Refinement of detecting atrial fibrillation in stroke patients: results from the TRACK-AF Study

BACKGROUND AND PURPOSE

Detection of occult atrial fibrillation (AF) is crucial for optimal secondary prevention in stroke patients. The AF detection rate was determined by implantable cardiac monitor (ICM) and compared to the prediction rate of the probability of incident AF by software based analysis of a continuously monitored electrocardiogram at follow-up (stroke risk analysis, SRA); an optimized AF detection algorithm is proposed by combining both tools.

METHODS

In a monocentric prospective study 105 out of 389 patients with cryptogenic stroke despite extensive diagnostic workup were investigated with two additional cardiac monitoring tools: (a) 20 months' monitoring by ICM and (b) SRA during hospitalization at the stroke unit.

RESULTS

The detection rate of occult AF was 18% by ICM (n = 19) (range 6-575 days) and 62% (n = 65) had an increased risk for AF predicted by SRA. When comparing the predictive accuracy of SRA to ICM, the sensitivity was 95%, specificity 35%, positive predictive value 27% and negative predictive value 96%. In 18 patients with AF detected by ICM, SRA also showed a medium risk for AF. Only one patient with a very low risk predicted by SRA developed AF revealed by ICM after 417 days.

CONCLUSIONS

A combination of SRA and ICM is a promising strategy to detect occult AF. SRA is reliable in predicting incident AF with a high negative predictive value. Thus, SRA may serve as a cost-effective pre-selection tool identifying patients at risk for AF who may benefit from further cardiac monitoring by ICM.

Computational models for detection of endocrinopathy in subfertile males

The observation that men with sperm density greater than 10 million/ml had low probability of endocrinopathy led to a refinement in the evaluation of subfertility. Using statistical methods, we sought to provide a more accurate prediction of which patients have an endocrinopathy, and to report the outcome as the odds of having disease. In addition, by examining the parameters that influenced the model significantly, the underlying pathophysiology might be better understood. Records of 1035 men containing variables including testis volume, sperm density, motility as well as the presence of endocrinopathy were randomized into 'training' and 'test' data sets. We modeled the data set using linear and quadratic discriminant function analysis, logistic regression (LR) and a neural network. Wilk's regression analysis was performed to determine which variables influenced the model significantly. Of the four models investigated, LR and a neural network performed the best with receiver operating characteristic areas under the curve of 0.93 and 0.95, respectively, correlating to a sensitivity of 28% and a specificity of 99% for the LR model, and a sensitivity and specificity of 56 and 97% for the neural network model. Reverse regression yielded P-values for the testis volume and sperm density of <0.0001. The neural network and LR models accurately predicted the probability of an endocrinopathy from testis volume, sperm density and motility without serum assays. These models may be accessed via the Internet, allowing urologists to select patients for endocrinologic evaluation at http://www.urocomp.org.

The future of sexual medicine for the urologist

Editor's note: Winston Churchill said, 'I never worry about action, but only inaction'. Experience has taught the medical profession that action, change and adaptation are the rule as novel technologies and therapies are introduced into the mainstream of medical care. Sexual medicine is no exception. Originally thought to be psychogenic in origin, it is now well accepted that erectile dysfunction (ED) is predominately organic in origin in most middle-aged men. Treatment of organic ED has evolved with the introduction of novel, oral therapies, such as phosphodiesterase inhibitors. Adaptation has also led to incorporation of ED into the treatment realm of the primary-care physician. As sexual medicine becomes increasingly non-surgical, the challenge to the surgical specialists will reside in their ability to change and adapt to this ever-burgeoning medical discipline. Lawrence Ross, President-Elect of the American Urological Association, discusses action and change below. If urologists are to remain involved in sexual medicine, then his action plan must be brought to fruition.

Surgical sperm retrieval for assisted reproduction

Intra-cytoplasmic sperm injection (ICSI) has revolutionized the treatment of male infertility by requiring only a single sperm to allow men whose infertility was previously considered to be uncorrectable to father a biological offspring. As a result, surgical sperm retrieval for assisted reproduction has developed to support this therapy. Microsurgical techniques have been applied to either identify areas of active spermatogenesis within the testis or to aspirate sperm-containing fluid or tissue. The combination of these techniques with in vitro fertilization (IVF)/ICSI has been shown to be a powerful approach to the treatment of azoospermic men. The availability of sperm cryopreservation offers an additional advantage, negating the need for synchronization of sperm retrieval and ovulation. Thus, the advanced methods for sperm retrieval discussed in this review also provide therapeutic options, as compared the traditional diagnostic testicular biopsy.

