Differentiation of patients with mild cognitive impairment and healthy controls based on computer assisted hand movement analysis: a proof-of-concept study

Mild cognitive impairment (MCI) is the prodromal phase of dementia, and it is highly underdiagnosed in the community. We aimed to develop an automated, rapid (< 5 min), electronic screening tool for the recognition of MCI based on hand movement analysis. Sixty-eight individuals participated in our study, 46 healthy controls and 22 patients with clinically defined MCI. All participants underwent a detailed medical assessment including neuropsychology and brain MRI. Significant differences were found between controls and MCI groups in mouse movement characteristics. Patients showed higher level of entropy for both the left (F = 5.24; p = 0.001) and the right hand (F = 8.46; p < 0.001). Longer time was required in MCI to perform the fine motor task (p < 0.005). Furthermore, we also found significant correlations between mouse movement parameters and neuropsychological test scores. Correlation was the strongest between motor parameters and Clinical Dementia Rating scale (CDR) score (average r: - 0.36, all p's < 0.001). Importantly, motor parameters were not influenced by age, gender, or anxiety effect (all p's > 0.05). Our study draws attention to the utility of hand movement analysis, especially to the estimation of entropy in the early recognition of MCI. It also suggests that our system might provide a promising tool for the cognitive screening of large populations.

Maxillomandibular osteotomy healing in a patient with hypophosphatemic rickets

Hypophosphatemic rickets is a hereditary disease of childhood that affects bone metabolism. Patients with this disease can have poor bony healing at growth centers due to impaired mineralization of the cartilaginous bone plates. The orthopedic literature has shown appropriate long bone healing in patients with rickets who are undergoing concurrent medical management. However, there has never been a report of successful osteotomy or fracture of the maxillomandibular skeleton in a patient with rickets with documented radiographic and clinical resolution. This report describes a case of successful Le Fort I osteotomy with bilateral mandibular sagittal split osteotomies with concurrent medical management in an 18-year-old female with hypophosphatemic rickets. Before surgery the patient was consented and understood that because there has never been a documented case such as this, she might especially risk complications including non-union, malunion, or unfavorable osteotomy splits. The intraoperative quality of the patient's bone was of normal caliber and allowed routine osteotomy creation and internal fixation with no complications. She was followed for over 3 years and showed uneventful healing. While this disease is especially rare, practitioners should be aware that acceptable healing alongside appropriate medical management has been documented.

Abstract 948: A novel antibody-drug conjugate that induces long-term tumor regression and anticancer stem cell activity

Antibody-drug conjugates (ADCs) selectively deliver cytotoxic agents to tumors and provide the potential for increased clinical benefit to cancer patients. We have developed an ADC consisting of an antibody against a target expressed on the surface of tumor cells that is site-specifically conjugated with a pyrrolobenzodiazepine (PBD) dimer payload (PBD-ADC). The tumor-associated antigen is overexpressed in many carcinomas, on both bulk tumor cells and cancer stem cells (CSCs), while normal tissue expression is limited, thus making it an ideal ADC target. The PBD payload was selected due to its picomolar potency and because, unlike tubulin inhibitors, it could be cytotoxic to CSCs as well as bulk tumor cells. The PBD-ADC is significantly efficacious in target-positive in vivo tumor models of gastric, breast and lung carcinomas, inducing long-term tumor regressions and demonstrates greater potency compared to ADCs conjugated with either tubulysin or auristatin payloads, both tubulin inhibitors. Additionally, the PBD-ADC significantly reduced the CSC population of tumors in vivo, unlike ADCs bearing tubulin inhibitor payloads. The PBD-ADC appears to be efficacious against tumors that have acquired resistance to a tubulysin-based ADC, however possible mechanisms of resistance to this PBD-ADC are being investigated. Collectively, this novel ADC represents a promising therapy that may deliver durable clinical responses in indications with unmet medical need.

