Interaction of von Willebrand factor with human platelets in the plasma milieu

The binding of von Willebrand factor (vWf) to stimulated platelets in the plasma milieu was performed using a radiolabeled monoclonal antibody to vWf. Plasma proteins specifically inhibited the thrombin- and ADP/epinephrine-induced vWf binding to activated platelets but did not inhibit the ristocetin-induced vWf binding. When normal plasma was heat defibrinated, monoclonal-labeled vWf was bound to platelets following thrombin or ADP/epinephrine stimulation. Furthermore, monoclonal-labeled vWf from afibrinogenemic plasma bound normally to platelets. The binding of vWf to stimulated platelets in either heat-defibrinated normal plasma or afibrinogenemic plasma was specifically inhibited by the addition of normal plasma fibrinogen in a concentration-dependent manner. At levels of fibrinogen less than 1 mg/ml, however, vWf binding could be demonstrated. The inhibition by fibrinogen of vWf binding to platelets was competitive and overcome by increased concentrations of vWf. These studies show that thrombin-induced and ADP/epinephrine-induced vWf binding to platelets does not occur in the plasma milieu, although at reduced levels of fibrinogen, vWf binding to stimulated platelets can be demonstrated.

A necropsy study of distribution of petechiae in non-sudden infant death syndrome

The distribution of visceral petechiae in patients whose deaths were caused by upper airway obstruction and disorders other than sudden infant death syndrome (SIDS) has not been systematically studied. The clinical and necropsy records and microscopic slides of 50 such cases were retrospectively reviewed. In cases in which the cause of death could reasonably be ascribed to lethal upper airway occlusion, petechiae were found only in thoracic viscera. When death was apparently not preceded by terminal changes in intrathoracic pressure, petechiae were found in viscera above and below the diaphragm. These findings suggest that intrathoracic petechiae occur as a consequence of pressure changes within the chest and indirectly support the hypothesis that the terminal mechanism in SIDS is upper airway obstruction.

The cellular electrophysiologic mechanism of the dual actions of disopyramide on rabbit sinus node function

To determine the contribution of disopyramide's suggested opposing direct depressant and indirect acceleratory actions on sinus node function, we studied the effects of disopyramide, 1 x 10(-7) to 1 x 10(-4) M, on isolated rabbit sinus node preparations using standard microelectrode techniques. Transmembrane potentials were recorded simultaneously from the sinus node and adjoining crista terminalis area. Disopyramide, as much as 1 x 10(-5) M, had no effects on the sinus cycle length. At a concentration of 1 x 10(-4) M, sinus cycle length was significantly prolonged due to prolongation of the sinus nodal action potential duration. During cholinergic blockade with atropine, 1 x 10(-6) M, disopyramide, 1 x 10(-7) to 1 x 10(-4) M, significantly prolonged sinus cycle length as a result of a prolongation of the sinus nodal action potential duration and a decrease of the slope of phase 4 depolarization. During cholinergic stimulation with carbamyl choline, 1 x 10(-9) M, disopyramide, 1 x 10(-7) to 1 x 10(-6) M, tended to reverse carbamyl choline-induced prolongation of the sinus cycle length (NS). This acceleratory action of disopyramide was caused by a significant increase of the slope of phase 4 depolarization. Disopyramide, 1 x 10(-7) to 1 x 10(-4) M, had no significant effects on corrected sinus node recovery time or on sinoatrial conduction time under any conditions studied. We conclude that disopyramide has a direct depressant action on normal sinus node cells at the upper therapeutic and toxic levels, which is enhanced during cholinergic blockade, and that disopyramide's acceleratory action appears only at much lower concentrations and only during cholinergic stimulation.

