Nocturnal hypoxemia severity and renin-angiotensin system activity in obstructive sleep apnea

RATIONALE

Obstructive sleep apnea (OSA) and nocturnal hypoxemia are associated with chronic kidney disease and up-regulation of the renin-angiotensin system (RAS), which is deleterious to renal function. The extent to which the magnitude of RAS activation is influenced by the severity of nocturnal hypoxemia and comorbid obesity has not been determined.

OBJECTIVES

To determine the association between the severity of nocturnal hypoxemia and RAS activity and whether this is independent of obesity in patients with OSA.

METHODS

Effective renal plasma flow (ERPF) response to angiotensin II (AngII) challenge, a marker of renal RAS activity, was measured by paraaminohippurate clearance technique in 31 OSA subjects (respiratory disturbance index, 51 ± 25 h(-1)), stratified according to nocturnal hypoxemia status (mean nocturnal SaO2, ≥90% [moderate hypoxemia] or <90% [severe hypoxemia]) and 13 obese control subjects.

MEASUREMENTS AND MAIN RESULTS

Compared with control subjects, OSA subjects demonstrated decreased renovascular sensitivity (ERPF, -153 ± 79 vs. -283 ± 31 ml/min; P = 0.004) (filtration fraction, 5.4 ± 3.8 vs. 7.1 ± 2.6%; P = 0.0025) in response to 60 minutes of AngII challenge (mean ± SD; all P values OSA vs. control). The fall in ERPF in response to AngII was less in patients with severe hypoxemia compared with those with moderate hypoxemia (P = 0.001) and obese control subjects after 30 minutes (P < 0.001) and 60 minutes (P < 0.001) of AngII challenge, reflecting more augmented renal RAS activity. Severity of hypoxemia was not associated with the blood pressure or the systemic circulating RAS component response to AngII.

CONCLUSIONS

The severity of nocturnal hypoxemia influences the magnitude of renal, but not the systemic, RAS activation independently of obesity in patients with OSA.

Ultra-fast track hospital discharge using conventional cardiac surgical techniques

BACKGROUND

Recent introduction of minimally invasive adult cardiac surgical techniques has emphasized the advantage of early hospital discharge. However, we chose an alternative approach to determine the safety, efficacy, and feasibility of ultra-fast track protocols while retaining both standard surgical exposure (median sternotomy) and conventional cardiac surgical techniques (hypothermia, cardiopulmonary bypass with cardiac arrest, and optimal myocardial protection).

METHODS

From September 1995 to January 1998, a total of 258 consecutive patients underwent cardiac procedures by a single surgeon. Acceleration of clinical pathways was used to initiate earlier discharges. Stringent postdischarge follow-up was implemented. Prospectively entered data were then analyzed retrospectively.

RESULTS

A variety of isolated as well as combined coronary and valve procedures were performed. Of the 258 patients operated on during this entire study period, a total of 144 patients (56%) were discharged within postoperative days 1 to 4 (ultra-fast track discharge). Over the past 12 months, this incidence increased to 70% (76 of 108 patients). Approximately 50% of these patients were operated on urgently or emergently. To date, there have been no deaths in this ultra-fast track group. There were eight brief readmissions, of which one was for rewiring of a noninfected sternal dehiscence, and the remaining were for cardiac diagnostic studies or a noncardiac problem altogether.

CONCLUSIONS

Conventional cardiac operation can allow ultrafast hospital discharges while retaining the advantage of time-tested techniques and providing wider application without requiring new or additional training or equipment.

Ectodermal dysplasia, cleft lip/palate, and severe cutaneous and osseous syndactyly in a mentally retarded girl: a new multiple malformation syndrome

A 13-year-old mentally retarded girl with severe cutaneous and osseous syndactyly of the hands and feet, cleft lip/palate, and ectodermal dysplasia is presented. We conclude that the pattern of malformations described represents a new multiple malformation syndrome. A comparison with Zlotogora-Ogür syndrome is presented.

The importance of immunoglobulin-breakdown supporting the growth of bacteria in oral abscesses

Oral bacteria play an important rôle in the causation of oro-facial abscesses. However, they can also be involved in brain, liver and lung abscesses. To persist, it is essential that these bacteria can grow on those sites. The main source of nutrients for growth in abscesses is likely to be tissue exudate, which is rich in serum-derived proteins, and relatively poor in free amino acids and carbohydrates. Degradation of intact proteins seems a crucial step in providing the peptides necessary for energy generation. The aim of this study was to investigate the capacity of microorganisms from asscesses to degrade serum proteins, in particular immunoglobulins. To this end, samples were taken by aspiration from 16 odontogenic abscesses. It was found that pus from abscesses differed strongly in the concentration of viable bacterial cells. The ability of the abscess microflora to degrade serum proteins was investigated after growth of the sample in heat-inactivated human serum. The microflora from abscesses with a high concentration (n = 10) of bacteria strongly degraded immunoglobulins, whereas breakdown of immunoglobulins was virtually absent after growth of the microflora from low-bacterial concentration (n = 6) abscesses. Bacteriological analyses revealed the presence of at least one proteinase-producing species, like Porphyromonas, black-pigmented Prevotella species, or Actinomyces meyeri, in abscesses with a high density of bacteria, but not in those with low bacterial density. The results indicate that the capacity to degrade intact proteins, in particular immunoglobulins, is a major determinant of bacterial growth in abscesses.