Citation Format: Jay W. Harper, Chris Lloyd, Shenlan Mao, Xin Lin, Nazzareno Dimasi, Phil Howard, Ellen O'Connor, David Farkas, Christopher Barton, Jeff Smith, Helen Zhong, Tracy Chen, Mary Jane Hinrichs, Marlon Rebelatto, Xiang-Qing Yu, Susan Spitz, Andrew Pierce, Dominic Lai, Hurt Elaine, Lilian van Vlerken-Ysla, Jalla Sanjoo, Katy Miller, Karen McCullough, Priya Kannan, Simon Thompson, Parthiv Mahadevia, Chris Martin, Robert Hollingsworth, Adeela Kamal. A novel antibody-drug conjugate that induces long-term tumor regression and anticancer stem cell activity. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 948. doi:10.1158/1538-7445.AM2015-948

Decline in serum hemoglobin in the 7 days after cardiac catheterization

OBJECTIVES

Bleeding is an established complication following cardiac catheterization and lower preoperative hemoglobin concentration is a potentially modifiable risk factor for adverse outcomes after cardiac surgery. However, typical changes in serum hemoglobin concentration after cardiac catheterization are poorly defined. The authors sought to identify the pattern of change in serum hemoglobin concentration within 7 days after cardiovascular catheterization, factors associated with this change and any association with adverse outcomes.

DESIGN

Retrospective observational study over a 1-year period.

SETTING

U.S. academic medical institution.

PARTICIPANTS

Participants were 284 adult patients with baseline hemoglobin concentration≥12 g/dL undergoing nonemergent cardiac surgery after cardiovascular catheterization via the femoral arterial route.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Lowest daily hemoglobin concentration was recorded where available for up to 7 days after catheterization and before surgery. Generalized estimating equations identified the pattern of change in serum hemoglobin while regression models identified factors associated with hemoglobin decline. Following cardiovascular catheterization average serum hemoglobin declined over time, reaching a nadir 1.4 g/dL (95% CI 1.0-1.8) below baseline 6 days after catheterization. A higher baseline hemoglobin concentration and lower body mass index were associated with greater maximal decline in hemoglobin concentration after catheterization. Acute preoperative hemoglobin decline was not associated with acute kidney injury (AKI) or a composite adverse outcome that may reflect organ ischemia.

CONCLUSIONS

In a cohort of patients before cardiac surgery serum hemoglobin declines during the week after cardiac catheterization, with maximal average decline observed 5 to 7 days after catheterization.

Are nanoporous materials radiation resistant?

The key to perfect radiation endurance is perfect recovery. Since surfaces are perfect sinks for defects, a porous material with a high surface to volume ratio has the potential to be extremely radiation tolerant, provided it is morphologically stable in a radiation environment. Experiments and computer simulations on nanoscale gold foams reported here show the existence of a window in the parameter space where foams are radiation tolerant. We analyze these results in terms of a model for the irradiation response that quantitatively locates such window that appears to be the consequence of the combined effect of two length scales dependent on the irradiation conditions: (i) foams with ligament diameters below a minimum value display ligament melting and breaking, together with compaction increasing with dose (this value is typically ∼5 nm for primary knock on atoms (PKA) of ∼15 keV in Au), while (ii) foams with ligament diameters above a maximum value show bulk behavior, that is, damage accumulation (few hundred nanometers for the PKA's energy and dose rate used in this study). In between these dimensions, (i.e., ∼100 nm in Au), defect migration to the ligament surface happens faster than the time between cascades, ensuring radiation resistance for a given dose-rate. We conclude that foams can be tailored to become radiation tolerant.

Acute kidney injury after cardiac surgery: does the time interval from contrast administration to surgery matter?

OBJECTIVE

The authors sought to evaluate the association between the time interval from contrast administration to cardiac surgery and postoperative acute kidney injury (AKI).

DESIGN

A retrospective observational study over a 1-year period.

SETTING

A US academic medical institution.

PARTICIPANTS

Six hundred forty-four adult patients undergoing nonemergent cardiac surgery.

