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Biomedical subjects

D Farkas

Publications and source records attributed to D Farkas.

13 recordsLinked to original sources
PubMed2006

Short-term changes in insulin resistance following weight loss surgery for morbid obesity: laparoscopic adjustable gastric banding versus laparoscopic Roux-en-Y gastric bypass.

BACKGROUND: Laparoscopic adjustable gastric banding (LAGB) and laparoscopic Roux-en-Y gastric bypass (LRYGBP) both effectively treat the insulin resistance associated with type 2 diabetes mellitus (T2DM). Restriction of caloric consumption, alterations in the entero-insular axis or weight loss may contribute to lowering insulin resistance after these procedures. The relative importance of these mechanisms, however, following LAGB and LRYGBP remain unclear. The aim of this study was to compare directly the short-term changes in insulin resistance following LAGB and LRYGBP in similar populations of patients. METHODS: Patient preference determined operation type. The Homeostasis Model Assessment for Insulin Resistance (HOMA IR) was used to measure insulin resistance. Preoperative values were compared to postoperative levels obtained within 90 days of surgery. Significant differences between groups were tested by ANOVA. RESULTS: There were no significant preoperative differences between groups. The 56 LAGB patients had a mean age of 42.5 years (25.7-63), BMI of 45.5 kg/m(2) (35-66) and preoperative HOMA IR of 4.1 (1.4-39.2). 75% of LAGB patients were female and 43% had T2DM. The 61 LRYGBP patients had a median age of 39.9 years (22.1-64.3), BMI of 45.0 kg/m(2) (36-62), and preoperative HOMA IR of 5.0 (0.6-56.5). 79% of LRYGBP patients were women and 44.3% had T2DM. Median follow-up for LAGB patients was 45 days (18-90) and for LRYGBP patients 46 days (8-88 days). LAGB patients had a median of 14.8% excess weight loss (6.9%-37.0%) and LRYGB patients 24.2% (9.8%-51.4%). Postoperative HOMA IR was significantly less after LRYGBP, 2.2 (0.7-12.2), than LAGB, 2.6 (0.8-29.6), although change in HOMA IR was not significantly different. Change in HOMA IR for both groups did not vary with length of follow-up or weight loss but correlated best with preoperative HOMA IR (LAGB r=0.8264; LRYGBP r=0.9711). CONCLUSIONS: Both LAGB and LRYGBP significantly improved insulin resistance during the first 3 months following surgery. Both operations generated similar changes in HOMA IR, although postoperative HOMA IR levels were significantly lower after LRYGBP. These findings suggest that caloric restriction plays a significant role in improving insulin resistance after both LAGB and LRYGBP.

Adult↗
PubMed2005

Precision measurement of the three 2(3)P(J) helium fine structure intervals.

The three 2(3)P fine structure intervals of 4H are measured at an improved accuracy that is sufficient to test two-electron QED theory and to determine the fine structure constant alpha to 14 parts in 10(9). The more accurate determination of alpha, to a precision higher than attained with the quantum Hall and Josephson effects, awaits the reconciliation of two inconsistent theoretical calculations now being compared term by term. A low pressure helium discharge presents experimental uncertainties quite different than for earlier measurements and allows direct measurements of light pressure shifts.

Journal Article↗
PubMed2005

Atomistic mechanisms of fatigue in nanocrystalline metals.

We investigate the mechanisms of fatigue behavior in nanocrystalline metals at the atomic scale using empirical force laws and molecular level simulations. A combination of molecular statics and molecular dynamics was used to deal with the time scale limitations of molecular dynamics. We show that the main atomistic mechanism of fatigue crack propagation in these materials is the formation of nanovoids ahead of the main crack. The results obtained for crack advance as a function of stress intensity amplitude are consistent with experimental studies and a Paris law exponent of about 2.

Journal Article↗
PubMed1996

[Growth of children with insulin-dependent diabetes. Study of 104 cases].

BACKGROUND: Results of studies of growth in children with diabetes mellitus are still conflicting. In a cross-sectional and longitudinal study, statural growth was analysed in a sample of diabetic children in order to specify its characteristics and relationship with various factors. POPULATION AND METHODS: One hundred and four children (53 girls and 51 boys) with insulin-dependent diabetes for more than 3 years have been studied (age at onset and duration of diabetes, respectively, 6.4 +/- 4.1 and 8.5 +/- 4.8 in girls; 6.1 +/- 3.9 and 7.9 +/- 3.9 in boys; m +/- SD). A control group included 51 boys (age: 8.9 +/- 2.9) and 49 girls (age: 9.3 +/- 2.7). Data were collected every three months. Hemoglobin A1c was measured using high performance liquid chromatography (normal range: 5.0 +/- 1.0%; m +/- 2 DS). RESULTS: At diagnosis, height (evaluated in SD) did not differ between diabetic children and controls. Three years before the onset of diabetes, boys were taller compared to controls (1.02 +/- 0.20 vs 0.41 +/- 0.17; P < 0.05; m +/- SEM). Children five years after the onset of disease were overweight compared to controls (girls: 0.96 +/- 0.16 vs 0.00 +/- 0.20; boys: 0.59 +/- 0.16 vs -0.04 +/- 0.15; P < 0.01; m +/- SEM). Longitudinal study showed a progressive decrease of mean growth velocity starting at least 2 years before the onset of diabetes and proceeding until the end of growth. From diagnosis to the end of height development, there was a growth loss of 0.66 SD in girls (p < 0.01) and 0.69 SD in boys (p < 0.05). This alteration of growth affected more clearly children who became diabetic before the onset of puberty, especially those with early-onset diabetes and bad metabolic control. Growth changes for the first 5 years of diabetes were significantly and negatively correlated with mean hemoglobin A1c levels (r = -0.57). Growth changes from the onset of diabetes to the end of growth were correlated with age at diagnosis, (boys: r = 0.73; girls: r = 0.37). During puberty, girls exhibited a reduced growth spurt, especially when they were overweight and received too low doses of insulin. CONCLUSIONS: On the whole, diabetic children were growing in normal range. Growth was adversely and mainly affected by early-onset diabetes, a long duration of disease, many years of poor metabolic control and, especially in adolescent girls, low doses of insulin and weight excess.

