Interactions between membrane IgM and the cytoskeleton involve the cytoplasmic domain of the immunoglobulin receptor

Cross-linking induced interactions between the membrane form of immunoglobulin (mIg) and the cytoskeletal matrix have been described by several groups. To date, the function of mIgM association with the cytoskeleton is not yet understood. Delineation of the molecular basis of these interactions will be instrumental in elucidating their function. We have previously shown that the Igα/β heterodimer is not required for ligand-induced mIgM binding to the cytoskeleton. In this study, we have investigated the role of other B cell-specific proteins in mediating these interactions. For this, we expressed mIgM in the non-hematopoietic human cervical carcinoma cell line HeLa S3 and verified the capacity of the surface-expressed IgM to interact with the cytoskeletal matrix upon cross-linking with anti-μ chain antibodies. We show here that only the mIgM molecule itself and no other B cell-specific protein(s) is required in mediating mIgM interactions with actin filaments. In an attempt to determine the cytoskeleton-binding site of mIgM we investigated the role of the cytoplasmic tail of mIgM (KVK) in binding the receptor to actin-based microfilaments. Using mutated forms of mIgM expressed in J558L cells, we show here that KVK plays a role in mediating these interactions. The absence of KVK did not, however, completely abrogate mIgM-cytoskeletal interactions, suggesting that there are additional molecular requirements for the ligand-induced mIgM binding to the cytoskeletal matrix.     

Various V-J rearrangement efficiencies shape the mouse λ B cell repertoire

The diversity of the B cell repertoire of C_x knockout mice is limited by the expression of four λ light chain types. Among the spleen B cells, λ1 is expressed by the majority (58%) of cells, and λ3 by the minority (8%), while λ2(V2) and λ2(Vx) are expressed in intermediate quantities (18% and 16%, respectively). To assess the influence of mechanistic pressures on the λ subtype distribution, the proportions of the different λ rearrangements were determined in various B cell subpopulations divided on the basis of the λ subtype expressed, and the VλJλ junction sequences were studied at different steps of B cell differentiation (pre-B, immature and mature B cells). The data show that (1) the ratio of productive/non-productive VJ junctions is determined by the nature of the λ segments that are rearranged as can be observed in the pre-B cells, (2) V1-J1 non-productive rearrangements are often found in the λ1-negative B cells in the periphery, and (3) V1J3 junctions are often non-productive regardless of the nature of the cells analyzed. Our results, therefore, suggest that a strong probability of initiating a V1-J1 rearrangement and a weak probability of giving a productive V1J3 junction are responsible for the λ1 dominance and the λ3 under-expression, respectively. The intermediate proportion of λ2(V2) subtype is most likely due to a probability of obtaining a productive joint that is better than that for V1J3 and a probability of initiating a rearrangement that is lower than that for V1J1. However, the λ2(Vx) cell proportion cannot be determined only by these parameters.     

猪血免疫球蛋白的分离及功能性研究

使用食品级的多聚磷酸钠（以下简称Ｓｐ）絮凝剂分离猪血浆中的免疫球蛋白，配合随机质心映射优化程序（ＲＣＯ）确定分离最佳条件，并用ＥＬＩＳＡ初步测定了粗制ＩｇＧ的各种功能特性。     

Angiotensinogen gene M235T polymorphism is not associated with diabetic nephropathy

BACKGROUND.: There is agreement that a family history of hypertension (HT),is a predictor for the risk of diabetic nephropathy (DN) inpatients with type 2 diabetes, and possibly also type 1 diabetes.It follows that genes related to the risk of hypertension mustalso be considered candidate genes for DN. The 235T allele ofthe angiotensinogen gene was found to be related to primaryHT. METHODS.: To examine whether it is predictive for DN as well, we examinedthe angiotensinogen gene polymorphism in 230 healthy local controls,423 patients with type 1 diabetes (n=180 with DN; n=243 withoutDN) and 663 patients with type 2 diabetes (n=310 with DN; n=353without DN). The angiotensinogen gene M235T polymorphism wasdetermined using PCR amplification. RESULTS.: The following results were obtained (i) no significant differenceof genotype distribution (type 1: MM/MT/TT(%) 27.6/57.2/15.2vs. 27.2/56.1/16.7 (P=0.92); type 2: MM/MT/TT (%) 31.7/48.2/20.1vs. 32.9/46.8/20.3 (P=0.93)) or allele frequencies (type 1:M 0.56 vs. 0.55 (P=0.795); type 2: M 0.56 vs. 0.56 (P=0.86))was found, between diabetic patients with or without DN, (ii)no difference was found between normotensive and hypertensivediabetic patients. CONCLUSION.: The data argue against a role of the angiotensinogen gene M235Tpolymorphism in the manifestation of diabetic nephropathy orhypertension in diabetic patients.     

糖尿病肾病患者血清TRPM7、Sirtuin-1与钙磷代谢、颈动脉钙化的相关性

目的 探讨糖尿病肾病（DN）患者血清瞬时受体电位通道7(TRPM7)、沉默调节蛋白-1(Sirtuin-1)与钙磷代谢、颈动脉钙化的相关性。方法 选取2020年12月—2022年11月成都大学附属医院收治的97例DN患者作为DN组,另取同期在该院就诊的120例2型糖尿病患者作为对照组。采用实时荧光定量聚合酶链反应检测血清TRPM7的表达,酶联免疫吸附试验检测血清Sirtuin-1水平。采用Pearson法分析DN患者血清TRPM7、Sirtuin-1水平与钙磷代谢的相关性,并通过多因素Logistic逐步回归模型分析DN患者颈动脉钙化的危险因素。结果 DN组血肌酐、尿素氮、血清TRPM7、血磷、颈动脉钙化率高于对照组（P <0.05）。DN组Sirtuin-1、血钙低于对照组（P <0.05）。Pearson相关性分析结果显示,DN患者血清TRPM7与血钙呈负相关（r=-0.247,P=0.000）,与血磷呈正相关（r=0.415,P=0.000）;DN患者血清Sirtuin-1与血钙呈正相关（r=0.367,P=0.000）,与血磷呈负相关（r=-0.505,P=0.00...     

