Inborn disorders of the malate aspartate shuttle.

Over the last few years, various inborn disorders have been reported in the malate aspartate shuttle (MAS). The MAS consists of four metabolic enzymes and two transporters, one of them having two isoforms that are expressed in different tissues. Together they form a biochemical pathway that shuttles electrons from the cytosol into mitochondria, as the inner mitochondrial membrane is impermeable to the electron carrier NADH. By shuttling NADH across the mitochondrial membrane in the form of a reduced metabolite (malate), the MAS plays an important role in mitochondrial respiration. In addition, the MAS maintains the cytosolic NAD+ /NADH redox balance, by using redox reactions for the transfer of electrons. This explains why the MAS is also important in sustaining cytosolic redox-dependent metabolic pathways, such as glycolysis and serine biosynthesis. The current review provides insights into the clinical and biochemical characteristics of MAS deficiencies. To date, five out of seven potential MAS deficiencies have been reported. Most of them present with a clinical phenotype of infantile epileptic encephalopathy. Although not specific, biochemical characteristics include high lactate, high glycerol 3-phosphate, a disturbed redox balance, TCA abnormalities, high ammonia, and low serine, which may be helpful in reaching a diagnosis in patients with an infantile epileptic encephalopathy. Current implications for treatment include a ketogenic diet, as well as serine and vitamin B6 supplementation.

Treatment efficacy of high-dose creatine supplementation in a child with creatine transporter (SLC6A8) deficiency.

BACKGROUND: Creatine transporter deficiency is an inborn error of metabolism caused by a deficiency in the creatine transporter protein encoded by the SLC6A8 gene. Previous treatment with creatine supplementation, either alone or in combination with creatine precursors (arginine or glycine), has been attempted; the efficacy of therapy, however, remains controversial. METHODS AND RESULTS: To analyze the treatment efficacy of high-dose creatine supplementation on creatine transporter deficiency, we reported a child diagnosed with creatine transporter deficiency, who was treated with a conventional dose of creatine (400 mg/kg/d) for 1 month, then twice the dose (800 mg/kg/d) for 2 months, and finally 3 times the dose (1200 mg/kg/d) for 3 months. The patient tolerated the treatment well and showed improvements in muscle mass and strength when the creatine dose was gradually increased to 1200 mg/kg/d. However, when assessed by proton magnetic resonance spectroscopy (H-MRS), the brain creatine concentration did not increase, and there was no improvement in speech and neurodevelopmental symptoms. CONCLUSION: We conclude that high-dose creatine supplementation (1200 mg/kg/d) alone improved muscular symptoms, but did not improve cognitive symptoms and brain creatine concentration assessed using H-MRS. Therefore, new treatment strategies are required for the management of creatine transporter deficiency.

Lessons Learned from Inherited Metabolic Disorders of Sulfur-Containing Amino Acids Metabolism.

The metabolism of sulfur-containing amino acids (SAAs) requires an orchestrated interplay among several dozen enzymes and transporters, and an adequate dietary intake of methionine (Met), cysteine (Cys), and B vitamins. Known human genetic disorders are due to defects in Met demethylation, homocysteine (Hcy) remethylation, or cobalamin and folate metabolism, in Hcy transsulfuration, and Cys and hydrogen sulfide (H2S) catabolism. These disorders may manifest between the newborn period and late adulthood by a combination of neuropsychiatric abnormalities, thromboembolism, megaloblastic anemia, hepatopathy, myopathy, and bone and connective tissue abnormalities. Biochemical features include metabolite deficiencies (e.g. Met, S-adenosylmethionine (AdoMet), intermediates in 1-carbon metabolism, Cys, or glutathione) and/or their accumulation (e.g. S-adenosylhomocysteine, Hcy, H2S, or sulfite). Treatment should be started as early as possible and may include a low-protein/low-Met diet with Cys-enriched amino acid supplements, pharmacological doses of B vitamins, betaine to stimulate Hcy remethylation, the provision of N-acetylcysteine or AdoMet, or experimental approaches such as liver transplantation or enzyme replacement therapy. In several disorders, patients are exposed to long-term markedly elevated Met concentrations. Although these conditions may inform on Met toxicity, interpretation is difficult due to the presence of additional metabolic changes. Two disorders seem to exhibit Met-associated toxicity in the brain. An increased risk of demyelination in patients with Met adenosyltransferase I/III (MATI/III) deficiency due to biallelic mutations in the MATIA gene has been attributed to very high blood Met concentrations (typically >800 µmol/L) and possibly also to decreased liver AdoMet synthesis. An excessively high Met concentration in some patients with cystathionine ß-synthase deficiency has been associated with encephalopathy and brain edema, and direct toxicity of Met has been postulated. In summary, studies in patients with various disorders of SAA metabolism showed complex metabolic changes with distant cellular consequences, most of which are not attributable to direct Met toxicity.