Apoptosis in the developing zebrafish embryo

Apoptosis is a major part of the normal development of many organ systems and tissues. The zebrafish (Danio rerio) has become a useful model for studying early development, and recent advances in techniques used to label apoptotic cells have made it possible to visualize apoptotic cells in this model system. We have used the in situ terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) to describe the temporal and spatial distribution of apoptotic cells during normal development of the zebrafish embryo from 12 to 96 h postfertilization. By counting labeled apoptotic cells, we have demonstrated transient high rates of cell death in various structures during development, and we have correlated these peaks with previously described developmental changes in these structures. Our analysis has focused on the nervous system and associated sensory organs including the olfactory organ, retina, lens, cornea, otic vesicle, lateral line organs, and Rohon-Beard neurons. Apoptosis is also described in other non-neural structures such as the notochord, somites, muscle, tailbud, and fins.

The transporter-like protein inebriated mediates hyperosmotic stimuli through intracellular signaling

We cloned the inebriated homologue MasIne from Manduca sexta and expressed it in Xenopus laevis oocytes. MasIne is homologous to neurotransmitter transporters but no transport was observed with a number of putative substrates. Oocytes expressing MasIne respond to hyperosmotic stimulation by releasing intracellular Ca(2+), as revealed by activation of the endogenous Ca(2+)-activated Cl(−) current. This Ca(2+) release requires the N-terminal 108 amino acid residues of MasIne and occurs via the inositol trisphosphate pathway. Fusion of the N terminus to the rat gamma-aminobutyric acid transporter (rGAT1) also renders rGAT1 responsive to hyperosmotic stimulation. Immunohistochemical analyses show that MasIne and Drosophila Ine have similar tissue distribution patterns, suggesting functional identity. Inebriated is expressed in tissues and cells actively involved in K(+) transport, which suggests that it may have a role in ion transport, particularly of K(+). We propose that stimulation of MasIne releases intracellular Ca(2+) in native tissues, activating Ca(2+)-dependent K(+) channels, and leading to K(+) transport.

Cloning of an aquaporin-like cDNA and in situ hybridization in adults of the mosquito Aedes aegypti (Diptera: Culicidae)

A cDNA encoding a putative water channel protein, aquaporin, was cloned from a cDNA library of Aedes aegypti Malpighian tubules. The cDNA encodes a 26.11 kDa protein similar to insect aquaporins from Haematobia irritans exigua (Diptera) and Cicadella viridis (Homoptera), and to mammalian aquaporin 4. Localization of the messenger RNA (mRNA) was performed by in situ hybridization of Malpighian tubules and analysed by fluorescence and confocal microscopy. The mRNA was localized in tracheolar cells associated with the Malpighian tubules. No signal was detected in the Malpighian tubule epithelium. The molecular mechanisms for water movement between tissues and tracheoles are not yet elucidated in insects. Our results suggest a model to explain fluid movements in tracheoles during insect respiration.

Steroid induction of a peptide hormone gene leads to orchestration of a defined behavioral sequence

At the end of each molt, insects shed the old cuticle by performing preecdysis and ecdysis behaviors. Regulation of these centrally patterned movements involves peptide signaling between endocrine Inka cells and the CNS. In Inka cells, we have identified the cDNA and gene encoding preecdysis-triggering hormone (PETH) and ecdysis-triggering hormone (ETH), which activate these behaviors. Prior to behavioral onset, rising ecdysteroid levels induce expression of the ecdysone receptor (EcR) and ETH gene in Inka cells and evoke CNS sensitivity to PETH and ETH. Subsequent ecdysteroid decline is required for peptide release, which initiates three motor patterns in specific order: PETH triggers preecdysis I, while ETH activates preecdysis II and ecdysis. The Inka cell provides a model for linking steroid regulation of peptide hormone expression and release with activation of a defined behavioral sequence.

Cytosolic phospholipase A2 (cPLA2) distribution in murine brain and functional studies indicate that cPLA2 does not participate in muscarinic receptor-mediated signaling in neurons

