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Biomedical subjects

J C Chan

Publications and source records attributed to J C Chan.

At least 433 records · Page 24Linked to original sources
PubMed1979

Hypophosphatemic rickets: effect of 1 alpha, 25-dihydroxyvitamin D3 on growth and mineral metabolism.

Growth retardation nearly invariably accompanies hypophosphatemic rickets. Studies were conducted in an adolescent male with this disorder as follows. Protocol I: age, 6 to 16 years; treatment per day, 5,000 to 80,000 units vitamin D2, 1,760 to 2,200 mg phosphorus, orally as buffered phosphate; growth velocity, 5 to 6 cm/year. Protocol II: age 16 to 17 years; treatment per day, 1 alpha,25-dihydroxyvitamin D3, 1 microgram; 2,200 mg of phosphorus, orally as buffered phosphate; growth velocity, 14 cm/year. The height improved from less than third percentile for the decade during study protocol I to the 25th percentile during protocol II. Mineral balance studies showed a reduction of urinary and stool phosphorus during treatment protocol II, while the patient was receiving metabolic diet. The serum phosphorus improved from 2.2 to 4.3 mg/dl and radiologic healing of rickets was documented. No hypercalcemic episode was encountered. The data support the contention that 1 alpha,25-dihydroxyvitamin D3 is the treatment of choice for hypophosphatemic rickets.

Adolescent↗
PubMed1978

Hematuria and proteinuria in pediatric patient. Diagnostic approach.

Some of the first clues suggestive of renal disease are hematuria and proteinuria, and when present in a child, deserve careful consideration. The clinical experience and diagnostic evaluations at a new renal unit are examined to familiarize the practicing urologists with the diagnostic approach which will generate the correct diagnosis. The indications and results of kidney biopsy in children are also presented.

Adolescent↗
PubMed1978

Clinical disorders of sodium, potassium, chloride, and sulfur metabolism. Diagnostic approach in children.

Information concerning normal concentrations of serum sodium, potassium, chloride, and sulfate as well as clinically useful data concerning absorption and excretion of these physiologically important ions are reviewed. Clinical approaches to diagnosis of these electrolyte disturbances are summarized with special emphasis on interpretation and treatment of some of these disorders in children.

Acute Kidney Injury↗
PubMed1978

Urinary sulfate excretion in children with classic renal tubular acidosis.

These studies quantitat the significantly elevated sulfate excretion in the urine of children with classic renal tubular acidosis as compared to six weight-matched controls (1.4 +/-0.5 vs. 0.7 +/- 0.2 mEq/kg/day;p less than 0.05). This sulfate loss may result in a subclinical sulfate deficiency which may contribute to a chondroitin sulfate metabolic disorder.,and thus contribute to the growth failure in children with real tubular acidosis. Futhermore, elevated urinary sulfate excretion may be an early diagnostic finding in infancy prior to the manifestation of renal acidification defects. It is not known whether the sulfate loss is related to a primary renal tubular defect or secondary to metabolic acidosis, although the increased sulfate excretion persisting after correction of metabolic acidosis would tend to suggest a primary defect. However, the normal plasma sulfate concentration and the relatively short period of study permit no definitive answer at this time.

Acidosis, Renal Tubular↗
PubMed1978

Hydrogen ion production secondary to metabolism of sulfur-amino acids and organic acids.

The rate of acid production in infants and young children was quoted to be 1-2 mEq/kg/day but in fact, the sole reference used in all these instances did not permit such quantitation. In order to evaluate the rate of endogenous acid production, we applied the quantitative technique of Lennon et al. in the following normal subjects, where column A represents hydrogen ion released from metabolism of sulfur-containing amion acids; column B represents hydrogen ion released from incomplete oxidation of organic acids; the sum A and B gives an estimation of endogenous net acid production (NAP).

Acids↗
PubMed1978

Hypophosphatemic vitamin D-resistant rickets: metabolic balance studies in a child receiving 1,25 dihydroxyvitamin D3, phosphate, and ascorbic acid.

A child with hypophosphatemic vitamin D-resistant rickets was treated for three years with the conventional vitamin D-inorganic phosphate supplementation followed by a new therapeutic regimen consisting of 1,25 dihydroxyvitamin D3 (1,25 (OH)2D3) and half of the previous phosphate supplementation. The effectiveness of the two treatment regimens was compared by calcium, phosphate, and magnesium balance techniques and by serial radiological examinations as well as careful height measurements. In addition, the lowering of the urinary pH with ascorbic acid supplementation seems to be associated with improvement in the renal tubular reabsorption of phosphate, but its distinct effect, separate from the rest of the treatment modalities, was not tested in this study. The conventional treatment did not correct the hypophosphatemia and alkaline phosphatase elevation, whereas the 1,25 (OH)2 D3-inorganic phosphate regimen is well tolerated and effective in achieving a sustained normalization of these variables. In addition, the improved growth and healing of rickets further attest to the efficacy of the new treatment.

Alkaline Phosphatase↗
PubMed1978

Hemodialysis and thyroid functions in children.

Evaluation of thyroid functions in 16 children receiving maintenance hemodialysis for a mean duration of 17 months showed that the serum T3, T4 and TSH were below normal concentrations for age. However, the measurements of these variables before and after the dialysis procedure did not show any significant changes. The possibility that the chronic uremia may give rise to abnormal TSH secretion and low T3, T4 concentrations is not tested in this study.

Adolescent↗
PubMed1978

Complex acid-base disorders in subacute necrotizing encephalomyelopathy (Leigh's syndrome).

This report describes a case of subacute necrotizing encephalomyelopathy (Leigh's syndrome) in a 7-month-old boy. The clinical data suggest an association with a disorder of renal tubular acidification, characterized by both (proximal) type II and (distal) type I renal tubular acidosis (hybrid type). Concomitantly, the initial uncompensated metabolic acidosis evolved into a mixed metabolic acidosis and respiratory alkalosis-features of this syndrome not previously reported.

Acid-Base Imbalance↗
PubMed1977

Effectiveness of 1 alpha-hydroxyvitamin D3 in children with renal osteodystrophy associated with hemodialysis.

Two children who were receiving maintenance hemodialysis were treated with 1 to 4 microng/day of 1 alpha-hydroxyvitamin D3 for 500 to 700 days, respectively. Sequential parathyroid hormone levels and radiologic evaluations showed considerable improvement in one patient. The second patient initially responded with healing of the bone disease. Subsequent deterioration may be related either to medical noncomplicance and/or interference by diphenylhydantoin in the subsequent hepatic 25-hydroxylation of 1 alpha-OH-D3.

Adolescent↗
PubMed1977

Kidney biopsy: analysis of patient data and indications for kidney biopsies.

To evaluate the use of the facilities of a teaching renal unit patient data during the last 33 months were studied. A total of 534 patients. The pattern of referrals, the major categories of renal diseases and the results of the kidney biopsies were examined to offer the urologist a profile of a new clinic and some guide lines concerning referrals for kidney biopsies.

Adolescent↗