Insulin-like growth factor binding protein-1 induces insulin release in the rat

Injections of human insulin-like growth factor binding protein (hIGFBP-1) are reported to induce hyperglycemia in the rat, suggesting that IGFBP-1 acutely regulates glucose homeostasis. We now report the effects on glucose and insulin levels of administering recombinant (r) hIGFBP-1. In a series of studies, normal and streptozotocin (STZ) diabetic male Wistar rats (180-210 g), fasted for 6 or 16 h, were injected with rhIGFBP-1 (i.v., 80-500 microg/rat). rhIGFBP-1 did not affect blood glucose acutely but did stimulate insulin release in normal rats (5 min post injection; PBS, 103.5 +/- 8.5; rhIGFBP-1 (500 microg), 166.8 +/- 15.7; rhIGFBP-1 (100 microg); 151.4 +/- 14.1% initial). rhIGFBP-1 pretreatment, in normal and diabetic rats, reduced the hypoglycemic response to rhIGF-I (diabetic rats after 20 min: PBS, 103.4 +/- 11.4; BP-1 (500 microg) +/- rhIGF-I (50 microg), 97.6 +/- 3.6; rhIGF-I, 48.2 +/- 4.3% initial) but did not affect the hypoglycemic response to des(1-3)IGF-I or insulin (0.5 U/kg). These studies show that rhIGFBP-1 causes insulin release, has a minimal effect on blood glucose, and inhibits the hypoglycemic effect of rhIGF-I. These data suggest that endogenous IGF-I tonically suppresses insulin secretion and imply that aberrant IGFBP levels or reduced IGF-I bioactivity may lead to chronic hyperinsulinemia.     

Variations in normal coronary vasodilatory reserve stratified by artery, gender, heart transplantation and coronary artery disease

OBJECTIVES: The purpose of the study was to assess the spectrum of coronary vasodilatory reserve values in patients with angiographically normal arteries who had atypical chest pain syndromes or remote coronary artery disease or were heart transplant recipients. BACKGROUND: The measurement of post-stenotic coronary vasodilatory reserve, now possible in a large number of patients in the cardiac catheterization laboratory, is increasingly used for decision making. Controversy exists regarding the range of normal values obtained in angiographically normal coronary arteries in patients with different clinical presentations. METHODS: Quantitative coronary arteriography was performed in 214 patients classified into three groups: 85 patients with chest pain syndromes and angiographically normal arteries (group 1); 21 patients with one normal vessel and at least one vessel with > 50% diameter lumen narrowing (group 2); and 108 heart transplant recipients (group 3). Coronary vasodilatory reserve (the ratio of maximal to basal average coronary flow velocity) was measured in 416 arteries using a 0.018-in. (0.04 cm) Doppler-tipped angioplasty guide wire. Intracoronary adenosine (8 to 18 micrograms) was used to produce maximal hyperemia. RESULTS: Coronary vasodilatory reserve was higher in angiographically normal arteries in patients with chest pain syndromes (group 1:2.80 +/- 0.6 [group mean +/- SD]) than in normal vessels in patients with remote coronary artery disease (group 2: 2.5 +/- 0.95, p = 0.04); both values were significantly higher than those in the post-stenotic segment of the diseased artery (1.8 +/- 0.6, p < 0.007). Coronary vasodilatory reserve in transplant recipients (group 3) was higher than that in the other groups (3.1 +/- 0.9, p < 0.05 vs. groups 1 and 2) as a group and for individual arteries. When stratified by vessel, coronary vasodilatory reserve was similar among the left anterior descending, left circumflex and right coronary arteries. There were no differences between coronary vasodilatory reserve values on the basis of gender for patients with coronary artery disease and transplant recipients. In group 1 (chest pain), there was a trend toward higher coronary vasodilatory reserve in men than in women (2.9 +/- 0.6 vs 2.7 +/- 0.6, p = 0.07). CONCLUSIONS: These findings identify a normal reference range for studies assessing the coronary circulation and post-stenotic coronary vasodilatory reserve in patients with and without coronary artery disease encountered in the cardiac catheterization laboratory.     

Repair of site-specific double-strand breaks in a mammalian chromosome by homologous and illegitimate recombination

In mammalian cells, chromosomal double-strand breaks are efficiently repaired, yet little is known about the relative contributions of homologous recombination and illegitimate recombination in the repair process. In this study, we used a loss-of-function assay to assess the repair of double-strand breaks by homologous and illegitimate recombination. We have used a hamster cell line engineered by gene targeting to contain a tandem duplication of the native adenine phosphoribosyltransferase (APRT) gene with an I-SceI recognition site in the otherwise wild-type APRT+ copy of the gene. Site-specific double-strand breaks were induced by intracellular expression of I-SceI, a rare-cutting endonuclease from the yeast Saccharomyces cerevisiae. I-SceI cleavage stimulated homologous recombination about 100-fold; however, illegitimate recombination was stimulated more than 1,000-fold. These results suggest that illegitimate recombination is an important competing pathway with homologous recombination for chromosomal double-strand break repair in mammalian cells.     

