Alterations of visual cortical connections in cats following early removal of retinal input.

The major afferent pathways to the visual cortex were studied in cats enucleated at postnatal days 0, 15, 30 and 60 using the retrograde tracer wheat germ agglutin conjugated horseradish peroxidase (WGA-HRP). Following enucleation at days 0 and 15, the lateral gyrus was shrunken and cortical thickness was decreased, but the thickness of layer I was increased relative to normal adult cats. The laminar portion of the lateral geniculate complex occupied only half its normal volume, but the pathway from the intralaminar nuclei to visual cortex was doubled in volume. The ipsilateral and contralateral claustrum and ipsilateral medial septal nucleus also provided increased input to visual cortex. The changes in these projection patterns were not as dramatic in the cats enucleated at days 30 and 60. The callosal pathway between areas 17 and 18 was also significantly altered in cats enucleated on the day of birth and at day 15. Callosal cells were found in the infragranular layers throughout area 18. The number of supragranular callosal cells in the medial half of area 18 and in area 17 was reduced to approximately one third the normal adult number, but the mediolateral extent of this zone was not reduced. In the infragranular layers, the callosal cell number was approximately twice that in adult cats, and they occupied at least twice their normal mediolateral extent. Following bilateral enucleation at days 30 and 60, the cell numbers and mediolateral extent of the callosal cell zones approximated those in normal adult cats. Taken together, these results indicate that early deafferantiation of a cortical area can alter the thalamic, extrathalamic and callosal connections of that area.     

Muscular strength and bone mineral density in haemodialysis patients

Purpose. The objective of this study was to determine the relationship between muscular strength and bone mineral density (BMD) in patients undergoing regular haemodialysis. Methods. The BMD was measured in the lumbar spine (L2L4) and in the proximal femur (femoral neck and trochanter) with dual-energy X-ray absorptiometry (DEXA (Lunar DPX). Muscular strength of the extensors, flexors and abductors muscles of the femur (proximal muscles) and extensors muscles of the back was measured with an isometric cynamometer. Thirty patients, 15 women with a mean age of 33.7 years (18-43) and 15 men with a mean age of 15.5 years (18-65) were included in the study. Results. There was a positive and significant correlation between the BMD of the femoral neck and muscular strength of the flexors (r=0.490, P<0.005), the extensors (r=0.658, P<0.01) and the abductors muscles of the femur (r=0.671, P <0.0008), as well as between the muscular strength of the flexors (r=0.413, P <0.02) and extensors muscles of the femur (r=0.433, P <0.01) with BMD of the trochanter. There was no correlation between the muscular strength of the back extensor muscles and the BMD of the lumbar spine (r=-0.119, P NS). There was no correlation between the BMD and the number of years of haemodialysis therapy (r=-0.032, P NS), the patient's age (r=-159, P NS), or the value of serum PTH (r=0.369, P NS) respectively. However, there was a significant correlation between the BMD of the femoral neck with muscular strength (r=0.602, P <0.05). Conclusion. This study reveals the close relationship that exists between muscular strength of the proximal muscles and the BMD of proximal femur in patients undergoing haemodialysis.     

Parathyroid hormone gene expression in Hyp mice fed a low-phosphate diet

Background: The murine analogue of X-linked hypophosphateaemia is the Hyp mouse; it has chronic phosphate depletion from an inherited defect of renal tubular reabsorption. Phosphate directly regulates the parathyroid (PT) in normal rats and it is of interest whether this regulation is intact in Hyp mice. Methods: Hyp mice were fed either a low-phosphate diet or control diet and PTH mRNA levels were measured. In addition changes in NMR-visible kidney and muscle intracellular phosphate potentials in normal and Hyp mice were determined. Mice were maintained on a low-phosphate (0.02%) or normal-phosphate (0.6%) diet for 24 and 72 h. Results: On the normal diet, Hyp mice had hypophosphataemia, normocalcaemia, and normal PTH mRNA levels. Phosphate deprivation for 72 h led to a profound fall in plasma phosphate, a slight but significant rise in plasma calcium, and a dramatic decrease in PTH mRNA, similar to that of normal mice fed this diet. Changes in kidney and muscle intracellular phosphate measured by NMR spectroscopy were not affected by diet or genotype. Conclusion: Dietary phosphate deprivation decreased Hyp mice PTH mRNA levels and caused no change in intracellular phosphate potentials. Therefore Hyp mice parathyroids' adapt appropriately to phosphate deprivation albeit at a lower threshold compared to normal mice.     

