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Biomedical subjects

G Christakis

Publications and source records attributed to G Christakis.

At least 19 recordsLinked to original sources
PubMed2005

Secular trends in cardiovascular risk factors among school-aged boys from Crete, Greece, 1982-2002.

OBJECTIVE: The aim of the present study was to examine secular trends in major cardiovascular disease (CVD) risk factors, that is, obesity and dyslipidaemia, among Cretan children during 1982-2002. DESIGN: Epidemiological survey. SETTING AND SUBJECTS: A total of 528 boys in 1982 and 620 boys in 2002, aged 12.1+/-0.1 y, were randomly selected from urban and rural regions throughout the county of Iraklio, Crete, Greece. Care was taken so that all procedures in 2002 closely matched those in 1982. RESULTS: Mean height, weight, and body mass index (BMI) were 1.1, 9.6, and 8.4% higher, respectively, in 2002 vs 1982 (P<0.001). The prevalence of overweight and obesity has risen by 63 and 202%, respectively (P<0.001). Contemporary children were found to have 3.6% higher total cholesterol (TC), 24.9% lower high-density lipoprotein-cholesterol (HDL-C), 25.3% higher low-density lipoprotein-cholesterol (LDL-C), 19.4% higher triacylglycerol, 36.6% higher TC/HDL-C ratio, and 60.3% higher LDL-C/HDL-C ratio compared with their peers in 1982 (P<0.003). These differences persisted even when adjusting for BMI (P<0.02). The proportion of children having abnormal lipid values was much greater nowadays than in the 1980s, yielding odds ratios of 1.4-8.8 (P<0.005). CONCLUSIONS: Results are indicative of a largely deteriorated CVD risk profile in Cretan children since 1982, and predict an unfavourable CVD morbidity and mortality for this population in the foreseeable future.

Body Mass Index↗
PubMed2005

Fatal Blastoschizomyces capitatus sepsis in a neutropenic patient with acute myeloid leukemia: first documented case from Greece.

Blastoschizomyces capitatus (formerly known as Geotrichum capitatum and Trichosporon capitatum) is a rare, yet an emerging, cause of invasive infections in immunosuppressed patients. Profound and prolonged neutropenia is the crucial predisposing factor for this yeast infection. Blastoschizomyces capitatus was isolated from peripheral blood cultures of a profoundly neutropenic patient with acute myeloid leukemia (M2 FAB). Despite administration of antifungal chemotherapy with liposomal amphotericin B at 4.5 mg kg(-1) daily, the patient succumbed 4 days after initiation of treatment. Infections attributed to B. capitatus have generally a poor prognosis, although the yeast shows in vitro susceptibility to antifungal agents. Low flucytosine, caspofungin acetate, voriconazole and amphotericin B minimum inhibitory concentration values were also recorded with our isolate. The clinical relevance of the in vitro susceptibility testing against the isolate and the current antifungal chemotherapy regimens against B. capitatus systemic infections are discussed.

Aged↗
PubMed2001

Renal dysfunction after cardiac surgery.

OBJECTIVE: To assess the causes and outcomes of patients with postcardiac surgery renal dysfunction. PATIENTS AND METHODS: A large cardiovascular data- base including pre-, peri- and postoperative serum creatinine concentrations from 2214 consecutive cardiac surgery patients was analyzed. RESULTS: Sixty-nine patients developed postoperative renal dysfunction, defined as at least a 15 mL/min decline in the creatinine clearance rate resulting in a value of less than 40 mL/min. These patients were significantly older, and had a higher incidence of previous cardiac surgery, diabetes, obesity, peripheral vascular disease, hypertension and poor ventricular function. Postoperatively, these patients had a higher occurrence of low output syndrome and myocardial infarction. Stepwise logistic regression predictors of postoperative renal dysfunction included the following: postoperative low output syndrome; repeat cardiac surgery; being older than 65 years; having diabetes; having poor left ventricular function; and having had valve surgery. Preoperative renal dysfunction (defined as a creatinine clearance of less than 40 mL/min) was not found to be one of the predictors. The mean creatinine concentrations of patients with mild postoperative renal dysfunction (defined as a creatinine concentration of less than 200 mmol/L on the fourth or fifth postoperative day) decreased significantly at the fifth postoperative day, while that of patients with severe postoperative renal dysfunction rose to a mean of 300 mmol/L six months postoperatively. The incidence of late dialysis (defined as a need for dialysis after postoperative day 10) approached 30% among patients with severe postoperative renal dysfunction and only 2% among patients with mild postoperative renal dysfunction. The early mortality rate (during the first postoperative month) was similar in both groups and approached 30%. CONCLUSIONS: Patients who develop postoperative renal dysfunction have a high mortality rate. Postoperative low cardiac output is the most important cause of postoperative renal dysfunction and, therefore, should be avoided. Patients with creatinine concentrations of less than 200 mmol/L at postoperative day 4 or 5 will probably resume normal renal function. Patients with creatinine concentrations of more than 200 mmol/L at days 4 and 5 have a 30% chance of needing long term dialysis.

