Modulation by calcium of the inhibitor activity of naturally occurring urinary inhibitors

The possibility that hypercalciuria could cause calcium stone formation through a mechanism other than by increasing urinary saturation of stone-forming calcium salts was explored. The effect of increasing calcium concentration on the inhibitor activity against the spontaneous precipitation of calcium oxalate was examined in whole urine (in the presence of naturally occurring inhibitors) and in synthetic media (with added inhibitors). In 11 patients with calcium nephrolithiasis, the induced hypercalciuria from calcium supplementation (600 mg/day) caused a significant fall in the urinary inhibitory activity against calcium oxalate precipitation, as shown by a decline in the formation product ratio from 12.6 +/- 1.1 SEM to 9.6 +/- 1.4 (P less than 0.005). In order to more fully explore this observation, the effect of increasing calcium concentration on the inhibitory activities of citrate (2 mM), chondroitin sulfate (0.05 mg/liter) and a heterogeneous group of naturally-occurring urinary inhibitors (1.0 mg/liter) against calcium oxalate precipitation was examined in vitro in synthetic solutions. The inhibitory actions of both citrate and chondroitin sulfate were significantly attenuated by increasing calcium concentration from 0.25 mM to 6.0 mM (P less than 0.01). However, raising the calcium concentration in synthetic media containing a mixture of partially purified urinary inhibitors produced a significant rise in the urinary inhibitory activity of this macromolecular mixture (P less than 0.01). We conclude that hypercalciuria can attenuate the inhibitory activities of citrate and chondroitin sulfate against calcium oxalate precipitation while at the same time accentuating the inhibitory activity of naturally-occurring urinary inhibitors.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of prolonged bedrest on the propensity for renal stone formation

The effect of prolonged bedrest immobilization on urinary risk factors for stone formation and on the propensity for the crystallization of calcium salts was examined in eight normal subjects. During 5 weeks of bedrest, the mean urinary calcium excretion rose during the first week and remained elevated (from 5.68 to approximately 7.50 mmol/day). Mean urinary phosphorus excretion increased by the second week of bedrest and remained elevated (from 2.70 to approximately 30.6 mmol/day). Urinary sodium and uric acid excretion rose slightly, as did urinary magnesium. Urinary pH, oxalate, and citrate changed slightly or not at all. Owing to these biochemical alterations, urinary saturation of calcium phosphate, calcium oxalate, and monosodium urate increased significantly during bedrest, but that of uric acid did not change. The inhibitor activity against the spontaneous nucleation of brushite (CaHPO4.2H2O) and calcium oxalate was not altered significantly by bedrest. Thus, the propensity for the crystallization of stone-forming calcium salts was enhanced by bedrest, suggesting that immobilization may confer increased risk for the formation of calcium-containing renal stones.

Experimental studies on the neurocardiovascular effects of urapidil

The major purpose of our study was to determine whether urapidil acts in the central nervous system (CNS) to lower arterial blood pressure. Once demonstrating a CNS antihypertensive action of urapidil we further set out to determine: (1) the relative role of a CNS antihypertensive action to the total antihypertensive effect of urapidil; (2) the brain site of action for the antihypertensive effect of urapidil; and, (3) the receptor mechanism whereby urapidil acts in the CNS to lower arterial blood pressure. Studies were conducted in chloralose-anaesthetised cats, and arterial blood pressure and heart rate were monitored. Drugs were administered intravenously (IV), into the cerebral ventricles (ICV), topically by application to the ventral surface of the medulla and by microinjection into specific nuclei. Receptor binding studies were also conducted using rat cerebral cortex homogenates. We found that injection of urapidil into the fourth ventricle decreased arterial pressure. Local application of urapidil to the ventral medullary surface also decreased arterial blood pressure. Microinjection of urapidil into one of the nuclei associated with the ventral surface of the medulla, the rostral part of the nucleus reticularis lateralis (rLRN), produced a similar degree of antihypertensive effect. The effect of urapidil was not altered by alpha 1-receptor blockade. Instead, the urapidil effect resembled that produced by drugs that stimulate serotonin (5-hydroxytryptamine)-1A receptors (B695-40 and 8-OH-DPAT). Furthermore, urapidil was found to have the highest potency for binding to serotonin-1A receptor sites (as compared to alpha 1- and alpha 2-receptor sites). Urapidil administered IV was shown to lower arterial blood pressure in part by blocking peripheral alpha 1-adrenoceptors but also, in high doses, by acting in the CNS to decrease central sympathetic outflow. These data indicate that urapidil is a unique drug, possessing both peripheral and CNS actions which contribute to its antihypertensive effect. Urapidil may also be unique in that its central action may involve activation of serotonin-1A receptors.

