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Previously, we have demonstrated that short bowel syndrome (SBS) patients suffer daily from D-lactic acidemia; in these patients rather high amounts of (bacterial) D-lactate emerge in blood and urine with a circadian rhythm. The aim of this study was to establish the microbial basis of D-lactic acidemia in SBS. Therefore, faecal flora of (young and adult) SBS-patients was analysed qualitatively and quantitatively, and compared to that of controls. The isolated bacterial species were screened for massive D- and/or L-lactate production after in vitro growth. After introduction of oral feeding in SBS-infants shortly after the resection, lactobacilli increased from < or = 1% up to 60 +/- 5% of the faecal flora within 2-3 weeks. In the faeces of patients with oral feeding the lactate producers Lactobacillus acidophilus and Lactobacillus fermentum were the major resident bacteria (each with 10(10)-10(12) cfu/g faeces). During active growth in vitro these lactobacilli produced massive amounts of D- and L-lactic acid from glucose. Use of oral antibiotics in two SBS-children did not reduce the total numbers of lactobacilli, but caused shifts within the intestinal populations of at least lactobacilli. It is concluded that the strongly reduced intestinal capacity for carbohydrate absorption and the oral consumption of easily fermentable carbohydrates form the physiological basis for D-lactic acidemia in SBS, and that the fermentative D-lactate production by intestinal bacteria, especially the abundant, resident lactobacilli, forms its microbial basis. In these patients the antimicrobial and therapeutic effects of antibiotics are unpredictable.

A case of a child presenting with congenital abnormalities at birth is reported. The early development remained severely retarded and acquired skills minimally. The head circumference centile decreased. Magnetic resonance imaging showed progressive neuronal atrophy and secondary delay in myelination. Dihydropyrimidine concentrations in body fluids were quantitated by NMR spectroscopy. Enzymatic assay in the liver biopsy revealed total deficiency of dihydropyrimidinase (DHP) (5,6-dihydropyrimidine amidohydrolase; EC 3.5.2.2). As such, the patient is the first with enzymatically proven DHP deficiency. Thus far dihydropyrimidinuria has been reported in three other patients with a variety of neurological abnormalities. A relation of the enzyme deficiency with the neurodegenerative clinical course in our patient is suggested.

Objectives: To further define the clinical spectrum of the disease for pediatric and metabolic specialists, and to suggest that the general pediatrician and pediatric neurologist consider succinic semialdehyde dehydrogenase (SSADH) deficiency in the differential diagnosis of patients with (idiopathic) mental retardation and emphasize the need for accurate, quantitative organic acid analysis in such patients., Patients: The clinical features of 23 patients (20 families) with SSADH deficiency (4-hydroxybutyric acid-uria) are presented. The age at diagnosis ranged from 3 months to 25 years in the 11 male and 12 female patients; consanguinity was noted in 39% of families., Outcome Measurements: The following abnormalities were observed (frequency in 23 patients): motor delay, including fine-motor skills, 78%; language delay, 78%; hypotonia, 74%; mental delay, 74%; seizures, 48%; decreased or absent reflexes, 39%; ataxia, 30%; behavioral problems, 30%; hyperkinesis, 30%; neonatal problems, 26%; and electroencephalographic abnormalities, 26%. Associated findings included psychoses, cranial magnetic resonance or computed tomographic abnormalities, and ocular problems in 22% or less of patients. Therapy with vigabatrin proved beneficial to varying degrees in 35% of the patients. Normal early development was noted in 30% of patients., Conclusions: Our data imply that two groups of patients with SSADH deficiency exist, differentiated by the course of early development. Our recommendation would be that accurate, quantitative organic acid analysis in an appropriate specialist laboratory be requested for any patients presenting with two or more features of mental, motor, or language delay and hypotonia of unknown cause. Such analyses are the only definitive way to diagnose SSADH deficiency; the diagnosis can be confirmed by determination of enzyme activity in white cells from whole blood. We think that increased use of organic acid determination will lead to increased diagnosis of SSADH deficiency and a more accurate representation of disease frequency. As additional patients are identified, we should have a better understanding of both the metabolic and clinical profiles of SSADH deficiency.