Age Distribution↗
PubMed2001

Analysis of explants and causes of mortality during long-term follow-up of the Toronto stentless porcine valve.

UNLABELLED: The long-term status of stentless porcine valves has not yet been defined. METHODS: 447 patients were followed at 6 IDE sites up to 10 years (total follow-up, 2024.3 pt years; mean, 4.5 years): 35% were over 70 years and 41% underwent concomitant coronary artery bypass grafting. RESULTS: 10 patients underwent reoperation for valve explant (0.5%/pt year) because of severe aortic incompetence (AI) from dilatation of the aorta, sinotubular junction or sinus of Valsalva with torn commissures or cusps (8 patients) and endocarditis with abscess and dehiscence (2 patients). Six of 8 patients with late AI had bicuspid native aortic valves (mean age, 39.8 years). Overall freedom from reoperation was 95.2%. Freedom from structural deterioration was 96.1% at 7 years (98.0% for patients >60 years). Of 49 late deaths (2.5%/pt year), 9 were valve related (0.5%/pt year), 10 cardiac related, and 30 because of noncardiac causes. Valve-related deaths were because of endocarditis (3), CVA (1), redo surgery (1), or unknown reasons (4). Noncardiac deaths were due mainly to cancer (19/30). At seven years, freedom from all cause death was 81.8% and freedom from valve-related death 96.9%. CONCLUSIONS: Late mortality after stentless valve replacement has been primarily because of comorbidities present at surgery or developing later. The Toronto stentless porcine valve is associated with a low rate of reoperation and valve-related death.

Adult↗
PubMed1999

Will stentless valves be durable? The Toronto valve (TSPV) at 5 to 6 years.

The early hemodynamic benefits of stentless aortic valves have been well documented. The issue of long-term functional integrity remains unanswered. We report the clinical results of a multicenter registry with prospective data on 621 patients monitored for 7.1 years. Patient data were collected and analyzed at St Jude Medical Inc, St Paul, Minnesota. In all, 66% of patients were male; the average age was 65.9 years +/-11.0 years, with 39% older than 70 years. Native aortic valves were bicuspid in 40.6%, 91.5% were calcified and 65.7% stenotic. Most valves implanted (83.1%) were sizes 25, 27, or 29 mm. Concomitant coronary bypass was performed in 42% of patients. Total follow-up time for the 621 patients was 1,944.5 valve years (mean 3.1 years per patient). At 5 years, 86.1% (n = 137) and at 6 years 80.4% (n = 51) were in New York Heart Association class I, and 78% had no or trivial atrial insufficiency. The average mean systolic gradient for all valves at 6 years was 4.0 mm Hg, and the peak gradient was 8.6 mm Hg. The effective orifice area varied from 1.4 cm2 (23-mm valve) to 2.7 cm2 (29-mm valve). The decrease in left ventricular mass index was significant and sustained. Actuarial survival at 6 years was 84.2%, and freedom from cardiac-related deaths was 90.1%. Freedom from valve-related deaths was 95.7%, and freedom from prosthetic endocarditis was 98.6%. There were no instances of primary tissue valve failure during follow-up, with 97.2% freedom from reoperation. The early hemodynamic benefits of the TSPV are well maintained during more than 6 years of follow-up, without evident valvular dysfunction. Longer follow-up time is required to validate durability, but there is increasing evidence for well-maintained structural and functional integrity.

Actuarial Analysis↗
PubMed1992

Nutritional status of institutionalized elderly in south Florida.