Rare crystalline nephropathy leading to acute graft dysfunction: a case report.

BACKGROUND: Adenine phosphoribosyl transferase (APRT) deficiency is a rare genetic form of kidney stones and/or kidney failure characterized by intratubular precipitation of 2,8 dihydroxyadenine crystals. Early diagnosis and prompt management can completely reverse the kidney injury. CASE PRESENTATION: 44 year old Indian male, renal transplant recipient got admitted with acute graft dysfunction. Graft biopsy showed light brown refractile intratubular crystals with surrounding giant cell reaction, consistent with APRT deficiency. Patient improved after receiving allopurinol and hydration. CONCLUSION: APRT forms a reversible cause of crystalline nephropathy. High index of suspicion is required for the correct diagnosis as timely diagnosis has therapeutic implications.

Eicosapentaenoic acid ameliorates hyperglycemia in high-fat diet-sensitive diabetes mice in conjunction with restoration of hypoadiponectinemia.

BACKGROUND/OBJECTIVE: Eicosapentaenoic acid (EPA) exerts pleiotropic effects on metabolic disorders such as atherosclerosis and dyslipidemia, but its effectiveness in the treatment of type 2 diabetes mellitus remains controversial. METHODS: We examined the antidiabetic effect of EPA in insulin receptor mutant (Insr(P1195L/+)) mice that exhibit high-fat diet (HFD)-dependent hyperglycemia. RESULTS: EPA supplementation was found to alleviate hyperglycemia of Insr(P1195L/+) mice fed HFD (Insr(P1195L/+)/HFD mice), which was accompanied by amelioration of increased gluconeogenesis and impaired insulin signaling, as assessed by glucose-6-phosphatase (G6pc) expression on refeeding and insulin-induced phosphorylation of Akt in the liver, respectively. We found that serum levels of adiponectin, the antidiabetic adipokine, were decreased by HFD along with the body weight gain in Insr(P1195L/+) mice but not in wild-type mice, suggesting that Insr(P1195L/+) mice are prone to hypoadiponectinemia in response to obesity. Interestingly, the blood glucose levels of Insr(P1195L/+) mice were in reverse proportion to their serum adiponectin levels and EPA supplementation ameliorated their hyperglycemia in conjunction with the restoration of hypoadiponectinemia. CONCLUSIONS: EPA exerts an antidiabetic effect in Insr(P1195L/+)/HFD mice, an HFD-sensitive, insulin-resistant animal model, possibly through its action against hypoadiponectinemia.

Biotin deprivation impairs mitochondrial structure and function and has implications for inherited metabolic disorders.

