Development of the blood-testis barrier in the domestic fowl (Gallus domesticus)

The formation of the blood-testis barrier (BTB) in the domestic fowl was studied at the electronmicroscopic level employing lanthanum as a tracer. No effective barrier could be demonstrated in testes before puberty, although several components of the Sertoli junctional complex such as focal tight junctions and desmosomes were already existent. The time of onset of meiosis after hatching showed great individual variation and meiosis did not occur synchronously in the tubules of a given testis. An effective barrier could first be detected in tubules containing early spermatids, and in which spermatogonia and primary spermatocytes at the leptotene stage were still within the open compartment. Thus, barrier formation was correlated with the occurrence of haploid germ cells. Complete compartmentation of seminiferous tubules, leaving only spermatogonia within the open compartment, was attained in tubules containing elongated spermatids of the maturation phase. In these tubules, primary spermatocytes at the leptotene stage were situated in an intermediate compartment.     

Chronic obstructive pulmonary disease with tracheostomy: report of case involving endodontic treatment

Modern medicine has made many advances in the capability to sustain life. The dental profession needs to keep up to date with these changes and be creative in caring for these individuals who are medically compromised and who require special care.¹¹ This sometimes requires the purchase of new equipment; other times it means modifying that which exists. In all instances, the level of care for these individuals requires a team approach and mandates education of all team members. In the case presented, the medical problems necessitated such a team effort to achieve optimal care.     

Free radicals and cardioplegia: the absence of an additive effect with allopurinol pretreatment and the use of antioxidant enzymes in the rat

The isolated perfused working rat heart model of cardiopulmonary bypass was used to assess whether (a) allopurinol pretreatment enhances resistance to normothermic (30 min) or hypothermic (4 h) ischemia; (b) addition of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) to cardioplegic and/or reperfusion solutions are protective; (c) any protective effects are additive. With normothermic ischemia, allopurinol pretreatment improved recovery of aortic flow from its control value of 25 +/- 3% to 48 +/- 6% (P less than 0.05). Similarly, SOD plus CAT used during both ischemia and reperfusion improved recovery of aortic flow from a control value of 28 +/- 4% to 48 +/- 6% (P less than 0.05). However, various combinations of the two types of intervention afforded no additive protection. Under hypothermic (21 degrees C) conditions, allopurinol pretreatment was not effective, whereas SOD and CAT added during ischemia and reperfusion improved recovery of aortic flow from its control value of 53 +/- 4% to 69 +/- 5% (P less than 0.05). This value was similar to allopurinol pretreatment and SOD plus CAT added during ischemia and reperfusion (69 +/- 6%: P less than 0.05). These results provide further evidence that reperfusion-induced free radical formation may adversely affect postischemic recovery of function. The absence of an additive effect suggests a common mechanism of action, which is likely to involve the free radical-generating enzyme xanthine oxidase; however, other mechanisms may exist. Our results further support the use of antifree radical intervention in conjunction with cardioplegia to protect the heart during ischemia and reperfusion.     

Use of Telemetered Electrograms in the Assessment of Normal Pacemaker Function

The facility of direct real-time endocardial electrogram recording offered by newer pacemaker models can be helpful in the assessment of normal pacemaker function. Confirmation of the main hallmarks of sensing (amplitude, slew rate, and timing of the electrogram) can be achieved. Assessment of pacing capture also can be made; techniques for further analysis using external signal averaging can enhance this. The measurement of atrial and ventricular electrograms by telemetry has led to alterations in the protocol used at implantation to allow for the input impedance of the sensing circuit of the pacemaker. Accurate measurements of retrograde VA conduction times and confirmation of normal upper rate limit behavior of ODD pacemakers can be achieved simply and reliably using telemetered electrograms from the permanent pacemaker system.     

Urinary excretion of 5-oxoproline (pyroglutamic aciduria) as an index of glycine insufficiency in normal man

1. The evidence is accumulating to suggest that glycine, the simplest amino acid, is conditionally essential in man. Benzoic acid, by conjugation with glycine to form hippuric acid, is known to deplete the free glycine pool of the body. Glycine is one substrate for the enzyme glutathione synthase (EC 6.3.2.3) and in the inborn error of metabolism in which glutathione synthase function is defective, increased quantities of 5-oxoproline are excreted in the urine. 2. An oral dose of 4-10 g sodium benzoate was given to six normal adults to deplete the metabolic pool of glycine, and the urinary excretion of 5-oxoproline was followed for 6 h. In five of the six, a significant increase in the urinary 5-oxoproline was seen within 3 h. 3. These findings show that 5-oxoprolinuria can result from limited glycine availability, and may provide a useful test for assessing glycine sufficiency in a range of physiological and pathological states.