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Biomedical subjects

J F Head

Publications and source records attributed to J F Head.

At least 37 records · Page 2Linked to original sources
PubMed1993

Breast carcinoma and the role of iron metabolism. A cytochemical, tissue culture, and ultrastructural study.

Transferrin receptors on proliferating and malignant cells are well documented. Iron is an essential micronutrient for cell growth that plays an important role in energy metabolism and DNA synthesis. Malignant cells requiring more iron modulate a transferrin receptor. Iron-bound transferrin interacts with this receptor, facilitating the transport of iron across the cell membrane. Transferrin is a glycoprotein and is the chief iron transport protein in mammalian blood. The more aggressive the tumor, the higher the transferrin receptor levels and the greater the proliferative index. We have found by cytochemical and ultrastructural studies that ferritin, an iron storage protein, is increased in breast cancer tissue. Anaplastic tumors have higher tissue ferritin levels. Tissue ferritin concentration may be an indirect method of measuring transferrin receptors and thus might be an index of proliferation and a prognostic indicator. Transferrin may be used as a carrier to target toxic therapy selectively to tumor tissue. A platinum transferrin complex (MPTC-63) has been developed and shown to be cytostatic in tissue culture, animal, and human studies. It also sensitizes tissue to agents that produce free radicals, such as adriamycin, and thus is synergistic with other drugs and radiation. Other transferrin complexes and conjugates of gallium, indium, and daunorubicin have also shown growth inhibition in tissue culture and animals. Human studies are in progress. By studying iron metabolism in breast cancer, we may be able to selectively inhibit tumor growth without toxic effects, and with other tumor biologic data be better able to select the stage I patient for adjuvant therapy.

Adenocarcinoma↗
PubMed1993

Rat annexin V crystal structure: Ca(2+)-induced conformational changes.

Annexins are a family of calcium- and phospholipid-binding proteins implicated in mediating membrane-related processes such as secretion, signal transduction, and ion channel activity. The crystal structure of rat annexin V was solved to 1.9 angstrom resolution by multiple isomorphous replacement. Unlike previously solved annexin V structures, all four domains bound calcium in this structure. Calcium binding in the third domain induced a large relocation of the calcium-binding loop regions, exposing the single tryptophan residue to the solvent. These alterations in annexin V suggest a role for domain 3 in calcium-triggered interaction with phospholipid membranes.

Amino Acid Sequence↗
PubMed1993

Evaluation of lymphocyte immunity in breast cancer patients.

One hundred forty-two breast cancer patients were evaluated for three functional immunologic parameters: the ability of their lymphocytes to proliferate in response to general T-(phytohemagglutinin) and B-lymphocyte (pokeweed mitogen) stimulators and their ability to proliferate in response to specific autologous tumor antigens. Tests were performed on patient blood specimens collected approximately 2 hours prior to surgery or 2-4 weeks following chemotherapy. T-lymphocyte functional competence was impaired in 83/142 (58%) of the patients, while B-lymphocyte competence was impaired in 34/142 (24%) of these patients. A total of 21/52 (40%) of the patients had lymphocyte immunity against autologous tumor antigen. There were weak associations between the ability of patients' T- and B-lymphocytes to function normally, and their ability to respond to autologous tumor-antigen. There was no relationship of age, tumor burden (clinical or pathological tumor size), extension to skin and/or muscle, or metastasis to any of the three immunological parameters. A relationship (p = 0.0463) between T-lymphocyte competence and pathological nodal status was observed; individuals that were node positive for disease, tended to have impaired T-lymphocyte function. When evaluating T- and B-lymphocyte competence and lymphocytic immunity against tumor antigen in pre- and post-chemotherapy patients, an immunologic rebound (increase in immune parameters shortly after completion of chemotherapy) was observed in some patients. These results demonstrate the utility of measuring these immune parameters in breast cancer patients, their relevance to the natural biology of the disease, and the influence that chemotherapy may have on host immune function.

Antigens, Neoplasm↗
PubMed1992

Annexin V forms calcium-dependent trimeric units on phospholipid vesicles.

The quaternary structure of annexin V, a calcium-dependent phospholipid binding protein, was investigated by chemical cross-linking. Calcium was found to induce the formation of trimers, hexamers, and higher aggregates only when anionic phospholipids were present. Oligomerization occurred under the same conditions annexin-vesicle binding. A model is proposed in which cell stimulation leads to calcium-induced organization of arrays of annexin V lining the inner membrane surface, thus altering properties such as permeability and fluidity.

Annexin A5↗
PubMed1992

Stereotaxic needle localization and biopsy of occult breast lesions: first year's experience.

