Instigation and control of treadmill locomotion in high decerebrate cats by stimulation of the hook bundle of Russell in the cerebellum

In high decerebrate cats, pulse train microstimulation of a restricted region of the midline cerebellar white matter produced a generalized increase in postural muscle tone in the neck, trunk, and limb extensor muscles, and air-stepping of all four legs on a stationary surface. On the moving belt of a treadmill, such stimulation produced well coordinated, fore- and hindlimb locomotion as evoked by stimulating the mesencephalic locomotor region (MLR). Microinjection of a neural tracer into the cerebellar locomotion-inducing site resulted in a bilateral retrograde labeling of cells limited to the fastigial nuclei simultaneously with anterograde labeling of fibers projecting bilaterally to the medial pontomedullary reticular formation (mPMRF) the vestibular complex and upper cervical segments. These results have led to our proposition that the effective cerebellar locomotor region (CLR) corresponds to the midline region of the hook bundle of Russell. Passing through this structure are crossed fastigioreticular and fastigiovestibular fibers, together with fastigiospinal fibers. Subsequently, we showed that CLR stimulation resulted in simultaneous short-latency synaptic activation of long-descending reticulospinal and vestibulospinal cells with high synaptic security. Clearly, the fastigial nucleus possesses potential capability to recruit and regulate posture- and locomotor-related subprograms which are distributed within the brainstem and spinal cord by the in-parallel activation of fastigiospinal, fastigioreticular, and fastigiovestibular pathways.

A di-synaptic projection from the lateral cerebellar nucleus to the laterodorsal part of the striatum via the central lateral nucleus of the thalamus in the rat

We have examined a cerebello-thalamo-striatal pathway from the lateral cerebellar nucleus (LCN) to the laterodorsal part of the striatum (LDS) through the central lateral nucleus (CL) using light and electron microscopy through the employment of a combination of anterograde and retrograde tracing techniques. Biotinylated dextran amine (BDA) was injected into the unilateral LCN, and used as an anterograde tracer. Cholera toxin B subunit (CTb), used for light microscopy, and wheat germ agglutinin-horseradish peroxidase (WGA-HRP), used for electron microscopy, were injected into the contralateral LDS as retrograde tracers. Light microscopic analysis showed a good overlap of the distribution of BDA-labeled axon terminals and CTb-labeled neurons in the middle third of the CL in both dorsoventral and rostrocaudal axes on the LDS injection side. Electron microscopy confirmed the presence of direct synaptic contacts between BDA-labeled terminals and WGA-HRP-labeled dendrites in the CL.

Changes in blood-retinal barrier permeability in form deprivation myopia in tree shrews

To study the correlation between blood-retinal barrier (BRB) permeability and development of form deprivation (FD) myopia, FD was induced in tree shrews. The refractive error and the axial dimensions of the optical elements were measured. Ocular fluorescence was measured before and after fluorescein-Na injection. The inward permeability (P(in)) of the BRB was measured before and 15, 30, and 45 days after FD was induced. FD eyes became significantly myopic 15 days after FD was induced (P<0.01), and myopia progressed 45 days after FD was induced compared with untreated controls. Neither anterior chamber length nor lens thickness changed significantly. The vitreous chamber in FD eyes, however, was significantly elongated from 15 days after FD was induced (P<0.01) compared with controls. The P(in) ratio (P(in) [FD eye]/P(in) [untreated control]), increased significantly 45 days after FD was induced (P<0.05). In FD myopia in tree shrews, the BRB permeability increases abnormally. Impaired BRB function might be a secondary effect of myopia development rather than the cause of myopia.

The cat neostriatum: relative distribution of cholinergic neurons versus serotonergic fibers

