PubMed Health⌕ Search

Biomedical subjects

C W Ludvigsen

Publications and source records attributed to C W Ludvigsen.

10 recordsLinked to original sources

Vitamin supplements and purported learning enhancement in mentally retarded children.

Dr. Ruth Harrell and her colleagues conducted a study in 1981 in which the administration of high dosages of vitamins were determined to dramatically improve the intellectual functioning of mentally retarded children. This paper documents the efforts of its authors to replicate the Harrell et al. research and, although no significant differences were found between active treatment groups and control groups at study's end, a thorough comparison is made between the two research efforts.

Adolescent↗

The failure of neonates to form red blood cell alloantibodies in response to multiple transfusions.

Red blood cell alloantibody production was studied in 90 neonates who received a mean of 14.1 transfusions (range 2-35) from an average of 8.9 donors during the first three months after birth. Standard antibody detection procedures were done with the use of a selected red blood cell panel. No unexpected alloantibodies were detected. These findings suggest, at a 99% confidence level, that neonates do not make red blood cell alloantibodies in response to transfusion, indicating that repeated compatibility testing is probably unnecessary. Thus, following initial antibody screening and compatibility tests, further compatibility testing can be eliminated.

Antibody Formation↗

A fluorometric high performance liquid chromatographic assay for vanillylmandelic acid (VMA) developed from a commercial kit method.

A fluorometric procedure based on the Bio-Rad Vanillylmandelic Acid (VMA) by High Performance Liquid Chromatography (HPLC) Test was developed. Detection by fluorescence provides better sensitivity and specificity than the Pisano spectrophotometric method. Use of a C18 mini-column extraction to extract VMA prior to HPLC analysis significantly reduced the late eluting peaks. A linear range was established up to 400 mumol/L of VMA. Within-run and between-run CV's were 3.0% and 3.7%, respectively. In a comparison of this fluorometric method with the Pisano spectrophotometric method, a linear regression of y = 0.807x + 2.185 was obtained with a correlation coefficient of 0.945. In the analysis of over 50 samples, no intereferences have been found.

Adrenal Gland Neoplasms↗

Creatine kinase variant type I in children with anoxic insult.

We evaluated 31 consecutive patients, including 11 children, with creatine kinase variants (CKV) in our laboratory during a year. All had a clinical history of central hypotonia with myocardial damage resulting in severe central hypoxia. Seven of the 11 were neonates and had Apgar scores of 2.8 (SD 2.3) at 1 min and 4.8 (SD 2.4) at 5 min, which reflected their severe birth hypoxia. For the seven neonates, the mean value for total serum creatine kinase (EC 2.7.3.2; CK) was 773 (SD 553) U/L. The mean percentage CKV was 20.7% (SD 12.5%). The other four children were being evaluated for failure to thrive; all had birth asphyxia with residual cerebral palsy and seizure activity. These older children had a lower percentage of CKV (7.3%, SD 1.01%) than did the neonates, but the total CK (725, SD 1335 U/L) was not significantly different. In four neonates there was a three- to 20-day delay in the appearance of CK variant, which followed a marked increase in total CK activity. Tissue necrosis is apparently an important factor in the pathogenesis of Type I CK variant.

Asphyxia Neonatorum↗

D-lactate encephalopathy.

Although D-lactate is not a product of human intermediary metabolism, absorption of D-lactate produced by abnormal intestinal bacteria can cause systemic acidosis in patients who have undergone gastrointestinal surgery, particularly jejunoileal bypass. In order to learn more about the prevalence of D-lactate encephalopathy, its occurrence in other disorders, and how well D-lactate concentration correlates with clinical symptoms, serum D-lactate levels were determined in several specific populations. D-lactate was undetectable (less than 0.5 mmol/liter) in 72 healthy volunteers and 57 obese persons. In 33 patients who had jejunoileal bypass, 16 reported symptoms consistent with D-lactate encephalopathy since surgery. Nine of these 16 had D-lactate levels greater than 0.5 mmol/liter (range 0.7 to 11.5 mmol/liter). Levels of D-lactate fluctuated over time, and in two patients, markedly elevated levels correlated with an encephalopathy accompanied by hyperchloremic metabolic acidosis and elevated anion gap. In 470 randomly chosen hospitalized patients, D-lactate level greater than 0.5 mmol/liter was found in 13 (2.8 percent), and 60 percent of these had a history of gastrointestinal surgery or disease. It is concluded that elevated serum D-lactate levels are relatively common in patients with jejunoileal bypass, and although more rare, occur in other gastrointestinal disorders as well. The symptoms of D-lactate encephalopathy are quite sensitive, but not necessarily specific for this disorder.

Acidosis↗

Kinetic enzymic assay for D(-)-lactate, with use of a centrifugal analyzer.

The D(-) isomer of lactic acid appears to cause a form of metabolic encephalopathy experienced by patients who have had jejunoileal bypass for morbid obesity. However, analysis for D(-)-lactate is not routinely available in clinical or reference laboratories. We describe an enzymic centrifugal-analyzer assay for D(-)-lactate in plasma or serum, with use of D(-)-lactate dehydrogenase. The method involves two-point kinetic calibration and preincubation of specimen and NAD+, thus eliminating the need for specimen-blanking or protein-precipitating pretreatment. This rapid, accurate, and precise assay should be helpful in evaluating patients with "short-bowel syndrome" who display confusion, lethargy, ataxia, or other central nervous-system disturbances that may be ascribable to D(-)-lactic acidosis.

Acidosis↗

Preliminary characterization of calcium binding in islet-cell plasma membranes.

Preliminary characterization of calcium binding was determined in a highly-enriched islet-cell plasma membrane fraction using a membrane filtration technique. Equilbrium calcium binding was specific, concentration dependent and saturable. Scatchard analysis indicated the existence of more than one class of calcium binding sites. The affinity constants and maximum binding capacities were 1.14 X 10(5) M-1 and 1.2 picomol/microgram protein and 1.17 X 10(3) M-1 and 64.8 picomol/microgram for the high and low affinity sites, respectively. Bound 45Ca2+ was dissociate from the plasma membranes in a biphasic manner in the presence of excess unlabelled calcium.

Animals↗

Standardization fo a digestion-filtration method for isolation of pancreatic islets.

Standardization of a technic for isolating large numbers of pancreatic islets is described. This procedure employed collagenase digestion of rat pancreatic tissue in a cylindrical wire screen in order to separate isolated islets from undigested pancreas. From this basic protocol the following conditions were established: (1) the duration of the initial digestion period was found to be optimal at six minutes; (2) three subsequent digestions of one minute each effected maximum islet yield; (3) the optimal initial collagenase concentration was found to be 1,000 U. (Worthington)/ml.; and (4) proper reductions of collagenase concentrations during the three subsequent digestions were found to be 50 per cent of each preceding incubation period. This method, combined with Ficoll gradient separation, yielded a mean of 800 islets per two rat pancreases. The isolated islets appeared morphologically intact, contained 0.36 +/- 0.05 mug. protein/islet, and demonstrated a normal biphasic release of insulin in response to stimulative levels of D-glucose. The present method provides a means for obtaining a large mass of viable islet cell tissue in a short time.

Animals↗