Single-Electron Detection and Spectroscopy via Relativistic Cyclotron Radiation

It has been understood since 1897 that accelerating charges must emit electromagnetic radiation. Although first derived in 1904, cyclotron radiation from a single electron orbiting in a magnetic field has never been observed directly. We demonstrate single-electron detection in a novel radio-frequency spectrometer. The relativistic shift in the cyclotron frequency permits a precise electron energy measurement. Precise beta electron spectroscopy from gaseous radiation sources is a key technique in modern efforts to measure the neutrino mass via the tritium decay end point, and this work demonstrates a fundamentally new approach to precision beta spectroscopy for future neutrino mass experiments.

Results of a search for cold flows of dark matter axions

Theoretical arguments predict that the distribution of cold dark matter in spiral galaxies has peaks in velocity space associated with nonthermalized flows of dark matter particles. We searched for the corresponding peaks in the spectrum of microwave photons from axion to photon conversion in a cavity detector for dark matter axions. We found none and place limits on the density of any local flow of axions as a function of the flow velocity dispersion over the axion mass range 1.98 to 2.17 microeV.

Magnitude and determinants of coronary artery disease in juvenile-onset, insulin-dependent diabetes mellitus

The risk of premature coronary artery disease (CAD) and its determinants were investigated in a cohort of 292 patients with juvenile-onset, insulin-dependent diabetes mellitus (IDDM) who were followed for 20 to 40 years. Although patients with juvenile-onset IDDM had an extremely high risk of premature CAD, the earliest deaths due to CAD did not occur until late in the third decade of life. After age 30 years, the mortality rate due to CAD increased rapidly, equally in men and women, and particularly among persons with renal complications. By age 55 years the cumulative mortality rate due to CAD was 35 +/- 5%. This was far higher than the corresponding rate for nondiabetic persons in the Framingham Heart Study, 8% for men and 4% for women. Angina and acute nonfatal myocardial infarction followed a similar pattern, as did asymptomatic CAD detected by stress test, so that their combined prevalence rate was 33% among survivors aged 45 to 59 years. Age at onset of IDDM and the presence of eye complications did not contribute to risk of premature CAD. This pattern suggests that juvenile-onset diabetes and its renal complications are modifiers of the natural history of atherosclerosis in that although they profoundly accelerate progression of early atherosclerotic lesions to very severe CAD, they may not contribute to initiation of atherosclerosis.

Hypertension: the major risk factor in juvenile-onset insulin-dependent diabetics

The prevalence of hypertension in various age groups of diabetics and its role as a risk factor in juvenileonset insulin-dependent diabetics followed for 40 yr after diagnosis was evaluated. The results show clearly that hypertension is more prevalent in diabetics of any age after age 24 yr than in the general population.

In this type of diabetes, although death due to renal disease occurs earlier than that due to coronary heart disease, both causes of death are significantly related to hypertension. Those patients with an onset of diabetes 13 yr of age or younger can expect to live longer following the diagnosis of diabetes mellitus than those with an onset after 13 yr of age, perhaps because hypertension appears at about the same age in both groups. Case/control analysis of the data shows that survivors have significantly less hypertension than those dying of renal or cardiac disease. Furthermore, the close temporal relationship between the onset of hypertension and the onset of proteinuria in patients with either renal or coronary deaths suggests that the hypertension in these patients is renal in origin.

Two other risk factors, smoking and serum lipids, were evaluated in this population. From the data thus far accumulated, neither smoking nor lipids appear to influence mortality significantly. We conclude that hypertension is the major additive risk factor for mortality in juvenile-onset insulin-dependent diabetics.

Decreased insulin requirement in acute renal failure in diabetic nephropathy

Twelve of 13 diabetics with azotemic nephropathy experienced exacerbation of renal failure and decreased insulin requirement after coronary angiography utilizing radiographic contrast material. The single patient who did not develop acute renal failure had no evidence of decreased insulin requirement. Eleven of 12 patients had decreased insulin requirement: mean decrement in insulin dose, 40%; mean decrement in fasting blood glucose level, 33%; mean decrement in peak blood glucose level, 42%. The 12th patient underwent peritoneal dialysis against hypertonic glucose without need of an increased insulin dose. Eight of 11 patients experienced a total of 19 insulin reactions; one patient was hypoglycemic continuously, despite infusion of glucose and discontinuation of insulin. The decrement of insulin requirement was not proportional to the rise in either serum creatinine or potassium concentrations. We suggest that when acute renal failure occurs in diabetics, decreased insulin requirement should be anticipated and the insulin dose lowered.

The effects of long-term therapy with oral hypoglycemic agents on the oral glucose tolerance test dynamics in male chemical diabetics

The effect of fixed doses of oral hypoglycemic agents and placebo (diet alone) on the blood glucose, serum insulin, triglyceride, and cholesterol responses during oral glucose tolerance tests done annually for up to four years' follow-up was studied, in a double-blind manner, in five groups of mild male chemical diabetics. The drugs used were chlorpropamide (100 mg. O.D.), tolbutamide (500 mg. b.i.d.), phenformin (50 mg. O.D.), acetohexamide (250 mg. O.D.), and placebo. Each subject was given an individualized diet aimed at attaining and maintaining ideal weight. Comparison by chi-square analysis between the placebo group and each of the drug groups showed (a) no significant differences with regard to the number of subjects with normal glucose tolerance in each of the tests and (b) no change in the insulin secretion dynamics. Comparison between the initial test and each of the subsequent tests within each group showed (a) a greater number of subjects with normal glucose tolerance in the first follow-up test in the chlorpropamide group only, (b) no change in the insulin secretion dynamics except in the chlorpropamide group, where there was an increased insulin/glucose ratio in the first follow-up test, and (c) no change in the fasting serum triglyceride and cholesterol levels.

Prevalence of diabetic retinopathy. Age, sex, and duration of diabetes

From a list of all patients seen at the Joslin Clinic in a recent 6-month period, a random sample of 965 was selected for record review by a clinic assistant. A house physician specializing in diabetes then verified and adjusted the assistant's work as necessary. The data were analyzed both by simple cross-classification and by fitting a multiple logistic risk function. As often reported previously, we found a strong positive association between retinopathy and duration of diabetes. One of our findings which has not been so clearly reported in earlier papers is that the positive association between retinopathy and age is limited to the group with diabetes of less than 10 years' duration. We also found sex differences in retinopathy prevalence which were not large enough to rule out attributing them to chance.

Diabetic glomerulosclerosis in children

A boy died in diabetic acidosis at the age of nine, after seven years of known diabetes. At necropsy there was diffuse glomerulosclerosis by light microscopy, evidenced by diffuse mesangial thickening of the peripheral glomeru-lar loops and irregular thickening of the capillary basement membrane of the glomeruli. Glomerulosclerosis is a rare finding in a person of this age as revealed in a review of the literature.