High density lipoprotein particle size restriction in apolipoprotein A-I(Milano) transgenic mice

Human carriers of apolipoprotein A-I(Milano) (Arg173 --> Cys substitution in apolipoprotein A-I) are characterized by an HDL deficiency in which small, dense HDL accumulate in plasma. Because affected individuals are heterozygous for this mutation, the full impact of apolipoprotein A-I(Milano) (apoA-I(Milano)) on HDL-cholesterol metabolism is unknown. In this study, apoA-I(Milano) transgenic mice were used to evaluate the extent of apoA-I(Milano) dimerization and HDL particle size restriction in the absence of wild-type apoA-I. Murine apoA-I knockout mice were utilized to express apoA-I(Milano) and human apoA-II in the presence of wild-type, human apoA-I (apoA-IMilano/A-Iwt/A-II) and in its absence (apoA-IMilano/A-II). Plasma HDL-cholesterol concentrations were similar (30 mg/dl) in both lines of apoA-I(Milano) transgenic mice. In the apoA-IMilano/A-Iwt/A-II phenotype, 14% of the apoA-I(Milano) formed homodimers and 33% formed heterodimers with apoA-II. ApoA-I(Milano) homodimers increased by 71% in the apoA-IMilano/A-II transgenics and was associated with an abundance of small, 7.6-nm HDL3-sized particles compared to the 9.5, 8.3, and 7.6-nm-sized particles in apoA-IMilano/A-Iwt/A-II mice. The unesterified cholesterol/cholesteryl ester mole ratio of HDL was elevated by 45% in apoA-IMilano/A-Iwt/A-II mice and by 90% in apoA-IMilano/A-II transgenics compared to wild-type (human apoA-I/A-II). Both apoA-I(Milano) transgenics possessed normal levels of plasma LCAT activity, but endogenous cholesterol esterification rates were reduced by 50% compared to controls. Thus, HDL particle size restriction was not the result of impaired LCAT activation; rather, dimerization of apoA-I(Milano) limited the esterification of cholesterol on endogenous HDL. In the absence of wild-type apoA-I, the more extensive dimerization of apoA-I(Milano) severely limited cholesteryl ester accumulation on plasma HDL accounting for the abundance of small, 7.6-nm HDL3 particles in apoA-IMilano/A-II mice.     

Acute aortic dissection complicating pregnancy

BACKGROUND: Acute aortic dissection occurring during pregnancy represents a lethal risk to both the mother and fetus. Our purpose was to study the prevalence, treatments, and outcome of this rare problem and to suggest therapeutic guidelines. METHODS: During the past 12 years, 6 pregnant women were admitted with an acute aortic dissection. Four had a type A and 2 had a type B dissection (Stanford classification). RESULTS: Two of the 4 patients with a type A dissection underwent a combined emergency operation consisting of first cesarean section and then ascending aortic repair. Cesarean section was carried out 5 days after the emergency procedure on the aorta in the third patient, and 16 weeks later in the fourth patient. All 4 fetuses were delivered alive. One fetus died 6 days later, but the other 3 are alive and well at long-term follow-up. Of the 2 patients with a type B dissection, 1 was operated on for celiac ischemia; the other was treated medically. In both cases the fetus died in utero. There were no maternal deaths in either group. CONCLUSIONS: Cesarean section with concomitant aortic repair is recommended for pregnant women with a type A dissection, depending on the gestational age. The maternal hemodynamic status will determine the sequence of the two procedures. Medical treatment is advised for patients with a type B dissection, but surgical repair is indicated if complications such as bleeding or malperfusion of major side branches occur.     

Effect of ifosfamide treatment on glutathione and glutathione conjugation activity in patients with advanced cancers

Several studies have suggested that the glutathione/glutathione S-transferase (GSH/GST) system is involved in resistance of tumors toward ifosfamide and other cytostatic agents. Besides, ifosfamide metabolites (in vitro) as well as ifosfamide treatment (in vivo) have been shown to decrease cellular GSH availability. In the present study, the in vivo effects of three different ifosfamide treatment schedules on the GSH/GST system were studied in patients with advanced cancers (n = 24): continuous i.v. infusions of 1300 mg/m2 daily for 10 days and 5000 mg/m2/day for 24 h, as well as a 4-h infusion of 3000 mg/m2 daily for 3 days. The GSH/GST system was characterized by administering bromisoval, a probe drug to assess GSH conjugation activity in vivo, as well as by daily monitoring of GSH concentrations in blood cells and plasma. Bromisoval pharmacokinetics was assessed before and at the end of the ifosfamide treatment. Blood cell GSH levels decreased significantly (P < 0.05) during the 3- and 10-day ifosfamide treatment schedules; the 24-h treatment had no effect. The ifosfamide treatment schedules had only minimal effects on bromisoval pharmacokinetics. Assuming that the kinetics of the probe drug provide an accurate reflection of enzyme activity, this suggests that GST activity remains unchanged. Because GSH conjugation of bromisoval enantiomers requires both GST activity and GSH availability, these results also indicate that, despite the 35% decrease in GSH in blood cells of two patient groups, the GSH availability of the cancer patients was not rate-limiting for GSH conjugation of bromisoval enantiomers. If GSH levels in blood cells reflect those in tumors/other tissues, the present results indicate that ifosfamide may be used clinically to decrease GSH levels. However, whether a 35% decrease is sufficient to increase tumor sensitivity toward (other) cytostatics remains uncertain.     