Effects of chemical mediators of anaphylaxis on ciliary function

We assessed the effects of selected chemical mediators of anaphylaxis on CBF in vitro. Ciliated epithelial cells were obtained from the trachea of conscious sheep with a cytology brush and suspended in a perfusion chamber containing KH. Ciliary activity was viewed microscopically and recorded on videotape for subsequent slow-motion analysis of CBF. Prostaglandin E1 (10(-8) M to 10(-6) M), prostaglandin E2 (10(-10) M to 10(-6) M), and leukotriene-C4 (10(-8) M) increased CBF between 7% and 33%. Histamine caused ciliostimulation only at the relatively high concentrations above 10(-5) M (7% increase in CBF), whereas prostaglandin F2 alpha (10(-10) M and 10(-6) M) was without effect. In no preparation was ciliary discoordination observed. These findings indicate that several chemical mediators of anaphylaxis stimulate CBF and that the previously described impairment of mucociliary transport in stable allergic asthma or antigen-induced bronchoconstriction is probably not caused by a primary alteration of ciliary function.     

Comparison of cord blood immunoglobulin E concentrations and maternal allergy for the prediction of atopic diseases in infancy

Total serum IgE levels were determined in 136 newborns and their mothers and in 54 of their fathers, using the paper radioimmunosorbent test (PRIST) technique. IgE specific antibodies for house dust (Dermatophagoides pteronyssinus), orchard grass, timothy grass, and cow's milk were measured with the radioallergosorbent test (RAST). One hundred thirty-three RAST assays were negative in newborns, and in three cases RAST for cow's milk was positive. Cord blood IgE ranged from 0 to 5.5 IU/ml (mean 0.32 ± 0.54 IU/ml); levels were significantly (p < 0.05) higher when maternal IgE was over 100 IU/ml and when mothers had received progesterone therapy during the pregnancy. Salbutamol administration or tobacco smoking during pregnancy did not influence newborn IgE. A clinical follow-up study was conducted in 83 infants for 9 mo. Nine infants developed definite atopic disease, and possible allergic diseases were noted in eight other infants. The IgE level at birth appeared to be more predictive for the development of allergy in infancy than the family history.     

Cytogenetic analysis in human breast tumors

Cytogenetic analysis using C-, G-, and Ag-nucleolus organizer region (NOR) staining techniques, performed on established cell lines as well as directly processed breast tumor effusions, revealed that: 1) chromosome No. 1 is involved in translocation; 2) based on 1q translocation chromosome, breast tumors could be classified into two groups; and 3) double minutes and homogeneously staining regions may be present in breast tumor cells in vivo as well as in vitro, and that homogeneously staining regions may exhibit some heterogeneity in staining.     

Relationship between numbers of beta adrenergic receptors in lymphocytes and disease severity in asthma

In order to assess the status of beta adrenergic receptors in bronchial asthma, binding studies using (−) [³H] dihydroalprenolol (DHA) were performed on lymphocytes of 10 control subjects and 11 stable asthmatic patients. Specific DHA binding was generally lower at all DHA concentrations in asthmatics. At 12 nM DHA concentration, specific DHA binding was 391 ± 40 fM/mg protein in controls and 263 ± 35 fM/mg protein for asthmatic subjects (p < 0.05). A highly statistically significant positive correlation between specific DHA binding (at 12 nM DHA) and FEV₁/FVC% was observed (r = 0.93, p < 0.01), with those asthmatic subjects with the more severe airway obstruction and disease severity showing lower DHA binding. The results of the study suggest that a lymphocyte beta adrenergic receptor defect may be present among some patients with asthma. The magnitude of the receptor abnormality appears to be related to disease severity and degree of airway obstruction as measured by FEV₁/FVC%. Documentation of drug consumption was made, and restriction of beta adrenergic agonists was attempted; theophylline and corticosteroids were the predominant drugs used in the study. Even with these precautions, it is possible that the differences in DHA binding observed among subjects are the results of greater drug (e.g., theophylline and corticosteroids) consumption by the clinically more severe patients. On the other hand, the lymphocyte receptor alteration noted may reflect a more general beta adrenergic receptor abnormality in bronchial asthma.     

Cytogenetic characterization of ten cases of Ph1-positive acute myelogenous leukemia

Chromosome banding analyses were made on 10 cases of Ph1-positive AML (7 M1 and 3 M2). The standard type Ph1 translocation, t(9q +;22q -), was identified in all of them. Karyotypically normal cells were observed in 6-65% of bone marrow metaphases at the initial cytogenetic examination of 7 patients, whereas the remaining 3 patients had only Ph1-positive cells at diagnosis. Follow-up studies performed in 5 cases indicated that the frequency of karyotypically normal cells increased up to 81-100% when the patients were in remission, whereas it was much reduced in relapse. In 5 cases, there was observed a clone of cells in which the Ph1 translocation was the sole karyotypic abnormality. Various types of other chromosome abnormalities, in addition to the Ph1, were observed in all cases, among which-7 was the most frequent, being found in three cases as a stem line. Other additional changes encountered were + Ph1, del(5), i(17q), - 10, + 18, + X, and various numerical and structural changes including certain secondary translocations that occurred in the Ph1 (22q -) or its partner (9q +). The types and frequencies of these additional changes appeared to be different from those found in the acute phase of CML or in Ph1-positive ALL.