To assess the nutritional status of an elderly nursing home population of South Florida, forty-seven persons with ages ranging from 65 to 96 years were studied. Complete clinical examination and anthropometric measures were performed, along with blood cell count, biochemical blood parameters and assessment of water-soluble vitamins levels. The most common clinical finding were edentulous (67%), general pallor (44%), hyperpigmentation (33%), dry skin (26%) and arcus corneitis (26%). Thirty-five percent of the studied population had cholesterol levels greater than 220 mg/dl. Triglyceride levels were also significantly elevated in a considerable subset of our subjects, with 30% having levels above threshold value of 150 mg/dl. Small proportions of subjects showed low levels of albumin (6%), total protein (28%), ascorbic acid (2%), and thiamin (9%). Forty-five percent of males were pyridoxine deficient, while 63% of the females presented such deficiency. This study underscores the need to define, with greater precision, the nutritional status of aged populations as well as improve our inadequate standards associated with the "normal" aging process. Nutritional intervention--only possible when appropriate standards are defined--can potentially serve not only to prevent the occurrence of significant morbidity and mortality, but can also be employed to enhance quality of life in the elderly individuals.

Aged↗
PubMed1991

Survival in a residential home: an eleven-year longitudinal study.

The length of survival and various risk factors were studied utilizing 408 residents (141 men, 267 women) of a large residential home. The subjects, aged 68 years or more at entry, admitted between 1978 and 1983, were physically independent, continent, and non-diabetic. They were followed until December 31, 1988, by which time 78% had died. The multivariate proportional hazard analysis showed the following entry variables to have the indicated effects on relative mortality rate ratios: 5-years' higher age (+10%, NS), persistent bacteriuria (+13%, NS), abnormal ECG (+26%, NS), current smoking (+63%, P less than 0.01), mildly impaired mobility (+96%, P less than 0.001), higher levels of in-study systolic pressure in 10-mm Hg steps (-4%, NS), higher entry serum cholesterol in 1-mmol/L steps (-7%, NS), and higher hematocrit in 5% steps (-14%, P less than 0.02). Female sex was associated with a +25% (NS) rate ratio; socioeconomic status and body weight were without effect. These data highlight the relative importance of specific factors associated with survival of persons within retirement homes and indicate that: (1) the presence of mild impairment of mobility at entry is by far the strongest predictor of early death; (2) smoking and lower hematocrit also exert important adverse effects; and (3) certain "risk factors", ie elevated systolic blood pressure and serum cholesterol, have a minimal protective effect, if any, in this age group.

Aged↗
PubMed1987

The cross-cultural study of U.S. and Greek adolescents: blood pressure data.

Blood pressures (BP) were determined in 1409 boys aged 8-16 years at three one-year intervals in New York City (NYC) and in Greece, areas of high and low incidence of coronary heart disease (CHD), respectively. Non-Greek American boys had significantly lower systolic and diastolic BP than all the Greek boys from NYC and from Greece. The boys residing in Crete and in Athens had higher BP than all other cohorts. After covariance adjustment for height, ponderal index and age, significant differences among the cohorts showed the non-Greek American cohort to have the lowest and the Cretan cohorts the highest BP levels. The Cretans lead a lifestyle noted for the absence of other risk factors for CHD. Thus, while the incremental increase in blood pressure might have a corresponding increase in CHD risk among individuals, there are fewer individuals in Crete at elevated risk overall based on the CHD experience of the U.S. and Greece.

Adolescent↗
PubMed1985

Cross-cultural validity of the Miami Structured Interview--1 for type A in children: the American-Hellenic Heart Study.

The Miami Structured Interview--1 was developed (1) to assess Type A behaviour in a broader age range of children than tested with previous interviews, and (2) for cross-cultural studies. This study examined the validity of the Miami Structured Interview--1 for assessing Type A behavior in 507 American and Greek preadolescent (ages 7-11) and adolescent (ages 12-16) boys. The interview was scored on voice stylistics such as speed of speech, word emphasis, and latency of response. Validity was tested using the Matthews Youth Test for Health (MYTH), a teacher rating scale of Type A behaviors. Interview determined Type A's received significantly higher MYTH scores than non Type A's for American adolescents (p less than 0.05), Greek preadolescents (p less than 0.01), and Greek adolescents (p less than 0.05). The interview also identified extreme groups of Type A's and Type B's for American adolescents (p less than 0.01) and Greek preadolescents (p less than 0.05). The findings support the cross-cultural validity of the Miami Structured Interview--1 and the Type A construct for children. Limitations of the Miami Structured Interview--1 are discussed.

Adolescent↗
PubMed1985

Determinants of risk for coronary artery bypass grafting in stable and unstable angina pectoris.