Mucosal injury and disruption of intestinal barrier function in HIV-infected individuals with and without diarrhea and cryptosporidiosis in northeast Brazil

The effects of AIDS-related diarrhea--with and without cryptosporidiosis and microsporidiosis--on intestinal function and injury were studied in 40 AIDS patients and 13 healthy volunteers from Fortaleza, Brazil. The differential urinary excretion of ingested lactulose and mannitol was used as a marker of barrier disruption and overall villous surface area. HIV-infected patients with diarrhea had a 2.8-fold higher lactulose to mannitol excretion ratio than HIV-positive patients without diarrhea and a 10.4-fold higher ratio than healthy volunteers. Moreover, those with crypotosporidial infection had a lactulose to mannitol ratio almost 6-fold greater than those without diarrhea and nearly 3-fold higher than those with non-cryptosporidial diarrhea. This effect involved both decreased mannitol excretion (decreased intestinal absorptive area) and increased lactulose excretion (mucosal barrier disruption). The single patient with microsporidial infection had a nearly 3-fold higher ratio than healthy volunteers. Alpha1-antitrypsin tests were positive in two of five (40%) HIV-positive patients with cryptosporidial infections compared with none of 12 HIV-infected patients with non-cryptosporidial diarrhea. These findings confirm that HIV infection is associated with profound intestinal dysfunction and injury, even in those without diarrhea. Disruption of the intestinal barrier is even greater, however, in HIV-infected patients with cryptosporidial diarrhea, with potential nutritional consequences.     

Emergency department repair of hand lacerations using absorbable vicryl sutures

The use of absorbable suture material has a number of potential advantages when compared to nonabsorbable suture. We conducted a 5-year retrospective study of 102 patients with hand lacerations and compared the quality of scar formation and healing in these patients. Those patients who did not have tendon, nerve, or bone injury were included in the study. Lacerations were repaired with either 5-0 Vicryl or nylon. There were no reported complications or infections in any study group patient. The quality of scar, when compared visually and by palpation, was the same at the end of 6 months. In addition, there was no difference in the incidence of scar retraction. We conclude that the use of absorbable suture material is an acceptable alternative in the repair of hand lacerations.     

Mutations in purine nucleoside phosphorylase deficiency

PURPOSE: The aim of this study was to investigate the incidence of unexpected malignant uveal melanoma in the age of ultrasound diagnostics and to highlight the reasons for misdiagnosis. PATIENTS AND METHODS: All eyes were surgically removed and histologic examination was performed between 1981 and 1995. The eyes were investigated for the incidence of uveal melanoma, and the history of the unexpected malignant melanoma of the uvea or ciliary body highlighted. RESULTS: 225 (18.7%) eyes with malignant melanoma out of 2583 enucleated eyes were found. Eight (3.6%) of 225 were clinically unexpected. The clinical misdiagnoses were secondary angle closure or open angle glaucoma (6), retinal detachment (5), iritis (1), scleritis (1), cataract (4) and an intraocular mass that was believed to be a metastasis of a colon carcinoma. Seven of eight eyes were blind, and one eye had light perception only. The longest follow up before enucleation was 13 years. On three eyes diagnostic ultrasound was reportedly performed without specific diagnosis of uveal melanoma. Surgery was performed on four eyes for reasons of uncontrollable intraocular pressure or retinal detachment up to five years before enucleation. Histologic diagnoses were 3 epitheloid-type, 2 spindel-type and 3 necrotic melanoma of the uvea. Four eyes showed scleral invasion by tumor cells and one eye an invasion into the episcleral space. CONCLUSIONS: Even today the rate of unexpected uveal melanoma, according to our study is 3.6%. Therefore, all blind eyes without visualisation of the posterior pole should be examined with ultrasound in order to diagnose an uveal melanoma prior to enucleation.