Characterization of Giemsa dark- and light-band DNA

Using synchronized cultures of V79-8 Chinese hamster lung fibroblasts, we either alternately labeled early- and late-replicating DNA, or substituted one of these with bromodeoxyuridine to separate them in CsCl density gradients or to identify the bromodeoxyuridine-containing chromosome bands by fluorescence microscopy. The Giemsa light R bands were shown to replicate in the first half of S phase, and the dark G bands were shown to replicate in the last half of S phase. S phase was bimodal, with a distinct pause in the rate of DNA synthesis that separated the period of R-band DNA synthesis from that of G-band DNA synthesis. G-band DNA was found to be 3.2% richer in AT than R-band DNA. Surprisingly, G- and R-band DNA appeared equally transcriptionally active in that alternate labels in chromatin were digested with the same kinetics by DNAase I, and in reassociation experiments, total poly(A)+ RNA drove nick-translated G- and R-band DNA probes similarly. G- and R-band DNA also reassociated with identical kinetics, demonstrating that they contain equal proportions of all kinetic-complexity classes of sequences.

A second zone of compensation during atrial premature stimulation: evidence for decremental conduction in the sinoatrial junction

125 consecutive patients with premature atrial stimulation were studied. Three demonstrated sinus node return cycles that were fully compensatory following premature atrial stimuli delivered early in diastole. This second zone of compensation was unaccompanied by significant alterations in the post-return cycle lengths or in P-wave morphology of the return cycle. To account for the occurrence of a complete compensatory pause following very early premature atrial depolarizations, we consider the possibility that retrograde conduction of the early atrial premature depolarization (APD) in the sinoatrial junction was delayed for a sufficient length of time to allow the sinus node to depolarize spontaneously on schedule. Collision between the APD and sinus beat would then occur despite the marked prematurity of the APD. Thus, the early APD had encountered the relative refractory period of the sinoatrial junction, suggesting that decremental conduction takes place within the sinoatrial region in man. These findings imply that there is the potential for reentry in the region of the human sinoatrial junction.

The relationship between life change events, social supports, and dysmenorrhea

A survey of 156 female undergraduate nursing students was conducted to determine the relationship between life change events and dysmenorrhea and the mediating effect of social supports on this relationship. Data were collected using the Anderson College Schedule of Recent Experience (subjects estimated personal readjustment to life changes), the Moos Menstrual Distress Questionnaire, and a social support index constructed by the authors. Correlations were obtained separately for high and low social support groups; these ranged from .19 to .62 and were significant (p less than .05) for both groups. Presence or absence of a confidant was the most discriminating social support dimension (r = .32 for those with a confidant and .62 for those without). For subjects using oral contraceptives there was no relationship between life change and dysmenorrhea, while users of other contraceptives showed a significant positive relationship (p less than .05). Life change and social supports together accounted for only 16% of the variance in menstrual distress scores. Methodological difficulties in using the life change and social support tools were identified.

Detection of herpes simplex virus (HSV) type-1 IgG and IgM antibodies by enzyme-linked immunosorbent assay (ELISA)

A sensitive enzyme linked immunosorbent assay (ELISA) is described for detection of herpes simplex virus (HSV) type 1, IgG and IgM antibodies. The antigen consisted of a crude extract of HSV infected human foreskin fibroblast cells. Specific horseradish peroxidase conjugated antisera were used to detect total immunoglobulin, IgG and IgM antibodies bound to viral antigen. The substrate was a solution of 5-aminosalicylic acid and hydrogen peroxide, which yielded a readily visible endpoint. Results obtained by the ELISA method were compared with the micro-complement fixation (CF) method on 36 sera. ELISA was shown to be at least 10-20 fold more sensitive than CF, with a correlation coefficient of 0.752 (p less than .001). HSV antibodies in these sera were mainly IgG, although IgM antibodies could also be detected by ELISA. HSV antibodies were not found in 16 cerebrospinal fluids from patients without HSV encephalitis (HSVE). ELISA appears to be a rapid, sensitive, and specific method for demonstration of IgG and IgM HSV antibodies. It may have possible application in the diagnosis of HSVE.

