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.     

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.     

Comparative study of long-term effects of surgical excision and excision combined with radiotherapy or chemotherapy in breast cancer: an analysis of 192 cases

Clinical data of 192 patients with breast cancer with a primary lesion of 2-5 cm (stage II according to the criteria recommended by the UICC) and with histopathologically confirmed positive axillary lymph nodes were analyzed. The patients were divided into three groups: 1) surgical excision alone; 2) surgery plus irradiation; and 3) surgery plus chemotherapy. It was shown that the 5-year survival rates for these groups were 40.5%, 61.0%, and 62.0%, respectively (P less than .05).     

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.     

Worldwide epidemiology and modes of transmission of delta hepatitis

Conclusions Since the discovery of HDV in 1977 byRizzetto and collegues (10), several studies regarding the pathogenesis, natural history and epidemiology of this infection have been accumulated. It emerges that HDV is an agent with unusual biologic properties which requires HBV replication for its expression. Given the obligatory association between HDV and HBV, transmission of HDV follows the same routes of HBV transmission. This implies that one expects HDV infection to be much more prevalent in countries with high HBsAg carrier rates. This is true in most areas of the world but not in Far East Asia. Endemicity of HDV is maintained in the community through the network of HBsAg carriers. HDV can be transmitted to HBV positive and negative individuals, but survives only after encountering the carrier. Recent outbreaks of severe epidemics of fulminant hepatitis due to HDV among the Yucpa Indians in Northern Venezuela, pointed out very clearly that HDV superinfection is an ominous risk for all populations where HBV is endemic.