Certain inborn errors of metabolism result from deficiencies in biotin containing enzymes. These disorders are mimicked by dietary absence or insufficiency of biotin, ATP deficit being a major effect,whose responsible mechanisms have not been thoroughly studied. Here we show that in rats and cultured cells it is the result of reduced TCA cycle flow, partly due to deficient anaplerotic biotin-dependent pyruvate carboxylase. This is accompanied by diminished flow through the electron transport chain, augmented by deficient cytochrome c oxidase (complex IV) activity with decreased cytochromes and reduced oxidative phosphorylation. There was also severe mitochondrial damage accompanied by decrease of mitochondria, associated with toxic levels of propionyl CoA as shown by carnitine supplementation studies, which explains the apparently paradoxical mitochondrial diminution in the face of the energy sensor AMPK activation, known to induce mitochondria biogenesis. This idea was supported by experiments on AMPK knockout mouse embryonic fibroblasts (MEFs). The multifactorial ATP deficit also provides a plausible basis for the cardiomyopathy in patients with propionic acidemia, and other diseases.Additionally, systemic inflammation concomitant to the toxic state might explain our findings of enhanced IL-6, STAT3 and HIF-1α, associated with an increase of mitophagic BNIP3 and PINK proteins, which may further increase mitophagy. Together our results imply core mechanisms of energy deficit in several inherited metabolic disorders.

Systemic primary carnitine deficiency: an overview of clinical manifestations, diagnosis, and management.

Systemic primary carnitine deficiency (CDSP) is an autosomal recessive disorder of carnitine transportation. The clinical manifestations of CDSP can vary widely with respect to age of onset, organ involvement, and severity of symptoms, but are typically characterized by episodes of hypoketotic hypoglycemia, hepatomegaly, elevated transaminases, and hyperammonemia in infants; skeletal myopathy, elevated creatine kinase (CK), and cardiomyopathy in childhood; or cardiomyopathy, arrhythmias, or fatigability in adulthood. The diagnosis can be suspected on newborn screening, but is established by demonstration of low plasma free carnitine concentration (<5 µM, normal 25-50 µM), reduced fibroblast carnitine transport (<10% of controls), and molecular testing of the SLC22A5 gene. The incidence of CDSP varies depending on ethnicity; however the frequency in the United States is estimated to be approximately 1 in 50,000 individuals based on newborn screening data. CDSP is caused by recessive mutations in the SLC22A5 gene. This gene encodes organic cation transporter type 2 (OCTN2) which transport carnitine across cell membranes. Over 100 mutations have been reported in this gene with the c.136C > T (p.P46S) mutation being the most frequent mutation identified. CDSP should be differentiated from secondary causes of carnitine deficiency such as various organic acidemias and fatty acid oxidation defects. CDSP is an autosomal recessive condition; therefore the recurrence risk in each pregnancy is 25%. Carrier screening for at-risk individuals and family members should be obtained by performing targeted mutation analysis of the SLC22A5 gene since plasma carnitine analysis is not a sufficient methodology for determining carrier status. Antenatal diagnosis for pregnancies at increased risk of CDSP is possible by molecular genetic testing of extracted DNA from chorionic villus sampling or amniocentesis if both mutations in SLC22A5 gene are known. Once the diagnosis of CDSP is established in an individual, an echocardiogram, electrocardiogram, CK concentration, liver transaminanses measurement, and pre-prandial blood sugar levels, should be performed for baseline assessment. Primary treatment involves supplementation of oral levocarnitine (L-carnitine) at a dose of 50-400 mg/kg/day divided into three doses. No formal surveillance guidelines for individuals with CDSP have been established to date, however the following screening recommendations are suggested: annual echocardiogram and electrocardiogram, frequent plasma carnitine levels, and CK and liver transaminases measurement can be considered during acute illness. Adult women with CDSP who are planning to or are pregnant should meet with a metabolic or genetic specialist ideally before conception to discuss management of carnitine levels during pregnancy since carnitine levels are typically lower during pregnancy. The prognosis for individuals with CDSP depends on the age, presentation, and severity of symptoms at the time of diagnosis; however the long-term prognosis is favorable as long as individuals remain on carnitine supplementation.

Pathology: a pictorial review. A selected atlas of paediatric liver pathology.

