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Biomedical subjects

M L Batshaw

Publications and source records attributed to M L Batshaw.

At least 19 recordsLinked to original sources
PubMed1994

Inborn errors of urea synthesis.

Inborn errors of urea synthesis can present in the newborn period as a catastrophic illness or later in childhood or adulthood with an indolent course punctuated by hyperammonemic episodes. Because symptoms mimic other neuropsychiatric disorders, it is common for there to be a delay in diagnosis, often with dire consequences. Diagnosis relies on the combination of clinical suspicion and the measurement of ammonium, lactate, and amino acids in plasma and organic acids and orotic acid in urine. Treatment involves nitrogen restriction combined with the stimulation of alternate pathways of waste nitrogen excretion. More recently liver transplantation has been performed as enzyme replacement therapy. The outcome is poor in children who survive prolonged neonatal hyperammonemic coma, with most manifesting developmental disabilities. The etiology of neuronal injury in this disorder is unclear but may involve some combination of ammonia/amino acid accumulation, neurotransmitter alterations, and excitotoxic injury. Gene therapy holds the promise of improved treatment in the future.

Amino Acid Metabolism, Inborn Errors↗
PubMed1993

Quinolinic acid in children with congenital hyperammonemia.

Levels of the excitotoxin quinolinic acid (QUIN) were measured in the cerebrospinal fluid of infants and children with congenital hyperammonemia. Twofold to tenfold elevations of QUIN were found in 4 neonates in hyperammonemic coma (QUIN range, 250-990 nM; control mean, 110 +/- 90 nM; p < 0.005). Similar elevations of neopterin were found (range, 24-75 nM; control mean, 9.0 +/- 4.9 nM; p < 0.005). In addition, significant elevations of QUIN were found in 14 older children with congenital hyperammonemia (mean, 50 +/- 20 vs 17 +/- 6 nM; p < 0.05). Neopterin levels were not elevated in these children. The QUIN may originate from an increase in tryptophan transport across the blood-brain barrier or from induction of indolamine-2,3-dioxygenase activity. These findings support a role for QUIN in the neuropathology of congenital hyperammonemia. They also suggest the potential utility of N-methyl-D-aspartate receptor-blocking agents or inhibitors of QUIN synthesis in the treatment of hyperammonemic coma.

Ammonia↗
PubMed1992

Brain serotonin2 and serotonin1A receptors are altered in the congenitally hyperammonemic sparse fur mouse.

In previous studies we documented an increase in the levels of the serotonin metabolite, 5-hydroxyindoleacetic acid, in the congenitally hyperammonemic sparse fur mouse. To extend these findings, brain serotonin receptors were studied in these animals. Radioligand binding assays were performed using [3H]ketanserin to label serotonin2 sites and 8-[3H]hydroxy(di-n-propylamino)tetralin to label serotonin1A sites in cortical membrane homogenates. The capacity (Bmax) for [3H]ketanserin binding was significantly lower (-21%; p less than 0.05) in sparse fur animals than in control animals; there was no change in affinity (KD). In contrast, the capacity for 8-[3H]hydroxy(di-n-propylamino)tetralin binding was significantly greater (26%; p less than 0.05) in sparse fur compared with control animals. No difference in affinity was observed. Using two behavioral assays, the functional responsiveness of these serotonin receptors was compared in sparse fur and control animals. Head twitch activity elicited by administration of the serotonin agonist quipazine was studied as a behavior mediated by serotonin2 receptors. Compared with controls, sparse fur mice demonstrated a significantly decreased head twitch response (p less than 0.005). Hypothermia elicited by administration of 8-hydroxy(di-n-propylamino)tetralin was studied as a physiologic response mediated by serotonin1A receptors. Although there were not overall group differences in the dose-response data, there was a significant increase in the hypothermia induced by 8-hydroxy(di-n-propylamino)tetralin in sparse fur compared with control mice (p less than 0.02) at the highest dose. These data provide further support for a link between hyperammonemia and alterations in the serotonin system.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1992

Quinolinate in brain and cerebrospinal fluid in rat models of congenital hyperammonemia.

Children with inborn errors of urea synthesis who survive neonatal hyperammonemic coma commonly exhibit cognitive deficits and neurologic abnormalities. Yet, there is evidence that ammonia is not the only neurotoxin. Hyperammonemia appears to induce a number of neurochemical alterations. In rodent models of hyperammonemia, uptake of L-tryptophan into brain is increased. It has been reported that in an experimental rat model of hepatic encephalopathy, in the ammonium acetate-injected rat, and in patients with hepatic failure and inborn errors of ammonia metabolism, quinolinate, a tryptophan metabolite, is increased. Elevations in quinolinate are of particular concern, as quinolinate could excessively activate the N-methyl-D-aspartate subclass of excitatory amino acid receptors, thereby causing selective neuronal necrosis. We sought to identify an animal model that would replicate the increases in quinolinate that have been associated with hyperammonemia in humans. Levels of quinolinate were measured in hyperammonemic urease-infused rats and ammonium acetate-injected rats. In the urease-infused rat, brain tryptophan was doubled, and serotonin and its metabolite 5-hydroxyindoleacetic acid were significantly increased. Yet, despite the increase in tryptophan and evidence for increased metabolism of tryptophan to serotonin, there were no observed increases of quinolinate in brain, cerebrospinal fluid, or plasma. In the ammonium acetate-injected rat, significant increases of 5-hydroxyindoleacetic acid in cerebral cortex were also observed, but quinolinate did not change in cerebrospinal fluid or cerebral cortex. In summary, we were unable to demonstrate an increase of quinolinate in brain or cerebrospinal fluid in these rat models of hyperammonemia.