INTERVENTIONS

No interventions were performed as part of the study.

MEASUREMENTS AND MAIN RESULTS

AKI was defined as an increase in serum creatinine by ≥0.3 mg/dL or ≥50% above baseline within the first 2 postoperative days or the commencement of renal replacement therapy within the same period. Using a contrast-to-surgery time interval >7 days as the baseline, multivariable logistic regression analysis determined the association between a contrast-to-surgery time interval ≤1 day or 2 to 7 days and postoperative AKI adjusting for potential confounding variables. The incidence of AKI within the study cohort was 21.9%. After adjusting for other covariates, there was no association between the contrast-to-surgery time and AKI (odds ratio [OR] ≤1 day = 0.93; 95% confidence interval [CI], 0.52-1.66; p = 0.81; OR = 2-7 days = 1.28; 95% CI, 0.78-2.11; p = 0.34).

CONCLUSIONS

In an appropriately selected population, cardiac surgery can be performed within 1 day of cardiovascular catheterization and contrast administration without an increase in the incidence of postoperative AKI. Recommendations to delay cardiac surgery for a specified period after contrast administration to reduce the risk of postoperative AKI are premature. Additional evidence is required before making recommendations on optimal surgical timing after contrast exposure.

Atomistic Studies of Plasticity in Nanophase Metals

Molecular dynamics computer simulation of nanocrystalline Ni and Cu with mean grain sizes ranging from 5 to 20 nm show that grain boundaries in nanocrystalline metals have structures similar to most grain boundaries found in conventional polycrystalline materials. Moreover, the excess enthalpy density in grain boundaries and triple junctions appears to be independent of grain in both, computer generated and experimental measured samples. Simulations of deformation under constant uniaxial stress demonstrate a change in deformation mechanism as function of grain size: at the smallest grain sizes all deformation is accommodated in the grain boundaries, at higher grain sizes, intragrain deformation is observed

Comparison of TEM Observations with Dislocation Core Structure Calcuiations in B2 Ordered Compounds

Dislocation core structures have been calculated using atomistic computer simulations in NiAl and other B2 compounds. In the present work the calculated dislocation core structure are correlated with the known deforniatiorn behavior of B2 alloys. It is found that for the high ordering energy compounds <111> dislocations do not split in the simulations, in agreement with the experimental observations. It is also found that core structures for certain <111> and 1/2 <111> dislocations are spread in { 112} planes, which is consistent with the slip plane often reported for these dislocations. For the < 100> dislocations several orientations of the dislocation line produce sessile core configurations, whereas other orientations produce relatively more glissile cores. However, a structural transition of each of these dislocation cores may be required before < 100> dislocations become mobile, and this is consistent with the limited tensile ductility observed in NiAl “soft” single crystals below 200°C. Core structure simulations for < 110> dislocations are also reported and are discussed with respect to the importance of these dislocations in the deformation of NiAl.

Interatomic Potentials for Al and Ni From Experimental Data and AB Initio Calculations

New embedded-atom potentials for Al and Ni have been developed by fitting to both experimental data and the results of ab initio calculations. The ab initio data were obtained in the form of energies of different alternative computer-generated crystalline structures of these metals. The potentials accurately reproduce basic equilibrium properties of Al and Ni such as the elastic constants, phonon dispersion curves, vacancy formation and migration energies, stacking fault energies, and surface energies. The equilibrium energies of various alternative structures not included in the fitting database are calculated with these potentials. The results are compared with predictions of total-energy tight-binding calculations for the same structures. The embedded-atom potentials correctly reproduce the structural stability trends, which suggests that they are transferable to different local environments encountered in atomistic simulations of lattice defects.