Indications for liver biopsy in children are often specific to this age group, especially in young children for the diagnosis of cholestasis. Since liver biopsies are quite unfrequent in the children population and concern rare but various diseases, it is recommended to entrust the analysis to a specialized liver pathologist, in a laboratory where cryoconservation, specific immuno-stainings, enzymatic studies, and electron microscopy can be performed. Histology is complementary to other methods for the diagnosis, and is valuable for the evaluation of the prognosis, especially the staging of fibrosis and the grading of inflammatory diseases. In cases of co-morbidity or difficult differential diagnosis, histology can also be of great value. For metabolic disorders, the liver tissue can also be used for enzyme detection or evaluation of iron or copper overload. Biopsy is also a key element in the management after liver transplantation. The microscopic images shown here are representative of the most frequent liver diseases in childhood and illustrate the data outlined during the conference.

Homocysteine in the prevention of ischemic heart disease, stroke and venous thromboembolism: therapeutic target or just another distraction?

PURPOSE OF REVIEW: Homocysteine has been proposed as a potentially modifiable risk factor for arterial and venous vascular disease. This notion is supported by a large body of literature derived from observations in patients with rare inborn errors of metabolism associated with homocystinuria, experimental studies, which show that homocysteine promotes atherogenesis and thrombosis and epidemiological studies, which in general suggest a graded and independent relationship between homocysteine and atherothrombotic vascular risk. RECENT FINDINGS: The current review briefly summarizes observational studies with emphasis on new meta-analyses linking homocysteine to ischemic heart disease, stroke, and venous thromboembolism. These data support weak associations between homocysteine and vascular risk. A number of recent large randomized controlled trials failed to demonstrate benefit for homocysteine lowering with B vitamin supplements in the prevention of cardiovascular events and venous thrombosis. These studies, however, may have been insufficiently powered to detect modest but clinically important treatment benefits. Therefore, completion of ongoing large randomized trials is essential. SUMMARY: At present, the status of homocysteine as a target for intervention in the prevention of atherothrombotic arterial and venous disease is uncertain. Current evidence does not support the use of B vitamin supplements to reduce vascular risk. Ongoing large randomized trials will provide further clarity on this subject.

Subacute combined degeneration of the spinal cord in cblC disorder despite treatment with B12.

Subacute combined degeneration (SCD) of the spinal cord is a characteristic complication of vitamin B12 deficiency, but it has never been neuropathologically demonstrated in a B12-inborn error of metabolism. In this report SCD is documented in a 15-year-old boy with early-onset cobalamin C (cblC) disorder. The neuropathologic findings included multifocal demyelination and vacuolation with predilection for the dorsal and lateral columns at the mid-thoracic level of the spinal cord, confirming the similarity of SCD in cblC disorder to the classic adult SCD due to vitamin B12 deficiency. SCD developed in this boy despite treatment for cblC disorder that began at 3 months of age. There is clinical and experimental evidence to suggest that a deficiency in remethylation with concomitant reduction in brain methionine may be the cause of SCD. In this patient plasma methionine levels were low without betaine and/or l-methionine supplementation and in the normal range for only a 2-year period during compliance with therapy. In cblC disorder, a consistent increase in blood methionine to high normal or above normal levels by the use of betaine and l-methionine supplementation may be helpful in preventing SCD. This is especially important now that the presymptomatic detection of cblC disorder is possible through the expansion of newborn screening.

Nutritional therapy improves growth and protein status of children with a urea cycle enzyme defect.

