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Biomedical subjects

W McAlister

Publications and source records attributed to W McAlister.

14 recordsLinked to original sources
PubMed1995

Hypercalciuria in osteogenesis imperfecta: a follow-up study to assess renal effects.

In 1991, we reported that hypercalciuria is a common finding in our pediatric patient population with osteogenesis imperfecta (OI) (17 of 47 = 36%). Here, we prospectively screened 12 of these hypercalciuric children, on average 4 years subsequent to the discovery of elevated urine calcium levels, for adverse effects on renal function. Despite an ad libitum decrease since initial investigation of about 30% in their previously normal dietary calcium intake (adjusted for body weight), 8 of the 12 patients remained hypercalciuric (urine calcium/creatinine > 0.62 mmol/mmol). We found, once again, that urinary calcium levels significantly correlated with the severity of the skeletal disease as assessed by z-score for height (r = -0.75, p = 0.005). Evaluation of kidney function, however, revealed: (i) normal routine urinalysis in all but 1 subject who had transient microscopic hematuria; (ii) unremarkable concentrating ability determined by fasting urine osmolality; (iii) normal creatinine clearance, and (iv) unremarkable ultrasonography to measure renal size and to screen for nephrocalcinosis or nephrolithiasis. Although no significant renal compromise was detected with these studies in our hypercalciuric pediatric OI patients, investigation of affected adults, especially those severely affected, will be important to assess whether this is a long-term problem and if adverse effects on the kidneys do develop.

Adolescent↗
PubMed1991

Rare primary cranial vault and base of the skull tumors in children. Report of 30 cases with a short literature review.

Twenty-six cases of rare primary cranial vault tumors are reported, together with 4 cases of primary tumors of the base of the skull and 3 cases of monostotic cranial neuroblastoma. Whereas some rare primary cranial vault tumors may present with characteristic radiographic patterns (e.g. hemangioma, aneurysmal bone cyst, osteoma, progonoma), most of them can be recognised only after histology. The most frequent tumor in the region of previous irradiation is osteosarcoma. The only "common" primary bone tumor of the base of the skull is chordoma. The radiological differential diagnosis of primary tumors of the skull vault and base is discussed.

Adolescent↗
PubMed1989

Extracorporeal membrane oxygenation for circulatory support after repair of congenital heart defects.

Extracorporeal membrane oxygenation was used for cardiovascular support in 13 infants and children with complex congenital heart disease and 1 premature neonate treated in preparation for pericardial patch tracheoplasty for long-segment tracheal stenosis. Nine patients were weaned from extracorporeal membrane oxygenation. There were five (36%) early deaths and four (29%) late deaths. Cannulation sites included right carotid/jugular vessels, femoral artery and vein, and right atrium and aorta. In 4 patients, the neck vessels were repaired at decannulation. Five survivors had normal growth and neurodevelopmental evaluations at follow-up. Extracorporeal membrane oxygenation can be successfully used as biventricular support in patients with intractable low cardiac output syndrome after repair of congenital heart disease. Best results are obtained in patients who have several hours of stability after operation before initiation of support. Hemorrhagic complications are reduced and long-term neurodevelopmental outcomes appear promising with right neck vessel cannulation and repair. No bleeding complications were observed in patients cannulated through the neck vessels.

Carotid Arteries↗
PubMed1988

Neurologic aspects of bronchopulmonary dysplasia.

Thirty seven infants were identified with bronchopulmonary dysplasia (BPD). Their hospital records were examined and survivors evaluated to determine the neurologic aspects of BPD. Five infants exhibited progressive neurologic disease; nine infants, Five infants exhibited progressive neurologic disease; nine infants, nonprogressive neurologic disease; and 19, normal neurologic outcome. In four, neurologic outcome was indeterminate because of early death. Thus, evaluation of this population of infants with BPD has established two syndromes of neurologic disease--progressive and nonprogressive. The patients with nonprogressive neurologic disease exhibited static neurologic deficits identical to those described in earlier reports of outcome in infants with BPD. The infants with apparently progressive neurologic disease had clinical courses comparable to the fatal pattern of cerebral deterioration previously described. The syndromes appear to be distinct in etiology and clinical presentation. Intraventricular hemorrhage complicated by hemorrhagic intracerebral involvement appears the factor most clearly associated with nonprogressive neurologic disease. The etiology of the striking progressive neurologic syndrome could not be so clearly established but appears to be related to the course and treatment of BPD.

