Maneesh Gupta

Pharmacologic rescue of lethal seizures in mice deficient in succinate semialdehyde dehydrogenase

Succinate semialdehyde dehydrogenase (ALDH5A1, encoding SSADH deficiency is a defect of 4-aminobutyric acid (GABA) degradation that manifests in humans as 4-hydroxybutyric (gamma-hydroxybutyric, GHB) aciduria. It is characterized by a non-specific neurological disorder including psychomotor retardation, language delay, seizures, hypotonia and ataxia. The current therapy, vigabatrin (VGB), is not uniformly successful. Here we report the development of Aldh5a1-deficient mice. At postnatal day 16–22 Aldh5a1−/− mice display ataxia and develop generalized seizures leading to rapid death. We observed increased amounts of GHB and total GABA in urine, brain and liver homogenates and detected significant gliosis in the hippocampus of Aldh5a1−/− mice. We found therapeutic intervention with phenobarbital or phenytoin ineffective, whereas intervention with vigabatrin or the GABAB receptor antagonist CGP 35348 (ref. 2) prevented tonic-clonic convulsions and significantly enhanced survival of the mutant mice. Because neurologic deterioration coincided with weaning, we hypothesized the presence of a protective compound in breast milk. Indeed, treatment of mutant mice with the amino acid taurine rescued Aldh5a1−/− mice. These findings provide insight into pathomechanisms and may have therapeutic relevance for the human SSADH deficiency disease and GHB overdose and toxicity.

Significant behavioral disturbances in succinic semialdehyde dehydrogenase (SSADH) deficiency (Gamma-Hydroxybutyric aciduria)

We report two adult patients with succinic semialdehyde dehydrogenase deficiency, manifesting as gamma-hydroxybutyric aciduria. For both, the clinical presentation included significant behavioral disturbances and psychosis (hallucinations, disabling anxiety, aggressive behavior, and sleep disorder), leading to multiple therapeutic attempts. Intervention with benzodiazepines appeared most efficacious, resulting in decreased aggression and agitation and improvement in anxiety. A review of 56 published and unpublished studies of SSADH-deficient patients revealed that 42% manifested behavioral disturbances, whereas 13% (predominantly adults) displayed psychotic symptomatology. To explore the potential biochemical basis of these behavioral abnormalities, we studied cerebrospinal fluid derived from 13 patients, which revealed significantly elevated GHB (65- to 230-fold), high free and total GABA (up to threefold), and low glutamine. Although within the control range, homovanillic and 5-hydroxyindoleacetic acids (end products of dopamine and serotonin metabolism, respectively) showed a significant linear correlation with increasing GHB concentration, suggesting enhanced dopamine and serotonin turnover. We conclude that elevated GABA combined with low glutamine suggest disruption of the glial-neuronal glutamine/GABA/glutamate shuttle necessary for replenishment of neuronal neurotransmitters, whereas altered dopamine and serotonin metabolism may be causally linked to the hyperkinetic movement disorders and behavioral disturbances seen in SSADH-deficient patients.

Adenoma detection rate increases with each decade of life after 50 years of age

BACKGROUND The adenoma detection rate (ADR) has recently been used as a quality measure for screening colonoscopy. We hypothesize that the ADR will increase with each decade of life after 50 years of age. OBJECTIVE The aim of this study was to define age-based goals for the ADR and advanced neoplasia to improve the quality of colonoscopy. METHODS Using the Clinical Outcomes Research Initiative database, we identified patients who underwent screening colonoscopy between 2005 and 2006. Pathology of polyp findings was reviewed, and the ADR and the prevalence of advanced neoplasia were calculated based on age and sex. RESULTS A total of 7756 polypectomies (44.9%) were performed on 17,275 patients between 2005 and 2006. Of these polyps, 56.3% (4363) were adenomas or more advanced lesions. The ADR was higher in men than women and increased with age. The ADR in men younger than age 50 was 24.7 (95% CI, 18.2-31.2); for those 50 to 59 years of age, it was 27.8 (95% CI, 26.5-29.1); for those 60 to 69 years of age, it was 33.6 (95% CI, 31.7-35.4); for those 70 to 79 years of age, it was 34.3 (95% CI, 31.5-37.1); and for those older than 80 years of age, it was 40.0 (95% CI, 32.9-47.1). The ADR in women younger than 50 years old was 12.6 (95% CI, 6.8-18.4); in those 50 to 59 years of age, it was 17.0 (85% CI, 15.9-18.1); for those 60 to 69 years of age, it was 22.4 (95% CI, 20.8-24.0); for those 70 to 79 years of age, it was 26.1 (95% CI, 23.7-28.5); and for those older than 80 years of age, it was 26.9 (95% CI, 21.4-32.5). LIMITATIONS The Clinical Outcomes Research Initiative database offers access to demographic information as well as endoscopy and pathology data, but there is limited clinical information about patients in the database. CONCLUSION The ADR, and, importantly, the rate of advanced neoplasia increased with each decade of life after the age of 50 and are higher in men than women in each decade of life.