Hyperinsulinemia in nondiabetic Asian subjects using specific assays for insulin, intact proinsulin, and des-31, 32-proinsulin

OBJECTIVE

To investigate the contributions of intact proinsulin and of des-31,32-proinsulin to fasting concentrations of insulin-like molecules in nondiabetic subjects from two ethnic groups (Asian and white) and to see whether Asian subjects are hyperinsulinemic compared with white subjects using highly specific assays for insulin.

RESEARCH DESIGN AND METHODS

We investigated subjects with normal glucose tolerance (NGT) (82 Asian and 67 white) and impaired glucose tolerance (IGT) (16 Asian and 13 white), diagnosed by using standard World Health Organization criteria. Highly specific monoclonal antibody-based assays were used to measure insulin, intact proinsulin, and des-31,32-proinsulin. An index of insulin secretion was derived as a ratio of incremental insulin to incremental glucose concentrations from 0 to 30 min during an oral glucose tolerance test.

RESULTS

Asian subjects with NGT, despite being significantly thinner than whites (BMI 24.4 +/- 3.5 vs. 25.7 +/- 3.7 kg/m2, P = 0.04), had a more central distribution of obesity (subscapsular-to-triceps skinfold ratios 1.36 +/- 0.69 vs. 1.17 +/- 0.41, P = 0.047). Asian subjects with NGT showed significant hyperinsulinemia 2 h after oral glucose load (plasma insulin median 274 pmol/l [range 26-1,505] vs. 186 pmol/l [27-720], P < 0.005) compared with whites. Asian subjects with NGT also had significantly higher insulin increments (P < 0.02) compared with white subjects and significantly higher fasting concentrations of intact proinsulin (median 2.7 pmol/l [range 0.9-14.1] vs. 2.1 [0.8-7.9], P < 0.02) but not of des-31,32-proinsulin. The ratio of proinsulin-like molecules to the total sum of three insulin-like molecules, however, was similar between Asian and white subjects with NGT and IGT.

CONCLUSIONS

These results indicate that when specific assays for insulin are used, Asian subjects show postglucose load hyperinsulinemia and fasting hyperproinsulinemia compared with white subjects, suggesting increased insulin secretion and/or the presence of underlying insulin resistance in this ethnic group. The contribution of proinsulin-like molecules to total insulin-like molecules was similar between Asian and white subjects with NGT and IGT, and there was no contribution to hyperinsulinemia in Asian subjects.

Plasminogen activator inhibitor (PAI-1) activity is elevated in Asian and Caucasian subjects with non-insulin-dependent (type 2) diabetes but not in those with impaired glucose tolerance (IGT) or non-diabetic Asians

In order to study the plasminogen activator inhibitor activity (PAI-1) in subjects at different risk of non-insulin-dependent diabetes and ischaemic heart disease we examined 89 subjects with diet controlled NIDDM (49 Caucasian, 40 Asian), 29 with impaired glucose tolerance (IGT) (13 Caucasian, 16 Asian), and 149 with normal glucose tolerance (67 Caucasian, 82 Asian). Diabetes was diagnosed by WHO criteria and highly specific, monoclonal antibody-based assays were used to measure insulin, intact proinsulin, and des 31,32 proinsulin. Subjects with NIDDM were significantly more obese, had more central distribution of obesity, higher fasting plasma specific insulin concentrations (NIDDM median 74 pmol l-1 vs IGT 41 pmol l-1, p < 0.01 and vs normals 34 pmol l-1, p < 0.001) and higher PAI-1 activity than normals and those with IGT (NIDDM 23.0 +/- 6.9 vs IGT 16.8 +/- 5.0, p < 0.001 and vs normals 17.1 +/- 6.9 AU ml-1, p < 0.001). However, PAI-1 activity was not significantly different between Asian and Caucasian normals (17.5 +/- 7.3 vs 16.5 +/- 6.4 AU ml-1, p = ns) and diabetic (22.8 +/- 7.3 vs 23.1 +/- 6.6 AU ml-1, p = ns) subjects. In addition to relationships with obesity and plasma triglyceride, PAI-1 activity, after controlling for age, sex, body mass index, and waist-hip ratio, was related to fasting insulin (partial r = 0.22, p < 0.001), intact proinsulin (partial r = 0.36, p < 0.001), and des 31,32 proinsulin concentrations (partial r = 0.33, p < 0.001) as measured by highly specific assays. The association of PAI-1 with diabetes was weakened but remained statistically significant (p = 0.042) after controlling for age, sex, ethnicity, obesity, plasma triglyceride, and all insulin-like molecules. We conclude that, although PAI-1 activity is raised in subjects with diet-treated NIDDM, it is normal in subjects with IGT and non-diabetic Asians, populations at high risk of NIDDM and ischaemic heart disease. Raised PAI-1 activity may play an important role in the pathogenesis of macrovascular disease in subjects with NIDDM, but is unlikely to explain excess risk of ischaemic heart disease in Asians and those with impaired glucose tolerance.