Oral bacteria play an important rôle in the causation of oro-facial abscesses. However, they can also be involved in brain, liver and lung abscesses. To persist, it is essential that these bacteria can grow on those sites. The main source of nutrients for growth in abscesses is likely to be tissue exudate, which is rich in serum-derived proteins, and relatively poor in free amino acids and carbohydrates. Degradation of intact proteins seems a crucial step in providing the peptides necessary for energy generation. The aim of this study was to investigate the capacity of microorganisms from asscesses to degrade serum proteins, in particular immunoglobulins. To this end, samples were taken by aspiration from 16 odontogenic abscesses. It was found that pus from abscesses differed strongly in the concentration of viable bacterial cells. The ability of the abscess microflora to degrade serum proteins was investigated after growth of the sample in heat-inactivated human serum. The microflora from abscesses with a high concentration (n = 10) of bacteria strongly degraded immunoglobulins, whereas breakdown of immunoglobulins was virtually absent after growth of the microflora from low-bacterial concentration (n = 6) abscesses. Bacteriological analyses revealed the presence of at least one proteinase-producing species, like Porphyromonas, black-pigmented Prevotella species, or Actinomyces meyeri, in abscesses with a high density of bacteria, but not in those with low bacterial density. The results indicate that the capacity to degrade intact proteins, in particular immunoglobulins, is a major determinant of bacterial growth in abscesses.

Unlabelled: We describe a patient with myelodysplastic syndrome with monosomy 7 presenting with a T-cell defect. He suffered from infections from the age of 10 years, when a CD4 deficiency and impaired lymphoproliferative responses in vitro were found. The only symptom of a myelodysplastic syndrome at that time was thrombocytopenia with giant platelets. Monosomy 7 was found in the bone marrow cells. At the age of 11 years he developed other characteristics of monosomy 7 including splenomegaly and anaemia. Some months later leukaemia was diagnosed., Conclusion: In non-HIV CD4 deficiency myelodysplastic syndrome has to be considered.

In children with cryptogenic Lennox-Gastaut syndrome we found a functionally impaired humoral immune response to a primary antigen (haemocyanin), despite signs of a triggered immune system consisting of elevated IgG concentrations. This combination of immunological findings, considered to be the expression of a dysbalanced-triggered as well as functionally impaired-immune system, has also been described in an auto-immune disease like systemic lupus erythaematodes in humans, and in genetically epilepsy-prone rats. The interactions between the immune system and the nervous system in Lennox-Gastaut syndrome will be discussed.

Immunological disturbances may result in altered immunoglobulin concentrations and kappa/lambda light chain (kappa/lambda) ratios. We measured the kappa/lambda ratios of total serum immunoglobulins and of polyclonal IgG, A, and M separately as well as concentrations of these immunoglobulins in fourteen patients with juvenile onset mixed connective tissue disease. When comparing the patient group with a reference group the mean serum IgG and IgA concentrations were respectively 2.98 G/L (p = 0.0012) and 0.79 G/L (p = 0.0114) higher in the group of patients with juvenile onset mixed connective tissue disease. The mean IgM concentration was 0.39 G/L (p = 0.0002) lower. The mean kappa/lambda ratios of total serum immunoglobulins, serum IgG, and serum IgA were respectively 0.20 (p = 0.0226), 0.28 (p = 0.0016) and 0.10 (p = 0.0732), higher in the group of patients with mixed connective tissue disease as compared with the reference group. Mean serum IgM kappa/lambda ratio, however, was 0.21 (p = 0.0046) lower. The alterations of the serum immunoglobulin concentrations and of the kappa/lambda ratios reflect immunological disturbances in patients with juvenile onset mixed connective tissue disease. The increased concentration of serum IgG and raised IgG kappa/lambda ratio and decreased concentration of serum IgM with decreased IgM kappa/lambda ratio indicate that the synthesis of kappa-bearing immunoglobulins mainly is affected.

