stroma consists primarily of reticular cells which ensheath sinuses as adventitial cells and branch into the surrounding hematopoietic space. They form a spongework on which hematopoietic cells are arranged. Erythroblasts, clustered into islets, and megakaryocytes lie just outside sinuses. Granulocytes, until the metamyelocyte stage, lie in the midst of the hematopoietic cords. Lymphocytes, monocytes and likely stem cells, are clustered about arterial vessels. Macrophages occur throughout the marrow. Fat cells occur adventitial to vascular sinuses and appear to be reticular cells which accumulate fat. Processes of reticular cells closely envelope hematopoietic cells or protrude into them. Reticular cells contain rough ER and are likely fibroblastic. The argyrophilic reticular fibers of the marrow are, however, slender and scanty. Reticular cells are rich in filaments and they may contain many microtubules. They are not phagocytic and possess few lysosomes. The reticular cell cover of a vascular sinus is lifted away as maturing hematopoietic cells approach the sinus, preparatory to crossing the endothelium and entering the circulation. Maturing granulocytes often show microvilli on reaching the basal endothelial surface. The level of eosinophils in the marrow may increase from approximately four to more than 20% after injection of trichinella larvae. Close distinctive association of reticular cells and eosinophils are marked. Reticular cells provide a physical spongwork on which hematopoietic cells are supported. But I postulate that they also trap and induce differentiation of hematopoietic stem cells, and sort the differentiating hematopoietic cells into characteristic locations in their spongework.

Animals↗
PubMed1976

Craniosynostosis, midfacial hypoplasia and foot abnormalities: an autosomal dominant phenotype in a large Amish kindred.

An unusual spectrum of craniofacial and foot abnormalities has been detected within a large midwestern Amish kindred. Enlarged great toes and craniofacial abnormalities suggested Pfeiffer acrocephalosynadactyly type V; however, thumb abnormalities were not present. Eighty-eight affected individuals were observed and another 50 were reliably reported to be affected. An autosomal dominant inheritance pattern was observed associated with variable expressivity. All affected individuals had some clinical or radiologic abnormality of the feet. The phenotypic expression was so variable that the entire spectrum of dominantly inherited craniofacial dysotoses-acrocephalosyndactylys (except the typical Apert syndrome) was seen within this kindred.

Child, Preschool↗
PubMed1976

Some effects of positively charged surface groups on cell aggregation.

A study was made of the effects of 2,3-dimethylmaleic anhydride (DMA), a reagent removing positive charges, on the aggregation and surface charge of embryonic chick neural retina cells. Neural retina cells, recovered from the dissociation procedure, were cultured on a gyratory shaker and the aggregate dimaeters formed in the presence of DMA or DMA-serum dialysate, following DMA-pretreatment, or in appropriate control cultures measured. The electrophoretic mobilities of similarly treated cells were also determined. In addition, cellulose acetate electrophoresis was carried out on samples of serum containing DMA, and the incorporation of 14C-amino acids into DMA-treated cells studied. Aggregates formed in the presence of DMA, or following DMA-pretreatment, were significantly smaller than aggregates from control cultures. The electrophoretic mobility of DMA-treated cells was significantly increased in serum-containing medium, but not serum-free Hanks' solution. At 24 h after removal of DMA-containing medium, the mobilities of pretreated cells were similar to those of controls. The electrophoretic pattern of DMA-treated serum was changed only with concentrations of DMA many times that affecting cell aggregation or mobility. DMA-serum dialysate did not significanlty reduce aggregate size. The incorporation of 14C-amino acids in DMA-treated cells and the structure of aggregates were unchanged from controls. It is concluded that positively charged consituents of the cell periphery play a demonstrable, but not limiting, role in cell aggregation, while a minor role for positive charges on serum protein cannot be totally excluded.

Amino Acids↗
PubMed1976

The sandwich holder.

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Cooking and Eating Utensils↗