Experimental evidences of 95 mTc production in a nuclear reactor.

95 mTc has been identified as by-product in some solutions of 99 mTc obtained by irradiation of molybdenum trioxide in a reactor neutron flux. The characterization was carried out using both measurements by gamma spectrometry and half-life determination. The possible ways that lead to the 95 mTc production in a nuclear reactor are discussed.

The consistency of the data for neutron fission averaged cross-sections of threshold reactions: a study on the cross-section of 46Ti(n,p)46Sc, 47Ti(n,p)47Sc, 48Ti(n,p)48Sc and 64Zn(n,p)64Cu reactions.

The consistency of the published values for fission averaged cross-sections of threshold reactions induced in a nuclear reactor is analyzed. The influence of the literature data involved in the determination of these cross-sections is discussed. Renormalizations based on cross-sections value for the standard reactions, isotopic abundances of the precursors and radiation emission probabilities of the radionuclide under study and the monitor, are applied to the evaluation of the cross-sections for the reactions: (46)Ti(n,p)(46)Sc; (47)Ti(n,p)(47)Sc; (48)Ti(n,p)(48)Sc; and (64)Zn(n,p)(64)Cu.

Rituximab treatment of idiopathic membranous nephropathy.

Idiopathic membranous nephropathy is a common cause of nephrotic syndrome whose pathogenesis may involve B-cell functions. Rituximab is a monoclonal antibody that binds to the CD20 antigen on B cells thereby deleting them. We conducted an open-label pilot trial of rituximab treatment in 15 severely nephrotic patients with proteinuria refractory to angiotensin-converting enzyme inhibition and/or receptor blockade but with adequately controlled blood pressure. Rituximab was given 2 weeks apart and, at 6 months, patients who remained proteinuric but had recovered B-cell counts were given a second course of treatment. Proteinuria was significantly decreased by about half at 12 months. Of the 14 patients who completed follow-up, full remission was achieved in two and partial remission in six patients based upon the degree of proteinuria. Side effects were minor; however, we found no relationship between the response and number of B cells in the blood, CD20 cells in the kidney biopsy, degree of tubulointerstitial fibrosis, starting proteinuria or creatinine values. Rituximab appears effective in reducing proteinuria in some patients with idiopathic membranous nephropathy but prospective identification of responsive patients was not possible.

Averaged cross sections for the reactions (68)Zn(n,p)(68g)Cu and (68)Zn(n,p)(68m)Cu for a (235)U fission neutron spectrum.

Making use of the method developed in our laboratory for the simultaneous determination of cross sections leading to both the ground and metastable states, we have measured the (68)Zn(n,p)(68g)Cu and (68)Zn(n,p)(68m)Cu reactions, using Zn enriched to 99.4% in its isotope (68)Zn. The measured cross sections are (15.04+/-0.35) and (3.69+/-0.30)microb for the ground and metastable state, respectively. However, a direct determination of the cross section leading to the metastable state gives a value of (4.75+/-0.38)microb. A possible reason for this discrepancy-which is outside experimental uncertainties-is that some tabulated values used in our calculations for the decay parameters of (68g)Cu and (68m)Cu, have either larger than quoted, or unknown systematic, uncertainties.

Emotional impact of retirement on physicians.

The current study sought to identify the factors underlying physicians' decision to retire, describe the emotional impact of retirement on physicians, measure quality of life in retirement, and identify coping strategies used by retired physicians. A questionnaire was sent to all 689 retired members of the Harris County Medical Society, and 323 (47%) responded. Data were analyzed using SPSS. Physicians overwhelmingly indicated positive reasons for retirement, although one third said that loss of autonomy and control in medical practice were factors. Participants were satisfied with retirement and enjoyed low levels of stress and depression. Spousal and personal health had the largest negative impact on retirement. Being prepared emotionally significantly affected physicians' attitudes. Longitudinal studies and research on the impact of managed care on the retirement experience are needed. Younger physicians need to be prepared for the emotional impact of retirement.

Insights into physician retirement.

Most physicians in this study retired because they thought the time was right, and they did not feel forced to do so. This situation may not be the case in the future with changes occurring in the practice of medicine. Most of the physicians were pleased with their retirement after they had completed an adjustment period, often lasting about a year. The most important factor involved in successful retirement was the health of the physician and his or her spouse. A good relationship with the spouse was important. Typically, relationships with spouses improved. If a physician has no spouse or poor spousal support, some other method of replacing the support network previously provided by staff, patients, and practicing colleagues is necessary. After retirement, the physicians in our study became comfortable with living on their savings. Strategies employed after retirement were diverse. Many of the retired physicians took advantage of increased time to exercise for enjoyment and for health. Although some of the retired physicians continued to pursue medical interests, many others discovered rewarding activities away from medicine, but rarely for financial compensation.

