Endothelin-1 release from atherosclerotic plaque after percutaneous transluminal coronary angioplasty in stable angina pectoris and single-vessel coronary artery disease

To assess the effects of percutaneous transluminal coronary angioplasty on endothelin-1 (ET-1) release, we assessed ET-1 concentrations at different sites of the coronary circulation in patients submitted to elective procedures. ET-1 levels immediately downstream from the plaque and ET-1 aortocoronary gradient increased significantly after the procedure, which was related to mechanical wall stress in patients only receiving balloons, but not in those undergoing stent percutaneous transluminal coronary angioplasty. No changes were found in the coronary sinus; these results suggest ET-1 release from the plaque rather than an ischemia/reperfusion-related production from the distal myocardium.

A homeobox gene, vax2, controls the patterning of the eye dorsoventral axis

We have identified a transcription factor specifically expressed in the developing vertebrate eye. We named this gene vax2 because of the high degree of sequence similarity to the recently described vax1. Both in the human and mouse genomes, vax2 is localized in the vicinity of the emx1 gene. This mapping assignment, together with the previously reported colocalization of Vax1 and Emx2 in mouse, indicates that the vax and the emx genes may be organized in clusters. vax2 has a remarkable expression domain confined to the ventral portion of the prospective neural retina in mouse, human, and Xenopus. The overexpression of either the frog Xvax2 or the human VAX2 in Xenopus embryos leads to an aberrant eye phenotype and, in particular, determines a ventralizing effect on the developing eye. The expression domain of the transcription factor Xpax2, normally confined to the ventral developing retina, extends to the dorsal region of the retina after overexpression of vax2. On the other hand, the expression of Xvent2, a molecular marker of the dorsal retina, is strongly reduced. Furthermore, vax2 overexpression induces a striking expansion of the optic stalk, a structure deriving from the ventralmost region of the eye vesicle. Altogether, these data indicate that vax2 plays a crucial role in eye development and, in particular, in the specification of the ventral optic vesicle.

Microalbuminuria and transcapillary albumin leakage in essential hypertension

Microalbuminuria (an increased urinary albumin excretion that is not detectable by the usual dipstick methods for macroproteinuria) predicts cardiovascular events in essential hypertensive patients. A possible reason for this behavior is that albumin leaks through exaggeratedly permeant glomeruli exposed to the damaging impact of subclinical atherogenesis. To evaluate this possibility, the transcapillary escape rate of albumin (TER(alb), the 1-hour decline rate of intravenous (125)I-albumin), a parameter that estimates the integrity of systemic capillary permeability, albuminuria, blood pressure, echocardiographic left ventricular mass, lipids, and body mass index were measured in 73 uncomplicated, glucose-tolerant men with essential hypertension and normal renal function; 53 were normoalbuminuric, and 20 were microalbuminuric. Twenty-one normotensive age-matched male subjects were the controls. TER(alb) was higher in hypertensives, a behavior explained in part by a positive correlation with blood pressure values, although body mass index, lipids, and left ventricular mass showed no association. Transcapillary albumin leakage values did not differ between normoalbuminuric and microalbuminuric patients and were unrelated to albuminuria. Blood pressure, particularly systolic, and cardiac mass were higher in microalbuminuric patients in whom albuminuria correlated with both cardiovascular variables and indicated the influence of the hemodynamic load on urinary albumin levels. Thus, TER(alb), a parameter influenced by the permeability surface area product for macromolecules and the filtration power across the vascular wall, is altered in essential hypertensives. However, this abnormality is dissociated from the amount of albuminuria, which is contrary to the hypothesis that a higher albumin excretion reflects a greater degree of systemic microvascular damage in essential hypertension.

[The management of syncope in the hospital: the OESIL Study (Osservatorio Epidemiologico della Sincope nel Lazio)]

BACKGROUND

While syncope is generally considered a frequent finding in clinical practice, no clear epidemiological evidence is available about the relevance of such an event in the general population of Italy.