During a 12-month period 115 patients with abnormal mammograms had stereotaxic needle localization and biopsy of nonpalpable breast lesions. The procedure was performed on a Fischer Mammotest II machine (Fischer Imaging; Denver, CO) and the biopsies were taken with a #18 gauge Bard biopsy needle using a Bard biopty gun (distributed by Bard Urological; Covington, GA; manufactured by Radiplast; Uppsala, Sweden). Mammographic lesions were suspicious matrix densities (85), clustered microcalcifications (22), or a combination of both (8). The pathologist recommended open biopsy in 16 per cent (18/115) of the patients. Pathology on the 18 open biopsies revealed that 11 (9 matrix densities and 2 calcifications) were carcinomas and true positives, whereas the other 7 (all matrix densities) were benign mastopathies and false positives. Further analysis of the pathologic data showed that there were three possible diagnoses from the needle biopsies on the patients that later went to open biopsy: cancer (6), very suspicious lesion (9), and slightly suspicious lesion without atypical hyperplasia (3). All 6 cancers were confirmed by open biopsy; about half (5/9) of the very suspicious lesions were cancer and none (0/3) of the slightly suspicious lesions were cancer. More cases, followed by open biopsy, are needed to refine the selection procedure for open biopsy and careful follow-up of the patients who did not have open biopsy will also be needed to determine the false negative rate. Excellent patient acceptance was found and the test was easy to perform in the office without serious complications. Furthermore, the test was cost effective because it avoided open biopsy in 97 patients.

Biopsy, Needle↗
PubMed1991

Small-angle X-ray scattering study of calmodulin bound to two peptides corresponding to parts of the calmodulin-binding domain of the plasma membrane Ca2+ pump.

The interaction between calmodulin (CaM) and two synthetic peptides, C20W and C24W, corresponding to parts of the calmodulin-binding domain of the Ca2+ pump of human erythrocytes, has been studied by using small-angle X-ray scattering (SAXS). The total length of the CaM-binding domain of the enzyme is estimated to be 28 amino acids. C20W contains the 20 N-terminal amino acids of this domain, C24W the 24 C-terminal amino acids. The experiments have shown that the binding of either peptide results in a complex with a radius of gyration (Rg) smaller than that of CaM. The complex between CaM and C20W revealed an interatomic length distribution function, P(r), similar to that of calmodulin alone, indicating that the complex retains an extended, dumbbell-shaped structure. By contrast, the binding of C24W resulted in the formation of a globular structure similar to those observed with many other CaM-binding peptides.

Amino Acid Sequence↗
PubMed1991

Small-angle X-ray scattering studies of calmodulin mutants with deletions in the linker region of the central helix indicate that the linker region retains a predominantly alpha-helical conformation.

Two mutant forms of calmodulin were examined by small-angle X-ray scattering in solution and compared with the wild-type protein. Each mutant has deletions in the linker region of the central helix: one lacks residues Glu-83 and Glu-84 (Des2) and the other lacks residues Ser-81 through Glu-84 (Des4). The deletions change both the radii of gyration and the maximum dimensions of the molecules. In the presence of Ca2+, the observed radii of gyration are 22.4 A for wild-type bacterially expressed calmodulin, 19.5 A for Des2 calmodulin, and 20.3 A for Des4 calmodulin. A reduction in the radius of gyration by 1-2 A on removal of calcium, previously observed in the native protein, was also found in the wild type and the Des4 mutant; however, no significant size change was observed in the Des2 mutant. The large calcium-dependent conformational change in calmodulin induced by the binding of melittin [Kataoka, M., Head, J.F., Seaton, B.A., & Engelman, D.M. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 6944-6948] was observed in all the bacterially expressed proteins. Each protein appears to undergo a transition from a dumbbell shape to a more globular conformation on binding melittin in the presence of calcium, although quantitatively the changes in the wild-type and Des4 proteins greatly exceed those in Des2. Modeling shows the central linker region of the molecule. Thus, the structure of the linker region is stable enough to maintain the average orientation and separation of the lobes yet flexible enough to permit the lobes to approach each other upon binding a peptide.

Amino Acid Sequence↗
PubMed1991

Enzymic composition and growth rate of human pleural mesothelioma transplants in nude mice.