BACKGROUND: Poor growth has been described in patients with urea cycle enzyme defects treated with protein-restricted diets, while protein status is seldom reported. OBJECTIVE: To assess the effects of nutritional therapy with a medical food on growth and protein status of patients with a urea cycle enzyme defect. METHODS: A 6-mo multicenter outpatient study was conducted with infants and toddlers managed by nutrition therapy with Cyclinex-1 Amino Acid-Modified Medical Food with Iron (Ross Products Division, Abbott Laboratories, Columbus, OH). Main outcome variables were anthropometrics and plasma amino acids (selected), albumin, and transthyretin concentrations. RESULTS: Seventeen patients completed the study. Mean (+/-SE) baseline age was 11.30+/-3.20 months (median 4.40 months; range 0.22-38.84 months). Length and weight z-scores increased significantly during the 6-month study. Head circumference increased, but not significantly. Three patients were stunted and two were wasted (-2.0 z-score) at baseline while at study end, only one patient was both stunted and wasted. The majority of patients increased in length, head circumference, and weight z-scores during study. Mean (+/-SE) plasma albumin concentration increased from 34+/-2g/L at baseline to 38+/-1g/L at study end. Plasma transthyretin increased from a mean (+/-SE) of 177+/-13 mg/L at baseline to 231+/-15 mg/L at study end. No correlation was found between plasma NH(3) concentrations and medical food intake. Plasma NH(3) concentration was positively correlated with the percentage of Food and Agriculture Organization/World Health Organization/United Nations recommended protein ingested. CONCLUSIONS: Intakes of adequate protein and energy for age result in anabolism and linear growth without increasing plasma NH(3) concentrations. Medical food intakes did not correlate with plasma NH(3) concentrations.

Breastfeeding experience in inborn errors of metabolism other than phenylketonuria.

Breastfeeding has been recommended for the dietary treatment of infants with phenylketonuria, but studies documenting clinical experience in other inborn errors of metabolism are very few. Seven infants diagnosed with methylmalonyl-CoA mutase deficiency (n=2), ornithine carbamoyltransferase deficiency (n=1), propionic acidaemia (n=1), isovaleric acidaemia (n=1), maple syrup urine disease (n=1) and glutaric acidemia type I (n=1) were tried with breastfeeding over two years. After the control of acute metabolic problems, an initial feeding period with a measured volume of expressed breast milk plus a special essential amino acid mixture was continued with breastfeeding on demand and with the addition of a special essential amino acid mixture. Two patients with methylmalonic acidaemia and one patient with glutaric acidaemia type I tolerated breastfeeding on demand very well, with good growth and metabolic control for periods of 18, 8 and 5 months, respectively. In the patient with propionic acidaemia, on-demand breastfeeding continued for 3 months but was terminated after two acute metabolic episodes. The patient with isovaleric acidaemia had insufficiency of breast milk and formula supplementation ended with breast milk cessation. In the patient with severe ornithine carbamoyltransferase deficiency, breastfeeding was stopped owing to poor metabolic control. The patient with maple syrup urine disease also experienced problems, both in metabolic control and in insufficiency of breast milk, resulting in termination of breastfeeding. Breastfeeding of infants with inborn errors of protein catabolism is feasible, but it needs close monitoring with attention to such clinical parameters as growth, development and biochemistry, including amino acids, organic acids and ammonia.

Liver histology of an afibrinogenemic patient with the Bbeta-L353R mutation showing no evidence of hepatic endoplasmic reticulum storage disease (ERSD); comparative study in COS-1 cells of the intracellular processing of the Bbeta-L353R fibrinogen vs. the ERSD-associated gamma-G284R mutant.