Short-term clarithromycin administration impairs clearance and enhances pharmacodynamic effects of trazodone but not of zolpidem

The kinetic and dynamic interactions of 5 mg zolpidem and 50 mg trazodone with 500 mg clarithromycin (4 doses given over 32 h) were investigated in a 5-way double crossover study with 10 healthy volunteers. The five treatment conditions were: placebo + placebo; zolpidem + placebo; zolpidem + clarithromycin; trazodone + placebo; and trazodone + clarithromycin. Coadministration of clarithromycin increased trazodone area under the curve, prolonged elimination half-life, increased peak plasma concentration (C(max)), and reduced oral clearance. In contrast, clarithromycin had no significant effect on any kinetic parameter for zolpidem. Clarithromycin did not potentiate sedation caused by zolpidem. However, clarithromycin coadministered with trazodone significantly increased self- and observer-rated sedation and ratings of feeling "spacey." Thus, short-term clarithromycin coadministration significantly impairs trazodone clearance, elevates plasma concentrations, and enhances sedative effects. However, clarithromycin has no significant kinetic or dynamic interaction with zolpidem.

High-pressure Food Processing

High pressure processing (HPP) of foods offers a commercially viable and practical alternative to heat processing by allowing food processors to pasteurize foods at or near room temperature. Pressure in combination with moderate temperature also seems to be a promising approach for producing shelf-stable foods. This paper outlines research needs for further advancement of high pressure processing technology. Kinetic models are needed for describing bacterial inactivation under combined pressure-thermal conditions and for microbial process evaluation. Further, identification of suitable surrogate organisms are needed for use as indicator organisms and for process validation studies. More research is needed to evaluate process uniformity at elevated pressure-thermal conditions to facilitate successful introduction of low-acid shelf-stable foods. Combinations of non-thermal technologies with high pressure could reduce the severity of the process pressure requirement. Likewise, processing equipment requires improvements in reliability and line-speed to compete with heat pasteurization lines. More studies are also needed to document the changes in animal and vegetable tissue and nutrient content during pressure processing, from types of packaging, and from storage.

Pharmacokinetic and Pharmacodynamic Interactions Between Zolpidem and Caffeine

The kinetic and dynamic interaction of caffeine and zolpidem was evaluated in a double-blind, single-dose, six-way crossover study of 7.5 mg zolpidem (Z) or placebo (P) combined with low-dose caffeine (250 mg), high-dose caffeine (500 mg), or placebo. Caffeine coadministration modestly increased maximum plasma concentration (C(max)) and area under the plasma concentration-time curve of zolpidem by 30-40%, whereas zolpidem did not significantly affect the pharmacokinetics of caffeine or its metabolites. Compared to P+P, Z+P significantly increased sedation, impaired digit-symbol substitution test performance, slowed tapping speed and reaction time, increased EEG relative beta amplitude, and impaired delayed recall. Caffeine partially, but not completely, reversed most pharmacodynamic effects of zolpidem. Thus, caffeine only incompletely reverses zolpidem's sedative and performance-impairing effects, and cannot be considered as an antidote to benzodiazepine agonists.

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.

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.

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.

High-frequency enhancement by an optical system for superresolution of temporally restricted objects

A system for superresolution of temporally restricted objects allows one to transmit ultrawideband optical signals (objects) through a narrow aperture. Such a system was proposed, improved, and implemented for one- and two-dimensional objects. Implementing frequency-plane enhancement in this system provides the ability of spatial filtering of ultrawideband objects. A method for spatial filtering in a system for superresolution of temporally restricted objects by use of a generalized Dammann grating is suggested. An experimental demonstration of high-frequency enhancement (high-pass filtering) of one-dimensional objects is presented.

Two-dimensional superresolution optical system for temporally restricted objects

Objects that vary slowly over time may be superresolved by use of moving gratings. A system of this kind was proposed three decades ago. However, such a system creates some distortion of the spectral response of the resolved objects, and it achieves superresolution in only one dimension. We propose an enhanced method based on Dammann gratings instead of regular gratings for achieving two-dimensional superresolution. The modified approach achieves results with undistorted output and relatively high light efficiency, and it is effective for both coherent and incoherent illumination. Preliminary results demonstrate the feasibility of the new approach.

[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.

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.

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.

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.