Although the operative risk and morbidity associated with coronary artery bypass grafting for chronic stable angina is exceptionally low, clinical and angiographic factors exist that may predict differing outcomes in patient subsets. Forty-five variables were prospectively recorded on all 1302 patients who underwent coronary artery bypass grafting at Toronto General Hospital over a 24-month period. Twelve selected variables were analysed by univariate and multivariate techniques. The patients were divided in two groups depending upon their clinical presentation (stable versus unstable angina) and the timing of surgery (elective versus urgent). The results of risk-factor analysis revealed that the unstable cohort had four predictors for operative mortality: sex, age, left ventricular function and left main coronary stenosis greater than 50%, whereas the stable cohort had only three predictors: sex, age and left ventricular function. The results for postoperative morbidity (perioperative myocardial infarction or low-output syndrome) showed that the unstable cohort had six predictors: sex, age, left ventricular function, timing of surgery, extent of coronary artery disease and the type of myocardial protection used. The stable cohort had only three predictors of morbidity, the same as for mortality. This analysis of multiple risk factors on patients grouped according to stability and timing of surgery clearly demonstrated determinants of risk in the two groups (operative mortality for the stable group of 2.9% versus 5.4% for the unstable group, and perioperative infarction rate for the stable group of 9.1% and for the unstable group of 13.7%).

Angina Pectoris↗
PubMed1983

Cord blood serum in newborns of diabetic mothers.

Serum cholesterol, triglycerides and lipoprotein cholesterol were measured in cord bloods from 117 newborns. Group I consisted of 39 infants of diabetic mothers and Group II (control) consisted of 78 newborns of non-diabetic mothers. The most significant difference in serum lipids between the two groups was the higher levels of LDL cholesterol and lower levels of HDL cholesterol in the newborns of diabetic mothers. Cord blood serum cholesterol was slightly, but not significantly, higher in children born of diabetic mothers. Serum triglycerides were also not significantly different between the groups. While it remains to be established whether elevated levels of LDL cholesterol and decreased levels of HDL cholesterol at birth in these infants represent a transient phenomenon, this study suggests that newborns of diabetic mothers may be predisposed early in life to LDL hypercholesterolemia and thus may be at a greater risk of developing coronary heart disease later in life.

Cholesterol↗
PubMed1983

Adipose tissue fatty acid composition of adolescents in a U.S.--Greece cross-cultural study of coronary heart disease risk factors.

Adipose tissue fatty acid composition was studied in 139 boys, a subgroup of 1521 subjects aged 8-16 participating in the United States (New York City)--Greece cross-cultural study of coronary heart disease risk factor development. Adipose tissue was obtained by an aspiration technique, followed by transmethylation of fatty acids and gas-liquid chromatographic analysis. Statistically significant differences were found among different cohorts in their adipose tissue content of saturated, monounsaturated and polyunsaturated fatty acids. All United States cohorts had significantly higher (p less than 0.0001) levels of saturated and polyunsaturated fatty acids and significantly lower (p less than 0.0001) monounsaturated fatty acids compared to the Greece cohorts. These relationships held for all three types of fatty acids whether the non-Greek cohort from New York City or the cohorts of adolescents of Greek descent who reside in New York City alone, were compared to the cohorts residing in Greece. The differences in the adipose tissue fatty acids between the cohorts may be an important expression of the biochemical milieu which contributes to the development of relatively low coronary heart disease rates in Greece compared to those in the United States.

Adipose Tissue↗
PubMed1980

Serum cholesterol binding reserve and high density lipoprotein cholesterol in patients on maintenance hemodialysis.

Serum cholesterol binding reserve (SCBR, the capacity of the serum to solubilize additional cholesterol), high density lipoprotein cholesterol (HDL . Ch) and serum levels of cholesterol and triglycerides were measured in 53 chronically uremic patients (40 men and 13 women) undergoing maintenance hemodialysis. The values were compared with those of controls (149 men and 28 women) matched for serum lipid levels. Hypertriglyceridemia and decreased HDL . Ch were observed among the patients, confirming previous reports. SCBR values of the patients were not significantly different from those of controls except in a small subgroup of uremic diabeties, whose SCBR values were markedly decreased. There was a positive correlation between SCBR and the duration for which the patients had been maintained by hemodialysis. The results suggest that patients with higher SCBR values have a better prospect for surviving long duration of hemodialysis.

Adult↗