Murine succinate semialdehyde dehydrogenase deficiency

Inherited succinic semialdehyde dehydrogenase (SSADH) deficiency (γ‐hydroxybutyric aciduria) is one of the few neurogenetic disorders of GABA metabolism, and one in which tonic‐clonic seizures associate with increased central nervous system GABA and γ‐hydroxybutyrate (GHB). To explore pathomechanisms and develop new preclinical treatment approaches, we developed a murine knockout model of SSADH deficiency. In the absence of intervention, SSADH−/− mice suffer 100% mortality at week 3 to 4 of life from generalized tonic‐clonic seizures. In this report, we summarize earlier studies indicating disruption of the GABA/glutamine axis in SSADH−/− mouse brain, effective pharmacotherapeutic approaches, preliminary gene‐therapy results, and electrophysiological analyses of mutant mice. We also present new evidence for oxidative stress in SSADH−/− mice, significant alterations of dopamine metabolism, and abnormal neurosteroid levels in brain, potentially implicating the GABAA receptor in pathogenesis. In SSADH deficiency, the accumulation of two neuroactive species, GABA and GHB, is significant because GABA is one of the earliest transmitters expressed in mammals, with key roles in synaptogenesis and myelination, whereas GHB displays a vast array of pharmacological actions. The SSADH−/− mouse may represent a useful model in which to explore the effect of GABA and GHB accumulation on central nervous system development and function. Ann Neurol 2003;54 (suppl 6):S81–S90

Focal neurometabolic alterations in mice deficient for succinate semialdehyde dehydrogenase

Metabolite profiling in succinate semialdehyde dehydrogenase (SSADH; Aldh5a1–/–) deficient mice previously revealed elevated γ‐hydroxybutyrate (GHB) and total GABA in urine and total brain and liver extracts. In this study, we extend our metabolic characterization of these mutant mice by documenting elevated GHB and total GABA in homogenates of mutant kidney, pancreas and heart. We quantified β‐alanine (a GABA homolog and putative neurotransmitter) to address its potential role in pathophysiology. We found normal levels of β‐alanine in urine and total homogenates of mutant brain, heart and pancreas, but elevated concentrations in mutant kidney and liver extracts. Amino acid analysis in mutant total brain homogenates revealed no abnormalities except for significantly decreased glutamine, which was normal in mutant liver and kidney extracts. Regional amino acid analysis (frontal cortex, parietal cortex, hippocampus and cerebellum) in mutant mice confirmed glutamine results. Glutamine synthetase protein and mRNA levels in homogenates of mutant mouse brain were normal. We profiled organic acid patterns in mutant brain homogenates to assess brain oxidative metabolism and found normal concentrations of Krebs cycle intermediates but increased 4,5‐dihydroxyhexanoic acid (a postulated derivative of succinic semialdehyde) levels. We conclude that SSADH‐deficient mice represent a valid metabolic model of human SSADH deficiency, manifesting focal neurometabolic abnormalities which could provide key insights into pathophysiologic mechanisms.

Seizure evolution and amino acid imbalances in murine succinate semialdehyde dehydrogenase (SSADH) deficiency.

Mice with targeted deletion of the GABA catabolic enzyme succinic semialdehyde dehydrogenase (SSADH) manifest lethal tonic-clonic seizures, amenable to pharmacologic rescue, at 3-4 weeks of life. In the current report, we characterized amino acid profiles in SSADH(-/-) brain utilizing whole brain and regional extracts (frontal and parietal cortex, hippocampus, and cerebellum) to develop hypotheses concerning epileptogenesis. Of 35 amino acids quantified, we found significant dysregulation in SSADH(-/-) mice for 11 (GABA, glutamate, glutamine, alanine, aspartate, serine, taurine, cystathionine, methionine, homocarnosine, and arginine) as compared to age-matched littermates both before, and following, the period of generalized convulsive seizures and status epilepticus. Our results reveal imbalanced amino acid levels potentially involved in the transition from absence seizures to generalized convulsive seizures resulting in SSADH(-/-) mice. We conclude that the SSADH(-/-) mouse represents a unique epileptic model with the potential to reveal novel aspects of excitatory/inhibitory interactions in the genesis of seizures.

Do indication and demographics for colonoscopy affect completion? A large national database evaluation.

Background and aim Indication for colonoscopy has not been examined as a predictor of colonoscopy completion. We hypothesized that colonoscopy conducted for colorectal cancer screening might have higher in completion rates than colonoscopy conducted for other indications. Methods The study design was a retrospective cohort. Colonoscopies recorded within the Clinical Outcomes Research Initiative database conducted between 1 January 2002 and 30 June 2003 were analyzed. Indication included: average-risk screening; surveillance; nonspecific abdominal symptoms; bleeding symptoms; or family history of colorectal carcinoma. Demographic factors and indication for colonoscopy were evaluated for the outcome of incomplete colonoscopy using logistic regression analysis. Results 129 549 Colonoscopy procedures were analyzed. Average risk screening seemed to be protective for completion (relative risk: 0.69; 95% confidence interval: 0.63–0.75). Bleeding and nonspecific symptoms had higher risk of incomplete procedure compared to other indications. Males had higher completion rates compared to females (relative risk: 0.62; 95% confidence interval: 0.58–0.66). Community setting had higher completion rates compared to academic or Veterans administration sites. Increasing age was associated with higher rate of incomplete colonoscopy. Conclusion Colonoscopy conducted for screening indication has comparable completion rates when compared with other indications. An overall completion rate of around 95% was noted in this study. This is the largest study to date verifying that completion rates are meeting recommended multisociety guidelines in the USA. Nonspecific abdominal symptoms in Caucasian population, female sex, advanced age, clinical setting, and ethnic groups African–American and Hispanic were found to have increased risk of incomplete procedure.