Effects of prostaglandin D2 on perinatal circulation

Prostaglandin D2 (PGD2) is a powerful antiaggregatory agent and contracts various types of smooth muscle preparations, including isolated canine and bovine pulmonary vessels. Pulmonary vascular responses of anesthetized fetal and adult goats and newborn lambs to PGD2 were evaluated in situ by means of an isolated perfused lower left lobe preparation. These experiments indicate that PGD2 is a pulmonary vasodilator in fetal goats, both a pulmonary vasodilator and vasoconstrictor in newborn lambs depending on the dose used, and a pulmonary vasoconstrictor in adult goats. Evidence is presented of an age-related change in pulmonary vascular response to prostaglandins. The responses of the pulmonary vasculature are dose dependent; however, there is not a significant dose-dependent relationship for systemic arterial pressure or heart rate with intrapulmonary infusions of PGD2. The inhibition of prostaglandin synthesis potentiates the pulmonary response to PGD2 in fetal goats. In contrast with other prostaglandins, PGI2, PGE2, and PGE1, which dilate both the fetal pulmonary and systemic circulations, PGD2 has minimal action on the systemic circulation over a wide range of doses.

A microassay for active and total renin concentration in human plasma based on antibody trapping

We have developed and validated a new enzyme-kinetic method for measurement of renin concentration (PRC) in human plasma, based on radioimmunoassay of angiotensin I generated during incubation of plasma and excess sheep or ox renin substrate. Angiotensin I breakdown during incubation is prevented by the presence of anti-angiotensin I serum. The assya does not require prior extraction of renin, is technically simple, and is sufficiently sensitive to measure subnormal renin levels. With minor modifications both "active and "total" renin may be measured. Assay results have been calibrated with the International Standard Renin. PRC measured by this technique correlates significantly with angiotensin I and II, plasma renin activity, and with the PRC method previously used by us.

Elimination of the delta wave in the Wolff-Parkinson-White syndrome. A misleading indicator of therapeutic effectiveness

A 66-year-old white woman with a greater than 20-year history of electrocardiographic evidence of the Wolff-Parkinson-White syndrome, including documented recurrent supraventricular tachycardias, was studied. Despite the disappearance of the delta wave after initiation of therapy with digoxin and quinidine sulfate, the patient continued to have frequent episodes of supraventricular tachycardia. At a time when the serum levels of digoxin and quinidine were in the therapeutic range, extensive electrophysiologic studies were performed. Supraventricular tachycardia at a rate of 160 beats per minute was initiated by induced atrial premature depolarizations. The circuit of tachycardia involved anterograde conduction through the pathway of the atrioventricular node and His bundle and retrograde conduction through the bypass tract. We concluded that elimination of the delta wave and other electrocardiographic characteristics of the Wolff-Parkinson-White syndrome cannot be relied upon to indicate successful pharmacologic prophylaxis for induction of tachyarrhythmia associated with this syndrome.

Characteristics of sinoatrial conduction in patients with coronary artery disease

Electrophysiologic studies were performed in 32 patients with angiographically documented coronary artery disease (CAD). Group I was composed of ten patients (31%) with severe stenosis (greater than or equal to 75%) proximal to the origin of the sinus node artery (SNA); group II was composed of five patients (16%) with moderate (50--75%) proximal stenosis; and group III was composed of 17 patients (53%) with insignificant (0--50%) proximal stenosis. The mean sinoatrial conduction time (SACT) for group I was 119 +/- 18 msec; group II was 84+/- 16 msec; and group III was 72 +/- 5 msec. The SACT was significantly longer in group I than in group III (P less than 0.005). In conclusion 1) in patients with CAD, SACT greater than 72 +/- 5 msec is abnormal; 2) the results suggest a pathogenetic role of CAD in the development of sinus node dysfunction; 3) the SACT is a more sensitive indicator of subtle sinus node dysfunction in CAD patients than is heart rate, sinus node response to artrial extrastimuli, or sinus node recovery time; and 4) the ability to diagnose sinus node dysfunction in its early stages and recognition that coronary artery disease is an etiologic factor may allow for the elucidation of the natural history of the sick sinus syndrome.