The enzymic composition of 7 human mesothelioma lines propagated in nude mice was compared with 4 of the original and 15 additional mesotheliomas sampled during the patients' surgery. The xenografts exhibited several-fold higher thymidine kinase (TK), uridine kinase (UK), phosphoserine phosphatase (PSP) and peptidyl proline hydroxylase (PPH) concentrations than the fresh human samples, while their DNA, gamma-glutamyl transpeptidase (GGT) and beta-galactosidase (Bgal) contents remained similar. The volume growth rate of the xenografts (doubling time, DT = 9.23 +/- 1.25 days) was much faster than that of tumors in the human host, and the decline of this rate with increasing nodule size was accompanied by decreases in TK and PSP concentrations. This first quantitative biochemical study of xenografted human neoplasms indicates that 1) pleural mesotheliomas, though preserving their histological characteristics after heterotransplantation, show considerable increases of enzymes in nucleic acid, collagen, and nonessential amino acid synthesis, and that 2) the concentration of TK is a good indicator of the different growth properties of tumors in a mouse rather than in the human host.

Animals↗
PubMed1990

Purification, crystallization, and preliminary X-ray diffraction analysis of rat kidney annexin V, a calcium-dependent phospholipid-binding protein.

We have purified annexin V, a monomeric 35-kDa protein, from rat kidney using calcium-dependent phospholipid chromatography. The identity of annexin V was confirmed by immunoblot analysis using monospecific anti-annexin V antibody. Large single crystals of annexin V in the presence of calcium have been grown from ammonium sulfate under a variety of conditions, with an optimum pH range of 7.5-8.0. The crystals diffract to at least 2.2 A Bragg spacing and are stable to x-rays. Preliminary crystallographic analysis reveals the space group to be R3, with hexagonal cell dimensions of a = b = 156.8 A and c = 36.9 A, and there is one molecule/asymmetric unit.

Animals↗
PubMed1989

Amino acid sequence of a low molecular weight, high affinity calcium-binding protein from the optic lobe of the squid Loligo pealei.

The amino acid sequence was determined for squid calcium-binding protein (CaBP), a low molecular weight, high affinity calcium-binding protein from squid optic lobe. The sequence shows this protein to consist of 149 amino acids with an N-acetylated N terminus. The protein has a molecular weight of 16,894 and is homologous to calmodulin, which is also present in squid optic lobe (Head, J. F., Spielberg, S., and Kaminer, B. (1983) Biochem. J. 209, 797-802). When the sequences of squid CaBP and bovine brain calmodulin are appropriately aligned, the proteins are found to share 68% identity, with a single residue insertion in squid CaBP, between domains III and IV. The four-domain structure of calmodulin appears to be retained in squid CaBP, which is consistent with the previously reported presence of four calcium-binding sites per molecule (Sheldon, A., and Head, J. F. (1988) J. Biol. Chem. 263, 14384-14389). The two tyrosines of squid CaBP are located in different halves of the molecule, one at the position corresponding to Tyr-138 in calmodulin, the other in an equivalent position in domain II. In addition, squid CaBP exhibits several differences in the region corresponding to the long central helix of calmodulin. These differences include the replacement of Lys-77 by glycine, Asp-78 by proline, and Ser-81 by proline. The sequence of this portion of the squid CaBP molecule suggests the protein is unlikely to possess the continuous long central helix found in calmodulin.

Amino Acid Sequence↗
PubMed1989

Neutrophil maturation and hypersegmentation promoted in normal bone marrow by a carcinoma-elaborated protein factor.

In rats with subcutaneously transplanted mammary carcinoma 5A (MC) and 2 to 10-fold elevations in the blood content of mature neutrophils, 30-50% of the neutrophils showed pronounced hypersegmentation. This phenomenon could be reproduced in liquid culture of bone marrow cells from normal (tumor-free) animals by 48 hr incubation with the MC host's serum, or with MC-conditioned medium whose activity was attributable to an over 50,000 MW protein. The effects in vitro, occurring without change in total cell number and accompanied by increases in gamma-glutamyltranspeptidase (GGT) and alkaline phosphatase (AP) activity, included decreases in the percents of progenitors (myeloblasts, promyelocytes, myelocytes, metamyelocytes and bands) and an increase in mature neutrophils 50% of which exhibited obvious hypersegmentation. Much less if any neutrophil hypersegmentation, and no statistically significant decrease in immature cells, occurred in response to the several colony stimulating factors (CSFs) tested, although (in addition to inducing GGT and AP) some CSFs did cause an increase in mature neutrophils. These investigations demonstrate the efficacy of a MC-elaborated blood-borne protein to promote myeloid cell maturation, and describe a system for the first time in which neutrophil hypersegmentation can be studied in vitro.

Animals↗
PubMed1989

Melittin binding causes a large calcium-dependent conformational change in calmodulin.