METHODS

The OESIL Study was designed and undertaken in 15 hospitals of the Italian region of Latium in order to assess the percentage of emergency-room visits and admissions due to syncope, as well as to analyze the in-hospital diagnostic work-up performed for this condition.

RESULTS

During a two-month observation period, 781 (372 males and 409 females, mean age 55.2 (22.8 years) consecutive patients came to the emergency rooms of the 15 hospitals included in the investigation due to a syncope spell (0.9% of emergency room visits); 450/781 patients (57.6%) were subsequently hospitalized (1.3% of all admissions): 48.0% of the admissions were admitted to a general medical ward, 29.3% to an observation ward, 13.3% to a cardiology section, 1.6% to a neurology section and 7.8% to other clinical sections (neurosurgery, general surgery). The mean duration of in-hospital stay was 6.9 (5.8 days; range 1-40 days). During the hospitalization period, 93.1% of patients underwent an ECG, 51.0% an EEG, 44.3% a CT scan of the central nervous system, 40.2% an echocardiogram and 19.5% a tilt-test. The syncope spell was considered to have a cardiovascular origin in 33.8% of the cases and a non-cardiovascular in 11.6% of the cases, while the origin was unknown in 54.4% of the cases.

CONCLUSIONS

Collected data support the idea that syncope represents a frequent event in the general population and is responsible for a significant percentage of emergency-room visits and hospital admissions. However, the performance of conventional diagnostic work-ups is far from being satisfactory.

Changing heat and moisture exchangers every 48 hours does not increase the incidence of nosocomial pneumonia

This prospective study was conducted to evaluate the risk of nosocomial pneumonia when changing heat and moisture exchangers every 48 hours in 1996 instead of every 24 hours in 1995 for patients needing continuous mechanical ventilation. Medical and surgical patients in the two periods did not differ in terms of demographic characteristics and markers of acute or underlying illnesses. The incidence density of nosocomial pneumonia was not different in the two groups. Extended heat and moisture exchanger use reduces circuit manipulation and cost.

The structure in solution of the b domain of protein disulfide isomerase

Protein disulfide isomerase (PDI) is a multifunctional protein of the endoplasmic reticulum, which catalyzes the formation, breakage and rearrangement of disulfide bonds during protein folding. It consists of four domains designated a, b, b and a. Both a and a domains contains an active site with the sequence motif -Cys-Gly-His-Cys-involved directly in thiol-disulfide exchange reactions. As expected these domains have structures very similar to the ubiquitous redox protein thioredoxin. A low-resolution NMR structure of the b domain revealed that this domain adopts a fold similar to the PDI a domain and thioredoxin [Kemmink, J., Darby, N.J., Dijkstra, K., Nilges, M. and Creighton, T.E. (1997) Curr. Biol. 7, 239-245]. A refined ensemble of solution structures based on the input of 1865 structural restraints shows that the structure of PDI b is well defined throughout the complete protein except for about 10 residues at the C-terminus of the sequence. 15N relaxation data show that these residues are disordered and not part of this structural domain. Therefore the domain boundaries of PDI can now be fixed with reasonable precision. Structural comparison of the PDI b domain with thioredoxin and PDI a reveals several features important for thiol-disulfide exchange activity.

Dissociation between albuminuria and insulinaemia in hypertensive and atherosclerotic men

