Nephropathy of type II diabetes: evidence for hereditary factors?

Family studies point to an important genetic element in the genesis of diabetic nephropathy, but it is not known whether renal abnormalities are present prior to the onset of diabetes. To address this issue we examined all consecutive patients suffering from type II diabetes with a duration of more than 10 years who attended a diabetes outpatient clinic. Ninety-four patients had nephropathy, 307 did not. All offspring who were phenotypically normal (no hypertension, normal oral glucose tolerance, non-smoking) and agreed to participate were examined, 26 from nephropathic and 30 from non-nephropathic diabetic parents. They were compared with 30 offspring matched for age, gender and BMI from non-diabetic parents as controls. We measured urinary albumin excretion under baseline conditions and at several time points after ingestion of 300 g cooked beef and submaximal treadmill exercise, respectively. In addition, casual blood pressure, ambulatory blood pressure, urinary albumin and urinary alpha-1-microglobulin were measured. Primary renal disease was excluded by clinical examination. Under baseline conditions, median urinary albumin excretion rate (AER; microgram/min) was significantly (P < 0.005) higher in offspring of nephropathic type II diabetic patients (7.8; range 1.04 to 19.5) than in the offspring of non-nephropathic type II diabetic patients (4.8; 0.36 to 17.5) and controls (4.4; 0.16 to 18.4). Submaximal treadmill exercise caused a greater proportional increase of AER in offspring of nephropathic type II diabetics (median 16-fold) than in offspring of non-nephropathic diabetic patients (6.3-fold) or controls (4.8-fold). In offspring of nephropathic diabetic patients casual and particularly ambulatory systolic blood pressures were significantly higher, but AER was not correlated with blood pressure. In summary, higher values, albeit within the normal range, for baseline and postexercise albuminuria were noted in phenotypically normal offspring of parents with type II diabetes and nephropathy. The observation suggests that changes in transglomerular albumin traffic are demonstrable prior to the onset of diabetes and diabetic nephropathy in subjects with a potential genetic predisposition to these conditions.     

Crack growth measurements on components under cyclic loading: comparison of different methods

The cyclic crack growth behaviour was measured by means of d.c. potential drop, a.c. potential drop, ultrasonic and crack-opening displacement (COD) methods. The methods were applied to component tests on straight pipes with an outer diameter of approximately 800 mm and a wall thickness of approximately 50 mm. The pipes were subjected to constant internal pressure (about 15 MPa) and either an alternating (or pulsating) or a quasi-static bending moment using d.c. potential drop, a.c. potential drop, ultrasonic and flaw-opening (COD) methods. The efficiency of the particular methods has been proved by comparison with fractographical analysis of the fracture surfaces.     

Detection of serum antibody responses in cattle with natural or experimental Neospora infections

Parasite-specific antibody responses were detected using an indirect fluorescent antibody (IFA) test in cattle that were naturally or experimentally infected with Neospora parasites. The test was developed using Neospora tachyzoites isolated from an aborted bovine fetus and grown in bovine cell cultures (isolate BPA1). In all cases, infections were confirmed by the identification of Neospora tachyzoites and/or bradyzoite cysts in fetal or calf tissues using an immunoperoxidase test procedure. Fifty-five naturally infected cows that aborted Neospora-infected fetuses had titers of 320-5,120 at the time of abortion. The titer of 6 cows that were serologically monitored over a prolonged period decreased to 160-640 within 150 days after they aborted infected fetuses. Two of the cows showed an increase in their Neospora titers during their subsequent pregnancy, and they gave birth to congenitally infected calves that had precolostral titers of 10,240-20,480. Postcolostral titers of these calves and of 4 other calves with congenital Neospora infections were all > or = 5,120, whereas calves with no detectable parasites had titers < or = 160. Two pregnant heifers that were experimentally infected with the BPA1 isolate at approximately 120 days gestation seroconverted to Neospora antigens within 9 days and developed peak titers of 5,120 and 20,480 within 32 days of infection. The fetus taken by caesarean section 32 days postinfection from 1 heifer and the full-term calf born to the other had Neospora titers of 640 and 10,240, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of magnetic resonance volume flow rates, angiography, and carotid Dopplers. Preliminary results