Pharmacokinetics of the enantiomers of mepivacaine after intravenous administration of the racemate in volunteers.

The pharmacokinetics of R(-)-mepivacaine and S(+)-mepivacaine were investigated in 10 healthy volunteers. The volunteers received racemic mepivacaine, hydrochloride (dose 60 mg) via a 10-min intravenous infusion. Blood samples were collected at gradually increasing intervals until 8 h after the start of the infusion. Plasma concentrations of the enantiomers were determined with a stereoselective high-performance liquid chromatographic (HPLC) method. Unbound fractions of the enantiomers were determined using equilibrium dialysis. The unbound fraction of R(-)-mepivacaine (mean +/- SD: 35.6% +/- 4.5%) was larger (P < 0.0001) than that of S(+)-mepivacaine (25.1% +/- 4.6%). The total plasma clearance and steady-state volume of distribution of R(-)-mepivacaine, based on total plasma concentrations (total plasma clearance [CL] = 0.79 +/- 0.12 L/min; volume of distribution at steady state [VSS] = 103 +/- 14 L) as well as on unbound plasma concentrations (plasma clearance of unbound drug [CLu] = 2.24 +/- 0.30 L/min; volume of distribution of unbound drug at steady state [Vuss] = 290 +/- 32 L), were larger (P < 0.0001) than those of S(+)-mepivacaine (CL = 0.35 +/- 0.06 L/min; Vss = 57 +/- 7 L; CLu = 1.43 +/- 0.24 L/ min; Vuss = 232 +/- 30 L). The terminal half-life (t1/2,Z) and mean residence time (MRT) of R(-)-mepivacaine (t1/2,Z = 113 +/- 17 min; MRT = 131 +/- 15 min) were shorter than those of S(+)-mepivacaine (t1/2,Z = 123 +/- 20 min, P < 0.02; MRT = 165 +/- 24 min, P < 0.0001). This study demonstrated a marked difference in the pharmacokinetics of the enantiomers of mepivacaine. The stereoselectivity can be partially explained by a difference in the plasma protein binding of the enantiomers.

Home blood pressure monitoring.

Blood pressure measurements made in the physician's office have been the standard for diagnosing hypertension and determining the efficacy of antihypertensive drug therapy. However, these measurements do not necessarily reflect a patient's usual blood pressures in other circumstances, such as at work or in the home. Accurate blood pressure measurements performed by the patient or a family member in an out-of-office setting can be integrated with office readings to assist in the management of hypertension.

Determination of aluminum and phosphorus in biological materials by reactor activation analysis using germanium as integral flux monitor and comparator.

A method for determination of aluminum and phosphorus in biological materials, based on activation in a nuclear reactor and measurement of 28Al, produced by the 27Al(n, gamma)28Al and 31P(n, alpha)28Al reactions, is described. Irradiations in the undisturbed and epicadmium spectra provide a two-equation system in order to determine the contributions of aluminum and phosphorus to the total activities. Germanium is used as an integral flux monitor and comparator, through the reactions: 74Ge(n, gamma)75Ge, 76Ge(n, gamma)77Ge, and 72Ge(n,p)72Ga.

Occult pulmonary malignancy in syndrome of inappropriate ADH secretion with normal ADH levels.

Although the syndrome of inappropriate ADH secretion (SIADH) has many causes, principally pulmonary, central nervous system or neoplastic disease, and drugs, patients may present with SIADH in whom the etiology is not readily evident. We measured serum ADH levels in such an individual in both the eunatremic and water-loaded states and found levels to be undetectable despite failure to dilute the urine. A small oat cell pulmonary carcinoma was ultimately diagnosed with lung tomograms and cytology. Following a partial response to water restriction, demeclocycline was effective in producing a water diuresis that restored the serum sodium concentration to normal. Patients with clinical SIADH but low serum ADH levels can harbor a malignant or benign process that, notwithstanding the low ADH levels, may still remain responsive to demeclocycline, suggesting either neoplastic production of a biologically-active, immunologically-inactive ADH-like peptide, or increased renal tubular sensitivity to ADH.

Remission and exacerbation of tumor-related nephrotic syndrome with treatment of the neoplasm.

