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Biomedical subjects

A L Friedman

Publications and source records attributed to A L Friedman.

At least 91 records · Page 5Linked to original sources
PubMed1987

Hypertension in babies following discharge from a neonatal intensive care unit. A 3-year follow-up.

Seventeen babies who developed hypertension (systolic BP greater than 113 mm Hg) after discharge from a neonatal intensive care unit were followed for a period ranging from 6 to 42 months. Five of the babies had an apparent cause for hypertension--one each had coarctation of the aorta, neuroblastoma, renal artery thrombosis, and two ureteropelvic junction obstruction. Umbilical artery catheters had been used in two additional babies. Ten of the babies had no obvious etiology for their hypertension. No prenatal, obstetrical or postnatal factor could be determined that predisposed these babies to hypertension. Sixteen of the babies were treated, 4 by surgical techniques and 12 by drugs--propranolol with or without chlorothiazide. All children treated medically were able to discontinue antihypertensives by 24 months of age. We conclude that follow-up of all babies discharged from the neonatal intensive care unit should include careful monitoring of blood pressure; that such infants may develop hypertension of unknown cause and that hypertension in this patient population is responsive to medication. Additional study is required to determine if babies discharged from neonatal intensive care units are at high risk for developing hypertension and to determine the natural history, prognosis and optimum treatment for the babies.

Female↗
PubMed1987

Granular juxtaglomerular cell hyperplasia caused by cyclosporine.

Histologic study of kidneys from rabbits given cyclosporine (CsA) revealed a marked hyperplasia of granular cells in the juxtaglomerular (JG) apparatus, but without a significant increase in the total cell number of JG cells. The increase in granular JG cells as compared with the control group was 204% and 406% for 30 mg/kg alternate days and 30 mg/kg daily groups, respectively. The increases for the lower-dosage groups were much smaller, although the increases were statistically significant for all but the 10 mg/kg alternate-days group. Other studies suggest that sympathomimetic activity of CsA may be the mechanism involved in granular JG cell hyperplasia.

Animals↗
PubMed1987

Severe renal osteodystrophy without elevated serum immunoreactive parathyroid hormone concentrations in hypomagnesemia due to renal magnesium wasting.

An 8 1/2-year-old girl presented with a long history of seizures, growth retardation, muscle weakness, gait disturbance, and hearing loss. Her evaluation revealed chronic moderate renal failure (serum creatinine 2.2 mg/dL), severe hypocalcemia (5 mg/dL), hyperphosphatemia (8.1 mg/dL), hypomagnesemia (1.5 mg/dL), increased urinary magnesium excretion (2 mg/kg/d), high fractional excretion of magnesium (21.7%), hypokalemia (3.2 mEq/L), and hyperkaliuria (26 mEq/L). Low circulating immunoreactive parathyroid hormone levels for the degree of the hypocalcemia (serum N-parathyroid hormone 212 pg/mL) and severe rickets without evidence of osteitis fibrosa cystica were found. The patient probably has primary renal leak hypomagnesemia (magnesuric hypomagnesemia) which caused impaired secretion of immunoreactive parathyroid hormone leading to severe hypocalcemia and calcium deficiency rickets. Treatment with magnesium and calcium supplements, calcitriol, and aluminum hydroxide resulted in marked clinical, biochemical, and radiologic improvement. Calcium deficiency rickets due to primary or secondary renal magnesium wasting in conjunction with moderate renal failure represents a largely unrecognized metabolic bone disease.

Aluminum Hydroxide↗
PubMed1986

Wilms' tumor detection in patients with sporadic aniridia. Successful use of ultrasound.

Eleven patients with sporadic aniridia have been followed up for periods of time ranging from eight months to ten years. The initial renal evaluation included an intravenous pyelogram and ultrasound. Ultrasound evaluation was then performed every four to six months until 8 years of age. After 8 years of age, evaluation was performed every six to 12 months. Two of 11 patients were found to have Wilms' tumors. Ultrasound was sensitive enough to find small lesions prior to extension from the kidney. Ultrasound evaluation permits early detection without repeated radiation, sedation, or contrast and offers an easy technique for follow-up of patients with sporadic aniridia who have a high likelihood of developing a Wilms' tumor.

Child, Preschool↗
PubMed1986

Asymptomatic primary hyperparathyroidism in children. Newer methods of preoperative diagnosis.

An asymptomatic 11-year-old boy was found to have primary hyperparathyroid secondary to an isolated parathyroid adenoma. This rare disorder of childhood can have asymptomatic hypercalcemia as its only manifestation. Parathyroid hormone assays and studies of urinary calcium excretion, especially the calcium-creatinine clearance ratio, distinguish parathyroid hormone excess from hypocalciuric forms of hypercalcemia. Real-time ultrasonography and dual-isotope subtraction scanning provide accurate, noninvasive, preoperative localization of abnormal parathyroid tissue. The prognosis of untreated, asymptomatic primary hyperparathyroidism in children is not known, and the indications for surgery are unclear. Diagnostic certainty is, therefore, especially important prior to surgical exploration.

