Nasal field loss in cats reared with convergent squint: behavioural studies.

1. The extent of the monocular visual field in cats reared with convergent squint in one eye was determined by a behavioural perimetry technique. 2. Significant reduction in the extent of the visual field was found in the squinting eyes. 3. The visual field defect is a graded one, located mainly in the nasal field, but in some cats extending into the temporal visual field. The defect includes a zone of absolute loss of response to stimuli at the extreme nasal field, adjacent areas of partial response and areas of 100% response in the periphery of the temporal field. 4. A direct relationship was found between the angle of horizontal deviation of the squinting eye and the amount of visual field loss: i.e. the larger the angle of squint, the greater the loss of nasal field. 5. It is suggested that the process leading to a loss in nasal visual field is independent of the loss of visual acuity in squinting cats, since the latter is not related to the angle of squint. 6. The significant loss in nasal visual field found by behavioural experiments in cats reared with a convergent squint thus correlates with comparable deficits found in the physiology and morphology of the lateral geniculate nucleus (Ikeda, Plant & Tremain, 1977), although the behaviourally determined loss of nasal field is greater than would be expected from the study of the response of the LGN neurones.     

Pulmonary granuloma caused by Pseudomonas andersonii sp nov

Pulmonary granuloma is a common lesion for which gram-negative bacteria are rarely implicated as a cause. Hence, most physicians are unaware of this etiology. We isolated a gram-negative bacterium from a surgically resected pulmonary granuloma in a 42-year-old, nonimmunocompromised woman. Within the necrotizing granuloma, numerous organisms also were demonstrated by Gram stain, suggesting a cause-disease relationship. Characterization of the bacterium by sequence analysis of the 16S ribosomal gene, cellular fatty acid profiling, and microbiologic studies revealed a novel bacterium with a close relationship to Pseudomonas. We propose a new species for the bacterium, Pseudomonas andersonii. These results suggest that the differential diagnosis of a lung granuloma also should include this gram-negative bacterium as a potential causative agent, in addition to the more common infections caused by acid-fast bacilli and fungi. This bacterium was shown to be susceptible to most antibiotics that are active against gram-negative bacteria.     

Enhanced 3D PET OSEM reconstruction using inter-update Metz filtering

We present an enhancement of the OSEM (ordered set expectation maximization) algorithm for 3D PET reconstruction, which we call the inter-update Metz filtered OSEM (IMF-OSEM). The IMF-OSEM algorithm incorporates filtering action into the image updating process in order to improve the quality of the reconstruction. With this technique, the multiplicative correction image--ordinarily used to update image estimates in plain OSEM--is applied to a Metz-filtered version of the image estimate at certain intervals. In addition, we present a software implementation that employs several high-speed features to accelerate reconstruction. These features include, firstly, forward and back projection functions which make full use of symmetry as well as a fast incremental computation technique. Secondly, the software has the capability of running in parallel mode on several processors. The parallelization approach employed yields a significant speed-up, which is nearly independent of the amount of data. Together, these features lead to reasonable reconstruction times even when using large image arrays and non-axially compressed projection data. The performance of IMF-OSEM was tested on phantom data acquired on the GE Advance scanner. Our results demonstrate that an appropriate choice of Metz filter parameters can improve the contrast-noise balance of certain regions of interest relative to both plain and post-filtered OSEM, and to the GE commercial reprojection algorithm software.     

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.      

The complexity of HLA class II (DRB1, DQB1, DM) associations with disseminated Mycobacterium avium complex infection among HIV-1-seropositive whites

Earlier associations of polymorphism in classic HLA class II (DRB1 and DQB1) genes have been extended to include the accessory genes DMA and DMB as determinants of disseminated Mycobacterium avium complex (DMAC) infection among HIV-1-seropositive whites. From the Multicenter AIDS Cohort study, 176 DMAC cases were matched with 176 controls in a nested case-control study. PCR-based HLA genotyping techniques were used to resolve variants of DRB1 and DQB1 to their four-digit or five-digit alleles, and single-strand conformation polymorphism was used to resolve sequences in exon 3 at each DM locus. The DMA*0102 allele occurred less frequently among DMAC cases than among controls (OR = 0.46, p =.02). Combinations of DRB1 alleles with or without specific DMA and DMB variants showed significant differences in distributions between the cases and controls, but both of the previously associated class II alleles (DRB1*1501 and DRB1*0701) showed stronger positive associations with DMAC in the absence than in the presence of DMA*0102. Apparent joint effects of DRB1 and DM allelic combinations on occurrence and timing of DMAC suggest that class II disease relationships may be better predicted by biologically plausible interactive combinations than by polymorphisms in individual genes.     

Short-term effects of streptozotocin-induced diabetes on the electrocardiogram, physical activity and body temperature in rats

A variety of contractility defects have been reported in the streptozotocin (STZ)-induced diabetic rat heart including alterations to the amplitude and time course of cardiac muscle contraction. Transmitter devices were surgically implanted in the peritoneal cavity of young adult male Wistar rats. Electrodes from the transmitter were arranged in Einthoven bipolar lead II configuration. Electrocardiogram (ECG), physical activity and body temperature data were continuously recorded with a telemetry system before and following the administration of STZ (60 mg kg-1). Heart rate (HR), physical activity and body temperature declined rapidly 3-5 days after administration of STZ. The effects became more conspicuous with time and reached a new steady state approximately 10 days after STZ treatment when HR was 255+/-8 beats min-1 in diabetic rats compared to 348+/-17 beats min-1 in age-matched controls. Heart rate variability (HRV) was also significantly reduced after STZ treatment (18+/-3 beats min-1) compared to controls (36+/-3 beats min-1). Reduced physical activity and/or body temperature may partly underlie the reduction in HR and HRV. Reductions in power spectral density at higher frequencies (2.5-3.5 Hz) suggest that parasympathetic drive to the heart may be altered during the early stages of STZ-induced diabetes. Short-term diabetes-induced changes in vital signs can be effectively tracked by continuous recording using a telemetry system.     

