Martin H. Schaffer

Structures of two cockroach neuropeptides assigned by fast atom bombardment mass spectrometry

Amino acid sequences have been assigned to two cockroach neuropeptides (greater than Glu-Val-Asn-Phe-Ser-Pro-Asn-Trp-NH2, M I, and greater than Glu-Leu-Thr-Phe-Thr-Pro-Asn-Trp-NH2, M II) by application of fast atom bombardment mass spectrometry, including high resolution and linked scan (metastable) studies. The peptides show considerable homology with two other invertebrate neuropeptides, adipokinetic hormone (AKH, from a locust) and red pigment concentrating hormone (RPCH, from a prawn), whose fast atom bombardment spectra were also studied. M I and M II are thus members of a family of structurally-related invertebrate neuropeptides.

Sequence analyses of adipokinetic hormones II from corpora cardiaca of Schistocerca nitans, Schistocerca gregaria, and Locusta migratoria by fast atom bombardment mass spectrometry

Structures of the second adipokinetic hormones (AKH IIs) from three locust species have been assigned by fast atom bombardment mass spectrometry. The AKH II hormone is identical in two Schistocerca species, S. nitans and S. gregaria, but is different in Locusta migratoria. Both AKH IIs are related to red pigment-concentrating hormone (RPCH) from prawns, Schistocerca AKH II being [Thr6]-RPCH and Locusta AKH II being [Ala6]-RPCH. Schistocerca AKH II is also bioactive in Locusta individuals.

Treatment of schizophrenia with ergot derivatives

Seven neuroleptic-free schizophrenic patients received bromocriptine and eight schizophrenic patients received CF 25-397, both ergot derivatives with dopamine agonist activity. Psychosis failed to improve in response to either drug at the relatively low doses administered. Unlike the antipsychotic property of apomorphine at low dose levels, neither of these ergot drugs improved schizophrenic symptomatology.

Rat gastrin's amino acid sequence determined from the nucleotide sequence of the mRNA ☆

Abstract Gastrin cDNA was synthesized using a synthetic oligodeoxynucleotide to specifically prime rat mRNA preparations for reverse transcription. Hybridization analysis using this cDNA indicated that rat gastrin mRNA is the same size as that which codes for hog gastrin. The amino acid sequence for rat gastrin 34 was determined from a partial nucleotide sequence analysis of the cDNA and indicates that in rat, as in other species, gastrin is synthesized as a larger precursor which is processed following two consecutive basic amino acids to yield molecules of 34 and 17 amino acids (gastrin-34 and gastrin-17).

DOPAMINE AGONIST TREATMENT OF SCHIZOPHRENIA

Apomorphine was administered to chronic schizophrenic patients with prominent psychotic symptoms despite ongoing neuroleptic treatment. Significant improvement in schizophrenic symptoms occurred. Ergot dopamine agonists failed to produce significant change in psychosis in a similar patient population. A decrease in dopamine-mediated neural transmission and subsequent symptom remission may result from dopamine autoreceptor stimulation by low dose apomorphine, whereas ergot derivatives fail to stimulate this presynaptic receptor.

Fast Atom Bombardment Mass Spectrometry of Biomolecules

Since its introduction in early 1981 [1], fast atom bombardment mass spectrometry (FABMS, liquid SIMS) has become a routine tool in many mass spectrometry laboratories [2]. In our Urbana laboratory, which serves scientists at other institutions as well as those on our campus, four double-focusing spectrometers (ZAB-SE, 7070E, 731, 311A) have FAB ion sources, and about as many FAB spectra as electron ionization spectra are run. The technique is still developing, however, and it is appropriate to describe here some recent advances as well as associated problems.