Cytosolic phospholipase A2 (cPLA2) catalyzes the selective release of arachidonic acid from the sn-2 position of membrane phospholipids and has been suggested as an effector in the receptor-mediated release of arachidonic acid in signal transduction. The potential role of cPLA2 as an effector in muscarinic acetylcholine receptor signaling was investigated through ectopic expression of either the m1 or m5 receptor in combination with cPLA2 in COS-1, CHO and U-373 MG cell lines. U-373 MG and COS-1 cells express undetectable or very low levels of cPLA2. CHO cell extracts are characterized by a significant endogenous PLA2 activity that was increased over 20-fold following transient expression with cPLA2 cDNA. However, in none of the cells lines did the co-expression of muscarinic receptor and cPLA2 result in a significant increase in muscarinic receptor-mediated arachidonic acid release over cells expressing muscarinic receptor alone. The distribution of cPLA2 mRNA and cPLA2 immunoreactivity in murine brain were determined in order to investigate a potential role for cPLA2 in neurotransmission. cPLA2 mRNA was expressed in white matter, including cells contained within linear arrays characteristic of interfascicular oligodendrocytes. cPLA2 immunoreactivity in white matter was evident throughout the processes of fibrous astrocytes. cPLA2 expression in gray matter was confined to astrocytes at the pial surface of the brain. cPLA2 mRNA was detected in pia mater, both at the brain surface and inner core of the choroid plexus. cPLA2 may not be directly linked to neurotransmission since enzyme expression, mRNA, and cPLA2 immunoreactivity were undetectable in neurons of murine brain. Support or regulation of neurotransmission may be provided through the activity of cPLA2 in glial cells.

Cloning of the V-ATPase B subunit cDNA from Culex quinquefasciatus and expression of the B and C subunits in mosquitoes

The V-ATPase B subunit cDNA isolated from the midgut and Malpighian tubules of Culex quinquefasciatus larvae has a 1476 bp ORF encoding a 492 amino acids protein with a predicted mass of 54.8 kDa. Northern blot analysis reveals the presence of 1.8 and 4.2 kb transcripts in larvae and a 3.0 kb transcript in pupae. A single 57 kDa protein band is detected in immunoblot analysis of protein extracts from C. quinquefasciatus and A. aegypti larvae. Using antibodies to the B subunits we demonstrate high-level expression of these subunits in ion-transporting cells of caeca and anterior midgut, and in Malpighian tubules and rectum. High V-ATPase expression was also observed in the larval salivary glands, central nervous system neurophile, the thoracic endocrine complex and in imaginal discs.

Isolation of the V-ATPase A and c subunit cDNAs from mosquito midgut and Malpighian tubules

Using conserved amino acid sequences for the design of oligonucleotide primers, we isolated cDNA clones for two subunits of the V-ATPase from the midgut and Malpighian tubules of Aedes aegypti larvae. The 3.1 kb cDNA of the A subunit of the peripheral catalytic V1 sector codes for a protein of 68.6 kDa. The protein contains conserved motifs, including an ATP/GTP binding site, found in all other A subunits. Southern analysis using the A subunit as a probe suggests the presence of only a single copy of gene in the Aedes aegypti. The 0.85 kb cDNA of the c subunit of the membrane H+ conducting V0 sector codes for a protein of kDa. This protein has four transmembrane domains and contains a conserved glutamic acid that serves as the binding site for dicyclohexylcarbodiimide. Southern analysis using the c subunit as a probe suggests the presence of more than one related gene in the genome of Aedes aegypti. Pileup analysis of various A and c subunits shows that these subunits fall into distinct clusters, including one in which all arthropod proteins are clustered.

Cloning, functional expression, and pharmacology of a GABA transporter from Manduca sexta

Termination of synaptic transmission occurs by several mechanisms that include uptake of the neurotransmitter molecules into the presynaptic neuron by specialized membrane transport proteins. We have cloned a (DABA)-sensitive gamma-aminobutyric acid (GABA) transporter from a cDNA library from Manduca sexta embryo. The cDNA clone, MasGAT, shows high sequence homology to known mammalian GABA transporters. The transcript is about 5.5 kb with an open reading frame of 1793 bp. Injection of a 2.2-kb cRNA from this clone into Xenopus oocytes results in [3H]GABA transport. A Michaelis-Menten kinetic analysis shows that GABA transport occurs by a high-affinity and saturable process, suggesting that it is carrier-mediated. Ion substitution studies also show the transport process to be highly dependent on extracellular Na+ gradient, a finding that is consistent with properties of known mammalian neurotransmitter transporters. Although MasGAT shares certain pharmacological similarities with known mammalian GABA transporters, this transporter is pharmacologically distinct from the known mammalian GABA transporters.

Microsurgical epididymovasostomy: predictors of success

The results of microsurgical epididymovasostomy for congenital and acquired vasoepididymal obstruction were retrospectively reviewed in 22 patients in an attempt to determine what preoperative or intraoperative factors might predict surgical success. The overall success rate, defined as sperm on postoperative semen analysis, was 48%. The presence of sperm on an intraoperative touch preparation from the epididymis was significantly correlated with response (chi-square 3.24, p < 0.10) and no patient without sperm on touch preparation had sperm on subsequent semen analyses. Testicular biopsy positive for spermatogenesis and presence of motile sperm on intraoperative touch preparation were not statistically significant predictors of response. These results suggest that presence or absence of sperm on intraoperative touch preparation is the only significant prognosticator of successful microsurgical epididymovasostomy.

