Mapping studies of the serum cholinesterase-2 locus (CHE2)

Summary Serum cholinesterase (butyrylcholinesterase, EC 3.1.1.8, BChE) is controlled by two genetic loci, CHE1 and CHE2. The CHE1 locus has been mapped to 3q, but the map location of CHE2 is uncertain. In an effort to clarify the location of CHE2, we combined all the published linkage analysis data for CHE2 (as summarized in the Keats Linkage Database) with the data from the UCLA Linkage Database. Exclusions with substantial portions of the genome could be made (notably with portions of chromosomes 1, 2, 3, 4, 6, 7, 8, 9, 14, 16, 18, 19, 20, 22, and LG1). Although not quite statistically significant , loose linkage (=0.32) of CHE2 with the haptoglobin locus on 16q22 was the most likely conclusion from the family data. In addition, calculating the lod score between CHE2 and the available linkage map of chromosome 16 (markers HBA, PGP, FRA16A, and HP) resulted in an overall lod score of 3.2. This result is particularly intriguing given the hybridization of a BChE cDNA (designated CHEL3) to the same region. Resolution of the issue will require more detailed linkage studies of CHE2 on chromosome 16 and a better understanding of the relationship between the CHE1 and CHE2 loci with respect to production of serum cholinesterases.     

Temporal adjustments in sympathoadrenal activity in rats with obesity-producing hypothalamic knife cuts

Sympathoadrenal activity was assessed in adult rats with obesity-producing hypothalamic knife cuts prior to and after the onset of gross obesity by measuring urinary excretion of norepinephrine and epinephrine and by determining rates of norepinephrine turnover in selected organs. Urinary excretion of norepinephrine, as an index of overall sympathetic nervous system activity, was approximately doubled throughout the 4-week study in knife-cut rats, as was intake of the high-fat diet. Three days after knife-cut surgery (before the onset of gross obesity) rates of norepinephrine turnover (ng X organ-1 X hr-1) were 23-33% lower in three of the four organs examined than in the corresponding organs of control rats; rates of norepinephrine turnover were depressed in pancreas, interscapular brown adipose tissue, and abdominal white adipose tissue and unchanged in hearts. Four weeks after surgery when gross obesity was evident, rates of norepinephrine turnover were accelerated in heart (+82%) and pancreas (+63%), but remained low in interscapular brown adipose tissue (-27%) and abdominal white adipose tissue (-28%). Adrenal medullary activity, assessed by urinary excretion of epinephrine, was suppressed within the 1st day after knife-cut surgery and remained suppressed for several weeks. Brown adipose tissue and white adipose tissue appear to be selectively excluded from the generalized activation of the sympathetic nervous system in adult hyperphagic rats with obesity-producing hypothalamic knife cuts. Activation of the sympathetic nervous system was associated with reciprocal suppression of adrenal medullary responses in knife-cut rats.     

Linkage analyses of multiple endocrine neoplasia, type 2 (MEN-2) with 23 classical genetic polymorphisms

Linkage analyses were performed in a single large family with multiple endocrine neoplasia, type 2 (MEN-2) between 23 classical genetic polymorphisms and MEN-2. We exclude close linkage of the locus for MEN-2 with ABO, ACP1, BF, ESD, Fy, GALT, GLO1, Jk, MNSs, P, PGM1, Rh and TF, as well as absolute linkage with GPT. These results raise to about 6% the proportion of the genome that has been excluded in this one family. Somewhat positive lod scores were obtained for GC (0.92 at theta = 0), GPT (0.73 at theta = 0.1) and HP (1.49 at theta = 0.05); although not statistically significant, these findings suggest regions of the genome that warrant additional study.     

