Complications of femoral and acetabular modularity

The versatility of modular total hip arthroplasties have rapidly extended their applications. However, these new interfaces can lead to complications that were not observed with monolithic components. These problems have been noted with modular femoral and acetabular components and have been associated with the generation of particulate debris. This article reviews the authors' clinical observations and histologic, biomechanic, and spectophotometric evaluations of modular total hip arthroplasties. New data comparing both synovial fluid metal levels in well-fixed and loose monolithic and modular prosthetic hip implants are presented. In modular total hip components, synovial fluid cobalt levels correlated positively with patient weight and length of implantation. The generation of particulate debris in modular total hip components may induce periprosthetic osteolysis. Taper locks for femoral components and locking mechanisms for the polyethylene liner and metallic cup must be designed to avoid the production of particulate debris.     

The action of low-intensity infrared laser radiation on skin afferents

Laser radiation modulates functional characteristics of mechanoreceptors. This inhibits impulse activity of the nerve endings from pain focus and reduces pain sensitivity of skin afferents, excitability of conductive nerve fibers. Changes in sensitivity become more pronounced with increasing duration of the exposure. By means of reflectory mechanism laser radiation may cause other general reactions of the body and enhance immune response of the skin.     

Carbon monoxide: effects on oxygenation of the fetus in utero

The partial pressure of oxygen in fetal blood decreases in proportion to the carboxyhemoglobin concentrations in fetal and maternal blood. Because fetal oxygen tensions normally equal 20 to 30 percent of the values for adults, this reduction can result in severe hypoxia of vital tissues. Decreases in oxygen tension may be a factor in the lower birth weights of infants born to women who smoke or are exposed to severe air pollution.     

Significance of arrhythmias in acute respiratory failure

Arrhythmias are as likely to strike patients with acute respiratory failure as patients with acute myocardial infarction. Both supraventricular and ventricular types were detected in half or more of the patients in two recent studies. Ventricular arrhythmias have a particularly bleak prognosis, since they often deteriorate into ventricular fibrillation or cardiac arrest. The exact causes of these arrhythmias are still a mystery, but metabolic abnormalities associated with respiratory failure are highly suspect. These disturbances can disrupt the transmembrane action potential of cardiac conducting tissue, causing electrophysiologic phenomena known to trigger arrhythmias. Until a specific etiology is confirmed, treatment should focus on identifying and correcting possible metabolic causes. Congestive heart failure--itself a cause of arrhythmias--also should be treated. Cardioversion and antiarrhythmic drugs should be used only in life-threatening situations.     

Diagnosis of respiratory-syncytial viral disease in adults

A method developed by the authors is described that consists in a quantitative test for the evaluation of the reactivity of the microvessels judging by the degree of changes in the resorption speed of isotopes from a tissue depot. In patients with essential hypertension an increased vascular reactivity was revealed with reference to angiotensin, noradrenalin and serotonin, as well as an increased duration of the effect of angiotensin. The highest vascular reactivity was noted in patients with stage II hypertension who have retained a hyperkinetic type of circulation.     

Presence of bifidobacteria in the rumen of calves fed different rations

The silent period in the agonist prior to rapid voluntary movement (premotion silent period) was observed in the lower limb muscles. The subject was asked to respond to the flashing light by performing a vertical jump as quickly as possible. The most consistent results were obtained in the extensors, particularly the quadriceps. The frequency of the silence of six subjects was 53% in the rectus femoris, 61% in the vastus medialis, and 72% in the vastus lateralis. A neural switching mechanism, directing excitation from preparation phase of jumping into rapid contraction phase, seemed to be attributable to the occurrence of the premotion silent period.