Expression of alfalfa mosaic virus RNA 4 in transgenic plants confers virus resistance

Agrobacterium-mediated transfer from a binary vector was used to produce transgenic Nicotiana tabacum plants that expressed coat protein of the plant virus, alfalfa mosaic virus (AMV). Expression levels of the chimeric gene, which was under the control of the cauliflower mosaic virus 19S promoter, were determined in primary transformed plants, in the progeny from self-fertilization and in the progeny from crosses to normal tobacco. RNA transcripts that were of the expected size as well as a protein of the M(r) and antigenicity of AMV coat protein accumulated in the transgenic plants. Plants that expressed the highest levels of coat protein developed fewer primary infections following inoculation with two strains of AMV and developed systemic infection slower than did plants that did not express coat protein. Resistance was specifically against virions of the AMV strains. AMV RNA and the unrelated virus, tobacco mosaic virus, were as infectious on progeny that expressed coat protein as they were on progeny that did not. The relationship between the virus resistance expressed by these transgenic plants and that observed in virus cross-protection is discussed.

Inhibition by citrate of spontaneous precipitation of calcium oxalate in vitro

Effect of citrate on the spontaneous precipitation of calcium oxalate was examined in synthetic media. Citrate significantly increased the formation product of calcium oxalate. This "direct" measure of inhibitor activity, representing activity product at the point of nucleation, rose by 76% by the addition of citrate sufficient to provide trivalent citrate concentration of 1.49 mM. Moreover, citrate inhibited calcium oxalate crystallization by complexing calcium and lowering calcium oxalate saturation. This "indirect" measure of inhibitor activity was assessed from the concentration product of calcium oxalate at the point of nucleation, since this measure should provide a reflection of both ion pair formation and direct inhibitor activity of citrate. The concentration product exceeded the formation product at all ionic (trivalent) citrate concentrations, particularly at high ionic citrate levels. At the ionic citrate concentration of 1.49 mM, the rise in the concentration product was 373%, which was nearly fivefold that observed for the formation product. The presence of ferric or aluminum cations at a physiologic concentration of 2 mg/l did not modify the increase in formation product produced by citrate. Thus, citrate inhibits calcium oxalate crystallization, largely by complexing citrate, but also by directly affecting nucleation. Presence of ferric or aluminum cations at a physiological concentration does not modify the inhibitor action of citrate.

New approaches to the estimation of migration flows from census and administrative data sources

Census data represent an important source of information about migration flows. However, existing estimation procedures based on intercensal projection are often inconvenient to apply and are sensitive to even quite small changes in enumeration completeness. 2 new estimation procedures applicable to data from 2 censuses are developed and illustrated using US data. The 1st method is essentially a modification of traditional intercensal projection techniques, but as a result of working with age groups rather than cohorts, it is simpler to apply and allows mortality of the migrants to be incorporated over the intercensal period. The 2nd method also uses information from 2 censuses, but also uses independent information on the age pattern of migration from administrative sources or from other census questions. The method uses the fact that the age pattern of recent migration is likely to be different from the age distribution of the overall population to distinguish between intercensal change due to migration and apparent intercensal change due to changes in enumeration completeness. If the method's assumptions are met, it is possible to estimate the relative coverage of the 2 censuses as well as the scale of the independent age pattern of migration relative to the coverage of 1 or other of the censuses. The illustrative applications of the methods to US data suggest that both can work reasonably well.

Hypotensive effect of urapidil: CNS site and relative contribution

The purposes of our study were to determine the contribution of the CNS to the hypotensive effect of urapidil in the cat and the specific brain site of action of this agent. For the first purpose, urapidil was studied on preganglionic sympathetic nerve activity, arterial pressure, and heart rate. Three systemic bolus doses of urapidil were administered (0.22, 0.44, and 1.3 mg/kg). All three doses lowered arterial pressure, and the highest dose produced a significant decrease in sympathetic nerve discharge in five of six animals studied. The lower two doses had no significant effect on sympathetic activity, and none of the doses altered heart rate. These results suggest that a high i.v. dose of urapidil is required to evoke hypotension by an action in the central nervous system (CNS). For the second purpose, urapidil was applied bilaterally to the intermediate area of the ventral surface of the medulla in doses of 25 and 50 micrograms. These doses caused decreases in arterial pressure of -6.1 +/- 2.2 (p less than 0.05) and -21.0 +/- 5.9 (p less than 0.05) mm Hg, respectively, but no change in heart rate. In addition, respiratory stimulation also occurred with the higher dose as respiratory minute volume increased by 81 +/- 14 ml/min (p less than 0.05). The highest dose of urapidil had no effect on arterial pressure when applied to other chemosensitive areas of the ventral surface of the brain. Comparative studies with prazosin (10 micrograms applied bilaterally to the intermediate area) indicated no hypotensive effect of this alpha 1-adrenoceptor blocking agent.(ABSTRACT TRUNCATED AT 250 WORDS)

