Mouse homologues of the human AZF candidate gene RBM are expressed in spermatogonia and spermatids, and map to a Y chromosome deletion interval associated with a high incidence of sperm abnormalities

An RNA-binding motif (RBM) gene family has been identified on the human Y chromosome that maps to the same deletion interval as the 'azoospermia factor' (AZF). We have identified the homologous gene family (Rbm) on the mouse Y with a view to investigating the proposal that this gene family plays a role in spermatogenesis. At least 25 and probably >50 copies of Rbm are present on the mouse Y chromosome short arm located between Sry and the centromere. As in the human, a role in spermatogenesis is indicated by a germ cell-specific pattern of expression in the testis, but there are distinct differences in the pattern of expression between the two species. Mice carrying the deletion Yd1, that maps to the proximal Y short arm, are female due to a position effect resulting in non-expression of Sry ; sex-reversing such mice with an Sry transgene produces males with a high incidence of abnormal sperm, making this the third deletion interval on the mouse Y that affects some aspect of spermatogenesis. Most of the copies of Rbm map to this deletion interval, and the Yd1males have markedly reduced Rbm expression, suggesting that RBM deficiency may be responsible for, or contribute to, the abnormal sperm development. In man, deletion of the functional copies of RBM is associated with meiotic arrest rather than sperm anomalies; however, the different effects of deletion are consistent with the differences in expression between the two species.      

Compartmentation of glycolysis and glycogenolysis in the perfused rat heart

Developing methods that can detect compartmentation of metabolic pathways in intact tissues may be important for understanding energy demand and supply. In this study, we investigated compartmentation of glycolysis and glycogenolysis in the isolated perfused rat heart using (13)C NMR isotopomer analysis. Rat hearts previously depleted of myocardial glycogen were perfused with 5.5 mm [U-(13)C]glucose plus 50 mU/mL insulin until newly synthesized glycogen recovered to new steady-state levels ( approximately 60% of pre-depleted values). After a short wash-out period, the perfusate glucose was then switched to [1-(13)C]glucose, and glycolysis and glycogenolysis were stimulated by addition of glucagon (1 microg/ml). A (13)C NMR multiplet analysis of the methyl resonance of lactate provided an estimate of pyruvate derived from glucose vs glycogen while a multiplet analysis of the C4 resonance of glutamate provided an estimate of acetyl-CoA derived from glycolytic pyruvate vs glycogenolytic pyruvate. These two indices were not equivalent and their difference was further magnified in the presence of insulin during the stimulation phase. These combined observations are consistent with functional compartmentation of glycolytic and glycogenolytic enzymes that allows pyruvate generated by these two processes to be distinguished at the level of lactate and acetyl-CoA.     

Synthesis and properties of photocross-linked poly(propylene fumarate) scaffolds

The photocross-linking of poly(propylene fumarate) (PPF) to form porous scaffolds for bone tissue engineering applications was investigated. PPF was cross-linked using the photoinitiator bis(2,4,6-trimethylbenzoyl) phenylphosphine oxide (BAPO) and exposure to 30 min of long wavelength ultraviolet (UV) light. The porous photocross-linked PPF scaffolds (6.5 mm diameter cylinders) were synthesized by including a NaCl porogen (70, 80, and 90 wt% at cross-linking) prior to photocross-linking. After UV exposure, the samples were placed in water to remove the soluble porogen, revealing the porous PPF scaffold. As porogen leaching has not been used often with cross-linked polymers, and even more rarely with photoinitiated cross-linking, a study of the efficacy of this strategy and the properties of the resulting material was required. Results show that the inclusion of a porogen does not significantly alter the photoinitiation process and the resulting scaffolds are homogeneously cross-linked throughout their diameter. It was also shown that porosity can be generally controlled by porogen content and that scaffolds synthesized with at least 80 wt% porogen possess an interconnected pore structure. Compressive mechanical testing showed scaffold strength to decrease with increasing porogen content. The strongest scaffolds with interconnected pores had an elastic modulus of 2.3+/-0.5 MPa and compressive strength at 1% yield of 0.11+/-0.02 MPa. This work has shown that a photocross-linking/porogen leaching technique is a viable method to form porous scaffolds from photoinitiated materials.     