Several subgingival microorganisms were tested for their ability to utilize human immunoglobulin G (IgG) as a substrate for growth. This was done using a protein-free chemically defined medium, supplemented with IgG. Stimulation of growth was observed for Capnocytophaga ochracea, Porphyromonas asaccharolytica, Porphyromonas endodontalis, Porphyromonas gingivalis, Prevotella intermedia, Prevotella oralis, Lactobacillus catenaforme and Streptococcus intermedius. Immunoelectrophoresis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a protein assay demonstrated that P. intermedia and P. endodontalis completely degraded the protein chains of IgG. Partial breakdown of IgG was observed for P. asaccharolytica and C. ochracea, whereas P. oralis cleaved the IgG heavy chain, yielding Fc and Fab fragments. All these bacteria utilized IgG as a substrate for growth. Binding studies using an enzyme-linked immunosorbent assay, revealed complete loss of in vitro antigen-antibody binding capacity after incubation of specific IgG with P. endodontalis and partial loss of binding with P. intermedia, P. gingivalis, C. ochracea or Fusobacterium nucleatum. Degradation or inactivation of IgG by oral bacteria is thought to be important in the causation of polymicrobial infections.

The light chain ratios and the concentrations of immunoglobulin G (IgG), IgA, and IgM were measured before, during, and after antileukemic therapy in 10 patients with common acute lymphoblastic leukemia. The concentrations of IgG, IgA, and IgM decreased substantially during treatment but recovered slowly after cessation of the therapy. The light chain ratios were not systematically affected, but at diagnosis the kappa/lambda ratios of total serum Igs, IgG, and in particular IgM were somewhat lower in the patient group compared with an age-matched reference group. It is concluded that, despite a decrease in serum Ig concentrations, virtually normal kappa/lambda ratios are preserved, indicating that kappa and lambda syntheses are affected to the same extent. These ratios remained normal for age during the recovery of the serum Ig concentrations; the features as described for the development of the light chain ratios in childhood were not observed.

A combination of humoral immunodeficiency and isolated growth hormone deficiency was observed in a girl with Mulibrey nanism. The humoral immunodeficiency consisted of subnormal concentration of serum IgG, in particular IgG2 and IgG4, and low concentration of serum IgM. Serum IgA and IgD were elevated, IgE was absent. Antibody response in vivo was very low or absent and opsonization in vitro was defective. Total B-cell number was low. In addition, the serum kappa/lambda light chain ratios within the immunoglobulin classes G, A, and M were abnormal. The defective antibody response may be linked to the abnormal kappa/lambda light chain ratios. Endocrine functions were normal except for isolated growth hormone deficiency. Therapy with human growth hormone resulted in increased growth velocity but did not improve humoral immune functions.

Ataxia telangiectasia (AT) is an autosomal recessive disorder characterized by telangiectasia, progressive ataxia, sinopulmonary infections and a combined immunodeficiency (usually consisting of IgA deficiency, IgE deficiency, IgG2 and IgG4 deficiency and a disturbed T cell immunity). The alpha-fetoprotein level is elevated. Cytogenetic studies reveal a very specific chromosome instability with multiple chromosome 7 and/or 14 rearrangements (preferential breakpoints 14q32, 14q12, 7q35 and 7p12). X-ray hypersensitivity is one of the hallmarks of the disease. Nijmegen Breakage Syndrome (NBS), an autosomal recessive disorder with some features of AT, was first reported in 1981. At this moment at least 19 patients have been recognized. Clinical symptoms are microcephaly from birth, a peculiar face, growth retardation, repeated respiratory tract infections and renal abnormalities. Immunological, cytogenetic and cell-biological findings in NBS are identical to AT. However, alpha-fetoprotein levels are not increased. A tendency toward malignancy has been demonstrated in both syndromes. Recently, we encountered three patients with variants of these syndromes.

