Pharmacokinetics of peptide T in patients with Acquired Immunodeficiency Syndrome (AIDS)

1. The pharmacokinetics of Dalal-peptide T-NH2 (peptide T) was determined during phase I clinical trials in patients with acquired immunodeficiecy disease (AIDS) and AIDS related complex (ARC). Drug levels were determined by specific RIA, and in some cases with HPLC analysis, after intraveneous (i.v.) or intranasal (i.n.), via metered sprayer, administration.

2. The plasma kinetics appeared to be bi-phasic with a first compartment half-life of 30 to 60 minutes and a second plasma clearence rate of 4 to 6 hours, observed for both routes of administration. Peptide T, in one individual was confirmed to be present at 6 hrs in plasma, determined after HPLC isolation followed by specific RIA.

3. Bioavailabilty, determined for a 2 mg test dose in six individuals was 9.3 ± 6.9 nmol/L. Peak plasma levels of 41 ± 30 nmol/L after 10 mg i.n., 2.8 ± 5.9 nmol/L after 2mg i.n., and 0.13 ± 0.07 nmol/L after 0.4 mg i.n. were observed. In two individuals tested, peptide T was detected in CSF at levels 20% of the corresponding plasma level 90 and 145 minutes post i.v. administration. Peptide T was not detected in urine. I.N. administration was well tolerated for times up to 21 months.     

Potent gp120-like neurotoxic activity in the cerebrospinal fluid of HIV-infected individuals is blocked by peptide T.

The envelope protein of the human immunodeficiency virus (gp120) causes neuronal death in developing murine hippocampal cultures or rat retinal ganglion cells. In HIV-infected individuals, gp120 released from HIV-infected macrophages or other cells in the brain has been proposed as the etiology for the pathophysiology of AIDS central nervous system (CNS) disease by diffusing to act at a distance to cause damage and/or death to neighboring neurons. In this study, 28 cerebrospinal fluid (CSF) samples from HIV-infected individuals (79% were WR stage 1 and 2) and neurological disease controls were tested, blind to the investigator, for the presence of in vitro neuronal killing activity. Neurotoxic activity was detected with peak effects at a 1:10(5) dilution in CSF from 9/18 HIV-infected individuals and 1/10 neurological disease controls. Thus half of CSF from early stages of HIV disease are characterized by the presence of neurotoxic activity which is not present in control CSF (Fischers exact test, P < 0.05). The neuronal toxicity by patient CSF could be prevented by peptide T (1 nM). A monoclonal antibody to mouse CD4, RL.172, also attenuated or prevented CSF-induced neuronal killing in all four CSF samples tested. In addition, an antiserum to peptide T previously shown to bind gp120 and neutralize both infectively and direct gp120 neurotoxicity, neutralized the CSF factor. gp120, or a modified small fragment, is suggested to be the responsible toxic molecular entity. These results may be relevant to the pathophysiology of HIV-related CNS disease and the mechanism by which peptide T causes improvements.     

Perspectives on the Mechanism of Action of Electroconvulsive Therapy: Anticonvulsant, Peptidergic, c-fos Proto-oncogene Effects

Although the mechanism of action of electroconvulsive therapy (ECT) in affective illness has remained elusive, it is hoped that the consideration of mechanisms underlying the anticonvulsant efficacy of ECT will provide new insights into its biochemical and neuroanatomical substrates. In the amygdala-kindling model, electroconvulsive seizures (ECS) inhibit both the development and completed phases of kindled seizure evolution, and therefore, ECS is a more potent anticonvulsant modality than carbamazepine, which inhibits only completed kindled seizures. Carbamazepine is increasingly recognized for its acute and prophylactic efficacy in bipolar affective illness. Thus, comparing and contrasting effects of ECS and carbamazepine may provide insights into overlapping mechanisms of anticonvulsant and psychotropic action. Anticonvulsant effects of ECS have been most closely linked to endogenous opiate substances, perhaps acting on delta-opiate receptors, but a wide variety of other neurotransmitter and peptidergic effects are also potential candidates. Electroconvulsive seizures in mice activate the proto-oncogene c-fos in many discrete areas of brain, including a variety of limbic sites, the ventromedial nucleus of the hypothalamus, and the cerebellum. As such, c-fos induction may provide both an anatomical map of areas potentially activated by ECS and a potential mechanism for initiating a sequence of events that may be important to the mechanism of action of ECT. Although the anticonvulsant effects of ECT may ultimately prove to be separable from those mediating its therapeutic effects in affective illness, seizures and anticonvulsant effects provide easily measurable endpoints for preclinical and clinical studies. Given this clarity of effect, potential anticonvulsant mechanisms can rapidly be identified, enabling direct testing of whether or not these same mechanisms are also critical to the therapeutic effects of ECT in affective illness.     