Comparative effects of overdrive on sinus and subsidiary pacemaker function

Recent evidence has suggested a difference in response to overdrive pacing dependent on the location of the pacemaker within the A-V conduction system. To test this hypothesis, the effects of overdrive pacing were evaluated in five anesthetized dogs with experimentally induced A-V block and in seven patients with advanced A-V block. In the animals, sinoatrial node recovery times were studied over wide ranges of rates (130 to 210 beats per minute) and durations (30 to 180 seconds) of atrial pacing. All sinus node recovery times were less than 600 msec. with a mean maximum pause of 0.540+/-0.043 seconds (M.+/-S.E.M.). In contrast, after ventricular pacing (rates 90 to 150 beats per minute; durations 30 to 180 seconds), subsidiary pacemaker recovery times were significantly greater (p less than 0.025) with a mean maximum recovery time of 28.4+/-8.3 seconds. In the seven patients studied, all sinus node recovery times were less than 1,400 msecs. with a mean maximum pause of 0.954+/-0.051 seconds. As seen with the experimental animals, a significantly longer (p less than 0.025 mean maximum subsidiary pacemaker recovery time of 3.55+/-0.92 seconds was observed. The present studies in both experimental animals and in man without evidence of sinus node dysfunction showed that sinus node recovery time was independent of both rate and duration of atrial overdrive pacing. In contrast, subsidiary pacemaker recovery time was correlated with both rate and duration of ventricular overdrive pacing. In both experimental protocols, subsidiary pacemaker recovery time was shown to exceed sinus node recovery time at all rates and at all durations of pacing. Postrecovery sinus node acceleration was consistently observed after atrial overdrive pacing. In contrast, postrecovery subsidiary pacemaker "depression" characterized ventricular overdrive pacing. It is concluded that subsidiary pacemakers are significantly more susceptible to overdrive suppression than the sinoatrial node, a feature of substantial clinical significance.

Inactive renin--a renin proenzyme?

Human plasma contains an inactive form of renin with a m.w. of 55,000, as against around 40,000 for active human renin. After acidification to pH 3.0 or incubation with trypsin, the inactive renin becomes more active and the molecular weight falls to that of active renin. In human kidney extracts, an increase in renin concentration also occurred after acidification. The inactive form of renin may be similar to that of rabbit kidneys, which contain an inactive renin that can be activated by removal of an acid-labile inhibitor. The question as to whether the inactive material is a renin proenzyme is discussed.

Phytohemagglutin-induced lymphocyte transformation in oral contraceptive users

Phytohemagglutin (PHA)-induced lymphocyte transformation (PILT) was determined in 217 women taking oral contraceptives and 203 control women by means of the uptake of 3H-thymidine into DNA of lymphocytes cultured in heterologous serum. Depressed PILT responses were observed in oral contraceptive users as compared with age-matched controls, and the magnitude of depression correlated with the duration of oral contraception and was inversely related to the clinical progestagenic potency of the component steroids. An additional group of 21 women, tested within 1 year (mean 3 months) of cessation of oral contraception, showed persistent depression of PILT responses. Suppression of lymphocyte transformation in autologous as compared with homologous, normal serum suggests that serum inhibitory factors amy be important. We found no evidence for a direct suppressive in vitro effect of synthetic estrogens and gestagens. The prevalence of autoantibodies in oral contraceptive users was similar to that in control subjects.

Self-image and emotional stability of Oedipal and non-Oedipal male homosexuals

The past several years have brought about some changes in the legal status of the homosexual in USA. In some states, the homosexual is labelled as a criminal; in others, homosexuality is not a legal affair. Psychological theories tend to consider the homosexual from two general positions: the Oedipal and the non-Oedipal. The present study was conducted to try to determine how Oedipal and non-Oedipal male homosexuals perceived their self-image and emotional stability. Significant differences were found between the two groups. Considering self-image, Oedipal subjects were found to be more negative. They had less self-worth, self-confidence and self-acceptance than non-Oedipal. They had more negative self-concepts, self-attitudes, and self-motivation. Oedipal homosexuals had less emotional stability. They had more emotional problems, shame, guilt, withdrawal, and depression than non-Oedipal subjects, as well as less success in sexual activity and commitment to the homosexual partner.