Learning-induced dynamic receptive field changes in primary auditory cortex of the unanaesthetized Mongolian gerbil

Learning-induced changes of the spectro-temporal characteristics of primary auditory cortex (AI) units were studied by response plane analysis of recordings from the AI in unanaesthetized Mongolian gerbils. Using response planes obtained prior to and after auditory discrimination training bins of significant change were identified and their spectro-temporal distribution was studied. Bins of significant changes were generally found to be distributed over the entire spectro-temporal receptive field but occurred most frequently within the first 100 ms of response in the spectral neighbourhood (1.5 octaves) of the frequency of the reinforced conditioned stimulus. Training-induced response decreases occurred early after 10 ms for reinforced conditioned tones and tones in the frequency neighbourhood. Response increases occurred so early only for non-reinforced tones in the neighbourhood of the reinforced frequency and occurred later (after 40 ms) for the reinforced tones. The results are discussed in the light of dynamic disinhibition.     

Effects of exogenous recombinant ovine interferon tau on circulating concentrations of progesterone, cortisol, luteinizing hormone, and antiviral activity; interestrous interval; rectal temperature; and uterine response to oxytocin in cyclic ewes

Interferon tau (IFN tau) is the conceptus-produced antiluteolytic signal in ruminants. Three experiments examined the effects of s.c. administration of recombinant ovine (ro)IFN tau on interestrous interval (IEI), oxytocin (OT)-induced uterine prostaglandin F2alpha metabolite (PGFM) production, rectal temperature (RT), respiration rate (RR), and plasma concentrations of progesterone, cortisol, LH, and antiviral activity (AVA) in plasma and uterine flushings. In experiment I, 20 ewes were treated s.c. with either 0, 1, 2, or 4 mg/day roIFN tau (0.7 x 10(8) U/mg; 5 ewes/dosage) from Days 11 to 15 of the estrous cycle (estrus = Day 0) and were challenged with OT (30 IU) on Day 15. Jugular blood samples were collected at -10, 0, 10, 20, 30, 40, 50, and 60 min relative to the OT challenge and assayed for PGFM. Recombinant oIFN tau increased IEI (16.7, 18.7, and 22.6 +/- 0.6 days for 0, 2, and 4 mg roIFN tau, respectively, p < 0.01). Recombinant oIFN tau did not affect peak PGFM response to OT (2309 +/- 172 pg/ml; p > 0.1). However, the 4 mg/day dosage delayed the time to peak PGFM (32.4 vs. 47.5 +/- 3.4 min; p < 0.01, 0 vs. 4 mg) and resulted in approximately 200% higher concentrations of PGFM at 60 min post-OT (0 vs. 4 mg/day, p < 0.07). Experiment II was similar to experiment I, except that only the 0- and 4-mg/day dosages of roIFN tau were administered. Ewes were hysterectomized on Day 16, and assay of uterine flushes detected no AVA from ewes treated with either 0 or 4 mg/day roIFN tau. In experiment III, 20 ewes were treated s.c. with either 0, 2, 4, or 6 mg roIFN tau on Day 12. Blood samples, RT, and RR were obtained at frequent intervals for 24 h, and plasma was assayed for progesterone, cortisol, LH, and AVA. Plasma AVA, which increased in a dose-dependent manner, was detectable within 60 min and remained elevated at 24 h compared to control values. RT (elevated 0.5-1.0 degrees C), RR, and cortisol increased in response to all dosages of roIFN tau, with peak values occurring 150-180 min postinjection. For all dosages of roIFN tau, plasma progesterone declined from 120 to 360 min posttreatment and then returned to pretreatment values by 24 h (p < 0.01) as compared to controls. Overall, exogenous roIFN tau altered uterine PGFM response to OT from a pulse to a gradual and sustained elevation and extended IEI with only a transient decline in progesterone and mild hyperthermia, effects that are not expected to compromise pregnancy.     

Correction of deficiencies in flexible fiberoptic sigmoidoscope cleaning and disinfection technique in family practice and internal medicine offices

We describe a 27-year-old primigravida suffering from cystic fibrosis. Her chest was colonised with Burkholderia cepacia and she was in respiratory failure for which she required constant nasal intermittent positive pressure ventilation. In view of her rapid deterioration, Caesarean section was performed under epidural anaesthesia at 25 weeks gestation. A live 790-g boy was delivered. Post-operatively she made steady progress for 5 days although still requiring nasal ventilatory support. Thereafter she developed pneumonia and required tracheal intubation and ventilation on the eighth day. Her increasing hypoxaemia and pulmonary hypertension failed to respond to any therapy including inhaled nitric oxide and she died on the tenth postoperative day.     

