Guidewire Facilitation of Internal Mammary Artery Cannulation

With the advent of widespread use of the internal mammary artery for coronary revascularization, high quality delineation of this conduit during angiography is necessary. We describe herein a safe, easy method to selectively cannulate the internal mammary artery based on a steerable angioplasty guidewire technique.     

Neurosecretory Dysfunction of Growth Hormone Secretion in Thalassemia Major

ABSTRACT. The growth retardation of children with thalassemia major is multifactorial. Along the endocrine axis of growth hormone (GH), serum somatomedin has been shown to be deficient and GH response to GH-relasing hormone impaired, while GH response to provocative stimuli is normal. We studied the spontaneous secretion of GH in seven patients with thalassemia major and growth retardation. Three of the patients were hypothyroid, and the other four were euthyroid. Spontaneous secretion of GH in all seven patients was subnormal: the number of pulses, the mean pulse amplitude, and the integrated concentration of GH were all lower than in 14 age- and sex-matched (10 pubertal and 4 prepubertal) control subjects. GH response to provocative stimuli was normal in the euthyroid patients. This pattern of response corresponds with the definition of neurosecretory dysfunction of GH secretion. It is concluded that the growth retardation of patients with thalassemia major is partly due to neurosecretory dysfunction of GH secretion.     

Effect of exposure time on the depth of polymerization of a visible light-cured composite resin

The effect of exposure time of a visible light source on the depth of polymerization and degree of hardness of a sample of Occlusin posterior composite resin was investigated. The border between cured and non-cured composite resin was identified by a change in colour and by applying pressure with a scalpel. Knoop hardness tests were performed perpendicular to the long axis of illumination. The composite resin nearer to the light source underwent more complete polymerization. Increased exposure time resulted in greater depth of cure. The rate of polymerization was greatest in the first 10 s. Maximum hardness measured up to a depth of 1 mm obtained after 80 s of exposure time. At greater depth, a decrease in Knoop hardness was observed. At exposures under 80 s, maximum hardness was not achieved even at a depth of only 1 mm.     

Design,synthesis, and testing of potential antisickling agents. 9. Cyclic tetrapeptide homologs as mimics of the mutation site of hemoglobin S

As part of our continuing search for new agents which might be useful for the treatment of sickle-cell anemia, we have synthesized two cyclic tetrapeptide homologs, cyclo(-Val-Glu[-Thr-Pro-]-OH) (1a) and cyclo(-Phe-Glu[-Thr-Pro-]-OH (1b), and a tetrapeptide lactone homolog cyclo(H-T-hr-Pro-Val-Glu-OH) (2). The intent was that these peptides would mimic a tetrapeptide region around the mutation site of HbS and thus be able to bind at the acceptor site of HbS and thereby inhibit polymerization. The synthesis of the linear peptides was accomplished in solution using both the polymeric reagent (PHBT) and DCC/HOBT methods; cyclization was accomplished by an improved method. ¹³C-n.m.r. studies were performed which allowed us to assign the conformation about the Thr-Pro bond in 1a and 2 as trans. The cyclic peptides were tested for their ability to increase the solubility of HbS under deoxygenating conditions, but only 1a had any antigelling activity, albeit low.     

The Relationship between Benzo(a)pyrene diol-Epoxide-DNA Adducts and Mutagenicity in the CHO/HPGRT Assay

The Relationship Between Benzo(a)pyrene diol-Epoxide–DNAAdducts and Mutagenicity in the CHO/HGPRT Assay. Recio, L.,SHUGART, L. R., and HSIE, A. W. (1987). Fundam. Appl. Toxicol.8, 243–252. We have studied the relationship between DNAadducts in Chinese hamster ovary (CHO) cells and mutagenicityas determined in the CHO/hypoxanthine–guanine phosphoribosyltransferaseassay. The cells were treated with benzo(a)pyrene 7,8-diol (BP-diol)in the presence of a bioactivation system, S9 mix. DNA bindingby bioactivation of BP-diol with S9 mix occurred with both stereoisomersof benzo(a)pyrene diol-epoxide (BPDE) in approximately equalamounts. The number of BPDE-DNA adducts (21–260 adducts/10⁶nucleotide base pairs) increased with increasing treatment concentrationsof BP-diol (1.4–x7.0 µm). A linear relationshipwas observed between the number of BPDE-DNA adducts and mutagenicity(89–605 mutants/10⁶ cloneable cells) over the concentrationrange of BP-diol assayed.     

The epitope specificity of heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is caused by antibodies (HIT-Abs) that bind to a complex of heparin and platelet factor 4. We investigated the epitope specificity of the HIT-Abs, and found that the HIT-Abs recognized solid-phase immobilized complexes with an optimum ratio of four to eight molecules of PF4 per molecule of heparin. To try to define the epitopes within the PF4 molecule, intact and reduced (linearized) PF4 was tested against 29 different sera from patients with HIT. In addition, eight different peptides that spanned the PF4 molecule were studied for their ability to bind to the HIT-Abs either alone or in the presence of heparin. With the exception of a subpopulation of patient samples (5/29, 17%), we found that reduced PF4 and the peptides were uniformly nonreactive with the HIT-Abs in the presence of heparin. Reduced PF4 and PF4 carboxy-terminal peptides with a minimum size of 19 amino acids were recognized by a minority (5/29) of HIT-Abs samples but only when heparin was present. The specificity of this subgroup of samples from patients with HIT was highly restricted and the loss of one amino acid (peptide reduced in length from 19 to 18 amino acids) rendered the peptides non-reactive. The clinical characteristics of these patients were similar to the other HIT patients.
These studies demonstrate that the majority of HIT-Abs recognize a noncontiguous conformational epitope on the PF4 molecule that is produced when four to eight PF4 molecules are bound together by heparin.     

THE EFFECT OF NEUROLEPTANALGESIA WITH INNOVAR ON THE METABOLIC RATE OF MAN

The metabolic rate of eight healthy adults did not change significantlyafter the introduction of neuroleptanalgesia with Innovar. Averageoxygen consumption decreased from the control value of 133 ml/min/sq.m±22(standard deviation) which is 98.6 per cent of predicted basalmetabolic rate, to 127±37 8 minutes after the injectionof Innovar (93.2 per cent), and was 141±17 25 to 30 minutesafter injection (105.5 per cent). Ventilation was controlled,keeping end-tidal carbon dioxide constant. Carbon dioxide excretionand the respiratory quotient did not change. Anatomical deadspaceand the ratio of deadspace to tidal volume both rose after induction.This study offers no support for the theory that Innovar "protects"by reducing metabolic demand for oxygen in man.