Sports anemia.

It is apparent that exercise can influence erythropoiesis and red cell survival in a variety of fascinating ways. A number of mechanisms have been reviewed that could lead to mild changes in the Hb or red cell mean corpuscular volume. In addition, athletes may be at high-risk to develop decreased iron stores. Nevertheless, iron deficiency anemia is uncommon and the ritual of routine iron supplementation is not recommended. Clearly, most of the mechanisms discussed lead to only subtle changes in the overall red cell numbers and indices. Yet there is a small subset of athletes who will have red cell changes that can only be attributable to participation in sports. The diagnosis of sports anemia, however, remains one of exclusion.     

Calciphylaxis – a topical overview

'Calciphylaxis', a calcification syndrome associated with ischaemic cutaneous necrosis, is acquired naturally in humans in disease states. It is a life and limb-threatening complication, usually observed in patients with renal disease and secondary hyperparathyroidism, but known to occur in the absence of renal or parathyroid disease. The reported mortality rate, which ranges from 60-80%, relates to wound infection, sepsis and organ failure. It is a small-vessel vasculopathy, which is estimated to occur in about 4% of haemodialysis patients. Clinically, violaceous, reticulate areas of cutaneous necrosis and eschar may be evident, particularly in the extremities. In addition to the clinical picture, a raised calcium phosphorous product, an elevated parathyroid hormone level, radiographic evidence of vessel and soft-tissue calcification and the finding of mural calcification affecting small arteries and arterioles on histopathology help to confirm the diagnosis of this entity which generally has a poor prognosis. A high index of suspicion and an active multidisciplinary management approach, with rigorous attention to wound care and prevention of sepsis, are vital in the management of these patients. In this overview, we discuss the pathophysiology, clinical features and associations, risk factors, diagnosis and management issues relating to calciphylaxis.     

Saturation and inversion transfer studies of creatine kinase kinetics in rabbit skeletal muscle in vivo

The steady-state kinetics of the creatine kinase reaction in rabbit skeletal muscle in vivo was investigated using inversion and saturation magnetization transfer techniques. Both techniques determined the forward rate of this reaction (creatine phosphate ATP) as approximately 0.3 s-1. This corresponds to a flux of 10 mumol creatine phosphate/s/g muscle. The saturation transfer technique underestimated the reverse reaction by approximately 56%. This result is likely due to the participation of ATP in other interactions in skeletal muscle not involving creatine phosphate.     

Mutations in the retinal guanylate cyclase (RETGC-1) gene in dominant cone-rod dystrophy

The dominant cone-rod dystrophy gene CORD6 has previously been mapped to within an 8 cM interval on chromosome 17p12-p13. The retinal- specific guanylate cyclase gene (RETGC-1), which maps to within this genetic interval and previously was implicated in Leber's congenital amaurosis, was screened for mutations within this family and in a panel of small families and individuals with various cone and cone- rod dystrophy phenotypes. A missense mutation (E837D) was identified in affected members of the CORD6 family, as well as a second missense mutation (R838C) in three other families with dominant cone-rod dystrophy. RETGC-1 is only the fourth gene to be implicated in cone-rod dystrophy and this is the first report of dominant mutations in this gene.      

Oocyte morphology does not affect fertilization rate, embryo quality and implantation rate after intracytoplasmic sperm injection

In this study, we compared the fertilization rate and embryo quality after intracytoplasmic sperm injection (ICSI) as they relate to oocyte morphology. A total of 654 ICSI cycles yielding 5903 metaphase II oocytes were observed. The oocytes retrieved in these cycles were divided into (i) normal oocytes, (ii) oocytes with extracytoplasmic abnormalities (dark zona pellucida and large perivitelline space), (iii) oocytes with cytoplasmic abnormalities (dark cytoplasm, granular cytoplasm, and refractile body), (iv) oocytes with shape abnormalities, and (v) oocytes with more than one abnormality (double and triple abnormalities). Intracytoplasmic vacuoles and aggregates of smooth endoplasmic reticulum were not recorded separately. The fertilization rate and quality of morphologically graded embryos did not differ between the groups. There were 77 cycles where all transferred embryos were derived from abnormal oocytes, and 164 cycles where all embryos were derived from normal oocytes. These cycles were studied further. The two groups were comparable regarding mean female age, duration of infertility, duration of ovarian stimulation, number of ampoules of gonadotrophin injected, and number of oocytes retrieved. Two clinical pregnancy rates (44.4 versus 42.1%) and implantation rates per embryo (10.3 versus 13.2%) were similar. In conclusion, in couples undergoing ICSI, abnormal oocyte morphology is not associated with a decreased fertilization rate or unfavourable embryo quality. Furthermore, embryos derived from abnormal oocytes yield similar clinical pregnancy and implantation rates when transferred compared with embryos derived from normal oocytes.      

Comparison between testosterone oenanthate-induced azoospermia and oligozoospermia in a male contraceptive study. IV. Suppression of endogenous testicular and adrenal androgens

Administration of supraphysiological doses of testosterone to normal men causes inhibition of spermatogenesis, but while most become azoospermic, 30-55% maintain a low rate of spermatogenesis. We have investigated whether there are differences in endogenous androgen production, of testicular and adrenal origin, which may be related to the degree of suppression of spermatogenesis. Thirty-three healthy Caucasian men were given weekly i.m. injections of 200 mg testosterone oenanthate (TE), 18 became azoospermic, while 15 remained oligozoospermic. Urinary excretion of epitestosterone, a specific testicular product, was reduced to <10% of pretreatment values, with no differences between the groups. Similar results were obtained for other markers of testicular steroidogenesis. Urinary and plasma adrenal androgens were also reduced during TE treatment: a statistically significant decrease in both (P < 0.001 and P < 0.05 respectively) was seen in the azoospermic but not oligozoospermic responders. These results suggest that testicular steroidogenesis is decreased to <10% by the administration of supraphysiological doses of exogenous testosterone. Differences in the degree of ongoing steroidogenesis in the testis do not appear to account for incomplete suppression of spermatogenesis, thus differences in androgen metabolism may underlie this heterogeneous response. A small but significant reduction in secretion of adrenal androgens was also detectable, the relevance of which is unclear.      

Central effects of aldosterone infused into the rat subcommissural organ region

D-Aldosterone (5 ng/microliter/h) was infused for 6 days into the region of the subcommissural organ (SCO) of conscious, adult male Sprague-Dawley rats. Aldosterone increased urinary sodium loss and the sodium/potassium ratio. Although probably central in origin, these effects still occurred when cannulae were displaced up to 1 mm from the targeted SCO placement. Aldosterone decreased adrenal medullary cross-sectional area without affecting cell density. This effect was highly dependent on proper cannula placement and was not observed when the cannula tip was not in contact with the cerebrospinal fluid of the pineal recess over the rostral two-thirds of the SCO. We conclude that aldosterone increases sodium excretion by an action in the SCO and/or adjacent structures. We also postulate a negative trophic relationship between mineralocorticoids and the adrenal medulla mediated by the SCO.