Studies on cell lines developed from the tissues of patients with galactosemia

Neonatal Acute Liver Failure

Neonatal acute liver failure (NALF) is a rare disease with a few known primary causes: gestational alloimmune liver disease (GALD), viral infections, metabolic diseases, and ischemic injury. Many cases still do not have a known cause. Laboratory evaluation may suggest a diagnosis. Most of the known causes have disease-specific treatments that improve outcomes. Survival is improving with better knowledge about and treatment options for GALD; however, overall mortality for NALF is still 24%. Liver transplant remains an important option for neonates with an indeterminate cause of NALF and those who do not respond to established treatments.

Mutated human embryonic stem cells for the study of human genetic disorders

Human embryonic stem cells (HESCs) are of great interest in biology and medicine due to their ability to grow indefinitely in culture while maintaining their ability to differentiate into all different cell types in the human body. In addition, HESCs can be used for better understanding the key developmental processes and can, therefore, serve for studying genetic disorders for which no good research model exists. Preimplantation genetic diagnosis of in vitro derived embryos results in affected-spare blastocysts with specific known inherited mutations.These affected blastocysts can be used for the derivation of disease-bearing HESCs, which would serve for studying the molecular and pathophysiological mechanisms underlying the genetic disease for which they were diagnosed. This chapter describes the methods to derive HESCs carrying mutations for inherited disorders.

Some highlights in the emergence of modern concepts of osteoarthritis

The present-day concept that osteoarthritis may be amenable to biological modification rather than a hopeless expression of old age or injury has historical roots in the period of 1935 through the early 1970s. One root was the structural and chemical delineation of the connective tissues: discovery of the proteoglycans and multiple molecular species of collagen. Another was the recognition of the ability of mature articular chondrocytes to replicate themselves rather than being terminally differentiated. A third was the elucidation of the engineering physiology of the joint: the role of matrix hydrophilia to the material properties of articular cartilage and biolubrication. Each root has direct relevance to ongoing therapeutic approaches to degenerative joint disease. The early epidemiological studies of Kellgren and Lawrence evolved into new techniques for testing their validity in clinical practice. Along the way there was a rich 2-way interaction between scientists and clinicians in arriving at these ideas.

The "Dutch DNA Repair Group", in retrospect

The "Dutch DNA Repair Group" was established about 35 years ago. In this brief historical review some of the crucial decisions are described that have contributed to the relative success of the research of this group. The emphasis of the work of this group has been for many years on the genetic analysis of nucleotide excision repair (NER) and genetic diseases based on defects in this repair process: xeroderma pigmentosum (XP), Cockayne syndrome and trichothiodystrophy.

Properties of acatalasic cells growing in vitro

Acatalasia, a disease due to homozygosity for a Mendelian gene, is characterized by the absence of the enzyme catalase from the tissues of the human body. Red cells from heterozygotes have enzyme activities about one-half normal. In this paper, the development of cell lines from skin biopsies on an affected homozygote, a heterozygote, and eight control patients is described. The cell type is the euploid "fibroblast." It was found that acatalasic cells lacked the enzyme, even after growing for many months in a medium rich in catalase. The control lines all had mean catalase activities double or more that of the heterozygous line. Selection experiments, in which the growth of cells exposed for 20 minutes to varying concentrations of hydrogen peroxide was measured, did not provide a system for preferentially eliminating acatalasic cells. Certain other experiments bearing on the enzymatic defect in this disease were performed.

METABOLIC CONTROLS IN CULTURED MAMMALIAN CELLS

A number of apparently unrelated factors are known to have a profound effect on the metabolism of cultured mammalian cells; and some of these may be operative as metabolic controls in the whole animal as well. The more complete exploration of (i) homotypic and heterotypic cellular interactions, (ii) the spontaneous transformations sometimes observed in cultured cells, (iii) the mode of action of cytotoxic agents, (iv) the multiple metabolic effects of viral infection, and (v) the conditions necessary for the maintenance of specialized function in cultured cells, can be expected to throw light on the basic mechanisms underlying such complex processes as differentiation, senescence, and cancer.