Adolescent↗
PubMed1993

Phaeochromocytoma in multiple endocrine neoplasia type 2 A: survey of 100 cases.

OBJECTIVE: We report clinical, biochemical, morphological and histological data of phaeochromocytoma in 40 French families and in apparently sporadic cases of multiple endocrine neoplasia (MEN) type 2 A (medullary thyroid carcinoma, phaeochromocytoma, with or without hyperparathyroidism). DESIGN: This retrospective study was obtained from cases registered by the 'Groupe d'Etudes des Tumeurs à Calcitonine' from 1968 to 1990. We analysed the cases having sufficiently precise data on phaeochromocytoma with Pigas Software. PATIENTS: Characteristics of phaeochromocytoma in 100 patients with MEN 2 A were reviewed. Phaeochromocytoma was bilateral in 51%. The disease was inherited in 94 patients from 40 families (40 probands, 54 relatives), and was apparently sporadic in six. RESULTS: In this series, diagnostic circumstances were highly suggestive of phaeochromocytoma in 39.8% of the cases, whereas in 43.2%, diagnosis was made through systematic investigations of patients, either before (27.3%) or after (13.6%) thyroidectomy, or after discovery of hyperparathyroidism (2.3%). Fifteen per cent of patients were detected by family screening. Sudden death occurred in 8.9%, malignant phaeochromocytoma in 3%, and ectopic tissue in 4% of the cases. Urinary metanephrines appeared to be the most sensitive screening test. The extent of clinical symptoms was not associated with a particular hormonal pattern. Bilateral adrenalectomy was performed in 60% (in one step in 50%, in two steps in 10%). In these patients, bilateral histological lesions were observed in 92.5%. Simultaneous diagnosis for adrenal and thyroid disease was made in 73.4%, but phaeochromocytoma may be diagnosed before (9.6%) or after (17%) medullary thyroid carcinoma, with an interval greater than 2 years in 25 cases. CONCLUSION: Owing to variable clinical symptoms of phaeochromocytoma in these 100 cases of MEN 2 A, systemic biological adrenal assay is required. The search for phaeochromocytoma in medullary thyroid carcinoma (and vice versa) has to be systematically performed, even in apparently sporadic cases. Screening for phaeochromocytoma must be repeated for years, owing to the frequency of bilateral adrenal disease.

Adrenal Gland Neoplasms↗
PubMed1991

DNA polymorphism analysis of HLA class II genes in unrelated children and in first-degree relatives with type I diabetes.

Eighty unrelated diabetic children, seventy healthy controls and hundred and ten affected and unaffected first-degree relatives of twenty multiplex families were investigated by restriction fragment length polymorphism analysis of HLA class II genes using five probe/enzyme systems: DRB and DQB/Taq I, DRB and DQB/EcoRI and DQB/BamHI according to standard procedures described in the 10th Histocompatibility Workshop protocol. Comparison between the unrelated diabetic patients and the controls confirmed the positive association of type 1 diabetes with DR3(w17)DQw2 Dw24 or Dw25 and DR4DQw8 and the negative association with DR2(w15)DQw6, DR4DQw7 and DR7DQw2 haplotypes. In multiplex families, similar allele associations were found and the distinction between haplotypes present in diabetic patients and those that segregated to healthy family members allowed to observe striking differences between the "affected" and "unaffected" haplotypes, particularly for the subtypes of DR3(w17) DQw2, DR4DQw3 and DR2DQw1 haplotypes. Heterozygous siblings who carried both DR3DQw2 and DR4DQw8 subtypes disclosed a highly increased risk and more than 80% of DR3/DR4 affected siblings received a paternal DR4DQw8 together with a maternal DR3DQw2. These observations indicate that several genetic aspects influence susceptibility to type 1 diabetes: 1) some particular HLA class II subsets; 2) the parental origin of the predisposing genes; 3) the synergistic effect of both haplotypes, in particular DR3DQw2 and DR4DQw8. These results may help to better specify susceptibility markers for risk prediction in siblings.

Adolescent↗
PubMedDate not supplied

Giant cell myocarditis: first report of disease recurrence in the transplanted heart.

A 51-year-old female underwent heart transplantation for endomyocardial biopsy-proved giant cell myocarditis complicated by rapidly progressive congestive heart failure unresponsive to immunosuppression. Preoperatively there was no evidence of an associated extracardiac granulomatous disease. Twenty-one months after heart transplantation, giant cell myocarditis recurred in the allograft associated with sustained ventricular arrhythmias. There remained an absence of concomitant extracardiac granulomatous diseases and infections. Increased corticosteroid therapy cleared myocardial inflammation but did not abolish ventricular arrhythmias, which required pharmacologic intervention and the insertion of an Intertach II antitachycardia pacemaker. Compared with a value of 0.56 obtained 1 year after heart transplantation, left ventricular ejection fraction decreased to 0.29 at the time of diagnosis of giant cell myocarditis and remained subnormal 6 months later. Because giant cell myocarditis can recur in the allograft, the candidacy of patients with this disease for heart transplantation must be carefully assessed.

Biopsy↗