A Tridimensional View of Intradermal Nevi as Revealed by Scanning Electron Microscopy

When scanning electron microscopy (SEM) was applied to the study of intradermal nevi, interesting tridimensional features were recognized. The free surface of the lesions showed ruffled keratinized cells. "Normal" hairs as well as "corkscrew" hairs emerged from the follicular openings. Nevus cells were either round or elongated and surrounded by connective tissue fibers.     

Conformation and dynamics of the chemotactic peptide formyl-L-methionyl-L-leucyl-L-phenylalanine in solution

Several conformational and dynamic features of the chemotactic peptide formyl-L-methionyl-L-leucyl-L-phenylalanine in solution have been delineated by investigations of NMR and IR spectroscopic parameters. Both 1D and 2D NMR experiments have been performed for detection of scalar and dipolar proton-proton connectivities, whereas ¹³C and ¹H relaxation parameters have been interpreted in terms of molecular dynamics. The main conformation appeared to be unfolded with the three hydrophobic side chains extending in divergent directions with respect to the backbone. The existence of relatively weak inter-molecular hydrogen bonds was demonstrated, involving the formamide end group, with increase in the hydrophobicity of the external surface.     

Effects of Oral Propafenone Therapy on Chronic Myocardial Pacing Threshold

The effects of oral propafenone therapy on pacing threshold were studied in 36 patients chronically paced for sick sinus syndrome or AV block. The pacemakers, all unipolar models and with noninvasive threshold measurement facilities, were: 9 VVI, 15 AAI, and 12 DDD. Each patient received an initial propafenone dose of 450 mg/day, that in 18 cases was increased to 900 mg/day. Threshold was tested at baseline and at each dosage after 7 days of therapy. With the lower propafenone dosage the threshold, measured at 2.5 V, rose from 0.14 +/- 0.10 to 0.21 +/- 0.16 msec (+55%) in the atrium (P less than 0.0001) and from 0.10 +/- 0.08 to 0.15 +/- 0.09 msec (+63%) in the ventricle (P less than 0.0001). In the 18 patients who received both dosages, the mean atrial and ventricular threshold increased from 0.12 +/- 0.10 to 0.17 +/- 0.14 msec with the lower dose and to 0.27 +/- 0.22 msec (+125%) with the higher dose (P less than 0.0001 for both increments). With the 900 mg/day dose, a threshold increment greater than or equal to 300% was observed in 15% of the stimulated chambers. A good linear correlation (r = 0.76) was found between the ventricular threshold increment and the drug induced QRS widening. In conclusion, treatment with oral propafenone increases atrial and ventricular stimulation threshold in pacemaker patients. Threshold increment is dose dependent and proportional to the drug induced QRS widening. In the majority of the cases the threshold increment is not clinically significant, but caution must be used in prescribing high doses of the drug to patients with high baseline threshold.     

Ultrastructural Basis for the Assay of Topical Acne Treatments. Transmission and Scanning Electron Microscopy of Untreated Comedones

After two decades of using systemic antibiotics as a main treatment for acne, emphasis is again being placed on topical agents. Thus, it is highly desirable to have a procedure whereby the activity of the various compounds can be evaluated by direct visualization. Scanning electron microscopy combined with transmission electron microscopy provide the tools for such in assay. This study describes the ultrastructure of untreated comedones and provides the baseline or control data necessary for testing topical treatments. Comedones obtained by punch biopsies or comedo extractors were processed for electron microscopy and studied with an ETEC Autoscan Scanning Electron Microscope and with Philips EM 300 and EM 301 Transmission Electron Microscopes. Microorganisms, keratinized cells, sebum, and hairs interact with each other to form the comedonal mass. Corynebacterium acnes and Pityrosporum ovale proliferate abundantly in close association with sebum and penetrate the keratinized cells. Fine structural details of bacteria and yeasts as well as features of host-microbial relationship have been elucidated.     

Transcutaneous Cardiac Pacing for Termination of Tachyarrhythmias

ALTAMURA, G., ET AL.: Transcutaneous Cardiac Pacing for Termination of Tachyarrhythmias. Transcutaneous cardiac pacing (TCP) was used for interruption of tachyarrhythmias in 31 patients: 20 with ventricular tachycardia (VT); eight with atrioventricular reentrant tachycardia (AVRT) and three had atrioventricular nodal tachycardia (AVNT). The stimulators used (Pace Aid 50/52) allow pacing at programmable rates (50–160 ppm) and output (10–200 mA at 20-msec pulse duration), when possible overdrive pacing was used. Short bursts of stimuli were delivered with increasing current intensity until interruption of the arrhythmia or to the maximum energy tolerated by the patient. VTs were interrupted in eight of the 20 patients: four of the six (67%) treated by overdrive pacing and four of the 14 (29%) were treated by underdrive pacing. Supraventricular tachycardias (SVT) were terminated in eight of the 11 patients: seven out of eight (88%) AVT, and one out of three AVNT (33%). We observed two cases of arrhythmia worsening: a VT acceleration and induction of ventricular fibrillation in a patient with AVNT. TCP was well tolerated by the majority of the patients. We conclude that TCP is an effective method for interruption of ventricular and supraventricular reentrant tachycardias, but the risk of arrhythmia worsening must be considered.     

Topical Halcinonide in Alopecia Areata and in Alopecia Totalis

When halcinonide cream was used for prolonged periods in patients affected by alopecia areata or alopecia totalis, marked and steady regrowth of hair was observed.     

Subcutaneous Fat Necrosis of the Newborn

Subcutaneous fat necrosis of the newborn (SFNN) developed in a 1-week-old black boy. His mother had received numerous medications for eclampsia. Birth was by Caesarean section and complicated by meconium aspiration. There were numerous nodules over the back, buttocks and extremities that yielded a caseous-like material. Microscopically, these nodules showed crystallization and necrosis of the fat. Hypoglycemia, pneumonia, oliguria, thrombocytopenia, seizures and urinary infection were associated with the cutaneous problem and led to a fatal outcome 2 weeks after birth.