Comparison of ultrasonographic findings in spontaneous abortions with normal and abnormal karyotypes

To determine whether ultrasonographic findings can predict the karyotype of spontaneous abortions, 137 pregnancies (54 spontaneous, 83 assisted ovulatory cycles) that subsequently aborted and had chromosome analysis performed on the products of conception were studied ultrasonographically. Transvaginal ultrasound was performed using an Acuson 128XP/10 with 7.5 MHz probe. The numbers of empty gestational sacs, small and normal for gestational size, embryonic poles and embryos with documented cardiac activity were calculated. The frequency of each of these findings in pregnancies with normal and abnormal karyotypes was compared. Of the 137 spontaneous abortions, 51 had normal chromosome analyses and 86 had abnormal karyotypes (68 aneuploidies and 18 polyploidies). Ultrasonographic findings in the 51 karyotypically normal pregnancies included 16 (31%) with empty gestational sacs, and 35 (69%) with embryonic poles, of which 24 (69%) were at least 1 week smaller than expected for gestational age and 11 (31%) were the expected size. Embryonic cardiac activity was documented in 22 (63%) of the 35 embryonic poles. Amongst 86 pregnancies with abnormal karyotypes, similar frequencies of ultrasound findings were found: 23 (27%) with empty gestational sacs, 42 (67%) with embryonic poles smaller than expected for gestational age, and 50 (79%) embryos lost after documentation of embryonic cardiac activity. No differences in the frequency of ultrasonographic findings of empty gestational sacs, small embryonic pole and embryonic cardiac activity were observed between karyotypically normal and abnormal spontaneous abortions. Ultrasonographic findings cannot predict the karyotype of spontaneous abortions.      

Gonadotrophin-releasing hormone agonist dose-dependency of pituitary desensitization during controlled ovarian hyperstimulation in IVF

The aim of this study was to find the minimal effective daily s.c. dose of the gonadotrophin-releasing hormone (GnRH) agonist, triptorelin acetate, that suppresses the GnRH-induced release of luteinizing hormone (LH) at time of human chorionic gonadotrophin (HCG) injection and thereby prevents spontaneous LH surges during in-vitro fertilization (IVF) stimulation cycles. Therefore, a double-blind, prospective and randomized titration study was performed. A total of 48 IVF patients were divided into four groups of 12 patients. Each group received a different dose of triptorelin acetate, namely 5, 15, 50 or 100 microg s.c. daily. Standard ovarian stimulation was carried out using urinary follicle stimulating hormone (FSH) preparations. A 500 microg GnRH test was performed 90 min before the HCG injection in order to measure the degree of pituitary desensitization. Spontaneous LH surges were not detected in any of the groups, although three patients in the 5 microg group had ovulated at the time of ovum retrieval. The pituitary LH response to the GnRH test at time of HCG, expressed as area under the curve (AUC), appeared to be dose-dependent. Thus, a daily s.c. dose of 100 microg triptorelin acetate appears to be too high, since adequate desensitization of the pituitary (i.e. no spontaneous LH surge) can be achieved with doses as low as 15 and 50 microg.      

Detection of hepatitis B antibody by a single-antibody radioimmunoassay.

A radioimmunoassay (RIA) for the measurement of antibody to hepatitis B surface antigen (anti-HB-s) in human and non-human sera is described. The principle is based upon our earlier observation that anti-HB-s and hepatitis B surface antigen (HB-s-Ag) are soluble in 4.5% w/v polyethylene glycol 4000 but that anti-HB-s-HB-s-Ag complex is precipitated. The use of activated charcoal suspended in polyethylene glycol and dextran solution facilitated the separation of this complex by centrifugation, thus improving reproducibility and sensitivity. The test is approx. 3-5000 times as sensitive as counterelectrophoresis. In a survey of a normal blood donor population, with an incidence of approx. 0.1% positive for HB-s-Ag by RIA, 7-8% were found to have anti-HB-s by this method.