Utility of transesophageal echocardiography and pulmonary artery catheterization during laparoscopic assisted abdominal aortic aneurysm repair

BACKGROUND: Advanced laparoscopic procedures are more commonly performed in elderly patients with cardiac disease. There has been limited data on the use of pulmonary artery catheters (PAC) and transesophageal echocardiography (TEE) to monitor hemodynamic changes. METHODS: We prospectively studied eight patients undergoing laparoscopic assisted abdominal aortic aneurysm repair. All patients had a PAC and all but one had an intraoperative TEE. Data included heart rate (HR), temperature (temp), pulmonary artery systolic (PAS) and diastolic (PAD) pressures, mean arterial pressure (MAP), central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP), cardiac index (CI), mixed venous oxygen saturation (MVO2), and oxygen extraction ratio (O2Ex) and was obtained prior to induction, during insufflation, after desufflation, during aortic cross-clamp, and at the end of the procedure. End diastolic area (EDA), a reflection of volume status, was measured on TEE. ANOVA was used for data analysis. RESULTS: No changes were noted in HR, temp, PAS, PCWP, CI, MVO2, and O2Ex. PAD and CVP were greater during insufflation compared with baseline and aortic cross-clamp without associated changes in EDA. MAP was higher at baseline compared with all other times during the procedure. CONCLUSIONS: Insufflation increased PAD and CVP. However, volume status as suggested by EDA and PCWP did not change. These data question the reliability of hemodynamic measurements obtained from the PAC during pneumoperitoneum and suggest that TEE may be sufficient for evaluation of volume status along with the added benefit of timely detection of ventricular wall motion abnormalities.     

Administration of recombinant bovine somatotropin to dairy cows for four consecutive lactations

Effects of long-term administration of recombinant bovine somatotropin (bST) to dairy cows on complete lactational performance [60 (+/- 3) to 284 (+/- 3) d in milk (DIM)] were studied for four consecutive lactations. Beginning on d 60 (+/- 3) postpartum, Holstein cows received biweekly injections (500 mg) of bST (n = 39) or a placebo (control; n = 39) during the first lactation of the study. Cows either continued on the same treatment (n = 26) or were switched to the opposite treatment (n = 29) during the second lactation. Cows that changed treatments were injected for only 16 wk during the second lactation. Six cows per treatment completed four consecutive lactations. Treatment with bST during the first lactation did not have a residual effect on milk yields during the second lactation. Injections of bST during the second lactation increased milk yield 6.5 kg/d from 60 (+/- 3) to 172 DIM. For the four lactations, cows receiving bST yielded 3.7 kg/d (14%) more milk and gained 52 kg (37%) more body weight than did controls. Pretreatment (from 0 to 56 DIM) milk yields in yr 2, 3, and 4 were not affected by previous bST treatment. Milk yield, efficiency of feed utilization, and body weights were enhanced in cows injected with bST for four consecutive lactations. Previous bST treatment did not diminish milk yields in subsequent lactations.     

Family members' uncertainty about parental chronic illness: the relationship of hemophilia and HIV infection to child functioning

Examined the relationships among parental and child uncertainty about fathers' illnesses and child internalizing problems. Participants included 65 families in which the father had hemophilia, approximately one half of the fathers also were HIV infected. Within each family, respondents included the father, the mother and one child. Outcome variables included both self- and parent-reported child internalizing behaviors. Results indicated that family members' illness uncertainty was intercorrelated, that child uncertainty about the father's illness predicted both anxiety and depressive symptoms in the child, and that mother's uncertainty predicted child-reported anxiety beyond the child's uncertainty.     

Susceptibility to hepatotoxicity in transgenic mice that express a dominant-negative human keratin 18 mutant

Keratins 8 and 18 (K8/18) are intermediate filament phosphoglycoproteins that are expressed preferentially in simple-type epithelia. We recently described transgenic mice that express point-mutant human K18 (Ku, N.-O., S. Michie, R.G. Oshima, and M.B. Omary. 1995. J. Cell Biol. 131:1303-1314) and develop chronic hepatitis and hepatocyte fragility in association with hepatocyte keratin filament disruption. Here we show that mutant K18 expressing transgenic mice are highly susceptible to hepatotoxicity after acute administration of acetaminophen (400 mg/Kg) or chronic ingestion of griseofulvin (1.25% wt/wt of diet). The predisposition to hepatotoxicity results directly from the keratin mutation since nontransgenic or transgenic mice that express normal human K18 are more resistant. Hepatotoxicity was manifested by a significant difference in lethality, liver histopathology, and biochemical serum testing. Keratin glycosylation decreased in all griseofulvin-fed mice, whereas keratin phosphorylation increased dramatically preferentially in mice expressing normal K18. The phosphorylation increase in normal K18 after griseofulvin feeding appears to involve sites that are different to those that increase after partial hepatectomy. Our results indicate that hepatocyte intermediate filament disruption renders mice highly susceptible to hepatotoxicity, and raises the possibility that K18 mutations may predispose to drug hepatotoxicity. The dramatic phosphorylation increase in nonmutant keratins could provide survival advantage to hepatocytes.