Adenoma↗
PubMed1986

Beneficial effect of moderate protein restriction on growth, renal function and survival in young rats with chronic renal failure.

We used the model of one-stage uninephrectomy and contralateral heminephrectomy to study the effect of protein restriction on growth and renal function in young (starting age 21 d) female rats. Normal, sham-operated, pair-fed, and chronic renal insufficiency (CRI) rats were fed a 6, 14 or 22% protein (casein) diet. Diets were otherwise isoenergetic and equivalent in sodium, potassium, chloride, phosphate and calcium. Weight, length, urinary protein and creatinine clearances were measured up to 6 mo of age. Regardless of group (normal, sham or CRI), animals fed a 6% protein diet weighed less and were shorter than animals fed 14 or 22% protein diets. No difference in growth could be found between 14 and 22% protein intake. However, animals with CRI fed 22% protein diet had a shorter survival time than animals fed 14 or 6% protein diets. Six percent protein intake led to a lower growth rate over the first 10-12 wk of age than 14 or 22% protein intake. We conclude that 14% protein intake in rats with CRI maintains normal growth and improves survival over 22% protein intake. Rats with CRI fed a 6% protein diet have improved survival compared to rats fed a 22% protein diet but suffer growth retardation.

Animals↗
PubMed1986

Biogenesis and light regulation of the major light harvesting chlorophyll-protein of diatoms.

The apoprotein of the major light harvesting pigment-protein complex from the diatom Phaeodactylum tricornutum (UTEX 646) is composed of two similar polypeptides of 17.5 and 18.0 kilodaltons (kD). The in vivo synthesis of these polypeptides is inhibited by the 80s protein synthesis inhibitor cycloheximide, but not by the 70s ribosome inhibitor chloramphenicol. When total poly(A)(+) RNA was used in in vitro protein synthesis, a number of polypeptides were synthesized with a dominant product at 22 kD. When the polypeptides were immunoprecipitated with monospecific antibodies to the 17.5 and 18.0 polypeptides, a single protein zone of 22 kD was detected. Immunoprecipitation with preimmune serum failed to precipitate detectable levels of protein at any relative molecular weight (M(r)). These findings indicate that the two apoprotein polypeptides of the diatom light harvesting pigment-protein are translated from polyadenylated message on cytoplasmic ribosomes as either a single or two (or more) similar M(r) precursor proteins. These findings also suggest that this protein is encoded in the nucleus.Photosynthetic light adaptation features of P. tricornutum UTEX 646 indicate that it responds to low light by increasing cell size and numbers of photosystem I and II reaction centers per cell, but does not change photosynthetic rate per cell or photosynthetic unit sizes significantly. When low light cells are exposed to higher photon flux densities, the in vivo incorporation of label into the apoprotein of the light harvesting complex decreases. In contrast, high light grown cells show rapid (<3 hour) increases in apoprotein synthesis when exposed to low light levels. This is the first demonstration of a specific role of photon flux density in regulating the synthesis of a major light harvesting pigment-protein during photosynthetic light adaptation.

Journal Article↗
PubMed1986

Alterations in rat renal glucose transport following in vivo use of Freund's adjuvant.

Alterations in rat renal glucose transport following in vivo use of Freund's adjuvant were examined. Lewis-Brown Norway rats were placed in four separate injection groups: tubular basement membrane plus adjuvant [complete Freund's adjuvant (CFA) plus pertussis]; adjuvant (CFA plus pertussis); CFA only; or pertussis only. Renal handling of glucose was assessed 14 days after a single injection. No in vivo changes were noted. No histologic differences among groups were noted. However, brush border membrane vesicles prepared from animals in groups 1, 2, and 3 showed a marked decrease in glucose uptake. Further, Michaelis-Menten kinetics demonstrated a decrease in apparent Km and Vmax for glucose in groups 1, 2, and 3. CFA alone can cause a change in brush border membrane vesicle uptake of glucose. The pathogenic mechanism behind CFA-induced transport changes remains unclear. However, studies employing CFA cannot dismiss Freund's adjuvant as "inert" and must take into account functional changes created by CFA alone.

Animals↗
PubMed1984

A diatom light-harvesting pigment-protein complex : purification and characterization.

