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Uncommon Form (uncommon + form)
Selected AbstractsMAINTENANCE OF ANDRODIOECY IN THE FRESHWATER SHRIMP, EULIMNADIA TEXANA: ESTIMATES OF INBREEDING DEPRESSION IN TWO POPULATIONSEVOLUTION, Issue 3 2000Stephen C. Weeks Abstract., Androdioecy is an uncommon form of reproduction in which males coexist with hermaphrodites. Androdioecy is thought to be difficult to evolve in species that regularly inbreed. The freshwater shrimp Eulimnadia texana has recently been described as both androdioecious and highly selfing and is thus anomalous. Inbreeding depression is one factor that may maintain males in these populations. Here we examine the extent of "late" inbreeding depression (after sexual maturity) in these clam shrimp using two tests: (1) comparing the fitness of shrimp varying in their levels of individual heterozygosity from two natural populations that differ in overall genetic diversity; and (2) specifically outcrossing and selfing shrimp from these same populations and comparing fitness of the resulting offspring. The effects of inbreeding differed within each population. In the more genetically diverse population, fecundity, size, and mortality were significantly reduced in inbred shrimp. In the less genetically diverse population, none of the fitness measures was significantly lowered in selfed shrimp. Combining estimates of early inbreeding depression from a previous study with current estimates of late inbreeding depression suggests that inbreeding depression is substantial (,= 0.68) in the more diverse population and somewhat lower (,= 0.50) in the less diverse population. However, given that males have higher mortality rates than hermaphrodites, neither estimate of inbreeding depression is large enough to account for the maintenance of males in either population by inbreeding depression alone. Thus, the stability of androdioecy in this system is likely only if hermaphrodites are unable to self-fertilize many of their own eggs when not mated to a male or if male mating success is generally high (or at least high when males are rare). Patterns of fitness responses in the two populations were consistent with the hypothesis that inbreeding depression is caused by partially recessive deleterious alleles, although a formal test of this hypothesis still needs to be conducted. [source] Posterior Ischemic Optic Neuropathy Associated With MigraineHEADACHE, Issue 7 2008Rod Foroozan MD Posterior ischemic optic neuropathy (PION) is an uncommon form of optic nerve ischemia that results from damage to the intraorbital, intracanalicular, or intracranial optic nerve. It has been reported perioperatively, in association with systemic vasculitis, and in the nonsurgical setting with no identifiable cause. Review of the literature reveals only 2 patients with PION associated with migraine in a single report. We report a patient who developed PION in the setting of a migraine headache without any other identifiable risk factors. [source] Glucose-6-Phosphate Dehydrogenase Deficiency Associated Stuttering Priapism: Report of a CaseTHE JOURNAL OF SEXUAL MEDICINE, Issue 12 2008David S. Finley MD ABSTRACT Aim., Stuttering priapism is an uncommon form of recurrent priapism whose etiology if often unknown. To date, there has been one report of a patient with stuttering priapism and glucose-6-phosphate dehydrogenase (G6PD) deficiency. Herein we describe the second-known case of recurrent priapism in a patient with G6PD deficiency. The pathophysiology of G6PD deficiency and its potential to cause priapism is reviewed. Methods., A case report is described of a 29-year-old African-American man with G6PD deficiency who presented with numerous episodes of recurrent ischemic priapism. Clinical data was reviewed. Results., Despite medical management with gonadotropin-releasing hormone (GnRH) agonist, an antiandrogen, and baclofen, he required several surgical procedures which also ultimately failed. A continuous phosphodiesterase type-5 inhibitor (PDE5) was started and the patient had no recurrences at 3-month follow-up. Conclusion., Idiopathic recurrent priapism may be explained by underlying hemolytic anemia associated with G6PD deficiency. Several possible mechanisms exist to explain this association, including hyperviscosity, direct endothelial dysfunction secondary to bare hemoglobin vasculotoxicity, and relative nitric oxide deficiency causing vasoconstriction and vascular smooth muscle proliferation. Finley DS. Glucose-6-phosphate dehydrogenase deficiency associated stuttering priapism: Report of a case. J Sex Med **;**:**,**. [source] Implications of amyloidosis on prostatic biopsyINTERNATIONAL JOURNAL OF UROLOGY, Issue 10 2004NATHAN LAWRENTSCHUK Abstract, Transrectal ultrasound-guided biopsy of the prostate is an integral step in the investigation of patients at risk of prostate adenocarcinoma. With an increasing number of biopsies being performed, uncommon forms of prostatic pathology will be identified more frequently. Amyloidosis of the prostate and/or the seminal vesicles may be noted on transrectal ultrasound-guided biopsy of the prostate and the implications of this histological diagnosis must be understood. We present our experience of two such cases of amyloidosis and review the literature regarding their management. [source] | ||||||||||