[Leiomyosarcoma of the uterus in young identical twins]

The authors describe the occurrence of a confirmed leiomyosarcoma and a tumor suspected of being a leiomyosarcoma in 23-year-old twin sisters. In one of them the tumor had caused clinical symptoms; in the second it was detected at the presymptomatic stage as a result of increased attention after detection of the first tumor. In the first case treatment consisted in an extended abdominal hysterectomy, sparing one ovary, with bilateral interiliac lymph node extirpation; in the second case, in an extended abdominal hysterectomy with both adnexae and bilateral interiliac lymph node extirpation. So far - 13 and 10 months after the initial treatment, respectively - there are no signs of continued tumor growth in either case.

Effect of amiloride with or without hydrochlorothiazide on urinary calcium and saturation of calcium salts

To assess the therapeutic role of amiloride in calcium nephrolithiasis, seven patients with renal stones were evaluated before and after 1 month of treatment each with amiloride (2.5 mg twice daily), hydrochlorothiazide (25 mg, twice daily), and both drugs at the same dosages. Although amiloride alone reduced urinary calcium in only two patients, it caused a slightly more prominent decline in urinary calcium when added to hydrochlorothiazide treatment in five patients. The urinary saturation of stone-forming salts (brushite and calcium oxalate) decreased significantly during treatment with hydrochlorothiazide alone or in combination with amiloride. Although the decrease in brushite saturation was slightly more marked with the combined treatment, the reduction in calcium oxalate saturation was equivalent during the two treatment phases. Although serum potassium was significantly reduced during combined treatment with amiloride and hydrochlorothiazide, this reduction was not as prominent as that occurring during treatment with hydrochlorothiazide alone. The results suggest that the addition of amiloride to hydrochlorothiazide treatment in calcium nephrolithiasis may be advantageous, because of its stimulation, though slight, of the thiazide-induced reduction of urinary calcium and saturation of calcium phosphate and because it may avert the development of severe hypokalemia.

A simple technique for assessing the propensity for crystallization of calcium oxalate and brushite in urine from the increment in oxalate or calcium necessary to elicit precipitation

In an effort to develop a simple and reliable method with which to assess the propensity for spontaneous nucleation of calcium oxalate and brushite in urine, the permissible increment of oxalate and calcium was calculated. This represented the additional amount of oxalate or calcium that could be added to urine in three hours before spontaneous precipitation of calcium oxalate or brushite was initiated. The permissible increment of oxalate inversely correlated (P less than 0.001) with the formation-product ratio-activity-product ratio discriminant score of calcium oxalate, which was previously shown to reflect a quantitative measure of the likelihood for spontaneous nucleation. Similarly, the permissible increment of calcium inversely correlated (P less than 0.001) with the formation-product ratio-activity-product ratio discriminant score of brushite. The permissible increments in oxalate and calcium were significantly lower (P less than 0.001) in patients with renal stones than in control subjects. Moreover, treatment with thiazides, allopurinol, sodium cellulose phosphate, orthophosphate, and diphosphonate significantly raised the permissible increment of oxalate in patients with stones. Thus, the permissible increment was reliable in discriminating "stone-forming" from control urine and in assessing response to treatment.

Contrasting effects of potassium citrate and sodium citrate therapies on urinary chemistries and crystallization of stone-forming salts