Serum immunoglobulin G, A and M concentrations and their respective kappa/lambda (kappa/lambda) light chain ratios were studied in 26 children with epilepsy. Fifteen had cryptogenic West syndrome or Lennox-Gastaut syndrome and 11 had other forms of childhood epilepsy. The results were compared to the data of a reference group of healthy children. The mean serum IgG and IgM concentrations were respectively 2.2 g/l (P = 0.007) and 0.4 g/l (P = 0.016) higher in the 26 children with epilepsy compared to the reference group. The kappa/lambda ratios of total serum immunoglobulins, IgG and IgM were respectively 0.10 (P = 0.057), 0.20 (P = 0.001) and 0.14 (P = 0.005) lower in the children with epilepsy than in the reference group. IgA concentration and IgA kappa/lambda ratio were not affected. There were no significant differences between the kappa/lambda ratios of the West and Lennox-Gastaut epilepsy and the other types of childhood epilepsies. The results are further evidence of reciprocal interaction between the nervous system and the immune system in childhood epilepsy.

Five patients with hyper-immunoglobulin D syndrome (hyper-IgD syndrome) were followed up for 3 to 8 years. In all patients studied, serum IgG3 was high. IgM decreased during the follow-up in all patients. In four of the patients serum IgA was elevated. In four patients the serum IgD kappa/lambda ratio was measured and was found to be raised in all. However, the serum total light-chain ratio and IgG, IgA, and IgM kappa/lambda ratios separately were virtually normal. In two of the patients, clinical symptoms preceded the increase in serum IgD. All patients had a history of severe reactions on immunizations in early childhood. We conclude that in hyper-IgD syndrome, other immunoglobulins may also be affected, in particular, IgA, IgM, and IgG3. The IgD light-chain ratio is also disturbed. We emphasize that clinical symptoms may herald immunological changes. This may be the result of an underlying factor causing both the clinical symptoms and, later, the increasing serum IgD levels.

The total kappa/lambda immunoglobulin light chain ratio and the kappa/lambda ratios within each of the serum immunoglobulin classes G, A, and M were measured in thirteen patients with humoral immunological disorders. Of those patients, eight had common variable immunodeficiency whereas five patients had other forms of humoral immunological deficiencies. Eleven patients had abnormal antibody response in vivo. All but three of the thirteen patients had clearly abnormal light chain ratios in one or more of the immunoglobulin classes. We conclude that humoral immunological disorders, usually characterized by abnormal heavy chain production and a disturbed antibody response, may frequently have a concomitant abnormal synthesis of the light chains resulting in an abnormal kappa/lambda light chain ratio.

Longitudinal serum immunoglobulin levels were studied in 36 children with selective IgA deficiency during a median follow-up period of 5 years. Twenty-five children were 'sporadic' cases, and 11 were 'familial'. Serum and saliva IgA levels in 23 children remained below 2 mg/l. Eight children with IgA levels above 2 mg/l showed considerable intra-individual variance in serum IgA, but remained IgA deficient. Five children at various ages developed IgA levels above 50 mg/l with detectable secretory IgA in saliva. In most of the children IgG subclass levels were found to be rather high, including at younger ages. There were no obvious differences between 'sporadic' and 'familial' cases except an association between IgD deficiency and serum IgA levels below 2 mg/l, and between serum levels of IgD above 1 IU/ml and of IgA above 2 mg/l, which was found to be significant in the 'sporadic' group but not in the 'familial' group.

Values for the kappa/lambda light chain ratio in immunoglobulins G, A and M and the total kappa/lambda ratio, measured by enzyme linked immunosorbent assay, were evaluated in serum samples from different age groups (114 children, aged from 1 month to 15 years, and 20 adults). The IgG kappa/lambda ratio decreased in the first 6 months and subsequently increased slowly during childhood towards the adult value of 2.0. The IgM kappa/lambda ratio increased at a greater rate than IgG kappa/lambda ratio in the first years of life and thereafter rose slightly throughout childhood to reach an adult value of 1.7. A decreasing IgA kappa/lambda ratio was found from 1 month of age onwards to an adult value of 1.1. The pattern of total kappa/lambda ratio was similar to the IgG kappa/lambda ratio with an adult value of 2.0.