Varicocele vein ligation in 565 patients under local anesthesia: a long-term review of technique, results and complications in light of proposed management by laparoscopy

Several recent reports have suggested that laparoscopic internal spermatic vein ligation provides a simpler, less debilitating and more cost efficient method of varicocele ligation than conventional surgical techniques. We analyzed the results of open varicocele ligation using local anesthesia in 565 patients for 10 years. All surgery was performed in the outpatient setting using 0.5% lidocaine. In most patients 50 to 200 mcg. fentanyl or 3 to 7 mg. midazolam were used for intravenous sedation. The average operating time, including the administration of anesthesia, was 39 minutes for unilateral and 71 minutes for bilateral procedures. All patients returned to light duty work in 24 to 48 hours and full strenuous physical activity within 1 week. The only complications encountered were 2 wound hematomas (0.3%), 4 minor wound separations (0.7%) and 41 hydroceles (7.3%). Semen improvement and pregnancy rates were similar to those reported in prior series. This study demonstrates that varicocele vein ligation can be done rapidly, efficiently and safely using local anesthesia with time of recovery and return to work comparable to those reported for laparoscopic techniques.

Vasovasostomy in rabbits using fibrin adhesive prepared from a single human source

We were interested in determining whether fibrin glue derived from a single human source could be used effectively to produce a sutureless vasovasostomy in the rabbit model. Fifteen rabbits were divided into two groups (7 control, 8 experimental) and underwent vasal transection and reanastomosis by conventional microsurgical suture techniques (control group) and sutureless anastomosis using single source fibrin glue (experimental group). The patency and tensile strength of the anastomoses were compared at four weeks and the anastomotic sites underwent histologic examination. This study demonstrated that a vasovasal anastomosis in the rabbit could be achieved using human single source fibrin glue with patency equivalent to a standard sutured anastomosis. The tensile strength of the glued anastomosis at four weeks was greater than the tensile strength of the sutured anastomosis.

Initial tract formation in the mouse brain

Mouse embryos from embryonic days 8.5-10.5 (E8.5-E10.5) were fixed and labeled with an antibody to neuron-specific class III beta-tubulin (Moody et al., 1987; Lee et al., 1990a,b) to reveal the first neurons, axons, and tracts in the brain. They were studied in whole-mounts and in light microscopic sections. Some conclusions were checked by labeling tracts in older embryos (E11.5 and E12.5) with the lipophilic dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine. The first immunoreactive cells appeared at E8.5, prior to neural tube closure, in the neural plate immediately caudal to the optic vesicle. Cells along the dorsal midline of the mesencephalon issued the first axons, on E9.0; the cells were the mesencephalic nucleus of the trigeminal nerve, and the axons formed its descending tract. The tract reached the level of the trigeminal ganglion by E10.0 but did not enter the ganglion until after E12.5. On E9.5, the number of labeled cells and axons in the alar plate of the presumptive diencephalon and mesencephalon had increased substantially, and many of the rostral ones coursed into the basal plate to enter longitudinal tracts there. Two tracts originated from cells in the basal plate: the tract of the postoptic commissure (from the base of the optic stalk to the level of the cephalic flexure) and the medial longitudinal fasciculus (from the level of the cephalic flexure caudally through the mid and hind-brains). By E10.0, a small mammillotegmental tract paralleled the tract of the postoptic commissure, but immunolabeling was so widespread that discrete tracts were impossible to discern in the presumptive diencephalon and mesencephalon. The more rostral regions remained lightly labeled. In the cerebral vesicle, the presumptive cerebral cortex, the first immunoreactive cells appeared at E10.0; they had multiple processes oriented parallel to the pia, and were identified as the Cajal-Retzius cells. By E10.5, no tracts had formed in the cerebral vesicle. All the tracts formed by E10.0 were superficial, in the subpial lamina. Those that can be identified in the adult brain are very deep structures. These results are compared with previous descriptions of the embryonic brains of amphibians, fish, birds, and other mammals, including humans.