Impaired hexose uptake by diploid skin fibroblasts from galactosaemic patients. Connection with cell growth and amino acid metabolism, and possible bearing on late-onset clinical symptoms

In skin fibroblasts of patients presenting with galactosaemia, either from galactose 1-phosphate uridyltransferase or galactokinase deficiency, a deficit in extracellular glucose utilization was observed. This deficit was constant over 3 weeks of continuous cell growth in a medium containing 5.5 mmol/L glucose as the only hexose, and homologous serum. Levels of glucose utilization by deficient skin fibroblasts were stable at about 65-70% of the glucose utilization of control normal skin fibroblasts. Cell morphology was normal, and cell growth was subnormal during this period. However, the energy provision appeared sufficient for cellular needs since cell growth in this glucose medium was observed not to depend on the presence of extracellular glutamine. In contrast, glutamine was required for growth of galactosaemic fibroblasts cultured in medium containing 5.5 mmol/L galactose. If expressed in many cell types, this impaired glucose uptake would be expected seriously to damage highly glucose-dependent tissues such as the central nervous system. This might be of relevance to the persistent neurological damage observed in many galactosaemic patients in spite of their compliance with an early strict galactose-free diet.

Culture of galactosaemic fibroblasts in the presence of galactose: effect of inosine

Fibroblasts from three galactosaemics had no galactose-1-phosphate uridyltransferase (GALT) activity. These fibroblasts cells were cultured in different media supplemented with dialysed fetal calf serum. Galactosaemic and control cell strains stopped growing in hexose-free medium. In glucose-free medium containing galactose, galatosaemic cells, in contrast to control cells, stopped growing after two days and died. In the same medium supplemented with inosine, they exhibited the same growth pattern as the control cell strains although in the presence of high concentrations of galactose-1-phosphate (Gal-1-P). These findings indicated that the glucose-free medium containing galactose supplemented with dialysed fetal calf serum and inosine, as a ribose donor, was appropriate for further in vitro investigations of galactose metabolism in galactosaemic cells.

Galactose metabolism in transferase-deficient galactosaemic and normal long-term lymphoid cell lines

The activity (mean +/- SD) of galactose-1-phosphate uridyl transferase in two long-term lymphoid cell lines from Caucasian patients with transferase deficiency galactosaemia, a heterozygote, and eight normal subjects was 0, 78 and 168 +/- 55 nmol UDPG consumed (mg protein)-1h-1, respectively. Also, no activity was found in erythrocytes and cultured fibroblasts from the patients. A small number of cells of the galactosaemic lines cultured in medium, in which galactose was substituted for glucose, survived for 37 days. Normal and galactosaemic lines incubated with D-galactose-[1-14C] liberated 218.2 +/- 65.6 and 18.1 pmol 14CO2 (mg cellular protein)-1 (6h)-1, respectively. The evolution of 14CO2 from D-glucose-[1-14C] was similar in normal and galactosaemic lines. In the presence of [3H]galactose the radioactivity incorporated into TCA-precipitated material of the galactosaemic lines was 6.8% of the normal lines. Approximately 26% and 1.3% of the total radioactivity was incorporated into molecular species with a molecular weight greater than 400,000 daltons in normal and galactosaemic cells, respectively. Similar molecules were identified in the cell-free medium of both normal and deficient cells except for an 18,000 daltons molecule identified only in the medium of the normal cells. These findings indicate that a small amount of galactose is metabolized in galactosaemic lines with no transferase activity.

Prenatal diagnosis of galactosemia and properties of galactose-1-phosphate uridyltransferase in erythrocytes of galactosemic variants as well as in human fetal and adult organs

The kinetic characteristics and isoelectrofocusing patterns of uridyltransferase and the concentrations of galactose-1-phosphate in hemolysates were investigated in a family with compound variants of Duarte and classical galactosemia. There were no significant differences in Km values between the genotypes. However, the isoelectrofocusing study with thin-layer polyacrylamide gels (PAGIF) as well as with agarose gels (AGIF) showed a distinctive difference. The enzyme from the Duarte variant resolved into at least two more activity bands at pH between 5.2 and 5.4. The accumulation of galactose-1-phosphate was observed only in homozygotes for classical galactosemia. Compound heterozygotes (G-D) without any clinical manifestations did not show an accumulation of galactose-1-phosphate. The isoelectrofocusing study of the enzyme in human tissues revealed their activity resolving into multiple bands, 6-8 bands at pH 5.50-6.00 and 1-3 bands at pH 4.9-5.2. No significant differences were found in the patterns between fetal and adult liver except that the intensity of the anodic bands (pH 4.9-5.2) was weaker in fetal tissues. Prenatal diagnosis of classical galactosemia was performed in nine families by measuring the enzyme activity in cultivated amniotic fluid cells. Absence of the enzyme activity in amniotic fluid cells was found in two cases, and in four cases the heterozygosity was diagnosed by a relative low enzyme activity, 30-50% of the activity in control cells cultured in parallel.