Acetates↗
PubMed1990

Behavioral deficits in rats with minimal cortical hypoplasia induced by methylazoxymethanol acetate.

Methylazoxymethanol, a short-acting antimitotic agent, produces marked cortical hypoplasia in fetuses when injected into pregnant rats. These offspring also have increased cortical concentrations of biogenic amines associated with hyperactivity and learning deficits. In this experiment, rats with a relatively mild degree of methylazoxymethanol-induced cortical hypoplasia were studied to determine whether these neurochemical and behavioral abnormalities persisted. Sprague-Dawley pregnant rats were injected intraperitoneally on day 15 of gestation with methylazoxymethanol acetate (25 mg/kg). Total brain weight was reduced by 12% and cortical slab weight by 28% in methylazoxymethanol-exposed offspring. They were more active than control rats and showed a trend toward slower learning in a swim maze. Affected offspring had increased cortical concentrations of norepinephrine, 5-hydroxyindoleacetic acid, and glycine. There was no significant difference in the concentrations of serotonin gamma-aminobutyric acid, aspartic acid, glutamic acid, or glutamine. Methylazoxymethanol-lesioned animals with mild cortical hypoplasia remained measurably hyperactive and may serve as a model for the study of neurotransmitter and neuropathologic abnormalities associated with hyperactivity in children with microcephaly.

Animals↗
PubMed1989

Prenatal diagnosis and heterozygote detection by DNA analysis in ornithine transcarbamylase deficiency.

This report summarizes our experience with DNA analysis using a complementary DNA probe for ornithine transcarbamylase in 24 individuals or families with deficiency of this enzyme. In four cases, including three reported elsewhere, a Taql restriction site alteration directly detected the mutation. In 10 additional cases, only an affected male was available, and results of DNA analysis using the Taql enzyme were normal. In 10 cases, family studies were performed with the use of restriction fragment length polymorphisms. Prenatal diagnostic studies were performed for three informative pregnancies, and two affected male fetuses were identified. Analysis of two restriction fragment length polymorphisms, Mspla and BamHl, was informative in 14 of 19 (74%) known carrier females and in 21 of 35 (60%) females (the total number studied). One female previously predicted to be a noncarrier by protein-loading test was determined to be a carrier by analysis of restriction fragment length polymorphisms. The frequency of Taql site alterations was 4 of 24 families (17%). These data illustrate the importance of DNA analysis, pedigree analysis, and biochemical testing in families with ornithine transcarbamylase deficiency to detect carriers and establish the diagnosis prenatally.

Blotting, Southern↗
PubMed1988

Transient postnatal elevation of serotonin levels in mouse neocortex.

Serotonin (5-HT), norepinephrine (NE) and 5-hydroxyindoleacetic acid (HIAA) levels were measured during ontogeny of frontoparietal cortex in Balb/C mice by high-pressure liquid chromatography (HPLC) with electrochemical detection. Unlike NE, the concentration of 5-HT was transiently elevated to more than twice the adult level during the first postnatal week; this was accompanied by increased HIAA content comparable to the adult, indicating elevated levels of 5-HT release. Since a transient hyperplasia of 5-HT-immunoreactive fibers and uptake sites has been observed previously in the same cortical areas, the transient elevation of 5-HT levels may play an important role in shaping early postnatal morphogenetic events in neocortex.

Aging↗
PubMed1988

Academic promotion at a medical school. Experience at Johns Hopkins University School of Medicine.

We studied promotions at Johns Hopkins University School of Medicine to determine whether clinician-teachers are less likely to be promoted or are promoted later in life than researchers and whether those who are promoted have more articles published than those who are not promoted. Over a five-year period, 93 percent of candidates for the rank of associate professor and 79 percent of the candidates for the rank of professor were promoted. There were no significant differences between clinical and research faculty members in terms of the probability that they would be promoted or their age at promotion to either associate professor or professor. Despite these findings, the responses to a questionnaire indicated that former faculty members perceived clinician-teachers as less likely than researchers to be promoted. Those who were promoted had had about twice as many articles published in peer-reviewed journals as those who were not promoted. We recommend improved counseling of medical school faculty members and more extensive discussion of the criteria for promotion and the chances of academic success.

Age Factors↗
PubMed1988

Therapeutic approaches to cobalamin-C methylmalonic acidemia and homocystinuria.