Early detection of visual field progression in glaucoma: a comparison of PROGRESSOR and STATPAC 2

AIM: To compare the performance of PROGRESSOR (pointwise linear regression) and STATPAC 2 (comparison with baseline values) in detecting early deterioration in the visual fields of glaucoma patients. METHODS: Visual field series from 19 untreated normal tension glaucoma eyes which were deteriorating on clinical grounds were analysed by PROGRESSOR and STATPAC 2. Progression criteria for PROGRESSOR were (1) inner points: slope < -1 dB/year, p < 0.05 and (2) edge points: slope < -2 dB/year, p < 0.05. Criteria for STATPAC 2 were p < 0.05 change probability for any point on three consecutive fields. Detection time was defined as the time interval between the initial field and the first field in which at least one progressing point was identified. Detection times produced by the two techniques were compared. RESULTS: PROGRESSOR and STATPAC 2 agreed on progression in all 19 eyes. Mean detection time for PROGRESSOR was 1.077 (SD 0.985) years and for STATPAC 2 was 2.161 (1.357) years. PROGRESSOR detected progression sooner than STATPAC 2 in 18 eyes (p < 0.01), Wilcoxon matched pairs signed rank test). PROGRESSOR detected progression earlier by a mean of 1.085 (0.936) years. CONCLUSIONS: PROGRESSOR consistently detected progression earlier than STATPAC 2. The PROGRESSOR software is a useful tool for the early detection of visual field deterioration in glaucoma.     

Potassium channels participate in gastric mucosal protection in rats with partial portal vein ligation

Glybenclamide, an adenosine triphosphate-dependent potassium (K+(ATP)) channel blocker, lowered portal pressure and attenuated the hyperdynamic splanchnic circulation in rats with partial portal vein ligation (PPVL). The purpose of this report was to confirm these observations and to test the hypothesis that glybenclamide could reduce acidified ethanol-induced gastric mucosal injury in rats with PPVL. Gastric mucosal blood flow (hydrogen gas clearance), systemic blood pressure, and portal pressure were monitored in rats with PPVL or sham operation (SO). Intravenous glybenclamide (20 mg/kg) or vehicle was administered, followed by intragastric acidified ethanol (0.15 N HCl and 15% ethanol). The area of gastric mucosal lesions was assessed by image analysis. In contrast to published findings, there was no significant elevation of portal pressure after glybenclamide administration in rats with PPVL. Glybenclamide did not alter the gastric mucosal hyperemia in these rats. Glybenclamide significantly increased mucosal injury. The data are consistent with the hypothesis that K+(ATP) channels play a role in protecting the gastric mucosa in rats with PPVL.     

Mechanisms of drug transfer across the human placenta

In this review we summarized literature data on the mechanisms of human placental drug transport studied in the isolated perfused placental cotyledon, placental membrane vesicles or trophoblastic cell cultures. Overall human placental drug transport rarely exceeds the transfer of flow-dependent and membrane-limited marker compounds. Interestingly, relatively often placental drug transfer appeared to be much smaller, indicating impaired trans-placental transport, depending on the physico-chemical characteristics of the drug or placental factors such as tissue binding or metabolism. Although in perfusion studies overall human placental drug transport occurs by simple diffusion, at the membrane level several drug transport systems have been found, mainly for drugs structurally related to endogenous compounds.     

Fibroblast silver loading for the diagnosis of Menkes disease

Hypotony from an inadvertent filtration bleb developed in the eye of a 66-year-old woman 1 year after phacoemulsification cataract surgery. The hypotony was treated with an autologous blood injection over the previous phacoemulsification incision. This technique successfully treated the hypotony without additional ocular surgery. The authors report an effective alternative treatment for hypotony induced by an inadvertent filtration bleb.     

Studies of the distribution of lipofuscin in the retinal pigment epithelium using high-resolution TV laser scanning ophthalmoscopy

BACKGROUND: The fundus autofluorescence imaging technique has been modified allowing improved image resolution (768 x 572 pixel). We present results of fundus autofluorescence studies using this technique. MATERIALS AND METHODS: Fundus autofluorescence was studied in 286 eyes of 143 patients with retinitis pigmentosa, macular dystrophies and age-related macular degeneration using a confocal laser scanning ophthalmoscope prototype (Zeiss, Oberkochen; excitation wavelength: 488 nm, cut-off filter at 521 nm). RESULTS: The spatial distribution of autofluorescence was different in all diseased eyes investigated compared to the normal pattern of fundus autofluorescence. Each disorder showed a specific fundus autofluorescence appearance. CONCLUSIONS: The advanced technique of imaging fundus autofluorescence allows detailed studies of the lipofuscin distribution. In vivo analysis of the dynamics of accumulation and degradation of lipofuscin in eyes with tapeto-retinal dystrophies and age-related macular disease may contribute to elucidation of the pathogenesis of these disorders.     

Peripheral somatic nerve function in relation to glucose tolerance in an elderly Caucasian population: the Hoorn study

Only sparse and contradictory data are available on peripheral somatic nerve function in relation to the total range of glucose tolerance. A random sample (n = 708) of people, stratified by age, sex, and glucose tolerance, from a Caucasian population aged 50 to 74 years was invited to undergo an examination including measures of large-fibre nerve function (ankle and knee reflexes, vibration sense, vibratory perception threshold (VPT) at the foot) and one measure of small-fibre function (thermal discrimination threshold (TDT) at the foot). A total of 267 subjects with a normal glucose tolerance (NGT), 167 with impaired glucose tolerance (IGT), 90 with newly diagnosed diabetes mellitus (NDM), and 73 with previously known diabetes (KDM) were included. KDM was associated with the highest prevalence of large-fibre nerve dysfunction. Within the range from NGT to NDM, most large-fibre function measures showed a decline with decreasing glucose tolerance. The TDT showed a decrease with an increase in fasting and post-load insulin levels (p < 0.05). We conclude that glucose intolerance is associated with impaired peripheral large-fibre nerve function, an association which seems to apply even in the non-diabetic range. Higher insulin levels were associated with a better small-fibre nerve function.