Injury of the rotator cuff. I. Morphological and patho-physiological basis

Authors summarize the basic features of the functional anatomy and pathogenesis of the rotator cuff tears, essential for clinical practice. On the basis of literary data and own experiences a new classification of the rotator cuff tears was elaborated that can be reliably used in operative indications.     

Early detection of prosthetic-hip loosening. Comparison of low- and high-viscosity bone cement

In 1987, we reported the 1-year migration of the prosthetic components in 16 hips followed by roentgen stereophotogrammetry after fixation with either low- or high-viscosity cement. We now report the migration of these prosthetic components during another 2 postoperative years. Eight acetabular components, four in each group, migrated cranially; and four femoral components, three in the low-viscosity and one in the high-viscosity group, migrated distally. All but two migrations were obvious 4 months postoperatively, which indicates that what is called late loosening is the result of late detection rather than of late occurrence of loosening. Low-viscosity cement did not provide improved prosthetic fixation.     

Surfactant-induced cell toxicity and cell lysis. A study using B16 melanoma cells

The effects of a variety of detergents (non-ionic, ionic and bile derivatives) on B16 melanoma cells have been examined. Two main effects can be clearly differentiated: loss of cell viability and cell lysis. Under our conditions, cell-surfactant interaction is highly dependent on the nature of the amphiphile (more specifically, on its critical micellar concentration). Loss of cell viability occurs at surfactant concentrations below the critical micellar concentration, i.e. the incorporation of detergent monomers into the cell membranes is enough to impair their barrier function, so that Trypan Blue is no longer actively secreted outside the cell. On the other hand, cell lysis only occurs at or near the critical micellar concentration of the detergent, i.e. when the bilayer-micelle transition may take place. Comparative studies using B16 cells and phospholipid vesicles indicate that the amount of detergent required to induce cell lysis is the same that produces disruption of the lipid bilayer. Thus, our results suggest that membranes are the primary target for the toxicologic effects of surfactants on cells. Moreover, they provide a rationale for the interpretation of other studies in this field: previous results from different laboratories are shown to fit very well our data.     

Optic disk neovascularization and retinal vessel diameter in diabetic retinopathy

We measured retinal vessel diameter before and after panretinal photocoagulation in 59 eyes with diabetic retinopathy and moderate to severe optic disk neovascularization. Treatment significantly reduced mean arteriolar and venular diameter. The diameter of the retinal arterioles after treatment correlated significantly with the amount of regression in disk neovascularization. Eyes with large diameter vessels after treatment usually had little or no regression of proliferative retinopathy, whereas regression was more frequently seen in eyes with smaller diameter vessels after treatment.     

Fetal cardiac arrhythmias: Doppler assessment

Pregnancies in which fetal cardiac arrhythmias are present are associated with an elevated perinatal and neonatal mortality. In this group various major and minor fetal malformations, including heart malformations, are more common. FECG and phonocardiogram give some information on the type of arrhythmia in favorable cases. Real-time imaging detects fetal heart malformations and late signs of heart failure. Fetal echocardiogram is of great aid for the classification of the arrhythmia and for the detection of heart malformations. By applying combined real-time linear array and pulsed Doppler technique in cases of fetal cardiac arrhythmia, important information on the fetal circulatory state can be obtained. Estimations of the volume blood flow guide the clinician in the practical handling of these cases. Volume blood-flow estimations can probably detect imminent fetal heart failure. Therapeutic effects can be followed, and the timing of delivery can be optimized taking the circulatory state into account. Within the fetal heart rate range 50 to 250 beats/min adequate blood circulation is usually maintained in the fetus. The peak velocity, the acceleration, and the rising slope are all increased in the postextrasystolic beat, indicating the existence of postextrasystolic potentiation in the fetal heart. These three parameters can be related to the ventricular filling time, supporting the opinion that the fetal heart follows the rules of the Frank Starling relationship. Fetal arrhythmias constitute also an experimental model for the study of fetal cardiac physiology.     

Disposition of the neuroleptic zuclopenthixol cosegregates with the polymorphic hydroxylation of debrisoquine in humans

The pharmacokinetics of a single oral dose of the neuroleptic drug zuclopenthixol (10 or 6 mg) was studied in 6 extensive and 6 poor metabolizers of debrisoquine. The peak plasma concentrations of zuclopenthixol did not differ between the phenotypes, whereas the plasma elimination half-life was significantly longer in poor than in extensive metabolizers (29.9 +/- 6.6 vs 17.6 +/- 6.9 h). Accordingly, the total oral plasma clearance was lower in poor than in extensive metabolizers (0.78 +/- 0.27 vs 2.12 +/- 0.65 1/h/kg). Ten of the volunteers had previously participated in a similar study in which the kinetics of perphenazine, another neuroleptic drug, were studied in poor and in extensive metabolizers of debrisoquine. There was a significant correlation between the oral clearance of perphenazine and that of zuclopenthixol among these 10 subjects. The study indicates that the disposition of zuclopenthixol, as well as that of perphenazine, is related to the genetically determined capacity to hydroxylate debrisoquine. The significance of this polymorphism for the clinical use of neuroleptics is discussed.     

High-resolution ultrasonography of the carpal tunnel

Twenty-eight wrists of 25 patients with carpal tunnel syndrome (CTS) and 28 wrists of 14 normal control subjects were studied with high-frequency real-time ultrasonography. Three general findings could be observed in CTS, regardless of its cause: swelling of the median nerve at the entrance of the carpal tunnel; flattening of the median nerve in the distal carpal tunnel; and increased palmar flexion of the transverse carpal ligament. Quantitative analysis proved these findings to be significant. We conclude that high-resolution sonography is able to diagnose median nerve compression in the carpal tunnel syndrome and to detect some of its potential causes.