Testosterone metabolism of fibroblasts grown from prostatic carcinoma, benign prostatic hyperplasia and skin fibroblasts

The metabolism of [1,2,6,7-3H]testosterone was assessed in fibroblast monolayers derived from tissue of 5 prostates with benign hyperplasia (BPH), 4 prostates with carcinoma (PC), and 3 biopsy samples of skin, 2 nongenital skin (NG) and 1 genital skin. The following metabolites could be identified: androstanedione androstenedione, dihydrotestosterone, androsterone, epiandrosterone, androstane-3 alpha, 17 beta-diol and androstane-3 beta, 17 beta-diol. Testosterone was metabolized much more rapidly in fibroblasts originating from prostatic tissue than in fibroblasts derived from NG. A significantly higher formation of 5 alpha-androstanes and 3 alpha-hydroxysteroids could be observed in fibroblasts from BPH as compared to PC. 17-ketosteroid formation exceeded 5 alpha-androstane formation in BPH, whereas 5 alpha-reduction was the predominant pathway in fibroblasts grown from PC and NG. Since testosterone metabolism in fibroblasts of prostatic origin therefore resembles in many aspects that in whole prostatic tissue, fibroblasts grown from prostatic tissues might be a valuable tool for further investigation of the pathogenesis of human BPH and PC.

Reversion from deficiency of galactose-1-phosphate uridylytransferase (GALT) in an SV40-transformed human fibroblast line

Control SV40-transformed human fibroblasts can be readily adapted to growth on medium containing galactose as sole hexose source (galactose-MEH). However, most cells from a line of SV40-transformed skin fibroblasts from a patient with galactosemia (galactose-1-phosphate uridylyltransferase (GALT) deficiency) died in galactose-MEM. Surviving cells of this line either grew in completely sugar-free media or had acquired significant amounts of GALT activity. Two presumptive revertant cell lines with GALT activity were characterized in detail. The expression of GALT in these two lines was stable in nonselective conditions. Each had different reaction maximum velocities with respect to uridine diphosphoglucose (UDPg) concentration as compared to residual activity in the parental cell strain or control cells. Both appeared to demonstrate heat-inactivation profiles for GALT than differed from the parental cells or controls. UDPG concentration was found to significantly alter the thermostability of GALT. A competitive radioimmunoassay for GALT showed that these two lines had amounts of the GALT protein comparable to that of the parental cell strain or control cells. The electrophoretic mobility of GALT from the two presumptive revertants was found to differ from control cells. It was concluded that structural gene changes were probably responsible for the apparent reversion in these lines.

Phosphoenolpyruvate carboxykinase activity in human amniotic fluid

Amniotic fluid samples obtained from normal pregnancies during gestation were used to quantitate the levels of phosphoenolpyruvate carboxykinase (PEPCK) activity. It is concluded that: (1) PEPCK activity was highest in the amniotic fluid cells of midtrimester pregnancies as compared to those of pregnancies close to term; (2) the activity of PEPCK seen in the amniotic fluid supernatant was about one fourth to one half of that seen in the amniotic cells; (3) the amniotic fluid supernatant PEPCK activity fluctuated very little during the entire gestation.

Galactosemia: alterations in sulfate metabolism secondary to galactose-1-phosphate uridyltransferase deficiency

Cultures of nonmutant as well as galactokinase-deficient fibroblasts incorporate 20 percent more [35S]sulfate when galactose is substituted for glucose in the medium; galactose-1-phosphate uridyltransferase-deficient cells incorporate 65.5 percent less. In addition to incorporating less [35S]sulfate, the uridyltransferase-deficient cells showed significant accumulation of intracellular galactose-1-phosphate within 4 hours after galactose exposure. Under the same conditions, no difference in [3H]uridine incorporation was observed. This metabolic alteration, occurring in response to galactose exposure, may be related to the pathophysiology of classical galactosemia.