Histopathology of rainbow trout exposed to a bleached kraft pulp mill effluent

The toxicity of an untreated bleached kraft pulp mill effluent was evaluated histopathologically, using rainbow trout. Gills, liver, kidney, spleen, digestive tract, and skin were examined in a 96-hr LC50 acute test. Fish exposed to lethal concentrations of effluent had an extensive fusion of gill lamellae. This lesion was also present in fish that survived the 96-hr LC50 acute test but to a lesser extent. Trout exposed for 20, 40, and 60 days to sublethal effluent concentrations were also examined. No lesions that could be attributed specifically to the effluent were observed, but exposed fish had a higher incidence of fin necrosis and damaged gills than the unexposed fish after 40 and 60 days. Loss of resistance to bacterial pathogens may be a significant stress-related effect of this effluent in fish exposed for long periods to low concentrations.     

Physiological dysfunction of dorsolateral prefrontal cortex in schizophrenia. III. A new cohort and evidence for a monoaminergic mechanism

We previously reported that compared with normals, patients with chronic schizophrenia have reduced regional cerebral blood flow (rCBF) in dorsolateral prefrontal cortex (DLPFC) during performance of the Wisconsin Card Sort Test (WCS), a DLPFC-related cognitive task, but not during nonprefrontal tasks, such as a simple number-matching (NM) test. We also found that unlike normals, patients failed to activate DLPFC during the WCS over their own baseline (NM) level. To explore the reproducibility of these findings, a new cohort of 16 medication-free patients underwent a series of xenon 133 inhalation rCBF studies under the following conditions: at rest, while performing the WCS, and while performing NM. The results confirmed our earlier findings. In addition, the concentrations in cerebrospinal fluid of homovanillic acid and 5-hydroxyindoleacetic acid correlated with prefrontal rCBF during the WCS but not during the NM test or at rest. The results show that behavior-specific hypofunction of DLPFC in schizophrenia is reproducible, and they implicate a monoaminergic mechanism.     

The ultrasound appearance of positive hip instability tests

In a study assessing the use of ultrasound in the detection of neonatal hip abnormalities, the clinical findings in unstable hips were correlated with the ultrasound appearance during the instability provocation tests. Both hip displacement and concentric reduction of the femoral head in relation to the acetabulum could be defined with the ultrasound image.     

Cultured fibroblasts in avian scleroderma, an autoimmune fibrotic disease, display an activated phenotype.

University of California, Davis, line 200 and 206 chickens spontaneously develop an autoimmune syndrome that has many features analogous to human scleroderma, including dermal fibrosis, antinuclear antibodies and antibodies to type II collagen. These birds also have thymic subcapsular epithelial defects and an abnormality in T cell calcium influx and proliferation in response to both T cell receptor-dependent and -independent activators. To determine whether fibroblast activation is a contributing factor to development of skin fibrosis in line 200/206 chickens, as it is in human scleroderma, we studied the collagen, non-collagenous protein and glycosaminoglycan (GAG) production of 34 separate fibroblast lines derived from the normal and fibrotic skin of line 200 and 206 chickens and from the skin of control chicken lines 058 and 254. The mean +/- SEM 24-h incorporation of 3H-proline or 3H-glucosamine into extracellular collagen, non-collagenous protein or GAG by first passage fibroblast lines derived from the fibrotic skin of diseased birds was 1,526 +/- 136, 859 +/- 82 and 25.7 +/- 1.3 dpm/10(3) cells, respectively, while fibroblast lines derived from the skin of control birds produced only 341 +/- 36, 343 +/- 42 and 15.2 +/- 1.4 dpm/10(3) cells. Similar differences in results were recorded for cell-associated production, and when collagen and non-collagenous protein production were assessed using non-radioactive electrophoretic methods. The activated phenotype of the fibroblast lines derived from the fibrotic skin of diseased birds persisted through 10 cell doublings in tissue culture. However, the ratio of type I:III collagen and the profile of GAG types produced were similar in all fibroblast lines studied. These results suggest that fibroblast activation is responsible for the skin fibrosis observed in this avian model of scleroderma.     

Chronic inflammatory effects of interleukin-1 on the blood-retina barrier.

The chronic effects of human recombinant IL-1 (hrIL-1) on the specialized vasculature of the central nervous system (CNS) and on the CNS itself have been examined over a 35-day period in the rabbit retina. A single intraocular injection of physiological levels of hrIL-1 (300 units) induced a biphasic inflammatory reaction with well-defined acute and chronic phases in the challenged eye. Quantitative histopathological examination of the vascularized portion of the retina in the IL-1-challenged eye documented a persistent mononuclear (MN) cell response that peaked 7-14 days post-challenge. Included in the MN cell count were perivascular plasma cells. Elevated protein levels in the vitreous persisted throughout the time points studied and alterations in vascular permeability of the epiretinal vessels were demonstrated by tracer leakage at 2 weeks post-challenge. The results show that exposure of the CNS-vasculature to IL-1 induces long-lasting inflammatory changes typical of a chronic inflammatory reaction.