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Biomedical subjects

S Hamada

Publications and source records attributed to S Hamada.

At least 325 records · Page 18Linked to original sources
PubMed1988

Primary thyroid lymphoma: evaluation with CT.

The appearance of primary thyroid lymphoma on computed tomographic (CT) scans and clinical data for 15 patients were analyzed. The CT appearances were classified into three types: 12 patients (80%) had a solitary nodule (type 1), two (13%) had multiple nodules (type 2), and one (7%) had a diffuse goiter (type 3). In 47% of cases, both lobes were involved. The tumors had a strong tendency to compress (80%) or infiltrate (53%) the surrounding structures. The frequency of calcification (7%) or necrosis (7%) was low. Most patients (87%) had a rapidly enlarging thyroid mass, and six (40%) complained of symptoms from obstruction. All patients had coexistent Hashimoto thyroiditis. In 13 of 15 patients (87%), a highly probable diagnosis of thyroid lymphomas was determined with CT and clinical findings. A staging workup with CT and clinical findings confirmed at biopsy will allow appropriate therapy and may lead to improved prognosis for patients with this condition.

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PubMed1988

Intracardiac malignant lymphoma detected by gallium-67 citrate and thallium-201 chloride.

An abnormal uptake of 67Ga and 201Tl in the right atrium was observed initially in a 77-yr-old man with superior vena cava syndrome. The pathological diagnosis of the surgically resected specimen was non-Hodgkin's malignant lymphoma in the right atrium. Thallium-201 is used as an imaging agent for malignant tumors. However, previous reports suggested that 201Tl scintigraphy may not be a useful method to detect cardiac involvement in patients with malignant neoplasms. In this case both 201Tl and 67Ga accumulation was observed in the intracardiac tumor by scintigraphy.

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PubMed1987

Streptococcal serotype carbohydrate represents a novel class of type 2 antigen which is T-independent.

Our studies reported here, fully characterize two unique type 2 antigens trinitrophenol (TNP)-M1 serotype carbohydrates (TNP-M1 g and TNP-M1 c) derived from streptococci, which fail to induce antibody responses in xid or neonatal mouse splenic cultures. These antigens generate brisk responses in normal spleen and Peyer's patch cell cultures of xid mice, all of which suggest that responses are elicited in the Lyb-3+, 5+ B subpopulation. The antibody responses to TNP-M1 g (and TNP-M1 c) are not dependent upon T cells. Furthermore, TNP-M1 carbohydrates induce anti-TNP plaque-forming (PFC) responses in cultures of small, resting splenic B cell populations without an added T cell requirement. Thus two categories of type 2 antigens are distinguished, one which requires T cells or derived factors, e.g., TNP-Ficoll, and a second TNP-carbohydrate antigen TNP-M1 that does not. Studies of the mitogenic and polyclonal B cell activation properties of M1 carbohydrates indicated that B cell proliferation is induced in both xid (Lyb-3-, 5-) and normal (Lyb-3-, 5- and Lyb-3+, 5+) splenic B cell subpopulations, but that differentiation to IgM synthesis fails to occur in the Lyb-3-, 5- B cell subpopulation. Thus M1 carbohydrates are unique probes that allow the selective induction of proliferation and differentiation of mature B cells that are presumably Lyb-3+, 5+. Because the M1 serotype carbohydrates induce polyclonal IgM synthesis and antigen-specific responses in only the mature B cell population in the absence of T cells, whereas TNP-Ficoll and other type 2 antigens require T cells or their derived factors, the Lyb-3+, 5+ B cell subpopulation may consist of a T cell-dependent and a T cell-independent compartment for responses to different carbohydrate type 2 antigens.

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PubMed1987

[Studies on cytosol thyroid hormone binding proteins in the rat liver: Part I. Stability and binding characteristics of thyroid hormone binding proteins].

Many studies demonstrated the presence of cytosolic thyroid hormone binding proteins (CTHBPs) in various tissues, but the physiologic significance of these CTHBPs is not clear, partially because of the lack of information about the physicochemical properties of CTHBPs as purified forms. Since the difficulty in isolating these CTHBPs is considered to be due to instability during the various procedures for their isolation, studies on the stability of CTHBPs of rat liver were performed using a charcoal binding method to separate bound and free hormones. Binding characteristics of CTHBPs of rat liver were also determined. Specific triiodothyronine (T3) binding sites of cytosolic T3 binding protein (CT3BP) of rat liver were destroyed as the time progressed in homogenate at 0 degrees C, and Aprotinin (500 U/ml) had little effect in protecting these binding sites. T3 binding sites were stable in the form of cytosol at -20 degrees C up to 10 weeks. Dithiothreitol (DTT) had no effect on T3 binding to cytosol. T3 binding to CT3BP was pH-dependent with maximum specific binding at pH 7.4. T3 binding to CT3BP was stable at 4 degrees C overnight but was destroyed rapidly at 37 degrees C. Interestingly, specific T3 binding sites of CT3BP were completely abolished by dialysis, and Ca2+ or Mg2+ had no effect on retaining the specific binding sites. Thus, CT3BP was supposed to require some dialysable small molecule(s) to maintain specific T3 binding sites. Scatchard plot of T3 binding to crude cytosol revealed a high affinity, limited capacity T3 binding site with affinity constant (Ka) of 5.9 X 10(7) M-1 and maximum binding capacity (MBC) of 118 ng/g. liver. Relative affinities of T3 analogues for CT3BP were determined by comparing the molar concentrations of T3 analogues required for 50% inhibition of tracer 125I-T3 binding. If the affinity of L-T3 was assigned 100, D-T3 would have a value of 66.1; L-T4, 22.3; D-T4, 16.5; Triac, 6.2; and both Tetrac and reverse T3 were less than 1. Thus, the binding characteristics of CT3BP were fundamentally different from those of nuclear T3 receptor. Cytosolic thyroxine (T4) binding protein (CT4BP) of rat liver was relatively stable compared with CT3BP in homogenate at 0 degrees C. CT4BP was also stable in the form of cytosol at -20 degrees C for 10 weeks. CT4BP was pH-dependent with maximum specific binding at pH 7.4. It was stable at 4 degrees C overnight but destroyed rapidly at 37 degrees C. Specific T4 binding was decreased by dialysis but not abolished completely.(ABSTRACT TRUNCATED AT 400 WORDS)