To better understand the links between circulating insulin and albuminuria in essential hypertension, the plasma insulin response t alpha a 75 gram glucose load and albuminuria were evaluated in 53 glucose-tolerant essential hypertensives and 12 controls. To allow any direct pressure-independent albuminuric effect of insulin to emerge more clearly, those same parameters were also evaluated in 20 glucose-tolerant normotensive patients with stable atherosclerotic peripheral vascular disease, a condition in which hyperinsulinaemia could be anticipated on the basis of previous reports. In response to glucose ingestion, hyperinsulinaemia was evident in both hypertensive and normotensive atherosclerotic patients, while, on average, urine albumin was elevated only in the former. When plasma insulin, systolic and diastolic blood pressure (BP) (by 24-h ambulatory BP monitoring), plasma glucose, triglycerides and body mass index were entered into a multiple regression analysis, only systolic BP appeared to exert an independent effect on urine albumin. Post-glucose load plasma insulin did not differ between hypertensive patients with (n = 14) and without (n = 39) microalbuminuria (albuminuria > 20 micrograms/min). In further analyses, insulin and systolic BP values were divided in quartiles: albuminuria did not differ across insulin quartiles, while it was significantly higher in the top (n = 21) vs the bottom (n = 21) systolic BP quartile. Thus, hyperinsulinaemia and microalbuminuria were unrelated variables in these hypertensive and atherosclerotic patients. Blood pressure, particularly systolic, emerged as a primary predictor of urinary albumin excretion, although the importance of this parameter needs to be proved prospectively.

Identification and characterization of CDS2, a mammalian homolog of the Drosophila CDP-diacylglycerol synthase gene

The general strategies of phototransduction in vertebrates and invertebrates share many similarities, but differ significantly in their underlying molecular machinery. The CDS gene encodes the CDP-diacylglycerol synthase (CDS) enzyme and is required for phototransduction in Drosophila. Using a bioinformatic approach, we have identified two novel transcripts (CDS1 and CDS2) highly homologous to the Drosophila CDS gene. We isolated and sequenced the CDS2 full-length cDNA and mapped the two genes to human chromosomes 20p13 (CDS2) and 4q21.1 (CDS1). Sequence analysis revealed that both genes are highly homologous to the Drosophila protein (64.4 and 58. 6% identity at the protein level between CDS and CDS2 and between CDS and CDS1, respectively). The mouse homologs for both genes were isolated and used in RNA in situ hybridization studies on adult and embryonic mouse tissue sections. These studies showed that Cds2 is highly expressed in the differentiating neuroblasts of the neural retina and in the central nervous system during embryonic development, while it was not detected in adult retina. Cds1, on the other hand, shows a high level of expression in the photoreceptor layer of adult retina, which strongly suggests a role for Cds1 in phototransduction. Knowledge of the expression pattern of these genes in mammals may shed light on the evolution of vision mechanisms and help in the evaluation of candidate genes for human retinopathies.

Fibrinogen and mortality in chronic critical limb ischaemia

OBJECTIVE

Plasma fibrinogen predicts cardiovascular events in patients with stable peripheral arterial occlusive disease, but its predictive value in patients with chronic critical limb ischaemia, a condition associated with a high risk of death, is unknown.

DESIGN

A prospective cohort study.

SETTING

Determination of fibrinogen and other potential predictors during clinic-based work-up of patients admitted for diagnostic and therapeutic evaluation.

SUBJECTS

A total of 108 patients (72 +/- 10 years, 78 males) with atherosclerotic occlusive disease and critical limb ischaemia (pain at rest and/or trophic lesions) followed up for a median period of 1.6 years). (range: 8 days-5.5 years; 218 patient-years).

MAIN OUTCOME MEASURES

Total mortality.

RESULTS

Forty-five deaths (71% cardiovascular) occurred during the follow-up. Baseline fibrinogen was higher in those who died in the early follow-up period (first 6 months), as were white cell count and serum creatinine, while haematocrit was lower. Plasma fibrinogen values correlated positively with white cell count, and negatively with haematocrit; other cardiovascular prognostic factors did not differ. Only plasma fibrinogen predicted survival independently in multivariate age-corrected Cox regression analysis. Relative risk of death doubled for each standard deviation above the mean and increased with each tertile increase in fibrinogen.