A girl with acute non-lymphoblastic leukaemia was treated with immunosuppressive chemotherapy. After cessation of therapy she had three consecutive episodes of infection due to Streptococcus pneumoniae from which she recovered and was shown to have developed a combined deficiency of both IgG2 and IgG4. The patient eventually relapsed and died 3 years after the initial diagnosis. The importance of measuring IgG subclasses in patients treated with immunosuppressive chemotherapy is discussed.

Formation of lactate and pyruvate from glucose was studied in cultured amniocytes and chorionic villus fibroblasts from controls, either untreated or treated with azide, an inhibitor of cytochrome c oxidase, or other inhibitors of the mitochondrial respiratory chain. Amniocytes with an established cytochrome c oxidase deficiency were also investigated. Control amniocytes treated with azide as well as cytochrome c oxidase deficient amniocytes displayed strongly increased lactate-to-pyruvate ratios after incubation with glucose, compared to control cells. Elevated lactate-to-pyruvate ratios were also found in chorionic villus fibroblasts in which complexes I, III or IV were inhibited by rotenone, antimycin or azide, respectively. We conclude that measurement of lactate and pyruvate production from glucose in cultured amniocytes and/or chorionic villus fibroblasts allows adequate prenatal diagnosis of systemic cytochrome c oxidase deficiency and presumably of other systemic deficiencies of mitochondrial respiratory chain enzymes.

An enzyme-linked immunosorbent assay is described for measuring kappa and lambda light chains within each of the serum immunoglobulin classes G, A and M. The detection limit was 0.06 U/L for total IgG, IgG kappa and IgG lambda, 0.2 U/L for total IgA, IgA kappa and IgA lambda and 0.5 U/L for total IgM, IgM kappa and IgM lambda. The concentrations of kappa plus lambda light chains from the three different immunoglobulins correlated well within those of total immunoglobulin G, A and M as measured by enzyme-linked immunosorbent assay or by immunonephelometry. Adult values for the kappa/lambda light chain ratio were found to be 2.0 for IgG kappa/lambda, 1.1 for IgA kappa/lambda and 1.7 for IgM kappa/lambda.

Clinical manifestations in 40 children with selective IgA deficiency were studied during a follow-up period of 2-10 years. The patients were divided into two groups: group I consisted of 25 children with "sporadic" IgA deficiency and group II of 15 children with "familial" IgA deficiency. Respiratory tract infections including otitis media were frequent in both groups. Concomitant IgG2-IgG4 deficiency was found in two patients in group I. Longitudinal serum IgG levels were elevated significantly in both groups. Atopic complaints were observed in 10 children of the "sporadic" group, but only in two of the "familial" group. However, elevated serum IgE levels were more often found in group II. Two children of group I were mentally retarded and chromosomal examination showed abnormalities in both. Anti-IgA antibodies were detected in one child in group I and three children in group II. These three patients had an IgA deficient mother with class-specific anti-IgA antibodies. Concomitant IgG4-IgE deficiency was found in all four.

A 9-month-old Turkish boy was diagnosed as having Griscelli disease (Chediak-Higashi-like syndrome). Clinical signs consisted of silver-grey hair and a relatively light skin colour, recurrent episodes of fever, with or without detectable infections, increasing hepatosplenomegaly, hypotonia and motor retardation. Laboratory studies showed pancytopenia of varying degree but neither inclusion bodies nor vacuoles were seen in his leucocytes. Serum immunoglobulin levels were normal except for a IgG2 deficiency. In the mixed lymphocyte reaction the stimulation capacity of the leucocytes was decreased. Microscopic examination of his hair and electron-microscopic examination of a skin biopsy further confirmed the diagnosis. Shortly before the diagnosis was made, the child developed cerebral symptoms with hemiparesis and convulsions. A CT scan suggested cell infiltration of the brain. A few weeks later the boy died of an infection.

Two families were investigated in which the mothers had selective IgA deficiency and circulating class-specific anti-IgA antibodies. Both gave birth to two children who were found to be IgA deficient. Three of these children developed anti-IgA antibodies before puberty. In vitro immunoglobulin production studies performed in the children of both families revealed an IgA B cell defect combined with IgA-specific excessive T suppressor function in all four. The mechanisms by which transplacental passage of maternal anti-IgA antibodies could have interfered with the developing IgA system in the offspring are discussed.