Outcome Following Surgical Therapy for Gastrointestinal Stromal Tumors

We have pursued an approach of complete resection for patients with gastrointestinal stromal tumors (GISTs), including multivisceral resection, for patients with disease involving adjacent organs. We have also extended the limits of resection to include patients with metastatic disease who were treated with imatinib mesylate. The aim of this study is to report the outcomes and prognostic factors associated with this clinical approach. Study subjects were identified using the pathology database at our institution; for inclusion in the study group, patients must have undergone surgical resection for a KIT-positive gastrointestinal stromal tumor between January 1992 and March 2004. We calculated survival by using the Kaplan-Meier method. Univariate and multivariate analysis was performed using log-rank analysis and the Cox proportional hazards model. Thirty-four patients met the study criteria. Fifty-nine percent of patients had GISTs of gastric origin, 20.6% had duodenal GISTs, and the remainder was comprised of a variety of other sites. Twenty-two (64.7%) patients underwent single-organ resection, and 12 patients (35.3%) underwent multivisceral resection. Estimated actuarial survival at 5 years was 65.2%. Seven patients (five patients with metastases, one patient with locally advanced disease, and one patient with organ-confined disease) received imatinib mesylate. Independent predictors of poor survival included incomplete resection, metastatic disease at presentation, and high mitotic index. Mitotic index and the presence of metastases remain the primary predictors of postoperative survival. Complete surgical resection, even if multivisceral resection is required, is associated with improved survival.

Constipation is not associated with an increased rate of findings on colonoscopy: results from a national endoscopy consortium

BACKGROUND AND STUDY AIMS There are no definite guidelines regarding colonoscopic evaluation for the indication of constipation, a common gastrointestinal complaint. The aim of our study was to determine the risk of finding significant lesions in patients undergoing colonoscopy for the indication of constipation alone compared with constipation with another indication or average-risk screening. PATIENTS AND METHODS A retrospective review of the Clinical Outcomes Research Initiative database was carried out for colonoscopies undertaken between 1 January 2000 and 30 June 2003. A total of 41,775 index colonoscopies performed for the indications of average-risk screening, constipation only or constipation with another indication were identified. Logistic regression analyses were performed for constipation alone versus constipation with another indication, and for constipation alone versus average-risk screening. RESULTS Constipation alone did not show any increased risk of significant findings on colonoscopy. Constipation and the presence of another indication, however, had a statistically significant increased risk of a significant finding on colonoscopy. The indication of constipation alone had a lower risk of significant findings on colonoscopy compared with average-risk screening. Variations in the definition of constipation used was a limitation of the study. CONCLUSIONS Colonoscopy for constipation alone has a lower yield for significant findings compared with average-risk screening and constipation with another indication; hence, colonoscopy should not be done for constipation alone.

Expression profiling reveals multiple myelin alterations in murine succinate semialdehyde dehydrogenase deficiency

SummarySuccinic semialdehyde dehydrogenase (SSADH) deficiency, a rare genetic defect of GABA degradation recently modelled in mice (SSADH−/− mice), manifests early absence seizures that evolve into generalized convulsive seizures and lethal status epilepticus in gene-ablated mice. Disrupted GABA homeostasis, in conjunction with the epileptic phenotype and increased gamma-hydroxybutyric acid (GHB), suggested that expression profiling with the U74Av2 Affymetrix system would reveal dysregulation of receptor genes associated with GABAergic and glutamatergic neurotransmission. Unexpectedly, we found significant downregulation for genes associated with myelin biogenesis and compaction, predominantly in hippocampus and cortex. These results were confirmed by: (1) myelin basic protein (MBP) immunohistochemistry; (2) western blotting of myelin-associated glycoprotein (MAG) and MBP; (3) qRT-PCR analyses of myelin-associated oligodendrocytic basic protein (MOBP), MAG, MBP and proteolipid protein (PLP) in hippocampus, cortex and spinal cord; (4) quantitation of ethanolamine and choline plasmalogens, all core myelin components; (5) evaluation of myelin content in brain sections employing toluidine blue staining; and (6) ultrastructural evaluation of myelin sheath thickness via electron microscopy. We speculate that increased GABA/GHB, acting through GABAergic systems, results in decreased levels of the neurosteroids progesterone and allopregnanolone [Gupta et al (2003) Ann Neurol54(Supplement 6): S81–S90] and phosphorylation of mitogen-activated protein (MAP) kinase, with resulting myelin protein abnormalities primarily in the cortex of SSADH−/− mice.