BACKGROUND: Type I fibrinogen deficiencies (hypofibrinogenemia and afibrinogenemia) are rare congenital disorders characterized by low or unmeasurable plasma fibrinogen antigen levels. Their genetic bases are represented by mutations within the three fibrinogen genes. Among the 11 reported missense mutations, a few have been characterized by expression studies and found to have an impaired fibrinogen assembly and/or secretion. Histopathological analyses were previously reported in two hypofibrinogenemic cases with discernible hepatic disease, revealing that both underlying mutations (gamma-Gly284Arg and gamma-Arg375Trp) were associated with hepatic fibrinogen endoplasmic reticulum storage disease (ERSD). OBJECTIVE: The objective of this study was to investigate the liver histology in an afibrinogenemic patient, homozygous for the Bbeta-Leu353Arg mutation, and to study the intracellular processing of the mutant protein. PATIENTS AND METHODS: Liver histology was evaluated by light microscopy, electron microscopy and immunocytochemistry. Intracellular processing of mutant fibrinogen was analyzed by pulse-chase labeling and immunoprecipitation experiments. Messenger RNA levels were determined by real-time reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: The histopathological characterization of the liver showed no signs of fibrinogen accumulation, a difference from the previously reported findings in two hypofibrinogenemic kindreds with ERSD. To evaluate whether the Bbeta-Leu353Arg mutation and the ERSD-associated gamma-Gly284Arg mutation affected intracellular fibrinogen trafficking differently, both mutant proteins were expressed in COS-1 cells. Bbeta-Leu353Arg led to a more severe secretion defect, but no differences that could explain phenotype-genotype correlation were found in the intracellular processing. Endoglycosidase-H analysis demonstrated a secretion block before translocation to the Golgi medial stacks. Real-time RT-PCR studies showed normal levels of the Bbeta mRNA in the patient's liver. CONCLUSIONS: The results confirm that Bbeta-Leu353Arg is associated with impaired fibrinogen secretion, but not with hepatic ERSD.

Visualization of mitochondria with green fluorescent protein in cultured fibroblasts from patients with mitochondrial diseases.

cDNAs for green fluorescent protein (GFP) and for a GFP fusion protein containing the presequence of human ornithine transcarbamylase (pOTC-GFP) were transfected into cultured human fibroblasts. GFP cDNA gave diffuse fluorescence throughout the cytoplasm and the nucleus, whereas pOTC-GFP cDNA gave mitochondria-associated fluorescence. Fluorescent mitochondrial structures could be classified into five patterns: thread-like mitochondria, fine thread-like ones, rod-like ones, granular ones, and granular ones with weak cytosolic fluorescence. pOTC-GFP mutants resulted in a loss of mitochondrial fluorescence and an appearance of weak fluorescence throughout the cytoplasm. pOTC-GFP cDNA was transfected into fibroblasts from patients with various mitochondrial diseases. Higher ratios of fibroblasts with granular mitochondria and those with fine thread-like ones were observed in a patient with Reye's syndrome and a patient with Kearns-Sayre syndrome. Weak cytosolic fluorescence was sometimes observed in fibroblasts from these patients. This method will be useful to analyze mitochondrial structural alterations and disorders of mitochondrial protein import.

Ethylmalonic aciduria: an organic acidemia with CNS involvement and vasculopathy.

Five infants from 3 families, one Egyptian, two Yemeni, are described with a progressive encephalopathy, four of whom have been studied in detail. All patients showed vascular lesions of the skin, characterized by waxing and waning petechiae and ecchymoses. Acrocyanosis was present in three patients. All patients showed retinal lesions characterized by tortuous veins. Protracted diarrhea was not a consistent finding, although they had metabolic crisis in association with diarrhea. They did not show failure to thrive. The neurologic symptoms were indicative of a progressive pyramidal tract disease. Three patients died following sudden emergence of severe basal ganglia, putaminal and head of caudate lesions. In one patient the CT changes in brain were suggestive of infarction. The patients who died manifested pulmonary congestion, or wet lung, and respiratory difficulties during the terminal stage of the disease. In all patients before and during the terminal event, mild-to-moderate hematuria, and in two RBC in CSF, was observed. In one patient there was mild hemoperitoneum at the terminal event. The urine organic acids indicated increased excretion of ethylmalonic, methylsuccinic, glutaric, and adipic acids. The patients invariably showed lactic acidosis, but no ketosis, during and in between the acidotic attacks of the disease. The acylcarnitine profile in blood of two patients showed a pronounced increase in C4 and C5 carnitine esters. In three patients, biopsies from petechiae indicated absence of an immune event, showing only fresh hemorrhage. An immunologic study in one patient was normal for the suppressor:cytotoxic lymphocyte ratio and concentration of interleukin-2 receptor during and in between hemorrhagic attacks. The cytochrome c oxidase activity in fibroblasts was normal. The rate of oxidation of glucose, leucine, isoleucine, valine, propionate and butyrate by fibroblasts was normal. The disease is not responsive to treatment with riboflavin, ascorbic acid, vitamin E, glycine, or carnitine. One patient remained stable on prolonged large doses of methylprednisolone. The biochemical defect leading to ethylmalonic aciduria in this disease remains unknown.

