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Biomedical subjects

A Spitzer

Publications and source records attributed to A Spitzer.

At least 109 records · Page 6Linked to original sources
PubMed1980

The renin angiotensin system in newborn dogs: developmental patterns and response to acute saline loading.

Plasma renin (PRC) and aldosterone concentrations are known to be high during early postnatal life. Whether this is related to the low rates of renal blood flow or to sodium homeostasis remains unknown. Measurement of PRC, renal blood flow, and its intrarenal distribution were performed in 1- to 3-wk-old puppies subjected to maneuvers known to stimulate or inhibit renin release. In the awake state, PRC was observed to be higher in 2-wk-old puppies than in older or younger dogs, (P less than 0.0001). Significant differences in PRC were also found between litters (P less than 0.0001), but they did not account for the age-related changes. Anesthesia resulted in a 3- to 5-fold rise in PRC, whereas saline expansion suppressed PRC at all ages, the fall tending to become progressively greater with age (P less than 0.09). There was no significant correlation between the age-related changes in PRC and those in renal blood flow or its intrarenal distribution. The results of these experiments demonstrate that in the newborn from a qualitative point of view, PRC changes appropriately in response to various stimuli. However, quantitative age-related differences exist in this regard, reflecting an initial immaturity of the feedback system.

Age Factors↗
PubMed1979

Late metabolic acidosis: a reassessment of the definition.

The term "late metabolic acidosis" is generally used to define a population of apparently healthy LBW infants who fail to grow and have a base deficit in excess of 5 mEq/l (CO2TOT less than 21 mM). A relationship between hypobasemia and the lack of appropriate growth was postulated. This conclusion was reached, however, in the absence of adequate information regarding the distribution of acid-base variables in healthy LBW infants. The results of this study demonstrate that the CO2TOT of LBW infants (n = 114) rises between birth and three weeks of life from a mean of 18.6 to 20.3 mM. The frequency distribution of CO2TOT values did not show any significant deviations from normality, and 2 SD included values as low as 14.5 mM. No difference in the rate of growth was detected between "hypobasemic" infants given a solution of bicarbonate calculated to bring their blood CO2TOT to greater than 21 mM and those given similar amounts of isotonic saline solution. The ability of the LBW infants to excrete an ammonium chloride load was not related to their acid-base status and was comparable to that of term infants. It is apparent that the definition of late metabolic acidosis needs to be reconsidered.

Acidosis↗
PubMed1979

Hemodynamic and excretory response of the neonatal canine kidney to acute volume expansion.

It is generally recognized that developing animals retain sodium due to an enhanced reabsorption in distal tubule segements, even when the amount administered is in excess of their needs. This study was designed to test the relationship between this relative inability to dispose of a saline load and the functional characteristics of the kidney during postnatal maturation. In addition, we explored the role played by some of the factors known to affect natriuresis in the adult subject. Measurements of sodium excretion, glomerular filtration rate (GFR), and renal blood flow (RBF) and its intrarenal distribution were made in three age groups of puppies and in adult dogs. During expansion the GFR rose rapidly and to a similar extent at all ages, but it fell thereafter, the rate of decline being much slower in adult than in developing animals (P less than 0.001). RBF and its intrarenal distribution were not altered by volume expansion. The degree of natriuresis did not reflect either the age-related or the expansion-induced changes in GFR. Fractional and absolute sodium excretion were substantially higher in 2-wk-old puppies than in either 1- or 3-wk-old animals (P less than 0.002). These findings demonstrate that the blunted renal response of the maturing animal to saline loading is due to the persistence of an enhanced tubular reabsorption rather than to a limitation in glomerular filtration.

Animals↗
PubMed1979

Evaluation of infants and children for kidney disease.

An attempt is being made to provide a logical framework for the differential diagnosis of kidney disease in children. The process is facilitated by the fact that the starting points heralding renal disease are rather limited, the great majority of the conditions presenting themselves as one of five signs or five syndromes. Within each of these categories a sequential approach permits passage from the most common diseases and innocuous methods of clinical investigation to more esoteric entities and invasive techniques.

Acute Kidney Injury↗
PubMed1976

Subtherapeutic dicloxacillin levels in a neonate: possible mechanisms.

A neonate treated initially with oxacillin intravenously for two weeks and who was receiving phenobarbital for a seizure disorder subsequently failed to achieve therapeutic levels of orally administered dicloxacillin, even when the dosage was as high as 175 mg/kg/day. Intestinal absorption was documented by high serum peak levels. The low trough levels correlated with a high urinary excretion rate. The possibillity that renal tubular transport of dichloxacillin was stimulated by administration of penicillin derivatives (and/or phenobarbital) is suggested, and the need for careful monitoring of serum levels of antibiotics in neonates is emphasized.

Administration, Oral↗
PubMed1976

The significance of focal sclerotic lesions of glomeruli in children.

To establish the relationship between the type of focal sclerotic lesion of glomeruli and the development of progressive renal disease, the clinical courses of 20 children with focal segmental and 7 with focal global sclerosis were analyzed. Only five patients, all of them with focal segmental sclerosis, did not have the nephrotic syndrome, although all had proteinuria. Results suggest that patients with focal global sclerosis have a course identical to that of children with the minimal lesion form of nephrotic syndrome: onset in early childhood, response to steroid therapy, and a relapsing, nonprogressive course. Focal segmental sclerosis, in constrast, is characterized by older age at onset, high incidence of nephritic symptoms, lack of response to steroid therapy, and a progressive course with histologic and functional deterioration. Since most published reports have not distinguished between these two entities, a more favorable prognosis in focal segmental sclerosis may be inferred than is actually the case.

Adolescent↗
PubMed1976

Radiopaque suppositories.

The authors describe the radiographic appearance of several commonly used rectal suppositories. Such drugs are sufficiently opaque to be seen on abdominal radiographs and may simulate excreted urographic contrast medium or stones. Errors in interpretation can be avoided by asking the patient about rectal medication or by taking lateral or delayed films.

Adult↗