Longitudinal immunological studies were performed in five patients with Bloom's syndrome. Serum IgG concentration showed no age-related increase. IgA levels were below the 10th percentile in childhood, but rose to normal in all but one. IgM was decreased in four patients at diagnosis and remained so in three of them. Cellular immunity results were very variable, even within one patient. An immunologic attrition was not demonstrated.

An infant with moderate muscular hypotonia and congenital lactic acidosis died suddenly at the age of 3 months. Autopsy revealed no abnormalities responsible for this unexpected death. Measurement of mitochondrial enzymes involved in energy production indicated a severely decreased total pyruvate dehydrogenase complex (PDHC) activity in muscle tissue (0.23 nmoles x min-1 x mg protein-1, control range 2.8-8.7) and moderately decreased PDHC activity in fibroblasts (0.27 nmoles x min-1 x mg protein-1, control range 0.37-2.32). The activity of the first component E1 (pyruvate dehydrogenase) in muscle tissue was 10 times lower than that of controls (0.008 nmoles x min-1 x mg protein-1, control range 0.10-0.25). The activities of dihydrolipoyl dehydrogenase (E3) and various other mitochondrial enzymes were normal. Immunochemical analysis in skeletal muscle tissue and fibroblasts demonstrated a decrease in the amount of the alpha and beta subunits of E1. The features of this patient are compared with those of other patients reported in the literature with immunochemically confirmed combined E1 alpha and beta deficiency.

Six patients are described in whom a deficiency of cytochrome oxidase in muscle tissue was found. Four patients suffered from the syndrome of 'floppy babies' with profound hypotonia, muscle weakness and failure to thrive. They died within the first 6 months of life. Two patients suffered from Leigh's and Alpers' syndrome, respectively. In all patients lactate level was elevated in one or more body fluids, whereas in 4 patients a generalized amino-aciduria was found. With electronmicroscopy structurally abnormal mitochondria were seen in the muscle of 5 out of the 6 patients.

A patient with infantile Gancher's disease is described. A marked decrease of the activity of beta-glucosidase at the lower pH 4.2 was found in peripheral blood leukocytes, whereas in cultured skin fibroblasts the activity at both pH'S 4.2 and 5.2 was decreased. Examining the leukocytes of the heterozygous parents the activities of beta-glucosidase at both pH's were within the values of controls, but the ratio's of activity of pH 5.2 to that at pH 4.2 were increased lying between the ratio's from the patient and controls.

Adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), 5'nucleotidase (5'NT), ecto-5'NT, hypoxanthine-guanine phosphoribosyltransferase(HGPRT), adenine phosphoribosyltransferase(APRT), adenosine kinase(AK), AMP deaminase (AMPD) and adenylate kinase(AdKin) activities were assayed in leukemic cells from bone marrow and/or peripheral blood of 43 newly diagnosed children with acute lymphoblastic leukemia(ALL). These enzyme activities have been investigated in relation to some immunological markers. ADA activity was higher in E-rosette positive leukemia(E+ ALL), while HGPRT, APRT, PNP, 5'NT, ecto-5'NT and AdKin activities were found to be lower in E+ ALL as compared to E- ALL. In common ALL (cALL) antigen positive leukemia, mean ADA activity was significantly lower as compared to cALL- leukemia, whereas PNP, 5'NT, ecto-5'NT and AdKin activities were significantly higher. cALL cells with cytoplasmic immunoglobulin M(IgM) heavy chains were found to have mean 5'NT activities twice as high as cALL cells lacking cytoplasmic IgM heavy chains. In two patients who had surface immunoglobulins on their cell membranes, low 5'NT activities were found. When measuring enzyme activities after 2-4 days of prednisone monotherapy, only mean ADA and HGPRT activities decreased in non-B, non-T ALL. These decreases were not significant in T-ALL patients. Mean enzyme activities in the leukemic cells of five patients with relapse were comparable to those in newly diagnosed patients, except for 5'NT, which was found to be within the activity range of control peripheral blood lymphocytes. It is concluded that ADA and AdKin activities are suitable as markers for E+ ALL and cALL+ leukemias respectively. 5'NT might help to distinguish between cALL cells having and lacking pre-B characteristics. Since 5'NT activity may also be decreased in B-ALL, it is not suitable as a T-ALL marker. Enzymes of purine metabolism in leukemic relapse need further investigation.

