Cell interactions controlling morphogenesis and gene expression in Dictyostelium.
Explore the source record for details and available documents.
Biomedical subjects
Publications and source records attributed to H Kim.
Explore the source record for details and available documents.
Serologic tests for amebiasis, utilizing antigens prepared from Entamoeba histolytica HK-9, axenic culture in Diamond's media, have demonstrated reproducible results with good clinical correlation. The indirect hemagglutination test was positive in 100 per cent of all cases with hepatic abscess, in 99 per cent of cases of amebic dysentery and in 60 per cent of asymptomatic carriers. A population of uninfected subjects yielded less than 1 per cent of individuals with demonstrable amebic antibodies. Similarly, the complement fixation test was 100 per cent positive for the liver abscess, 91 per cent positive for patients with amebic dysentery, 23 per cent positive for asymptomatic carriers, and 0 per cent positive for the uninfected control group. The antibody responses to amebic antigens are discussed.
Explore the source record for details and available documents.
One hundred and twenty-six cases of nodular lymphoma have been classified cytologically by the criteria of Rappaport, and have been divided into three architectural groups, based on the degree of nodularity. Eighty-five percent of the patients have been followed for at least 5 years after initial therapy. Analysis of actuarial survival curves reveals that patients in the poorly differentiated lymphocytic and mixed histiocytic-lymphocytic categories with the three architectural patterns ("nodular only," "nodular with focal diffuse," and "nodular with diffuse") have similar long-term and disease-free survivals. Nevertheless, any degree of nodularity imparts a more favorable prognosis than diffuse lymphoma of coreresponding cell type. In the small number of patients with a nodular lye than in the other two histiocytic type, associated with diffuse areas, the prognosis is less favorable than in the other two histologic groups. Thus, a nodular lymphoma of so-called histiocytic type with diffuse areas may behave more like a diffuse than nodular lymphoma, and warrants appropriate therapy.
The cyclic AMP metabolism of cultured epithelial cells was investigated. Epinephrine or 1-methyl,3-isobutylxanthine (MIX) alone had no effect on cyclic AMP levels in intact cells, whereas the combination of the two agents yielded a 6- to 10-fold increase in cyclic AMP levels. Both basal and stimulated cyclic AMP levels decreased with increasing cell density. Cell-free adenylate cyclase preparations were stimulated markedly by epinephrine or isoproterenol in the absence of MIX. Since the epithelial cells were found to have a relatively small amount of cyclic nucleotide phosphodiesterase (PDE) activity, the requirement for MIX to visualize intact cell responsiveness to epinephrine could be explained only partially by its PDE inhibitory properties.
Characterization of the cyanogen bromide (CNBr) fragments of the beta chain of human haptoglobin revealed five major fragments resulting from cleavage of four methionyl residues. The fragments were isolated by gel filtration in guanidine-HCl on Sepharose 6B and Bio-Gel P10 and P60. Compositional analyses of the five cyanogen bromide fragments accounted for 248-253 amino acid residues in agreement with the number of residues determined for the intact beta chain. Most of the carbohydrate was attached to CNBr II. Automated amino-terminal sequence analysis and carboxyl-terminal hydrolysis with carboxypeptidase of the haptoglobin beta chain and cyanogen bromide fragments identified 139 residues, or about 55% of the beta-chain molecule. The placement of the fragments within the beta-chain molecule was established by sequence analysis of whole beta chain and a plasmin cleavage fragment. The position of CNBr V was confirmed by the absence of homoserine or homoserine lactone. Cyanogen bromide reaction of intact haptoglobin 1-1 resulted in the isolation of a beta-chain fragment, CNBr III, covalently attached to the intact alpha1 chain by a single disulfide bond. The beta chain was shown to have primary structural similarities to the chymotrypsin family of serin eproteases. Partial sequence analysis of CNBr V established the region which is comparable to the serine-195 active-site region: /Asp-Thr-Cys-Tyr-Gly-Asp-Ala-Gly-Ser-Ala-Phe/ (residues 189-199, chymotrypsinogen A numbering). The active-site serine-195 is replaced by alanine; however, the specificity residue of the trypsin-like enzymes, Asp-189, is preserved. Several minor cyanogen bromide cleavage products were also identified in yields of up to 15%. These minor cleavage products give evidence that tryptophanyl residues in proteins, or glycoproteins, are also susceptible to cyanogen bromide cleavage.