Nitric oxide mediates intestinal hyperaemic responses to intraluminal bile-oleate

It has long been recognized that intestinal blood flow increases at mealtimes. Mesenteric hyperaemia is also evoked by activation of sensory peptidergic nerves. Our studies explored the possible role of endogenous nitric oxide (NO) in the rat intestinal vasodilator response to luminal instillation of an oleic acid plus bile mixture before and after acute intrajejunal instillation of capsaicin and after chronic pretreatment with capsaicin. In anaesthetized rats we measured jejunal blood flow (BF) with an ultrasonic Doppler flowmeter and systemic arterial pressure (AP) with a pressure transducer. Intestinal perfusion with 80 mM oleic acid in bile increased BF by 98±12%. Instillation of 4 mg of capsaicin into the jejunal lumen initially increased BF by 42±9% but was followed by vasoconstriction. Inhibition of NO synthase with 25 mg/kg i.v. N-nitro-L-arginine (L-NNA) decreased BF by 27±5% and increased AP by 37±11%. After treatment with L-NNA and after acute and chronic administration of capsaicin, the bile-oleate-induced maximal increases in BF above control levels were 42±7%, 65±12%, and 58±8%, respectively. The observed inhibitory effect of L-NNA on the intestinal hyperaemic response to the bile-oleate mixture was reversed by pretreatment with L-arginine (100 mg/kg i.V.). In capsaicin pretreated rats the subsequent bile-oleate-induced hyperaemia was reduced in magnitude but the inhibitory effects of L-NNA were proportionately the same as in animals not receiving capsaicin. These findings support the hypothesis that NO is involved with bile-oleate-induced mesenteric hyperaemia.     

Neutrophil activation in anti-proteinase 3-positive vasculitis--a prospective study

In vitro studies have demonstrated that antineutrophil cytoplasmic antibodies (ANCA) have the capacity to activate neutrophils. Whether circulating neutrophils in patients with vasculitis are activated is under debate. Eight consecutive patients with antiproteinase 3 (PR3) positive acute vasculitis were included in this prospective study. Neutrophil expression of adhesion molecules, Fc-receptors and the ANCA-antigen PR3 was analysed and clinical characteristics were documented at inclusion and after 1, 3, 6 and 9 months in the same individuals. As additional markers of inflammation and endothelial activation interleukin-8 and soluble vascular cell adhesion molecule-1 in serum were analysed at the same time points. The expression of adhesion molecules on circulating neutrophils, CD62L and CD11b after in vitro N-formyl-methionyl-leucyl-phenylalanine stimulation was significantly decreased at diagnosis and after 1 month but returned to normal levels after 3-9 months. The neutrophil expression of Fc-receptor IIIb (CD 16) was decreased at diagnosis but normalized after 1-9 months. The main finding was an activated neutrophil adhesion phenotype at diagnosis and after 1 month, with normalized expression of adhesion molecules at 3-9 months. A pathological regulation of adhesion molecules may have implications on the endothelial damage seen in vasculitis.     

Response suppression by extending sine-wave gratings within the receptive fields of neurons in visual cortical area V3A of the macaque monkey

Even though there are many more cycles of the "optimal" grating extending across the receptive fields of cells in V3A than of cells in V1 and V2, the spatial frequency bandwidths in V3A are no narrower than in V1 or V2. Thus, the inputs to V3A cells are not combined in a phase coherent manner across the entire receptive field. Moreover, the defined receptive fields of cells in V3A are generally surrounded by suppressive regions which are, on average, much stronger than those found for neurons in V1 and V2. Even within the classical receptive field, most neurons in V3A respond far more vigorously to a limited patch of a few cycles of a grating at the preferred spatial frequency than to wider grating stimuli. This intra-receptive field suppression demonstrates a new level of response complexity, and suggests that V3A cells may antagonistically combine nonlinear mechanisms that themselves encode stimulus energy over a restricted region of space and spatial-frequency.     

Adrenergic,purinergic, and endothelial mediators and modulators of norepinephrine-induced mesenteric autoregulatory escape

We evaluated the effects of potential factors in autoregulatory escape from norepinephrine-induced vasoconstriction in rat anterior mesenteric artery. We determined mesenteric artery blood flow velocity with a pulsed Doppler, sonic flowmeter, and systemic arterial blood pressure with a transducer. A 4-min norepinephrine infusion (0.125–1.0 × 10^–8 M/min) intravenously evoked a dose-dependent, initial vasoconstriction that was followed by rapid escape of blood flow toward or above the control value during sustained norepinephrine administration. Neonatal capsaicin treatment enhanced vasoconstrictor responses to norepinephrine but failed to affect escape parameters. Propranolol decreased norepinephrine-induced escape dose dependently. Adenosine deaminase attenuated escape, and the combination of this enzyme plus propranolol nearly abolished escape from norepinephrine-induced vasoconstriction. Methylene blue also diminished autoregulatory escape. These findings suggest that norepinephrine-induced autoregulatory escape involves simultaneous -adrenoceptor, purinergic, and endothelial mediation. Norepinephrine-evoked mesenteric vasoconstriction appears to involve predominantly ₂-adrenoceptors and is modulated by peptidergic sensory nerves and adenosine.NIH grant number supporting these studies: USPHS # DK37050.