Comparison of the distribution pattern of leukemic and normal bone marrow cells, obtained by density gradient centrifugation, may give information about the location of the blockade in the differentiation pathway from stem cell to mature leukocyte, as is supposed to exist in acute leukemia. As a control group 12 children with acute lymphoblastic leukemia (ALL), in complete remission and after cessation of all antileukemic therapy, were studied. By centrifugation over a discontinuous bovine serum albumin (BSA) density gradient, good reproducibility of the partition of the bone marrow cell population was obtained, with a peak in the more dense region. The cells capable of incorporation of [3H] thymidine in vitro were present predominantly in the lower density range. In 9 patients with lympho- or myeloproliferative malignancies (3 with o-cell ALL, 2 with T-cell malignant lymphoma, 1 with B-cell malignant lymphoma, 3 with various malignancies of the myeloid-monocytoid series) similar fractionation on the BSA gradient revealed a different cell partition pattern as compared with the control group. The peak of the distribution curve was located in the less dense region. Highest [3H] thymidine incorporation values were measured in vitro with cells from the lower density region. At last the importance of purely practical considerations in the choice of material for density gradient fractionation is stressed. Application of density gradient centrifugation methods could probably be helpful in attributing to cells from acute leukemia a place in the normal differentiation pathway.

The clinical identification of patients with defects in the mitochondrial respiratory chain is almost impossible. We describe screening tests that should be performed in order to select those patients in whom a skeletal muscle biopsy should be carried out for more specific biochemical assays. The importance of performing in vivo function tests is stressed. The biochemical diagnosis in disorders of the respiratory chain is presented and the application of immunological methods discussed.

A patient with demyelination is described. Lactate levels were elevated in serum, urine, and cerebrospinal fluid. A decreased pyruvate oxidation rate due to a pyruvate dehydrogenase complex deficiency was demonstrated in muscle and cultured fibroblasts. In muscle mitochondria no structural abnormalities were seen. The clinical course was progressive and the patient died at the age of 6 months.

The influence of storage on urinary albumin concentration was prospectively studied with use of overnight urine specimens (Albustix negative) from 73 diabetic patients. From each urine sample four aliquots were taken. One was stored at 4 degrees C and assayed within two weeks, the other three were stored at -20 degrees C and assayed within two weeks and after two and six months. Albumin concentration was measured with laser immunonephelometry. The detection limit, 1 mg/L, suffices for the screening of diabetic patients for microalbuminuria. After storage for two and six months at -20 degrees C, significantly lower albumin concentrations were found. The difference was mainly caused by lower concentrations found in urine samples in which a precipitate had formed, which was the case in 22 and 25 samples, respectively. Thus, freezing of urine samples for determination of low concentrations of albumin may yield falsely low results. Urine samples are best stored at 4 degrees C and assayed within two weeks.

The exact role of adenosine in the adenosine deaminase (EC 3.5.4.4) deficiency-related severe combined immunodeficiency disease has not been ascertained. We analysed the effects of adenosine, in the presence of the adenosine deaminase inhibitor, deoxycoformycin, on cell growth, cell phase distributions and intracellular nucleotide concentrations of cultured human lymphoblasts. Adenosine had a biphasic effect on cell growth and cell cycle distribution of a partial hypoxanthine phosphoribosyltransferase (EC 2.4.2.8) deficient MOLT-HPRT cell line. After 24 h of incubation, 60 microM adenosine inhibited cell growth more extensively than did 100 and 200 microM adenosine. The distribution of the MOLT-HPRT cells in the various phases of the cell cycle showed a similar biphasic pattern. Adenosine concentrations in the medium below 10 microM caused accumulation of adenine ribonucleotides and depletion of phosphoribosylpyrophosphate, UTP and CTP in the cells. This was associated with inhibition of cell growth. Medium adenosine concentrations above 10 microM neither resulted in accumulation of adenine ribonucleotides nor in inhibition of cell growth.