Analysis of Variance↗
PubMed1985

Mineral homeostasis in very premature infants: serial evaluation of serum 25-hydroxyvitamin D, serum minerals, and bone mineralization.

This study was designed to evaluate the role of vitamin D sufficiency, as reflected in serum 25-hydroxyvitamin D (25-OHD) concentrations, on serum minerals and bone mineralization in very premature infants. Seventy-two infants (mean +/- SD gestation 30.1 +/- 2.5 weeks, mean +/- SD birth weight 1178 +/- 278 gm) were observed serially for the first 3 months of life. Mean serum calcium and phosphorus values, but not magnesium, remained low prior to 12 weeks. The percentage of infants with moderate to severe hypomineralization was 75% at 3 weeks, 55% at 6 weeks, 54% at 9 weeks, and 15% at twelve weeks. Low serum calcium and phosphorus values, high alkaline phosphatase activity, and moderate-severe hypomineralization were more frequent in infants weighing less than 1000 gm and in those with lower mineral intake. With a 400 IU vitamin D supplement, 45% of infants could maintain an initially normal serum 25-OHD concentration or increase low concentrations, whereas 55% had falling or persistently low (less than or equal to 15 ng/ml) 25-OHD concentrations. Birth weight and mineral intakes were comparable in these two groups, yet the group with the lower serum 25-OHD concentration had lower serum calcium and higher alkaline phosphatase values, and a higher percentage of moderate to severe hypomineralization. Regardless of birth weight, mineral intake, or 25-OHD concentration, increases in serum calcium and phosphorus values and in mineralization were seen at postconception term (12 weeks in most infants, nine weeks in those weighing 1250 to 1600 gm). At 12 weeks of age, but not before, serum 25-OHD concentration was directly correlated with serum calcium (r = 0.47, P less than 0.01) and serum phosphorus (r = 0.47, P less than 0.01) and inversely correlated with alkaline phosphatase values (r = -0.71, P less than 0.01). Mineral availability and 25-OHD sufficiency both appear to be important and to act synergistically, with neither totally compensating for the other.

Alkaline Phosphatase↗
PubMed1985

Absorption, dosage, and effect on mineral homeostasis of 25-hydroxycholecalciferol in premature infants: comparison with 400 and 800 IU vitamin D2 supplementation.

Because the efficiency of vitamin D absorption or hepatic uptake and 25-hydroxylation appears decreased in very premature infants, the routine use of 25-hydroxycholecalciferol (25-OHD3) supplementation has been suggested. Absorption studies of a 3 micrograms/kg orally administered dose of 25-OHD3 showed peak serum 25-hydroxyvitamin D2 and -vitamin D3 (25-OHD) concentrations at 4 to 8 hours similar in timing but of lesser magnitude to those seen in adults. Administration of 1 microgram/kg birth weight/day of 25-OHD3 corrected moderately low, but not very low serum (25-OHD) concentrations, and 2 micrograms/kg BW/day resulted in rapid and sustained increase in serum 25-OHD. Administration of 800 IU ergocalciferol (D2) also produced significantly higher serum 25-OHD concentrations than those in infants given 400 IU vitamin D2, but increases in serum 25-OHD were more gradual than in infants given 25-OHD3. In treatment trials with infants weighing less than 1500 gm, those given 800 IU D2, compared with those given 400 IU D2, had higher serum calcium concentrations and less frequent moderate or severe hypomineralization. Infants given 2 micrograms/kg BW 25-OHD3 had a significant increase in serum phosphorus values, but a decrease in serum calcium and magnesium concentrations, and parathyroid hormone also was suppressed to low normal values. The frequency of moderate to severe hypomineralization remained the same as in infants given 400 IU D2. In a subgroup of infants, serum 1,25-dihydroxyvitamin D was elevated over adult values, both in infants given 25-OHD3 (68.5 +/- 8.4 pg/ml) and in infants given vitamin D2 (60 +/- 6.7 pg/ml). Serum vitamin D concentrations were undetectable in four of six infants receiving 25-OHD3, but were elevated (5 to 31 ng/ml) in four infants receiving vitamin D2. Although 800 to 1000 IU D2 can be recommended as routine vitamin D supplementation in very premature infants fed standard formula, the use of 25-OHD3 requires further study.

Absorption↗
PubMed1979

Serum concentrations of 25-hydroxyvitamin D in rickets of extremely premature infants.

