Catherine E. Costello

Glutaric acidemia A metabolic disorder causing progressive choreoathetosis

A boy with glutaric acidemia had psychomotor retardation first noted at age 6 months, recurrent metabolic acidosis, and a progressive quadriparesis with choreoathetosis. He died at age 31/2 years. Cultured skin fibroblasts lacked glutaryl-CoA dehydrogenase activity. There was a biochemical, but not a clinical, response to dietary restriction of lysine and tryptophan. The caudate and putamen of the brain showed severe loss of nerve cells and fibers with proliferation of astrocytes, as well as markedly reduced γ-aminobutyric acid and glutamate decarboxylase activity.

Reliability of the toxic screen in drug overdose

To determine the reliability of the laboratory in detecting drugs taken by overdosed patients, we evaluated laboratory performance on an unbiased sample of actual clinical specimens. Replicate serum and urine samples from a series of 20 consecutive clinically overdosed patients were sent to three commercial laboratories and one academic research laboratory for identification and quantification of intoxicating agents. All laboratories used the advanced analytical techniques of gas chromatography–mass spectrometry. The results suggest that laboratories do not reliably identify drugs in the serum of overdosed patients, partly because of technical limitation, partly because of laboratory error, and possibly because of inadequate specimens. Drugs judged responsible for the overdose were identified in only 50% to 70% of the cases, depending on the laboratory. Reported concentrations sometimes varied over a 10‐fold range.

Kinetic equivalence of stable-isotope-labeled and unlabeled phenytoin

Stable isotope labeling (SIL) of a drug results in a higher molecular weight than that of the unlabeled drug. SIL tracer doses can be quantitated separately from unlabeled drug by gas chromatography–mass spectrometry (GC‐MS) without exposing the patient to radiation. The higher molecular weight of SIL drug could cause a higher energy of activation for (and slowing of) metabolic reactions (“isotope effect”). To evaluate possible isotope effect, three dogs and three men were infused with a mixture containing equal amounts of SIL (2‐13C‐1,3‐15N2) and unlabeled phenytoin (PHT). Plasma and urine were collected at regular intervals. Concentrations of SIL and unlabeled PHT and HPPH (the major metabolite of PHT) were determined by GC‐MS. Within each subject there was no trend for concentrations of SIL PHT or HPPH to be higher or lower than concentrations of their unlabeled analogs (p > 0.20 to 0.90). There was no difference in the distribution and elimination half‐lifes (t½s), volume of distribution, volume of central compartment, or clearance of the two forms of PHT. Thus, no isotope effect was found.

Identification of the Reye's Syndrome “serum factor”

Summary Reyes Syndrome serum stimulates O2 utilization in preparations of isolated rat liver mitochondria and causes mitochondria to swell. The substance responsible for the respiratory activity has been purified by ion exchange chromatography and isolated in one of three ways: crystallization, high voltage electrophoresis, or high pressure liquid chromatography. All three methods yielded active material with identical UV spectra. Further analysis by GC-mass spectrometry and infrared spectroscopy revealed the active substance to be uric acid. Uric acid probably does not cause mitochondrial injury, but it may deserve attention as a possible prognostic marker in Reyes Syndrome.

Phencyclidine (Sernylan) poisoning

Case 1. A 3-year-old white boy presented to the emergency ward approximately two hours after ingesting three tablets described by his parents as tranquilizers. The patient became quite lethargic 1 89 hours after ingestion and then rapidly progressed to an unresponsive state. On admission he was comatose with persistent opisthotonic posturing. Respirations were slow and shallow with intermittent gasps. Pupils were miotic in midposition with alternating vertical and horizontal nystagmus. Deep tendon reflexes were depressed. Shortly after admission the patient had a respiratory arrest but responded to assisted ventilation, Elective intubation was performed, the stomach was lavaged, and supportive therapy instituted. Four hours after ingestion respirations became regular. At eight hours, the opisthotonic posturing

Occurrence of novel branched-chain fatty acids in refsum's disease

Two novel branched-chain fatty acids, which appear to be unsaturated analogs of phytanic acid, have been observed in sera and urine of patients with Refsums disease. They occur in both phospholipids and neutral lipids, and have been isolated and characterized.

Synthesis, mass spectral characterization and immunoadjuvant activity of some novel lipophilic derivatives of muramyl dipeptides

Some novel lipophilic derivatives of N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) have been prepared and rigorously evaluated by spectroscopic means. Fast atom bombardment and field desorption mass spectrometry provided information about both molecular weight and structural detail. The new MDP derivatives have been tested in guinea pigs for immunoadjuvant activity using egg albumin as the model antigen. Amongst these derivatives, 6-O-[3-(5-cholesten-3 beta-yloxycarbonyl) propionyl]-N-acetylmuramyl-L-alanyl-D-isoglutamine (CSMDP), 6-O-[3-1,2-dipalmitoyl-sn-glycero-3-carbonyl) propionyl]-N-acetylmuramyl-L-alanyl-D-isoglutamine (GSMDP) and N-palmitoyl muramyl-L-alanyl-D-isoglutamine (PMDP) possessed significantly better activity than MDP, as judged by the antigen-specific antibody and delayed hypersensitivity responses in the immunized animals. In addition, CSMDP was found to induce strong delayed hypersensitivity response even in saline. These three active compounds were also tested for their pyrogenic response in rabbits, and were found to be lesser pyrogenic than MDP. Some of these MDP derivatives hold promise as adjuvants in immunization.

Rearrangement of 3-ketoceramide

Abstract N-Acetyl 3-ketosphingosine was converted under mild alkaline conditions to an unknown nonpolar compound with a good yield. From its mass, infrared, and NMR spectra, the structure of the unknown compound was deduced to be 2-tridecyl-5-(N-acetylamino)-tetrahydro-γ-pyrone. This rearrangement occurred by an intramolecular Michael-type addition reaction.

The Use of FAB for the Solution of Difficult Mass Spectral Problems

FARMS promises to be a highly useful addition to the repertoire of mass spectral ionization methods available for structural studies. We describe here the experimental procedures being used in our studies and a few typical examples of the application of FARMS to current research problems.

PHENCYCLIDINE. NINE CASES OF POISONING

In nine cases of phencyclidine hydrochloride poisoning, early signs of overdose included drowsiness, nystagmus, miotic pupils, blood pressure elevation, increased deep tendon reflexes, ataxia, anxiety, and agitation. In more severe cases, seizures, spasticity, and opisthotonos were seen in addition to deep coma and respiratory depression. Treatment included removal by emetics or lavage, hydration, and a quiet, reassuring environment. Spasticity, agitation, and ocular manifestions responded to diazepam. Psychiatric intervention was instituted after the patients were stable and no longer agitated.