In the period 1975-1983 22 patients, aged 4-36 months were seen with severe transient normochromic, normocytic anaemia caused by a transient erythroblastopenia. In 20 patients bone marrow aspirations were obtained; they showed erythroblastopenia. In ten cases we observed young lymphoid cells, suggesting a diagnosis of acute lymphoblastic leukaemia. One patient suspected of a leukaemia, was studied in more detail. All patients showed reticulocytopenia. MCV and HbF were within normal range. During recovery reticulocytosis and higher levels of HbF were found. Except for blood transfusion in most patients, therapy (e.g. corticosteroids) was not necessary. Spontaneous recovery is a feature of this kind of erythroblastopenia, contrasting with congenital hypoplastic anaemia.

A girl was presented suffering from generalised weakness and cardiorespiratory insufficiency. She succumbed at the age of 5 months. Lactate levels were elevated in serum, cerebrospinal fluid and urine. Histopathological examination revealed a mitochondrial myopathy. In muscle tissue the cytochrome oxydase activity was strongly reduced. The content of cytochromes b and aa3 was very low. At autopsy a cardiomyopathy was found.

The metabolism of pipecolic acid ahs been studied in three patients suffering from the cerebro-hepato-renal syndrome of Zellweger. A marked pipecolic aciduria was observed in these patients and serum levels of pipecolic acid were also elevated. From in vivo studies evidence was obtained that a disturbance in the catabolic pathway of pipecolic acid was present in all patients. This conclusion was based on the delayed return of the serum pipecolic acid concentration to the fasting concentration after oral loading of the patients with DL-pipecolic acid. Moreover, no increase in the excretion of alpha-amino adipic acid was observed in the patients after loading, in contrast with the control subjects, who showed a marked increase in the excretion of this metabolite of pipecolic acid. Further evidence for the presence of a metabolic defect in the catabolism of pipecolic acid was obtained from the observation that patients excreted significantly higher amounts of pipecolic acid during the loading experiment.

In children with hemolytic-uremic syndrome endotoxin determinations were carried out in the peripheral circulation in order to get evidence for the hypothetical role of endotoxin in the pathogenesis of the disease. For this purpose the Limulus test was used to determine endotoxin activity in 16 patients with hemolytic-uremic syndrome. In the plasma of these patients no endotoxin could be detected above the lower detection limit of 100 pg/ml, although in all patients with septicemia due to gram-negative bacilli the test was positive.

The toxicity of guanosine and deoxyguanosine in the presence or absence of the purine nucleoside phosphorylase inhibitor, 8-aminoguanosine, for malignant lymphoid cell lines and mitogen-stimulated peripheral blood lymphocytes has been studied. Deoxyguanosine inhibited the proliferation of lymphoid cells more strongly than guanosine. Addition of 100 microM 8-aminoguanosine neither enhanced nor diminished the toxicity of guanosine to the lymphoid cells. Only the toxicity of deoxyguanosine for the leukemic T cell line, MOLT 4, and the leukemic nonBnonT cell line, KM-3, was enhanced by the addition of 100 microM 8-aminoguanosine. These data suggest a possible role of purine nucleoside phosphorylase inhibitors in the treatment of lymphoproliferative disorders of the T-acute lymphoblastic leukemia (ALL) as well as the nonBnonT-ALL subclass.

A family with dihydropyrimidine dehydrogenase (DPD) deficiency is presented. In 3 persons a complete deficiency, and in 3 others a partial deficiency was detected in cultured fibroblasts. Two homozygote subjects and 1 heterozygote subject suffered from epileptic manifestations, in one of these homozygote subjects also microcephaly was found. DPD deficiency might be an etiological factor in the clinical picture of these patients. An autosomal recessive mode of inheritance of this deficiency was found.