Axonogenesis and morphogenesis in the embryonic zebrafish brain

We have examined early neuronal differentiation and axonogenesis in the fore- and midbrain of zebrafish embryos to address general issues of early vertebrate brain development. AChE expression and HNK-1 antibody immunoreactivity were used as markers for differentiated neurons and axons, respectively. The pattern of neuronal differentiation followed a stereotyped sequence. AChE-positive cells first appeared between 14 and 16 hr in three small, isolated, bilaterally symmetrical clusters on the surface of the brain. The three clusters--the dorsorostral, ventrorostral, and ventrocaudal clusters--proved to be the progenitors of the telencephalon, ventral diencephalon, and mesencephalic tegmentum, respectively. With further development, more cells were added to these three clusters, and new clusters appeared in the anlage of the epiphysis (18 hr) and in the pituitary and dorsal mesencephalon (by 24 hr). Subsequently, as more neurons differentiated, the gaps of unlabeled cells were reduced; by 48 hr, the cluster boundaries were indistinguishable. Axonogenesis also followed a stereotyped sequence. The first HNK-1-labeled processes arose from the first three clusters of AChE-positive cells and connected the clusters. The earliest axonal growth cones appeared at 16 hr, directed caudally from two to three neurons of the ventrocaudal cluster and pioneering the ventral longitudinal tract. By 18 hr, the tract of the postoptic commissure was initiated by growth cones directed caudally from the ventrorostral cluster toward the ventrocaudal cluster. By 20 hr, axons from the dorsorostral cluster projected ventrally to form the supraoptic tract. The other dorsoventral tracts (the dorsoventral diencephalic tract and the tract of the posterior commissure) became evident between 20 and 24 hr. These observations provide a continuous record of the topological distortions involved in the conversion of the tubular embryonic brain into the contorted adult form. The telencephalon, ventral diencephalon, and hypothalamus originate from the same rostrocaudal level of the neural tube. The pattern of differentiation demonstrated that the early development of the rostral neural tube occurs simultaneously in several independent centers, similar to the overtly segmental development of the hindbrain.

Molecular cloning and characterization of the B subunit of a vacuolar H(+)-ATPase from the midgut and Malpighian tubules of Helicoverpa virescens

Using the polymerase chain reaction (PCR) a 0.8-kb product was amplified from cDNA made from the midgut and Malpighian tubules of fifth instar larvae of Helicoverpa virescens. This 0.8-kb PCR product was then used to isolate a clone of the B subunit of the V-type ATPase from a cDNA library made from the same tissues. The cDNA clone encodes for a protein of 55 kDa which shows very high amino acid homology to other known B subunits of V-type ATPases. The transcript size of the B subunit in the midgut of H. virescens was 2.3 kb, and a transcript of identical size was also detected in the Malpighian tubules. Northern blot analysis revealed the presence of a homologous transcript of 2.6 kb in the midgut of Manduca sexta and PCR analysis also confirmed the presence of such a transcript in the Malpighian tubules and the nervous system of M. sexta, and in the midgut Malpighian tubules of Culex quinquefasciatus. The presence of the V-type ATPase in the Malpighian tubules of lepidopteran insects suggests that the transport of ions across the cell membrane in this tissue is also probably driven by a similar process as that observed in the midgut of these insects.

Azoospermia: a complication of hydrocele repair in a fertile population

Although minor complications have been reported, hydrocelectomy generally is considered to be a safe procedure. We recently treated 3 patients who became azoospermic after hydrocele repair. Of the patients 2 underwent bilateral and 1 unilateral hydrocelectomy. All 3 patients had iatrogenic injury to the vas deferens or epididymis after hydrocele repair.

The development of a simple scaffold of axon tracts in the brain of the embryonic zebrafish, Brachydanio rerio

We have examined neuronal differentiation and the formation of axon tracts in the embryonic forebrain and midbrain of the zebrafish, between 1 and 2 days postfertilisation. Axons were visualised with three techniques; immunocytochemistry (using HNK-1 and antiacetylated tubulin antibodies) and horseradish peroxidase (HRP) labelling in whole-mounted brains, and transmission electron microscopy. Differentiation was monitored by histochemical staining for acetylcholinesterase (AChE). These independent methods demonstrated that a simple grid of tracts and commissures forms the initial axon scaffold of the brain. At 1 day, the olfactory nerve, four commissures, their associated tracts and three other non-commissural tracts are present. By 2 days, these tracts and commissures have all greatly enlarged and, in addition, the optic nerve and tract, and three new commissures and their associated tracts have been added. Small applications of HRP at various sites revealed the origins and projections of some of these earliest axons. Retrogradely labelled cell bodies originated from regions that were also positive for AChE activity. At 1 day, HRP-labelled axons were traced: (1) from the olfactory placode through the olfactory nerve to the dorsal telencephalon; (2) from the telencephalon into the tract of the anterior commissure and also to the postoptic region of the diencephalon; (3) from the hindbrain through the ventral midbrain and diencephalon to the postoptic commissure; (4) from the dorsal diencephalon (in or near the epiphysis) to the tract of the postoptic commissure; (5) from ventral and rostral midbrain through the posterior commissure. Three new projections were demonstrated at 2 days: (1) from the retina through the tract of the postoptic commissure to the tectum; (2) from the telencephalon to the contralateral diencephalon; and (3) from the telencephalon to the ventral flexure. These results show that at 1 day, the zebrafish brain is impressively simple, with a few small, well-separated tracts but by 2 days the brain is already considerably more complex. Most of the additional axons added onto pre-existent tracts rather than pioneered new ones supporting the notion that other axons play a crucial role in the guidance of early central nervous system (CNS) axons.