Correction of the metabolic defect in propionic acidemia fibroblasts by microinjection of a full-length cDNA or RNA transcript encoding the propionyl-CoA carboxylase beta subunit.

Propionyl-CoA carboxylase (PCC) is a mitochondrial, biotin-dependent enzyme, composed of an equal number of alpha and beta subunits, that functions in the catabolism of branched-chain amino acids and other metabolites. Mutations of the PCCA (alpha subunit) or PCCB (beta subunit) gene cause the inherited metabolic disease, propionic acidemia. We report the cloning of a full-length cDNA encoding the beta subunit of human PCC. The open reading frame encodes a pre-beta polypeptide of 539 amino acids (58,205 Da). The cDNA was introduced into the expression vector, pRc/CMV, and microinjected into the nucleus or, as ribotranscripts, into the cytoplasm of fibroblast lines from patients with defects of the beta subunit. The restoration of function was monitored by autoradiography of PCC-dependent [14C]-propionate incorporation into cellular protein. These results confirm the completeness of the clone and demonstrate the capacity for beta subunits derived from the microinjected cDNA or RNA to be transported into mitochondria and assembled with endogenously derived alpha subunits to form functional PCC.

Triosephosphate isomerase deficiency. A case report with neuropathological findings.

A 12-year-old girl had chronic nonspherocytic hemolytic anemia due to triosephosphate isomerase deficiency. Developmental and motor delay and muscular weakness were followed by cerebellar dysfunction and finally spasticity with hyperreflexia. Abnormal histopathological findings were hyaline cell bodies and axonal "spheroids" in the hypothalamus and cerebellar cortex, severe neuronal loss in the dentate and olivary nuclei, and partial loss of cerebellar Purkinje's and granular layer cells (olivocerebellar atrophy).

Brindled mottled mouse: morphological changes of brain and visceral organs in hemizygous males following copper supplementation.

Intraperitoneal injections of cupric chloride prevent neuronal degeneration in the hemizygous brindled mottle mouse, MO br/Y, a murine model of kinky hair syndrome (KHS) in humans. At 6-9 months after two i.p. injections, the brain of MO br/Y revealed slightly increased amounts of lipofuscin pigments in the cerebral cortical neurons, cytoplasmic inclusions in the thalamic neurons, and axonal spheroid formation in the tuber cinereum, cerebellum and brain stem. Increased numbers of mitoses, bizarre hyperchromatic giant nuclei, and numerous clear vacuoles were frequently seen in the proximal renal tubular epithelium. Numerous myelin figures were conspicuous features in these epithelial cells at ultrastructural level. Such changes were not found in the littermate controls but in the heterozygous brindled mottled mouse, MO br/ +, identical changes were noted in equal or even higher frequency. These observations suggest that cupric chloride injections effectively modify the expression of the genetic defect in MO br/ Y.

The renal lesion in congenital chloride diarrhea.

Congenital chloride diarrhea is an inherited defect of active intestinal Cl- transport which results in a large wastage of electrolytes and water. The effects of this disease and of replacement therapy on renal histology, function, growth, and the renin-angiotensin-aldosterone system were studied in 18 patients. When the patients were given KCl supplement, histologic findings included juxtaglomerular hyperplasia hyalinized glomeruli, calcifications, and arteriolar changes. Renal function and growth were reduced, and the hormonal activities were high. These abnormalities were evidently due to chronic dehydration. The dehydration could be corrected by increasing the dose of KCl, but only the addition of NaCl corrected the hyperaldosteronism. Adequate replacement therapy prevented the renal involvement.