Pre- and Postjunctional Effects of Diadenosine Polyphosphates in the Guinea-pig Vas Deferens

The pre- and postjunctional activities of a number of diadenosine polyphosphates were examined in the guinea-pig isolated vas deferens at the level of the membrane-potential, using a modified sucrose-gap technique. P¹,P³-Di(adenosine 5′)triphosphate (Ap₃A), P¹,P⁴-di(adenosine 5′)tetraphosphate (Ap₄A) and P¹,P⁵-di(adenosine 5′)pentaphosphate (Ap₅ A) all caused concentration-dependent depolarization of the smooth muscle membrane. The potency order was: Ap₅A > Ap₄A. Ap₃A. P¹, P²-Di(adenosine 5′)pyrophosphate (Ap₂A) did not evoke depolarization even at the highest concentration tested (1 mM). All the dinucleotides caused a reduction in the amplitude of evoked excitatory junction potentials (e.j.ps). The potency order was: Ap₅A = Ap₄A > Ap₃A > Ap₂A. The depolarizations evoked by the dinucleotides were markedly reduced by the selective P_2X-purinoceptor antagonist, pyridoxalphosphate-6-azophenyl-2′,4′-disulphonic acid (PPADS, 10 μM), as was the amplitude of the fully facilitated e.j.p. The inhibition of the e.j.p. evoked by Ap₃A and Ap₂A was reduced by the P₁-purinoceptor antagonist, 8-p-sulphophenyltheophylline (8-pSPT, 50 μM), but that evoked by Ap₅A and Ap₄A was not. Thus, Ap₃A, Ap₄A and Ap₅ A evoke depolarization of the guinea-pig vas deferens via P_2X-purinoceptors, and additionally Ap₂A and Ap₃A exert a prejunctional effect via P₁-purinoceptors. The prejunctional activity of Ap₄A and Ap₅A is mediated via an undefined purinoceptor, which is neither P₁ nor P_2X.     

Influence of carbamoylation on some analytical properties of basic polypeptides

The effect of carbamoylation on the assay or identification of histones and polylysine was investigated. Incubation with sodium cyanate decreased the positive charge on these polypeptides as judged by changes in the binding of methyl orange or the electrophoretic mobility. Histones in chromatin appeared less accessible to carbamoylation than isolated histones. Carbamoylation of proteins under conditions in which there was little or no effect on the Lowry procedure could affect their assay by methods utilizing metachromasia with Coomassie Blue G. The Bradford assay has low sensitivity for HI histone and polylysine but this can be increased by preincubation with sodium cyanate. More extensive carbamoylation of polylysine caused decreased sensitivity which was the only response seen with core nucleosomal histones and bovine serum albumin when preincubated with sodium cyanate. It was concluded that the sensitivity for HI histone and polylysine in assays dependent on metachromasia with Coomassie Blue G may be changed by factors which decrease the positive charge on these polypeptides.     

Pediatric transtracheal and cricothyrotomy airway devices for emergency use: which are appropriate for infants and children?

Cricothyrotomy or insertion of a transtracheal device is a life-saving maneuver that may be performed on an emergent or semi-elective basis as a means of bypassing an obstructed upper airway. A surgeon is trained to perform this life-saving procedure whereas most anesthesiologists are not facile with the scalpel. It is for this reason that many percutaneous devices have been developed for use by surgeons and nonsurgeons alike. Unfortunately, the majority of such devices are designed for use in adults and/or teenagers but are not appropriate for neonates and infants. The unique anatomy of the infant larynx, the small size of the cricothyroid membrane, and the technical difficulty of locating the correct anatomical structures make the use of most of these devices impractical if not outright dangerous in neonates and infants. This paper will review many (but not all) of the available devices, associated literature, pitfalls and dangers. It is emphasized that each clinician should become familiar with the advantages and disadvantages of these devices and obtain training with simulators or animal models. A strategy for management of the 'cannot ventilate, cannot oxygenate, cannot intubate' situation should be developed with age and size appropriate equipment.     

The Alcohol Use Disorders Identification Test (AUDIT) as a screen for at-risk drinking in primary care patients of different racial/ethnic backgrounds

This study examined the operating characteristics of the Alcohol Use Disorders Identification Test (AUDIT) as a screen for "at-risk" drinking in a multi-ethnic sample of primary care patients, from a family practice center located in the southwestern United States. A probability sample of 1333 family medicine patients, stratified by gender and racial/ethnic background (white, African-American and Mexican-American) completed the AUDIT, followed by the Alcohol Use Disorders and Associated Disabilities Interview Schedule (AUDADIS) to determine ICD-10 diagnoses. Indicators of hazardous alcohol use and alcohol-related problems were included as measures of "at-risk" drinking. Despite differences in the spectrum of alcohol problems across patient subgroups, there was no evidence of gender or racial/ethnic bias in the AUDIT as indicated by Receiver Operating Characteristic Curve analysis. Excluding abstainers from the analysis had little impact on screening efficacy. In this patient population, the AUDIT appears to be an unbiased measure of "at-risk" drinking.     

Brief Report: Use of Phytohemagglutinin to Stimulate Hematopoiesis in Humans

PHA therapy was administered to three patients with bone marrow suppression, two with "idiopathic aplastic anemia" and one with myelofibrosis.One patient with aplastic anemia showed increased marrow erythroid activity; the others had no response. Review of the available data on PHAtherapy suggests that states of marrow depression related to known etiologiesmay respond more readily than idiopathic states. Further studies are neededbefore definitive conclusions can be drawn as to the true efficacy of this agent.

Submitted on June 29, 1965 Accepted on September 11, 1965