Initial clinical trials with a tubless lithotriptor

The Medstone 1050 is a new tubeless lithotriptor developed in the United States. Under Food and Drug Administration guidelines a human treatment protocol has been developed. The first 50 patients treated at a single site and followed for a minimum of 3 months are presented. All stones treated were 3 cm. or less in longest dimension and located in the renal pelvis, calices or proximal ureter. An adequate fragmentation rate of 90% was achieved in this group. There were no significant complications in any patient. A larger multicenter study presently is underway.

Differential ascending projections to aural regions in the 60 kHz contour of the mustache bat's inferior colliculus

The inferior colliculus of the mustache bat is similar in many respects to the inferior colliculus of more commonly studied mammals. However, the isofrequency contour devoted to processing 60 kHz, the dorsoposterior division (DPD) is greatly expanded, encompassing an area approximately equal to one-third of the central nucleus. Of particular significance is that monaural and binaural neurons are segregated in the DPD into 4 spatially distinct aural regions. In this study we exploit the great enlargement of the 60 kHz region in the central nucleus of the inferior colliculus (ICc) of the mustache bat to determine the source of ascending projections to the 4 different aural regions of the DPD. Small iontophoretic deposits of HRP were made within each of the physiologically defined aural regions, and the locations and numbers of retrogradely labeled cells in the auditory brainstem nuclei were determined. Two major features of collicular organization were found. The first is that each aural region receives a unique set of projections from a subset of lower auditory nuclei and thus is distinguished both by its neural response properties and by the pattern of ascending projections it receives. The dorsomedial EE region receives inputs primarily from the ipsilateral intermediate nucleus of the lateral lemniscus (INLL) and ventral nucleus of the lateral lemniscus (VNLL), and the contralateral ICc. In contrast, the ventrolateral EE region receives projections from the ipsilateral medial superior olivary nucleus (MSO), VNLL, and INLL. The inputs to the EI region originate primarily from the dorsal nucleus of the lateral lemniscus (DNLL) and lateral superior olivary nucleus (LSO) bilaterally and from the ipsilateral INLL. The afferents to the EO region include the contralateral cochlear nucleus, the ipsilateral VNLL and INLL and MSO. The second major organizational feature is that the binaural nuclei of the brain-stem project upon the DPD in a more restricted manner than do some of the lower monaural nuclei, such as the VNLL and INLL, which project in a more widespread manner. The unique set of projections terminating in each aural region of the DPD suggests that the neurons should have substantially different properties, even when neurons in different regions are of the same general aural type. Moreover, the elucidation of the micro-organization of the DPD provides insights into the different ways that binaural properties of DPD neurons are created by the convergence of inputs from particular subsets of lower auditory nuclei.(ABSTRACT TRUNCATED AT 400 WORDS)

Origin of ascending projections to an isofrequency region of the mustache bat's inferior colliculus

The inferior colliculus of the mustache bat is similar in most respects to the inferior colliculus of more commonly studied mammals, but one isofrequency contour, the dorsoposterior division, is greatly overrepresented. The present study utilizes this specialization of the auditory system in the mustache bat to determine the total set of ascending projections to a single isofrequency contour of the inferior colliculus. Within the dorsoposterior division, neurons are all very narrowly tuned to 60 kHz, the major component of this bat's echolocation call. The afferent projections to this isofrequency contour were identified by making deposits of horseradish peroxidase (HRP) within the dorsoposterior division after physiologically defining its borders. Two other frequency representations are present in the central nucleus of the inferior colliculus of the mustache bat, the anterolateral division in which there is an orderly progression of frequencies from 59 down to 20 kHz, and the medial division in which frequencies from 63-120 kHz are represented. In additional experiments, the afferent projections to the medial and anterolateral divisions were examined, providing an anatomical description of the tonotopicity of the lower auditory nuclei. Deposits of HRP in the DPD labeled cells in each of the lower brainstem auditory nuclei that have previously been shown to project to the entire central nucleus of the inferior colliculus. The ascending projections to the dorsoposterior division include contralateral projections from the cochlear nucleus and inferior colliculus, ipsilateral projections from the medial superior olive, ventral and intermediate nuclei of the lateral lemniscus, and bilateral projections from the lateral superior olive and dorsal nucleus of the lateral lemniscus. In most of the nuclei, labeled cells were confined to specific portions of the nuclei, often forming "slabs" of labeled cells across the rostrocaudal extent of most nuclei. These slabs presumably represent the 60 kHz representation in each of the lower nuclei. When deposits of HRP were made into other frequency band representations of the inferior colliculus, in either the medial or anterolateral division, labeled cells again formed slabs in each lower nucleus. However, the location of the slab varied as a function of the best frequency of neurons at the deposit site, and labeled cells were not present within the 60 kHz representation. These results show the general tonotopy of the mustache bat's brainstem auditory nuclei, and with respect to the dorsoposterior division, clearly reveal the total set of projections to a single isofrequency region.(ABSTRACT TRUNCATED AT 400 WORDS)