A 61-year-old man presented with nephrotic syndrome in March 1978. Renal biopsy revealed mesangial and endocapillary proliferation with no underlying cause found. One year later, evaluation of back pain resulted in the finding of undifferentiated adenocarcinoma with compression fracture of the T-11 vertebra. Local irradiation relieved the pain and ameliorated the nephrotic syndrome. In 1981 the nephrotic syndrome recurred. Evaluation revealed metastases to the right pelvis and to the brain without an identifiable primary lesion. Irradiation of these lesions reduced protein excretion to 50 to 150 mg/day. A gastric carcinoma was later found. Exacerbation of nephrotic syndrome may herald exacerbation of tumor activity as occurs in Hodgkin's disease. Survival with tumor-related nephrotic syndrome is not invariably poor, and treatment of metastases may be worthwhile in similar patients in whom only partial tumor reduction is possible.

Autonomic and baroreflex function after captopril in hypertension.

Absent reflex tachycardia with captopril therapy suggests blunting of circulatory reflexes, perhaps contributing to antihypertensive efficacy, and angiotensin converting enzyme inhibition may alter sympathetic function. Captopril effects on autonomic function were investigated in five severe hypertensive patients. Mean blood pressure fell in all patients (from 141 +/- 6 to 119 +/- 7 mm Hg, p less than 0.02) without orthostatic blood pressure fall or increase in heart rate (both p greater than 0.1) on captopril. Captopril did not alter baroreflex sensitivity as tested by amyl nitrile hypotension or phenylephrine hypertension (both p greater than 0.1). Comparison of these severely hypertensive patients to age matched normotensive control subjects did reveal markedly blunted baroreflex sensitivity in both the amyl nitrite test (by 89%, p less than 0.01) and the phenylephrine test (by 83%, p less than 0.01), suggesting that baseline blunting of baroreflex function may in part account for absence of reflex tachycardia. Captopril diminished the cardioacceleration after cold stress (from 61 +/- 38 to 23 +/- 43 msec, p less than 0.05) as well as the blood pressure fall after alpha-adrenergic blockade (from 46 +/- 13 to 24 +/- 9 mm Hg, p less than 0.05), suggesting diminished sympathetic stimulation of resistance vessels and decreased sympathetic participation in blood pressure maintenance, possibly at the prejunctional synaptic level. Four biochemical indices of sympathetic activity did not change. Thus captopril-treated patients had blunted reflex tachycardia, commensurate with blunted baroreflex function at baseline, and physiologic and pharmacologic evidence of diminished sympathetic activity was obtained with captopril therapy. Whether diminished sympathetic activity is involved in captopril's antihypertensive effect has not been determined.

Baroreflex dysfunction in patients with adult-onset diabetes and hypertension.

Ten patients with adult-onset diabetes in whom diabetes antedated the appearance of hypertension were evaluated. These patients had evidence of diabetic autonomic neuropathy, including significant orthostatic hypotension (four patients), impotence (three patients), and evidence of diabetic peripheral sensorimotor neuropathy (nine patients) in clinical testing and nerve conduction study results. Baroreflex function was evaluated by multiple hemodynamic tests, including inhalation of amyl nitrite and intravenous administration of phenylephrine, before and after parasympathetic blockade with atropine, and the cold pressor test; results were compared with results in normal control subjects, patients with essential hypertension, and two subgroups of uremic patients undergoing maintenance hemodialysis. Baroreflex function was significantly abnormal in the diabetic patients and was consistent with combined parasympathetic and sympathetic motor nerve (efferent) dysfunction in the baroreflex arc. There was a significant inverse correlation between the degree of orthostatic hypotension in the diabetic patients and their baroreflex response to phenylephrine (r = -0.680, p less than 0.05). There was no significant correlation between supine hypertension in the patients with diabetes and any of the hemodynamic or biochemical parameters examined. The results suggest that orthostatic hypotension in these patients is related to baroreflex dysfunction. However, baroreflex dysfunction does not appear to be a factor in the development of hypertension in these patients, although more studies with normotensive diabetic patients are needed to confirm this point.

Hypertension in adult onset diabetes mellitus: abnormal renal hemodynamics and endogenous vasoregulatory factors.