Nine premature infants developed radiographic and biochemical rickets at a mean +/- SD of 12.6 +/- 2.8 weeks of age. Serum 25-hydroxyvitamin D concentrations were all low, with a mean of less than 3.6 +/- 2.1 ng/ml. The mean average daily intake of vitamin D since birth had been 300 +/- 181 IU, and the mean average daily intake during the week of diagnosis was 587 +/- 313 IU. All of the infants were extremely premature (mean weight 948 +/- 153 gm, mean gestation 27.7 +/- 1.1 weeks), and were being fed either a low-calcium "human milk-like" formula or a soy formula. It is postulated that low-calcium intake may have increased 25-OHD utilization in the face of a decreased ability of the extremely premature infant to produce 25-OHD. Because of multiple factors leading to both decreased production and possible increased utilization of 25-OHD, such infants have an increased requirement for vitamin D to maintain normal serum 25-OHD concentrations, and daily intakes of at least 400 IU vitamin D orally must be assured. Serum 25-OHD measurements and radiographs may be important in following infants at risk.

Humans↗
PubMed1978

Meconium aspiration syndrome. Neonatal and follow-up study.

One year's experience with MAS in a neonatal intensive-care unit is analyzed with follow-up information. Seventeen patients or 3.7% of all admissions had MAS. Four patients (23.5%) died of acute respiratory failure. Two patients with MAS and persistence of the fetal circulation required cardiac catheterization to exclude cyanotic congenital heart disease. No survivors had persistent chronic lung disease. However, two of three patients with MAS and seizures had significant psychomotor retardation at follow-up examination.

Amniotic Fluid↗
PubMed1978

Prepyloric gastric antral web: a puzzling epidemic.

Antral webs and diaphragms are considered a rare cause of gastric outlet obstruction in infants and children. A radiographic diagnosis of antral web was made in 28 children during a 26-mo period. Nonbilious, often projectile vomiting was the predominant presenting symptom in 24 infants who were less than 6 mo of age. The older children complained of pain, vomiting, fullness after eating, and eructation. The characteristic radiologic finging was a wirelike transverse septum 1--2 cm proximal to the pylorus. Poor antral filling was an important early clue in the radiographic search for the webs. Pyloroplasty was performed in 20 patients, frequently after failure of medical management of symptoms. Coexistent congenital abnormalities were present in 28% of patients. A search for environmental and familial factors has failed to elucidate any teratogenic influences in this population.

Abnormalities, Multiple↗
PubMed1977

Antral diaphragm--a cause of gastric outlet obstruction in infants and children.

Gastric outlet obstruction in infants and children may be due to a partial, prepyloric antral diaphragm. Twelve new patients are added to the 32 described previously. Onset of symptoms varied from shortly after birth to five years. Nonbilious vomiting was the most common presenting symptom. Radiographic evaluation requires specific technique for demonstration of the web and to differentiate this from pylorospasm and pyloric stenosis. Gastroscopy was employed in three patients. Repair usually consisted of incision of the web and construction of a patulous gastric outlet. All patients remained asymptomatic after operation. The etiology of the webs remains unknown, but they may result from an excessive local endodermal proliferation early in gastric development.

Abnormalities, Multiple↗
PubMed1976

Intestinal stricture in necrotizing enterocolitis.

In a 3-yr period, eight infants among 43 survivors of acute NEC developed intestinal stricture. Four infants developed multiple stricture after proximal diversion procedures, and four had single strictures after medical therapy. Nineteen cases of intestinal stricture after NEC were collected from the literature. Radiographic examinations at the time of the acute disease were not predictive of the risk of subsequent stricture. Histologic examination showed various stages of wound healing, most prominently in the submucosa. Stricture should be considered as the cause of intestinal malfunction in any child who survives acute NEC.

Constriction, Pathologic↗
PubMed1975

The Kniest syndrome.

Explore the source record for details and available documents.

Abnormalities, Multiple↗
PubMed1975

Studies on the healing of anastomoses of small and large intestines.

It is well known that large intestine anastomoses tend to leak much more frequently than do small intestine anastomoses. These studies were undertaken to elucidate the pathophysioplogic basis of this phenomenom. Single layer interrupted silk suture anastomoses were performed in both the distal part of the ileum and the distal part of the colon in 29 dogs. The anastomoses were resected at one through eight days and 19 to 31 days after operations. Collagen response, vascular response and bursting strength at the site of anastomoses were investigated. The results demonstrated a statistically significant decrease in the collagen and vascular response of the large versus the small intestine. This differential response may play a role in the mechanism of the relatively high incidence of suture line separations observed after colonic anastomoses.

Animals↗