Effects of potassium citrate therapy (60 mEq/day) on urinary chemistries and crystallization were compared to those of sodium citrate treatment in five patients with uric acid lithiasis. Both alkali treatments significantly increased urinary pH (P less than 0.001), from 5.35 +/- 0.18 SD to 6.68 +/- 0.14 for potassium citrate and 6.73 +/- 0.20 for sodium citrate. During potassium citrate therapy, urinary calcium significantly declined from 154 +/- 47 mg/day to 99 +/- 23 mg/day (P less than 0.01) and urinary citrate rose from 398 +/- 119 mg/day to 856 +/- 103 mg/day (P less than 0.001). The urinary saturation (activity product ratio) of calcium oxalate decreased from 3.21-fold to 1.69-fold saturation (P less than 0.01), and the inhibitor activity against calcium oxalate precipitation (formation product ratio) significantly increased. However, sodium citrate therapy did not significantly decrease urinary calcium (to 139 +/- 24 mg/day), although it increased urinary citrate substantially (to 799 +/- 89 mg/day, P less than 0.01). Urinary environment became supersaturated with respect to brushite (calcium phosphate) and monosodium urate. The inhibitor activity against calcium oxalate precipitation was not significantly altered for the whole group; in two patients, it decreased by more than 30%. The results indicate that (1) both alkali therapies are equally effective in preventing uric acid stone formation because of their ability to increase urinary pH, and (2) potassium citrate may prevent the complication of calcium nephrolithiasis in patients with uric acid stones, whereas sodium citrate may not.

[A note on the use of information concerning the residence of surviving siblings to estimate emigration]

"Two improvements are presented in the previously developed method for measuring international emigration based on information provided by surviving siblings. The first is a simplification of the procedure for estimating surviving siblings when the information does not exist because they all live abroad. The second...is a procedure for estimating the distribution by age of the surviving emigrant siblings using models." The improved procedures are applied to data for Barbados. (summary in ENG)

Mineral oil vacuum distillation method for nitrosamines in fried bacon, with thermal energy analyzer: collaborative study

Nine laboratories participated in a collaborative study of a method for determining 6 nitrosamines, dimethylnitrosamine, diethylnitrosamine, dibutylnitrosamine, nitrosopiperidine, nitrosopyrrolidine, and nitrosomorpholine, in the 5-17 ppb range. The coefficients of variation for repeatability were 10.8, 8.5, 10.4, 8.5, 8.7, and 7.8% with corresponding coefficients of variation for reproducibility of 16.4, 12.0, 13.6, 10.8, 11.2, and 10.3% and recoveries of 89.6, 91.6, 84.7, 90.0, 89.6, and 88.1%, respectively. The method was adopted official first action.

Mineral Oil Vacuum Distillation Method for Nitrosamines in Fried Bacon, with Thermal Energy Analyzer: Collaborative Study

Nine laboratories participated in a collaborative study of a method for determining 6 nitrosamines, dimethylnitrosamine, diethylnitrosamine, dibutylnitrosamine, nitrosopiperidine, nitrosopyrrolidine, and nitrosomorpholine, in the 5-17 ppb range. The coefficients of variation for repeatability were 10.8, 8.5,10.4, 8.5, 8.7, and 7.8% with corresponding coefficients of variation for reproducibility of 16.4, 12.0,13.6,10.8,11.2, and 10.3% and recoveries of 89.6, 91.6, 84.7, 90.0, 89.6, and 88.1%, respectively. The method was adopted official first action.

[The different sequelea of hyaline membranes in the adult and in the newborn (author's transl)]

The sequelae of pulmonary hyaline membrane in the newborn and in the adult are demonstrated. At both ages the forming and the increased cellularity of the alveolar interstitium are identical. The latter is accompanied by a reduction of the number of capillaries and tends to change into interstitial fibrosis. The further outcome of the intraalveolar exudate is different: in the newborn the hyaline membranes are completely dissolved whereas they are organized in the adult. In the late stages of this process the lung of the newborn shows varying diameters of alveoli and squamous metaplasias of the bronchiolar epithelium. These changes are known as bronchopulmonary dysplasia and impress as honey-comb lung in x-ray. As explanations of the different reactions to pulmonary hyaline membranes preexisting damage in the lung of the adult, a different function of the macrophage system, a different resistance against toxins, disturbances of blood circulation and the postnatal continuing growth of the lung of the newborn are discussed.

[Notes on estimating the age distribution of emigrant surviving children]

"A procedure is described to obtain an age distribution of emigrant surviving children from the reports of such children obtained from women by a census or survey. A simple form of the procedure, requiring a minimum of calculation, is shown to work almost as well as the more elaborate form, and is recommended for most uses. "These new procedures, explicitly introducing an age model of migration, yield age distributions which are substantially different from, and probably more realistic than those obtained through the use of model fertility and mortality schedules alone.... The age distributions of migrant children [in Colombia] as obtained in this paper are compared with those obtained by Somoza.... The procedure described here produces a total almost 10 percent higher because it shifts the age distribution of the migrant children towards higher ages with lower proportions of surviving mothers." (summary in ENG)