Surface structure changes of rat adipocytes during lypolysis stimulated by various lypolysis stimulated by various lypolytic agents

A qualitative and quantitative electron microscopic study was performed on rat adipocytes during stimulation of lipolysis by various agents. Scanning electron microscopy of control cells revealed a spherical cell with a textured glycocalyx surface exhibiting small irregular projections. Globular surface evaginations or protrusions measuring 8-18 μM in diameter were seen on cell hemispheres, and there was an average of one protrusion for every two hemispheres examined. Distribution analysis showed that 60 percent of the hemispheres had no protrusions, and 25, 10, and 5 percent of the hemispheres had one, two or three protrusions, respectively. Thin-section and freeze- fracture electron microscopy of the protrusions showed a small triglyceride droplet surrounded by a thin cytoplasmic rim that was continuous with the main cytoplasmic matrix. The glycocalyx coating and plasma membrane extended from the cell surface onto, and over, the protrusion. Scanning microscopy of cells stimulated by lipolytic agents, including epinephrine, adrenocorticotropic hormone, theophylline, and dibutyryl cyclic AMP, revealed a dose-dependent increase in the number of protrusions per cell hemisphere. Maximal concentrations of lipolytic hormones cuase an average 2.5-fold increase in the number of protrusions per hemisphere without changing the average size of the protrusions. Only 40 percent of the stimulated cell hemispheres exhibited no protrusions; over 15 percent of the cells contained three or more; and a number of the protrusions were multilobulate. Insulin prevented the increase in the number of protrusions and the change in distribution caused by the lipolytic hormones but did not prevent the increase caused by theophylline and dibutryl cyclic AMP. The data suggest that the protrusions are a structural feature of the cell and may be related to the lypolytic pathway. These observations may help explain some of the discrepant biochemical data relating to hormonal stimulation of lipolysis.     

Disc erosion in Models 103 and 104 of Beall mitral valve prostheses

Three cases of severe disc variance and erosion of the Teflon-disc Beall mitral valve prosthesis (Models 103 and 104) are reported. In two patients, the Beall mitral valves were excised and replaced with two Bj?rk-Shiley mitral valves. The remaining patient did not survive, and at autopsy, the lens was found at the aortic bifurcation level. Because of this potentially lethal complication, careful follow-up of patients with Beall mitral valve prostheses (Models 103 and 104) is recommended.     

The role of histamine in implantation in the rabbit.

When disodium cromoglycate, an inhibitor of histamine release, was instilled into the uterine lumen on Days 5 or 6 of pregnancy, the number of blastocysts implanting was significantly (P less than 0.002) reduced. Simultaneous instillation of histamine and disodium cromoglycate prevented the effect.     

Monocyte chemoattractant protein-1 in obesity and type 2 diabetes. Insulin sensitivity study

Objective: Our goal was to test any association between human plasma circulating levels of monocyte chemoattractant protein‐1 (cMCP‐1) and insulin resistance and to compare monocyte chemoattractant protein‐1 (MCP‐1) adipose tissue gene expression and cMCP‐1 in relation with inflammatory markers. Research Methods and Procedures: cMCP‐1 was measured in n = 116 consecutive control male subjects to whom an insulin sensitivity (S_i) test was performed. Circulating levels of soluble CD14, soluble tumor necrosis factor receptor type 2 (sTNFR2), soluble interleukin‐6 (sIL‐6), and adiponectin also were measured. Subcutaneous adipose tissue samples were obtained from n = 107 non‐diabetic and type 2 diabetic subjects with different degrees of obesity. Real‐time polymerase chain reaction was used to measure gene expression of MCP‐1, CD68, tumor necrosis factor‐α (TNF‐α), and its receptor TNFR2. Results: In the S_i study, no independent effect of cMCP‐1 levels on insulin sensitivity was observed. In the expression study, in non‐diabetic subjects, MCP‐1 mRNA had a positive correlation with BMI (r = 0.407, p = 0.003), TNF‐α mRNA (r = 0.419, p = 0.002), and TNFR2 mRNA (r = 0.410, p = 0.003). In these subjects, cMCP‐1 was found to correlate with waist‐to‐hip ratio (r = 0.322, p = 0.048). In patients with type 2 diabetes, MCP‐1 mRNA was up‐regulated compared with non‐diabetic subjects. TNF‐α mRNA was found to independently contribute to MCP‐1 mRNA expression. In this group, CD68 mRNA was found to correlate with BMI (r = 0.455, p = 0.001). Discussion: cMCP‐1 is not associated with insulin sensitivity in apparently healthy men. TNF‐α is the inflammatory cytokine associated with MCP‐1 expression in subcutaneous adipose tissue.