L1 knockout mice show dilated ventricles, vermis hypoplasia and impaired exploration patterns

L1 is a neural cell adhesion molecule mainly involved in axon guidance and neuronal migration during brain development. Mutations in the human L1 gene give rise to a complex clinical picture, with mental retardation, neurologic abnormalities and a variable degree of hydrocephalus. Recently, a transgenic mouse model with a targeted null mutation in the L1 gene was generated. These knockout (KO) mice show hypoplasia of the corticospinal tract. Here we have performed further studies of these KO mice including magnetic resonance imaging of the brain, neuropathological analysis and behavioral testing. The ventricular system was shown to be abnormal with dilatation of the lateral ventricles and the 4th ventricle, and an altered shape of the Sylvius aqueduct. Additionally, the cerebellar vermis of the KO mice is hypoplastic. Their exploratory behavior is characterized by stereotype peripheral circling reminiscent of that of rodents with induced cerebellar lesions.      

Characterization of Wolbachia infections and interspecific crosses of Aedes (Stegomyia) polynesiensis and Ae. (Stegomyia) riversi (Diptera: Culicidae)

Prior studies have identified a complicated pattern of interspecific hybridization between members of the Aedes (Stegomyia) scutellaris (Walker) mosquito group, which includes medically important vectors of bancroftian filariasis and dengue. Here, we report that two members of the group, Aedes polynesiensis Marks and Aedes riversi Bohart & Ingram, are both infected with intracellular Wolbachia bacteria. Sequencing of the Wolbachia wsp gene demonstrates that the infections differ from each other and from Wolbachia infections previously reported in mosquitoes. Aedes polynesiensis is the first mosquito identified with a wMel Wolbachia type. Intraspecific crosses of infected and aposymbiotic lines generated via antibiotic treatment show that the Wolbachia infections in both species cause high levels of cytoplasmic incompatibility. Interspecific crosses show that the two species are reproductively isolated. However, repeating the interspecific crosses with aposymbiotic mosquito strains demonstrates that the Wolbachia infections play a role in preventing hybrid offspring. We discuss Wolbachia infections in relation to better defining the evolutionary relationships and causes of speciation within the group, understanding the basis for the observed east-to-west gradient in filarial refractoriness, and developing novel genetic control measures.     

Mycobacterium chelonae causing otitis media in an ear-nose-and-throat practice

Seventeen cases of otitis media caused by Mycobacterium chelonae were detected among patients seen at a single ear-nose-and-throat (ENT) office (Office A) in Louisiana between May 5 and September 15, 1987. All the patients had a tympanotomy tube or tubes in place or had one or more tympanic-membrane perforations, with chronic otorrhea that was unresponsive to standard therapy with antimicrobial agents. Middle-ear exploration in six patients revealed abundant granulation tissue; multiple granulomas and acid-fast bacilli were demonstrated on a section of tissue from one patient with a nonhealing mastoidectomy incision. Thirteen of the 14 ear isolates obtained from patients seen in Office A had the same unusual pattern of high-level resistance to aminoglycosides. M. chelonae and other nontuberculous mycobacteria were recovered from several sources of water in Office A, as well as in another ENT office (Office B) in a neighboring city that was visited by the index patient. Only one additional case was detected in Office B during the same period. Otologic instruments in Office A were cleaned in an ultrasonic bath with tap water and a liquid detergent; the contents of the bath were changed only once weekly. Instruments in Office B were placed in boiling water between patient examinations. This outbreak establishes M. chelonae as an agent of otitis media and underscores the need for high-level disinfection or sterilization of ENT instruments between examinations to prevent the transmission of this organism to patients in the office setting.     

Psychosocial factors related to long-term survival with HIV/AIDS

Only a few studies of long-term survivors of AIDS (those who survive more than twice the median expected time) have been done but these reveal a constellation of psychological characteristics including, but not limited to, those with active coping, social support, life involvement, ability to communicate, and active collaboration with one's doctor. Another related literature consists of longitudinal studies following people infected with the HIV virus to determine whether psychological characteristics are related to disease progression. These studies have focused on coping, depression, negative expectancies and social support as predictors. This article reviews and integrates the two bodies of literature combining the variables identified into four psychosocial strategies related to longer survival with HIV/AIDS: following healthy self care; maintaining connectedness; having a sense of meaning or purpose in life; and maintaining perspective. Affect, beliefs, and behaviour are all seen as important. Biological variables, SES and psychological resources that the person brings to the situation and external stresses are seen as important variables to consider in prediction studies. The pathways through which these four strategies may operate (both psychological and biological) to impact on health are discussed. Psychological pathways include distress and behavioural disengagement, while biological pathways involve the sympathetic nervous system, neuroendocrine and immune mediation. Finally suggestions for future research are given.