The interaction between calmodulin and its target protein is a key step in many calcium-regulated cellular functions. Melittin binds tightly to calmodulin in the presence of calcium and is a competitive inhibitor of calmodulin function. Using melittin as a model for the target peptide of calmodulin, we have found a large Ca2+-dependent conformational change of calmodulin in solution induced by peptide binding. Mg2+ does not substitute for Ca2+ in producing the conformation change. Small-angle x-ray scattering has shown that calmodulin exists as a dumbbell in solution, similar to that observed in the crystalline state. Our present measurements reveal that the overall structure of the Ca2+-calmodulin-melittin complex is not a dumbbell but a globular shape. Upon binding melittin, the radius of gyration decreases from 20.9 to 18.0 A and the largest dimension decreases from 60 to 47.5 A. In the absence of calcium, however, melittin has little effect on the solution structure of calmodulin.

Animals↗
PubMed1988

Calcium-binding properties of two high affinity calcium-binding proteins from squid optic lobe.

We have studied the calcium-binding properties of two high affinity calcium-binding proteins from squid optic lobes: one, squid calmodulin (SCaM), similar to bovine brain calmodulin (BCaM), the other, squid calcium-binding protein (SCaBP), distinct (Head, J.F., Spielberg, S., and Kaminer, B. (1983) Biochem J. 209, 797-802). Equilibrium dialysis measurements on the squid proteins (and BCaM) were made at 100 mM KCl in the presence and absence of 3 mM Mg2+, and at 400 mM KCl in the presence of 3 mM Mg2+, which more closely resembles the conditions in the squid. SCaM, SCaBP, and BCaM each bind a maximum of 4 Ca2+ ions/molecule of protein under the ionic conditions tested. SCaBP has a higher affinity than SCaM or BCaM for Ca2+ at 100 mM KCl in the absence of Mg2+. However, in the presence of Mg2+, half-maximal binding to SCaBP occurs at a similar pCa value to that observed with calmodulin. Increasing the KCl concentration reduces the affinity of all three proteins for Ca2+. UV absorption measurements showed that the binding of 4 Ca2+ ions/molecule is necessary to complete spectral changes in SCaBP, compared to two for the calmodulins. While Ca2+ causes perturbations in aromatic chromophores in SCaM and SCaBP, Mg2+ causes a significant perturbation only in SCaBP. These Mg2+-induced changes differ qualitatively from those induced by Ca2+.

Animals↗
PubMed1988

Identification of a calsequestrin-like protein from sea urchin eggs.

Following studies on calcium transport by isolated smooth endoplasmic reticulum from unfertilized sea urchin eggs (Oberdorf, J. A., Head, J. F., and Kaminer, B. (1986) J. Cell Biol. 102, 2205-2210) we have purified and partially characterized a calsequestrin-like protein from this organelle isolated from eggs from Strongylocentrotus droebachiensis and Arbacia punctulata. Muscle calsequestrin from sarcoplasmic reticulum is well characterized as a calcium storage protein. The egg protein resembles calsequestrin in its behavior in purification steps, electrophoretic mobility, blue staining with Stains-all on polyacrylamide gels, and its calcium binding and amino acid composition. Purification was attained with DEAE-cellulose and hydroxyapatite chromatography. The egg protein Mr of 58,000 in the Laemmli gel system is reduced to 54,000 under Weber-Osborn (neutral) conditions, thus showing a pH dependence in its mobility, although less than occurs with muscle calsequestrins. 25% of its amino acids are acidic and 10% basic. It binds 309 nmol of Ca2+/mg of protein, within the range reported for cardiac calsequestrin. Antigenically, the sea urchin egg protein is related to cardiac calsequestrin capable of binding anti-cardiac calsequestrin antibody.

Amino Acids↗
PubMed1988

Enhancement of gamma-glutamyl transpeptidase expression in bone marrow cells by colony stimulating factors.

Studies on blood serum from mammary carcinoma (MC) hosts, which promoted gamma-glutamyl transpeptidase (GGT) expression by normal rat bone marrow cells in liquid culture, were extended to various granulocyte-macrophage colony stimulating factors (CSFs). GGT concentration per cell was found to increase (without change in total cell number) by incubation for 48 h with purified CSF-2 gamma and CSF-1 (but not interleukin-3), with human giant cell elaborated GM-CSF and L-cell conditioned medium, as well as with the 3 MC preparations (host serum, MC extract and MC conditioned medium). GGT-inducing ability (per milligram protein) ranked the 7 preparations in the same order as did their proliferative effect (number of colonies per milligram protein) in the standard mouse bone marrow agar culture system. The quantitative correlation between these two kinds of activities (linear for their logarithmic values) was highly significant, r = 0.976, p less than 0.001. The alkaline phosphatase concentration of bone marrow cells in liquid culture was also increased in the presence of the same 7 preparations, and this again was proportional (r = 0.985, p less than 0.001) to their colony stimulating potential.

Animals↗