Prenatal diagnosis of galactosemia

Prenatal diagnosis of disorders of galactose metabolism was done in one instance in a family with a known galactokinase deficiency and in six cases in five families at risk for galactosemia. The galactokinase activity in cultured amniotic cells was found to be normal, and the diagnosis was confirmed postnatally. In the six pregnancies at risk for galactosemia, four were considered to be unaffected and two to be affected. Of the latter, one was carried to term, and the erythrocyte transferase activity of the baby was shown to be absent. The other pregnancy was terminated, and examination of fetal tissues by biochemical studies confirmed the diagnosis. This experience substantiates the concept that prenatal diagnosis of disorders of galactose metabolism is feasible.

Prenatal diagnosis of inborn errors of metabolism

More than 50 inborn errors of metabolism can be diagnosed in the fetus. This is accomplished by evaluation of constituents of the cell free amniotic fluid or of cultured or uncultured amniotic fluid cells. Only those syndromes with specific abnormal contributions to amniotic fluid can be so diagnosed. Currently diagnosable diseases and their assay methods are reviewed. Such assay methods must be able to differentiate the unaffected heterozygote from the affected homozygote.

Studies on the regulation of the three enzymes of the Leloir pathway in cultured mammalian cells. I. Effect of substitution of galactose for glucose as the sole hexose in the medium in human diploid cell strains and in a rat hepatoma line

In human diploid cell strains, the substitution of galactose for glucose as the sole hexose in the medium had no measurable effect on the specific activity of the cell protein for any of the three enzymes of the Leloir pathway. These enzymes are galactokinase, alpha-D-galactose-1-phosphate: UDP glucose uridyl transferase and UDP galactose 4-epimerase. A cell strain from a patient with galactosemia had no detectable activity for the transferase. The substitution of galactose for glucose in the medium of these cells (which has been shown to cause the cells to accumulate galactose-1-phosphate) also failed to affect cellular activity for the three enzymes. Similarly, the three activities failed to respond to the substitution of galactose for glucose in cultures of a rat hepatoma line. Cells of this line have been shown by others to perform a number of the tissue-specific functions of liver. The failure of galactose to stimulate increasd cellular activity for the three enzymes represents a striking difference between the behavior of these enzymes in human diploid cell strains and their behavior in E. coli.

Galactose and glucose metabolism in galactokinase deficient, galactose-1-P-uridyl transferase deficient and normal human fibroblasts

Despite the genetic interruption of the Leloir pathway both galactosemic patients and galactosemic fibroblasts can convert galactose to CO2 and TCA precipitable products, although at less than the normal rate. These observations stimulated investigations into the identity of the alternative metabolic routes which allows for galactose metabolism in the absence of in vitro galactose-1-P-uridyl transferase. Four lines of galactosemic cells, each without detectable gal-transferase, produced 14CO2 from [1-14C]-galactose (0.094 mumoles in 20 cc of medium) at approximately 39% +/- 16% the rate of transferase positive cells over a 48-hour period. However, galactokinase deficient fibroblasts produced 14CO2 and TCA precipitable products from [1-14C]-galactose or [U-14C]-galactose at only 3% to 9% the rate of normal fibroblasts. Therefore it seems likely that gal-transferase deficient fibroblasts must first synthesize galactose-1-P for further metabolism of galactose.

Detection of inborn errors of metabolism: galactosemia

Radioautography of cultured, human, galactosemic and nongalactosemic cells shows that, in the presence of 0.05M D-galactono-gamma-lactone, the former incorporate much less galactose in acid-insoluble form than the latter. Presumably the lactone inhibits incorporation of the labeled galactose into pathways which do not require galactose-1-phosphate uridylyltransferase activity. Definite differences between the galactosemic and nongalactosemic condition can be demonstrated with as few as 100 to 1000 cells. This approach may be useful in facilitating prenatal detection of several kinds of inborn errors of metabolism.

Galactose utilization in galactosemia

Cultures of human galactosemic fibroblasts without detectable transferase activity were able to convert [1-(14)C]galactose to (14)CO(2) to the same extent as normal cells, but did so at a significantly slower rate. The utilization of galactose in both normal and galactosemic cells was strongly inhibited by glucose at physiologic concentrations.

Diagnosis of metabolic disease

Use of sophisticated diagnostic procedures for the ever-growing list of metabolic disorders can be reserved for relatively few cases if simple screening procedures are employed in the presence of certain specific clinical signs.