Dimer-tetramer association constants (K2,4) of derivatives of CO-hemoglobins A and S specifically carbamoylated at the NH2-terminal valine residues were measured. Reactivites of the beta-93 sulfhydryls of the hemoglobin A derivatives were also investigated. As compared with the association constants of the parent molecules, the values of K2,4 of both hemoglobin types are raised by carbamoylation of the alpha-chain NH2 terminus, lowered by carbamoylation of the beta-chain NH2 terminus, and raised by carbamoylation of both termini. The apparent second-order rate constant for reaction of p-mercuribenzoate (PMB) with the beta-93 sulfhydryls is, however, unchanged by carbamoylation. These two observations are interpreted to indicate that in the liganded molecule structural changes are produced at the interface between dimers but not in the region of the beta-93 sulfhydryls. From the combination of the K2,4 measurements with ligand-binding data for the same derivatives (Kilmartin, J. V., et al. (1973), J. Biol. Chem. 248, 4039; Nigen, A. M., et al. (1974), J. Biol. Chem. 249, 6611) the carbamoylation-induced changes in the dimer-tetramer association constants of the unliganded derivatives were estimated to be of magnitude equal to or smaller than those in K2,4. It is concluded that much of the change in oxygen affinity that occurs upon carbamoylation of hemoglobins A and S can be accounted for without invoking extensive structural changes in the unliganded molecule.
Explore the source record for details and available documents.
Intracranial heterotransplantation in the nude, athymic mouse has been found to be an effective method for the experimental growth of human malignant lymphomas. Transplants of 11 primary lymphomas and six derived cell lines yielded a high take rate (90%) and a low mean latent period (36 days). Relatively small inocula produced extensive intracerebral infiltrates which could be identified as human in origin by immunofluorescence. Although confined to the central nervous system and meninges, the tumors were highly invasive and displayed morphologic features strikingly similar to those of the original primary tumors. Heterotransplantation of the lymphomas to extracranial sites was only rarely successful. Nude mice previously grafted with isologous neonatal thymuses failed to develop intracerebral tumors. Secondary cell cultures successfully established from several of the intracranial heterotransplants were found to be infected with NIH type-C xenotropic virus. The distinctive growth patterns and other neuropathologic features of the heterotransplants are described, and the relevance of these observations to the development of intracerebral lymphomas in immunosuppressed organ transplant recipients is noted. This method of studying human malignant lymphomas in vivo may permit better histopathologic characterization of the tumors, and may serve as a basis for further experimental lines of investigation, including viral, immunologic, and therapeutic studies.
Among the malignant lymphomas of the diffuse, poorly differentiated lymphocytic type, a cytologically distinctive form can be recognized. It is composed of immature lymphoid cells that are indistinguishable from the cells of acute lymphoblastic leukemia (ALL). Although these neoplasms usually have been classified as malignant lymphoma, lymphoblastic type, they contain, in addition to lymphoblasts, prolymphocytes in varying proportions. On the basis of the nuclear morphology, malignant lymphoma of the lymphoblastic type, (MLLB) can be further divided into those with and those without convoluted nuclei. In our series both groups had the following clinical features in common: 1) frequent occurrence in children and adolescents; 2) clinical presentation with mediastinal masses in 50% of cases; 3) a high incidence of bone marrow and perpheral blood involvement during the course of the disease; and 4) rapid progression of the disease with a median survival of 8 months. Our observations indicate that nuclear convolutions are helpful but not essential for the recognition of a clinicopathologic entity which is histologically and cytologically characterized by 1) the immaturity of the lymphoid cells indistinguishable from the lymphoblasts and prolymphocytes of ALL and 2) a high mitotic index. Because of the frequency with which MLLB progresses into ALL, systemic therapy may be indicated even before this progression is hematologically evident. This indicates the need for morphologic recognition of this malignant lymphoma regardless of the presence of nuclear convolution, age of the patient, and site of presentation.
Explore the source record for details and available documents.
The clinical records and histologic material from 29 cases of malignant histiocytosis (MH) have been reviewed, as well as autopsy findings in 14 cases. The mean age was 31 years, with a 2.2:1 male to female preponderance. Major physical findings included temperature elevation, lymphadenopathy, hepatomegaly, splenomegaly, and preterminal jaundice. Common laboratory findings were anemia, leukopenia, and thrombocytopenia. The median survival was 6 months, the mean 14 months, and the range from 1 month to 8 years. The histologic features observed in lymph nodes, liver, spleen, and bone marrow have been emphasized, as well as features useful in differential diagnosis. In contrast to our experience with the non-Hodgkin's lymphomas, bone marrow aspiration was superior to biopsy in assessing marrow involvement. Unusual manifestations included soft tissue infiltration in 5 cases; 2 of these patients presented with a soft tissue mass. The distinctive clinical as well as histologic findings warrant recognition and separation of MH from other hematopoietic disorders.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.