A light-harvesting pigment-protein complex was isolated from the diatom Phaeodactylum tricornutum using the zwitterionic detergent CHAPS (3-[3-cholamidopropyl)dimethylammonio]-1-propanesulfonate). Detergent-solubilized membranes were fractionated by sucrose density gradient centrifugation into three components. The medium density fraction contained chlorophyll a, chlorophyll c, and fucoxanthin. This fraction was purified by DEAE-ion exchange chromatography, and contained chlorophyll a, chlorophyll c, and fucoxanthin in a molar ratio of 2.4:1.0:4.8. Fluorescence emission and excitation spectra of the isolated complex demonstrated that light energy absorbed by chlorophyll c and fucoxanthin was coupled to chlorophyll a fluorescence. Upon denaturation, the apoprotein yielded a polypeptide doublet at 17.5 to 18.0 kilodaltons which accounted for 30 to 40% of the toal membrane protein. These findings indicate that this pigment-protein complex is a major component of the diatom photosynthetic lammellae. The quantitative amino acid composition of the apoprotein was very similar to those reported for other membrane-bound pigment-protein complexes. Based on the protein to chlorophyll a ratio of 7700 grams protein per mole chlorophyll a for the complex, each apoprotein molecule contains, to the nearest integer, two chlorophyll a, one chlorophyll c, and five fucoxanthin molecules. Polyclonal antibodies raised against the 17.5 to 18.0 kilodaltons apoprotein showed a monospecific reaction with only the 17.5 to 18.0 protein zone from denatured P. tricornutum membranes as well as to the nondenatured pigment-protein complex. It appears that this complex is common to other diatom species.

Journal Article↗
PubMed1983

Effect of captopril on the renin-angiotensin system in hypertensive children.

Nine patients with refractory hypertension, ranging in age from 6 to 18 years, were given captopril. The underlying cause of hypertension varied widely, but in all patients captopril produced a marked decrease in blood pressure. After treatment with captopril, patients showed an increase in plasma renin activity and plasma angiotensin I levels, with a concomitant fall in plasma angiotensin II and plasma aldosterone concentrations. Our data are similar to those reported in adults, and support the view that one mode of action of captopril is mediated via a decrease in plasma angiotensin II concentration.

Adolescent↗
PubMed1983

Renal adaptation to altered dietary sulfur amino acid intake occurs at luminal brushborder membrane.

The beta-amino acid transport capabilities of rat renal epithelium were assessed using brushborder membrane vesicles (BBMV). Taurine, a metabolically inert sulfur-containing amino acid, was studied with emphasis on the renal adaptation to dietary sulfur amino acid alteration. Three isoproteinic diets were given to Sprague-Dawley rats: low-sulfur-amino-acid diet (LTD), normal-sulfur-amino-acid diet (NTD), and high-taurine diet (HTD). Our studies demonstrated that taurine is actively transported into membrane vesicles by a sodium-dependent transport system. This transport is enhanced by hyperpolarization with valinomycin and decreased by dissipation of the sodium gradient by gramicidin. On LTD (compared to NTD), plasma taurine, urinary taurine, and fractional excretion of taurine were reduced. On HTD (compared to NTD), plasma taurine, urinary taurine, and fractional excretion of taurine were elevated. In vitro studies in BBMV from NTD animals revealed a Km of 40 microM and Vmax of 102 pmoles/mg protein/30 sec. Other beta-amino acids significantly inhibited BBMV taurine accumulation. BBMV taurine uptake was enhanced after LTD (compared to NTD) and diminished after HTD (compared to NTD). These studies indicate that a renal adaptation to dietary alterations in sulfur-containing amino acids occurs and that the luminal brushborder membrane participates in the adaptation. Renal adaptative mechanisms to dietary change may serve to help conserve amino acids during deprivation and to excrete amino acids during periods of excess.

Adaptation, Physiological↗
PubMed1983

Renal adaptation to alteration in dietary amino acid intake.

The nonessential beta-amino acid taurine, which is inert in renal tissue, was used to study the renal adaptation to dietary taurine change. Three isoproteinic diets were employed: HTD--high in taurine, NTD--normal taurine, and LTD--deficient in the taurine precursors cysteine and methionine. When compared with NTD, HTD resulted in an increase in the urinary excretion and fractional excretion of taurine, whereas LTD led to a decrease in urinary excretion and fractional excretion of taurine. In vitro studies demonstrated an increase in the Vmax of the high-affinity, low-capacity uptake system with no change in "apparent" Km following LTD. Complete adaptation developed within days after the diet was changed (NTD to HTD = 3 days; NTD to LTD = 3-6 days). These studies demonstrate that the renal response to altered dietary amino acid can be evaluated and that adaptation occurs for the beta-amino acid taurine. The renal response serves to conserve taurine during periods of deprivation and to dispose of taurine during periods of excess. The renal adaptation to restricted taurine intake seems to occur through an increase in transport sites (increased Vmax) or change in flux at the transport sites, with no change in transport affinity (unaltered apparent Km).

Aging↗
PubMed1983

Clinical systemic lupus erythematosus with dense deposit disease.

A 12-year-old girl with signs and symptoms of lupus erythematosus and nephritis had, by renal biopsy, glomerular capillary loop deposits identical in location and composition to those described in children with the dense deposit lesion of membranoproliferative glomerulonephritis, Type II. Following of prednisone therapy, serologic and clinical abnormalities resolved. The patient has experienced excellent growth and no recurrence of disease while receiving alternate-day prednisone therapy. The dense deposit lesion has not previously reported in patients having signs and symptoms of lupus glomerulonephritis.

Biopsy↗