BACKGROUND AND PURPOSE: We compared the results of conventional angiography, carotid Doppler, and magnetic resonance angiography volume flow rates to determine the clinical utility of volume flow rate assessment of blood flow to the anterior circulation in patients with carotid occlusive disease. METHODS: From 11 symptomatic patients, a total of 22 extracranial carotid arteries were studied with all three techniques. The studies were independently read, and regression analysis was used to compare the measurements. RESULTS: Carotid Doppler measurements of the distal extracranial carotid arteries were proportional to the inverse of the extracranial carotid volume flow rate (r = .53, R2 = 29%, P < .01), volume flow rates were proportional to the inverse of measured percent stenosis on angiography (r = .84, R2 = 71%, P < .01), and Dopplers were proportional to angiography (r = .94, R2 = 90%, P < .01). Symptomatic Doppler systolic velocity was significantly higher (P < .002), symptomatic measured stenosis was significantly higher (P < .002), and symptomatic volume flow rate was significantly lower (P < .01) than their respective asymptomatic-side values. These preliminary observations, however, may well change once a large data set, especially one in which more patients with high-grade carotid stenosis are included, is studied. CONCLUSIONS: Assessment of carotid volume flow rates by magnetic resonance angiography quantifies flow reduction secondary to atherosclerotic occlusive disease. The easily obtained flow data add both documentation of arterial flow characteristics related to internal carotid stenosis and information regarding the adequacy of collateral pathways.     

High-power passively mode-locked semiconductor lasers

We have developed optically pumped passively mode-locked vertical-external-cavity surface-emitting lasers. We achieved as much as 950 mW of mode-locked average power in chirped 15-ps pulses, or 530 mW in 3.9-ps pulses with moderate chirp. Both lasers operate at a repetition rate of 6 GHz and have a diffraction-limited output beam near 950 nm. In continuous-wave operation, we demonstrate an average output power as high as 2.2 W. Device designs with a low thermal impedance and a smooth gain spectrum are the key to such performance. We discuss design and fabrication of the gain structures and, particularly, their thermal properties     

Angiotensin II receptor type 1 mRNA is upregulated in atria of patients with end-stage heart failure

There is increasing evidence that pathological changes in the myocardium during chronic heart failure (CHF) are partly regulated through the activation of the renin-angiotensin system (RAS), an effect mediated by the angiotensin II type 1 receptor (AT1R). We examined the expression of cardiac AT1R mRNA in normal (atria, n=7; ventricle, n=3) and end-stage CHF human hearts (atria, n=8; ventricle, n=14). Tissue was snap-frozen immediately after explantation during orthotopic cardiac transplantation; control specimens were obtained from healthy donor hearts rejected for technical reasons. Northern blots of purified total mRNA from each tissue were hybridized with a random primed radiolabeled probe for the coding sequence of AT1R. Stringent conditions were used for both hybridization (5X SSC, 65 degrees C) and washing (0.5X SSC, 0.1% SDS, 65 degrees C) of the membrane. Left and right atrial tissue showed low levels of AT1R mRNA expression in the controls, with statistically significant upregulation of expression in tissue from pathological hearts; CHF atria 1.28+/-0.86 optical density (OD) units, control atria 0.56+/-0.31 OD units, P=0.05 (mean+/-s.d.). There were undetectable levels in ventricles from either control (2/2) or dilated hearts (7/7). The results were independent of the etiology of the heart failure and suggest that increased levels of atrial AT1R mRNA may occur in response to elevated atrial pressures in heart failure.     

Electrical conductivity in iodine-doped ethyl cellulose

The electrical conductivity of solution-grown ethyl cellulose (EC) films, 5–30 μm thick, has been studied in the sandwich configuration (metal–EC–metal) as a function of iodine concentration from 0.5 to 5.0 wt% ratio. The studies were conducted in the temperature range 333–383 K, while the field was varied over the range (3.0–5.5) × 10⁴V/cm. Aluminium was used as the lower electrode, while the upper electrode was of Al, Ag, Cu, Au or Sn. Certain transient effects such as a large burst of current immediately after the application of field were observed. An attempt was made to identify the nature of the current by comparing the observed dependence on electric field, electrode material and temperature with the respective characteristic features of the existing theories of electrical conduction. The results show that the electrical conduction follows Ohm's law at lower fields, while at higher fields, space-charge limited current (SCLC) was observed. It was also found that Richardson–Schottky emission was responsible, to some extent, for the transport of charge carriers in the polymer. The conductivity of the films increased on doping with iodine. The dopant molecules are considered to act as additional trapping centes and provide links between the polymer molecules in the amorphous region, thus resulting in the formation of charge transfer complexes.