CONCLUSIONS

Fibrinogen predicted death in these elderly arteriopaths with critical limb ischaemia, particularly those who died in the first months following critical ischaemia. Inflammatory stimuli secondary to severely defective tissue oxygenation and possibly sepsis and necrosis, might have stimulated fibrinogen, an acute-phase reactant, thereby compromising organ perfusion through increased blood viscosity and/or promoting thrombosis.

EYA4, a novel vertebrate gene related to Drosophila eyes absent

We have isolated a family of four vertebrate genes homologous to eyes absent (eya), a key regulator of ocular development in Drosophila. Here we present the detailed characterization of the EYA4 gene in human and mouse. EYA4 encodes a 640 amino acid protein containing a highly conserved C-terminal domain of 271 amino acids which in Drosophila eya is known to mediate developmentally important protein-protein interactions. Human EYA4 maps to 6q23 and mouse Eya4 maps to the predicted homology region near the centromere of chromosome 10. In the developing mouse embryo, Eya4 is expressed primarily in the craniofacial mesenchyme, the dermamyotome and the limb. On the basis of map position and expression pattern, EYA4 is a candidate for oculo-dento-digital (ODD) syndrome, but no EYA4 mutations were found in a panel of ODD patients.

Mab21, the mouse homolog of a C. elegans cell-fate specification gene, participates in cerebellar, midbrain and eye development

A multitude of regulatory genes are involved in phylogenetically conserved developmental cascades required for the patterning, cell-type specification, and differentiation of specific central nervous system (CNS) structures. Here, we describe the distribution of a mouse transcript encoding a homolog of the C. elegans mab-21 gene. In the nematode tail, mab-21 is required for the short-range patterning and cell-fate determination events mediated by egl-5 and mab-18, two homeobox genes homologous to Abd-B and Pax6, respectively. In mouse midgestation embryogenesis, Mab21 is expressed at its highest levels in the rhombencephalon, cerebellum, midbrain, and prospective neural retina. Our data and the genetic interactions previously documented in the nematode suggest that Mab21 may represent a novel, important regulator of mammalian cerebellum and eye development.

Structural alterations of alpha-crystallin during its chaperone action

The small heat-shock protein, alpha-crystallin, has chaperone ability whereby it stabilises proteins under stress conditions. In this study, alterations in the structure of alpha-crystallin during its interaction with a variety of substrate proteins (insulin, alpha-lactalbumin, ovotransferrin and serum albumin) under stress conditions have been examined using visible absorption, 31P-NMR and 1H-NMR and fluorescence spectroscopy. The fluorescence and 31P-NMR data imply that during the chaperone action of alpha-crystallin under reducing conditions, there is a slight increase in hydrophilicity of its N-terminal region and an alteration in flexibility of its C-terminal region, but overall, alpha-crystallin does not undergo a gross structural change. The fluorescence data suggest that substrate proteins interact with alpha-crystallin in a molten globule or intermediately folded state. The same conclusion is made from 1H-NMR spectroscopic monitoring of the interaction of alpha-crystallin with substrate proteins, e.g. the insulin B chain. The stoichiometry of interaction between alpha-crystallin and the various substrate proteins reveals that steric factors are important in determining the efficiency of interaction between the two proteins, i.e. on a molar subunit basis, alpha-crystallin is a more efficient chaperone protein with smaller substrate proteins. Comparison is also made between the high-molecular-mass (HMM) complexes formed between alpha-crystallin and ovotransferrin when reduced and heat stressed. Under heating conditions, fluorescence spectroscopy indicates that the HMM complex has a greater exposure of hydrophobicity to solution than that formed by reduction. Furthermore, in interacting with heated ovotransferrin, the C-terminal extension of the alphaB-crystallin subunit preferentially loses its flexibility suggesting that it is involved in stabilising bound ovotransferrin. By contrast, this extension is only partially reduced in flexibility in the HMM complex formed after reduction of ovotransferrin. The functional role of the C-terminal extensions in the chaperone action and the overall quaternary structure of alpha-crystallin is discussed.