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PubMed1987

[Studies on cytosol thyroid hormone binding proteins in the rat liver: Part II. Alterations of thyroid hormone binding proteins in various thyroid function states].

Alterations of binding characteristics of cytosolic thyroid hormone binding proteins (CTHBPs) were examined in livers of rats with different thyroid function. Seven days after thyroidectomy, rats were divided into three groups. Group I received no treatment. Group II was treated with 230 ng triiodothyronine (T3)/100 g body weight per day for three days, and Group III with 40 micrograms T3/100 g body weight per day for three days. On the fourth day, each rat was given 0.7 microCi of 125I-T3/100 g body weight intraperitoneally and exsanguinated two hours later. During three days' treatment, body weight in Group II increased significantly compared with that in Group I (P less than 0.05), and body weight in Group III actually decreased. The ratio of liver weight to body weight in Group II was significantly higher than that in Group I or Group III (P less than 0.01). Percent distributions of 125I-T3 in cytosol fraction per liver or concentrations of cytosolic protein did not differ significantly among these three groups. Serum T3 concentrations (mean +/- SD ng/ml: Group I; not detectable, Group II; 0.50 +/- 0.27, Group III; 7.10 +/- 2.31), cytosolic T3 concentrations (mean +/- SD ng/ml: Group I; not detectable, Group II; 0.59 +/- 0.26, Group III; 10.38 +/- 3.08) and mitochondrial alpha-glycerophosphate dehydrogenase activities (mean +/- SD delta OD500 millimicrons/min/mg: Group I; 28.0 +/- 1.5, Group II; 46.7 +/- 7.3, Group III; 267.7 +/- 9.1) suggested that Group I was in hypothyroid state, Group II in euthyroid state and Group III in thyrotoxic state. Binding characteristics of cytosolic T3 binding protein (CT3BP) were different among the three groups.(ABSTRACT TRUNCATED AT 400 WORDS)

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PubMed1987

[Studies on cytosol thyroid hormone binding proteins in the rat liver: Part III. Partial purification and binding characteristics of thyroxine-binding protein in hypothyroid rat liver cytosol and serum].

Cytosolic thyroxine-binding protein (CT4BP) was partially purified from rat liver cytosol obtained 10 days after thyroidectomy using Sephadex G-200 gel filtration, and its binding characteristics were analyzed in displacement experiments using a charcoal binding method to separate bound and free hormones. Serum T4-binding proteins were also partially purified, and their binding characteristics were similarly determined. Sephadex G-200 gel filtration of liver cytosol from thyroidectomized rats revealed that CT4BP had an apparent molecular weight of 100 X 10(3) daltons. CT4BP had a very high affinity constant (Ka) of 2.2 +/- 10(10) M-1 and a small maximum binding capacity (MBC) of 5.1 X 10(-9) g/mg. protein for T4. Relative affinities of T4 analogues for CT4BP (if the affinity of L-T4 was assigned a value of 100, then D-T4 would have a value of 25.3; L-T3, 16.6; D-T3, 2.3; reverse T3, 1.4 and both Tetrac and Triac less than 1) showed that CT4BP had a rigid specificity for alanine-side chain of T4-molecule. This CT4BP was not demonstrated when cytosol from normal rat liver was used. Sephadex G-200 gel filtration of rat serum obtained 10 days after thyroidectomy revealed two T4-binding proteins. The faster peak (Peak I; MW about 100 X 10(3) daltons) was eluted before the albumin peak, and the slower peak (Peak II; MW about 56 X 10(3) daltons) appeared after the albumin peak. Peak I was barely detectable when normal rat serum was used. Peak I had a higher Ka of 2.0 X 10(10) M-1 and a smaller MBC of 3.9 X 10(-9) g/mg. protein than Peak II (Ka; 8.9 X 10(8) M-1, MBC; 3.7 +/- 10(-7) g/mg. protein). Relative affinities of T4 analogues for Peak I (L-T4 100, D-T4, 34.9, L-T3 11.1, D-T3 1.8, reverse T3 6.8, Tetrac 0.25 and Triac 0.1) showed that Peak I had a rigid specificity to alanine-side chain of T4 molecule, but Peak II had little specificity to this side chain (L-T4 100, D-T4 9.2, L-T3 2.1, D-T3 1.0, reverse T3 14.3, Tetrac 69 and Triac 26.3). Thus, Peak I had a similar binding characteristics to those of human thyroxine-binding globulin (TBG), and Peak II was comparable to human thyroxine-binding prealbumin (TBPA). The results that both molecular weight and binding characteristics were similar between CT4BP and Peak I suggest that both proteins are identical, being comparable to human TBG. This must be clarified in future.

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