Base analogue mutagenesis in yeast and its modulation by pyrimidine deoxynucleotide pool imbalances: incorporation of bromodeoxyuridylate and iododeoxyuridylate

Cells of the yeast, Saccharomyces cerevisiae, which are auxotrophic for thymidylate (tmpl) can also incorporate analogues of thymidylate. When the base analogue, 5-bromodeoxyuridylate, is incorporated into tmpl yeast cells it is lethal and mutagenic. Both lethality and mutation induction can be drastically altered by perturbation of the pyrimidine nucleotide pools. Analysis of mutation induction, bromodeoxyuridylate incorporation into DNA, and cell viability under various conditions revealed: (1) lethality and mutagenesis can be uncoupled, (2) thymidylate enhances mutagenesis and deoxycytidylate suppresses it, (3) mutation induction is not correlated with the magnitude of bromodeoxyuridylate incorporation into DNA. Therefore, in yeast, the pyrimidine nucleotide pools have a powerful effect on bromodeoxyuridylate mutagenesis. Both bromodeoxyuridylate and iododeoxyuridylate are extensively incorporated into the DNA of tmpl yeast cells; however, iododeoxyuridylate is non-mutagenic. Replication proceeds at the same rate in the presence of the natural substrate or either analogue. When cells are supplied with thymidylate and bromodeoxyuridylate together, there is no discrimination against bromodeoxyuridylate as a DNA precursor. However, in the presence of thymidylate and iododeoxyuridylate, there is a 3 to 1 discrimination against iododeoxyuridylate as compared to thymidylate.

Alloplastic spermatoceles: a 5-year experience

We implanted 14 alloplastic spermatoceles in 8 patients with congenital absence or atresia of the vas deferens or anejaculation. The surgical technique and results of aspirations are detailed. Five spermatoceles yielded sperm: 2 for prolonged periods (4 1/2 to 11 months) and 1 produced motile sperm considered adequate for artificial insemination.

Binaural response organization within a frequency-band representation of the inferior colliculus: implications for sound localization

The auditory system of the mustache bat (Pteronotus parnellii) contains a disproportionately large representation of a narrow frequency band, corresponding to the dominant, 60 kHz component of its echolocation signal. In the inferior colliculus (IC), the 60 kHz representation comprises an architectonically distinct region called the dorsoposterior division (DPD), which is accessible for detailed physiological study. We examined the topographic distribution of binaural responses within this one frequency-band representation of the inferior colliculus. We describe two primary results. First, neurons with different binaural response properties are spatially segregated into one of four binaural response-specific regions of the DPD: a large region of monaural (EO) responses; two regions containing neurons excited by sound from both ears (EE); and a region containing neurons excited by one ear and inhibited by the other (EI). Regions dominated by 60 kHz EI responses are also found in the lateral extremity of the IC, probably within the external nucleus. These results demonstrate functionally defined subdivisions in a single frequency-band representation of the IC. Moreover, they suggest that brain stem auditory projections to the DPD and/or intrinsic connections within the DPD are highly organized. Second, within the EI region of the DPD, there is a systematic shift in the sensitivity of EI multiunit responses to interaural intensity disparities (IIDs). Dorsally, EI neurons are suppressed only by relatively loud ipsilateral sounds, and there is a systematic decrease in the relative ipsilateral intensity required for suppression at more ventral recording sites. This result demonstrates that neurons sensitive to a sound localization cue are systematically organized within a frequency-band representation of the inferior colliculus. It has implications for the manner in which the location of a sound source is encoded within the primary auditory pathway.

Evaluation and treatment of the infertile man

Increasing numbers of patients are seeking treatment for infertility. The primary care physician is often the first professional to face this diagnostic challenge. Recent developments in the diagnosis and treatment of the infertile man have led to increased success in management of the infertile couple. This article reviews these developments.