The use of hydroxocobalamin (OH-B12), betaine, carnitine, and folinic acid were studied in two children with the cobalamin C form of methylmalonic acidemia and homocystinuria. When daily injections of 1 mg OH-B12 were discontinued for 3 weeks, there was no significant change in total plasma homocysteine or methionine levels and only a modest increase in methylmalonate. Orally administered OH-B12 1 mg/d in one patient was associated with an increase in plasma homocystine and a decrease in methionine within 1 month. Withdrawal of betaine 250 mg/kg/d was also associated with a rise in plasma homocystine and a fall in methionine levels. Carnitine 100 mg/kg/d lead to an increase in urinary excretion of propionylcarnitine, but did not affect plasma methylmalonate levels. No beneficial biochemical effect of folinic acid could be documented at a dose of 25 mg/d. Our results suggest that daily injections of OH-B12 are not necessary to maintain metabolic control and that orally administered OH-B12 is unlikely to be effective. Betaine appears to act synergistically with OH-B12 and should be part of the treatment regimen. Although there are theoretical reasons for using L-carnitine and folinic acid, we could not document their effectiveness in these two patients.

Administration, Oral↗
PubMed1988

Effect of sodium benzoate and sodium phenylacetate on brain serotonin turnover in the ornithine transcarbamylase-deficient sparse-fur mouse.

Herein we examine the effects of sodium benzoate and sodium phenylacetate on feeding and central serotonin turnover in a child with citrullinemia and in an animal model of congenital hyperammonemia, the ornithine transcarbamylase-deficient sparse-fur (spf/y) mouse. In the child, when the benzoate/phenylacetate dosage was increased from 200 to 375 mg/kg/day each, feeding decreased. There was an accumulation of benzoate and phenylacetate in blood and cerebrospinal fluid as well as an increased concentration of 5-hydroxyindoleacetic acid, a neurochemical marker for serotonin turnover, in cerebrospinal fluid. In the mouse, sodium benzoate had a biphasic effect on both plasma ammonium levels and brain serotonin turnover. Two percent oral benzoate was associated with an increase in ammonium level, while a 3% dose led to a decrease in ammonium. There was a similar effect on serotonin turnover noted in both the hyperammonemic spf/y and control CD-1/y mice. Sodium phenylacetate did not have a consistent effect on serotonin turnover. The mechanism by which benzoate increases brain serotonin turnover appears to involve competition with tryptophan for albumin binding sites. This results in increased free tryptophan in serum and brain. We speculate that some of the clinical symptoms of benzoate intoxication may be a consequence of altered serotonin turnover in the brain. We suggest that drug levels be monitored during therapy.

Administration, Oral↗
PubMed1987

Treatment of urea cycle disorders.

Recent advances in the treatment of inborn errors of urea synthesis have significantly decreased mortality. Treatment has included combining a high-quality low-protein diet with supplements of deficient metabolites and stimulation of alternate pathways of waste nitrogen excretion. Long-term alternate pathway therapy, using sodium benzoate and sodium phenylacetate, has generally been unassociated with signs of toxicity. However, acute intoxications have simulated hyperammonemic crises. Neurologic outcome appears to be primarily a function of duration of neonatal hyperammonemic coma, although ongoing accumulation of urea cycle intermediates may also play a role. Early recognition and treatment are critical if a good outcome is to be possible.

Amino Acid Metabolism, Inborn Errors↗
PubMed1987

Congenital deficiency of two polypeptide subunits of the iron-protein fragment of mitochondrial complex I.

Recently, we described a patient with severe lactic acidosis due to congenital complex I (NADH-ubiquinone oxidoreductase) deficiency. We now report further enzymatic and immunological characterizations. Both NADH and ferricyanide titrations of complex I activity (measured as NADH-ferricyanide reductase) were distinctly altered in the mitochondria from the patient's tissues. In addition, antisera against complex I immunoprecipitated NADH-ferricyanide reductase from the control but not the patient's mitochondria. However, immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of complex I polypeptides demonstrated that the majority of the 25 polypeptides comprising complex I were present in the affected mitochondria. A more detailed analysis using subunit selective antisera against the main polypeptides of the iron-protein fragments of complex I revealed a selective absence of the 75- and 13-kD polypeptides. These findings suggest that the underlying basis for this patient's disease was a congenital deficiency of at least two polypeptides comprising the iron-protein fragment of complex I, which resulted in the inability to correctly assemble a functional enzyme complex.

Humans↗
PubMed1986

Positron emission tomographic study of D2 dopamine receptor binding and CSF biogenic amine metabolites in Rett syndrome.

We report on the first positron emission tomographic study of dopamine receptor binding in Rett syndrome. The patient is a 25 year old Austrian woman diagnosed at age 2 and followed since then by Rett. A computed axial tomogram (CT scan) showed cortical atrophy, and enlarged ventricles but normal structure of the caudate/putamen. Following the CT scan 20 mCi of 11 C N-methyl spiperone, a butyrophenone with a high affinity for dopamine D2 receptors was administered intravenously. The patient was found to have dopamine D2 receptor binding activity in the low normal range. The caudate/cerebellar activity ratio was below the mean regression line (p = 0.10) that relates the CA/CB ratio as a function of age. Levels of cerebrospinal fluid neurotransmitter metabolites were normal.

Adult↗