We evaluated 10 adult onset diabetics who developed hypertension well after the onset of glucose intolerance. Systemic and renal hemodynamics, intravascular volume, the renin-angiotensin-aldosterone axis, and the renal kallikrein-kinin system were examined at extremes of sodium intake, and compared to results from matched normotensive and essential hypertensive subjects. On unrestricted sodium diet, the diabetics, compared to normotensives, had significantly decreased blood volume (p less than 0.01), and preservation of renal plasma and blood flow, but significantly elevated renal vascular resistance (p less than 0.05), decreased creatinine clearance (p less than 0.01), and decreased filtration fraction (p less than 0.01). On restricted sodium intake, diabetics, compared to normotensives, had reduced urinary kallikrein activity (p less than 0.01) and reduced ambulatory plasma renin activity (p less than 0.01). Essential hypertensives were similar to diabetics in that both had reduced intravascular volume, elevated renal vascular resistance, and reduced levels of stimulated urinary kallikrein and ambulatory renin activities, but plasma aldosterone concentrations were reduced in diabetics compared to both normotensives and essential hypertensives under all dietary conditions. The ratio urinary kallikrein activity/supine plasma renin activity in diabetics correlated with renal blood flow (p less than 0.05), and inversely with renal vascular resistance (p less than 0.05). We conclude that these hypertensive diabetics have multiple abnormalities in intrarenal hemodynamics that may be related, in part, to abnormal activities of the renal enzymes renin and kallikrein. The kallikrein defect may be an etiologic factor in their hypertension.

Coccidioidomycosis in renal replacement therapy.

The potential risk of coccidioidomycosis has led to concern about the advisability of maintaining renal transplantation programs in endemic areas. We reviewed the charts of 721 patients undergoing dialysis and 260 renal transplant recipients in Arizona to determine the incidence, risk factors, and clinical course of coccidioidomycosis in these immunosuppressed populations. Symptomatic infection occurred in six (0.83%) patients undergoing dialysis and 18 (6.9%) transplant recipients. Male sex and blood type B predisposed to dissemination. Urine cultures for fungus were important diagnosis aids. Four of six patients with infection limited to the thorax and five of 18 patients with dissemination remained alive after seven months to 7 1/2 years. Although the rate of dissemination (75%) and mortality (63%) from coccidioidomycosis were high, the incidence of infection was low and does not preclude renal transplantation in Arizona. Those who have received transplants elsewhere should be advised not to move or to visit areas endemic for coccidioidomycosis.

Simultaneous tuberculosis and coccidioidomycosis in end stage renal disease.

During a ten year period, tuberculosis and coccidioidomycosis occurred in less than one and three percent respectively of 380 patients who had received dialysis and renal transplants in Southern Arizona. In two patients, who were immunosuppressed by diabetes, renal failure, and inanition, these infections were concurrent and diagnosis was delayed. Because the occurrence of both illnesses in two patients is unlikely by chance alone and because both infections were present when symptoms developed, potentiation of one infection by the other may have occurred.

Renal hemodynamic changes during long-term antihypertensive therapy.

Studies of renal hemodynamics were carried out in 84 patients with essential hypertension during long-term antihypertensive therapy with a number of drugs. Renal perfusion was maintained or enhanced despite a fall in mean arterial pressure during therapy with hydrochlorothiazide, furosemide, clonidine, prazosin, and the combination of guanabenz and hydrochlorothiazide. Renal perfusion deteriorated during long-term treatment with propranolol. Renal hemodynamics may be enhanced, maintained, or adversely influenced depending on the choice of antihypertensive agent.

Clinical correlates in hypertensive patients with left ventricular hypertrophy diagnosed with echocardiography.

Seventy-three hypertensive patients were evaluated with M mode and two dimensional echocardiography. Left ventricular hypertrophy was found in 37 patients (51 percent); 29 had concentric hypertrophy and the remaining 8 had disproportionate septal thickening. Factors that did not influence the distribution of patients in the group with left ventricular hypertrophy and normal subjects included (1) duration of hypertension, (2) level of blood pressure, (3) age, (4) body surface area, and (5) race. More of the patients who had a normal left ventricular mass (32 or 89 percent) than of those who had hypertrophy (22 or 59 percent) were receiving two or more antihypertensive drugs. Electrocardiography was very insensitive in identifying left ventricular hypertrophy in these patients. The presence of increased left ventricular mass was associated with a greater incidence of other target organ disease.

Recovery from rapidly progressive glomerulonephritis. Improvement after plasmapheresis and immunosuppression.

Two patients with rapidly advancing renal insufficiency underwent biopsy and were found to have crescentic glomerulonephritis. Patient 1 demonstrated findings compatible with Goodpasture's syndrome. Crescents were present in 100% of his glomeruli. Patient 2 had findings of immune complex-mediated glomerulonephritis and crescents in greater than 90% of his glomeruli. Both patients were treated with high-dose prednisone, cyclophosphamide, and plasmapheresis. Patient 2 additionally required hemodialysis for a brief period. Renal function improved in both patients and has not deteriorated after follow-up of 14 and 18 months, respectively. Repeated renal biopsies were performed in each patient. Our findings suggest that clinical improvement and histologic healing are possible in rapidly progressive glomerulonephritis despite the initial presence of crescents in every glomerulus.