Properties of human epididymal sperm obtained from an alloplastic spermatocele: motility assessment and penetration of zona-free hamster oocytes in the presence and absence of caffeine

Sperm were collected over a period of months from a human alloplastic spermatocele implanted at the corpus/caudal epididymal junction and were evaluated for their maturity, motility, and ability to capacitate and acrosome react, as assessed by the hamster zona-free oocyte sperm penetration assay (SPA). A mean of 11 X 10(6) sperm were obtained with each aspiration, with 34% to 40% being mature, normal forms. Motility was poor; 15% +/- 5% showing nonprogressive movement. SPA results were 22% +/- 3% oocyte penetration. Addition of 7.5 mM caffeine markedly enhanced motility and improved the SPA results. After 30 minutes' exposure, the motility was 45% +/- 5%, with all spermatozoa exhibiting progressive movement. This stimulation was maintained over a 24-hour period. When caffeine was present during the 2-hour preincubation for the SPA, penetration rates increased to 50% +/- 10% (P less than 0.05). These results demonstrate that the poor-quality sperm retrieved from a human alloplastic spermatocele can be improved with exogenous stimulation and suggest that their fertilizing capacity may be enhanced by this treatment.

A functional organization of binaural responses in the inferior colliculus

Binaural responses are segregated within an enlarged isofrequency region of the mustache bat's inferior colliculus. In the part of this region containing E-I responses, there is an orderly shift in the sensitivity of unit clusters to interaural intensity disparities, having implications for the representation of auditory space within isofrequency regions of the inferior colliculus.

Routine hormonal screening of infertile men: is it worthwhile?

More than 800 men referred for infertility have been evaluated in a male infertility clinic. Routine hormonal screening of these patients has included at various times thyroid function studies, 24-hour urine samples for 17-ketosteroids and pregnanetriol, serum dehydroepiandrosterone-sulfate, serum 17-alpha-hydroxy progesterone, testosterone and prolactine in some instances. The results of this hormonal screening are analyzed and discussed from the point of view of positive diagnostic findings and success of treatment. An outline and recommendations for the routine use of such studies are made.

Clomiphene treatment of the idiopathic hypofertile male: high-dose, alternate-day therapy

Increasing reports suggest that clomiphene citrate (clomid) is useful in the treatment of idiopathic hypofertile males. Recent studies have advocated low-dose, cyclic therapy (25 mg daily for 25 days, 5 days' rest) and, although significant clinical responses have been reported, the hormone response has been erratic. This study of 53 patients, given high-dose, alternate-day therapy (100 mg three times/week), shows an over-all positive response rate of 66% and a pregnancy rate of 26%. Significant gonadotropin and testosterone surges were seen in the responders, but a selective lack of a follicle-stimulating hormone surge was noted in a small group of nonresponders. Clomiphene given in this dosage seems to be safe for periods of up to 15 months and appears to be a rational and useful agent for the treatment of this patient group.

What about the other kidney?

Sophisticated diagnostic techniques have made the isolation of renal lesions more accurate. However, it must be remembered that simultaneous bilateral kidney pathology can exist in any patient. The most obvious lesion may not be the most important. Four cases are presented to illustrate this point.

Effect of metabolic inhibitors on vasopressin-stimulated transport systems in the toad bladder

Vasopressin increases the permeability of receptor cells to water and, in tissues such as toad bladder, to solutes such as urea. While cyclic AMP appears to play a major role in mediating the effects of vasopressin, there is evidence that activation of the water permeability system and the urea permeability system involves separate pathways. In the present study, we have shown that inhibitors of oxidative metabolism (rotenone, dinitrophenol, and methylene blue) selectively inhibit either vasopressin-stimulated water flow or vasopressin-stimulated urea transport. There was no inhibition, however, when exogenous cyclic AMP was substituted for vasopressin, and little to no inhibition when the potent analogue 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP) was employed. Rotenone had no effect on adenylate cyclase activity or cyclic AMP levels within the cell; dinitrophenol decreased adenylate cyclase activity minimally. Additional studies with vinblastine and nocodazole, inhibitors of microtubule assembly, demonstrated an inhibition of vasopressin and cyclic AMP-stimulated water flow but showed no effect on urea transport. We would conclude that water and urea transport, as examples of hormone-stimulated processes, have different links to cell metabolism, and that in addition to cyclic AMP, a non-nucleotide pathway may be involved in the action of vasopressin.

Epidermoid cysts of testis: rationale for conservative management

The literature on epidermoid cyst of the testis is reviewed, and 2 additional cases are presented. Etiology and pathology of the disease are discussed. Our review revealed that 85 per cent of patients have undergone orchiectomy for this benign disease. Diagnostic characteristics of this lesion are emphasized so that in selected cases enucleation of the pidermoid cyst may be considered without violating the principles of cancer surgery.