The distribution of choline acetyltransferase (ChAT)-containing neurons and serotonin (5-HT)-containing nerve fibers in the cat neostriatum was investigated by use of immunohistochemical techniques. Both ChAT- and 5-HT-staining techniques were applied to alternate brain sections, thereby allowing a precise comparison of the distribution pattern of ChAT-immunopositive cells (ChAT cells) and 5-HT-immunopositive fibers (5-HT fibers). In the neostriatum, ChAT cells were strongly stained throughout their cell bodies and proximal (first-order) dendrites. The majority of them were multipolar cells with a soma diameter of 20-50 microm (long axis)x10-30 microm (short axis). In the caudate nucleus, ChAT cells were evenly and diffusely distributed except for the dorsolateral region of its rostral half, in which latter region they were distributed in loosely formed clusters. In the rostral portion of the putamen, the density of ChAT-cell distribution was like that in the medial region of the caudate nucleus. In contrast, this distribution was more dense in the caudomedial region of the putamen, adjacent to the globus pallidus. 5-HT fibers in the neostriatum were dark-stained, of quite fine diameter (<0.6 microm), and they contained small, round varicosities (diameter, usually 0.5-1.0 microm, but some >1.0 microm). Such 5-HT fibers were distributed abundantly throughout the caudate nucleus and putamen. In the rostrocaudal portion of the caudate nucleus, their density was high in its dorsal and ventral components, and low in the middle component. Throughout the putamen, 5-HT fibers were distributed homogeneously in the mediolateral and dorsoventral directions. In the caudal portion of the putamen adjacent to the globus pallidus, the 5-HT fibers had a higher density while maintaining their homogenous distribution pattern. In the two main divisions of the striatum, the so-called 'patch' (acetylcholinesterase (AChE)-poor) and 'matrix' (AChE-rich) compartments, there was a near-even distribution of 5-HT fibers and terminals. The above results suggest that the 5-HT-dominated, raphe-striatal pathway is optimally arranged for modulating the activity of both the intrinsic and the projection neurons of the neostriatum.

Widespread calcium deposits, as detected using the alizarin red S technique, in the nervous system of rats treated with dimethyl mercury

It has been reported that the alizarin red S technique may be used to visualize both intracellular and extracellular calcium deposits. Using this method histologic observations of the nervous system were made in rats that were given dimethyl mercury at 5 mg/kg per day for 12 consecutive days, and killed on days 1, 4, 7, 10, 12, 24, 32, 49, 100 and 140 (day 0 was the day that the final dose was administered). Neuronal degeneration with calcium deposition was found in the nervous system from day 4 onward. In the cerebellum alizarin red S-positive granules became gradually larger with time after dimethyl mercury administration, and large calcospherites were observed from day 32 onward. In contrast, the visualization of calcium deposits in the cerebral cortex was restricted to days 10-12. Calcium deposits were found in the ascending axons of the dorsal root ganglion neurons (dorsal fascicles of the spinal cord), but not in their perikarya. These findings suggest that widespread calcium deposition could occur in the nervous system following dimethyl mercury exposure, and that in the rat the mechanism of calcium deposition differs depending upon the brain region.

Corneal and lens autofluorescence in young insulin-dependent diabetic patients

To study the early ocular abnormalities in young diabetic patients, corneal and lens autofluorescence was measured by fluorophotometry in 30 eyes of 30 insulin-dependent diabetic patients without retinopathy. The lens [f(l)] and the corneal [f(c)] autofluorescence values in diabetic patients were significantly higher than in controls. In diabetic patients, f(l) was significantly correlated with the duration of diabetes, the f(c) was significantly correlated with the duration of diabetes and the indices of metabolic control, i.e. HbA1c and fructosamine. Our study demonstrated that young diabetic patients clearly had corneal and lens abnormalities before the appearance of overt diabetic retinopathy. The f(c) value might be a good indicator of metabolic control in diabetic patients.

A novel class of highly potent and selective A1 adenosine antagonists: structure-affinity profile of a series of 1,8-naphthyridine derivatives

A series of 1,8-naphthyridine derivatives (12-36), bearing a phenyl group in position 2 and various substituents in positions 4 and 7, were synthesized in an attempt to obtain potent, selective antagonists for the A1 adenosine receptor subtype. The compounds were tested to evaluate their affinity for A1 compared with A2A and A3 adenosine receptor subtypes. In binding studies in bovine brain cortical membranes, most of the compounds showed an affinity for A1 receptors in the low nanomolar range and two in the subnanomolar range with an interesting degree of A1 versus A2A and A3 selectivity. Comparison of the 4-substituted derivatives indicated that 4-OH substitution, with a 4-quinoid structure, causes an increase in the A1 and A2A affinity and generally also in A1 selectivity. The kind of substitution in position 7 can greatly modulate the affinity: the most interesting substituents in this position seemed to be electron-withdrawing groups; in particular the 7-chloronaphthyridine 25d showed a remarkable selectivity (A2A/A1 ratio of 670, A3/A1 ratio of 14,000) associated with a higher A1 affinity (Ki = 0.15 nM). NMR studies on these compounds 12-36 indicated that the 4-OH-substituted ones prefer the tautomer in which the oxygen in position 4 is in the quinoid form and the nitrogen in position 1 is protonated. Theoretical calculations are in agreement with the NMR data.

[Comparison of the circadian variation of the time of onset of acute myocardial infarction and of attack of vasospastic angina without significant stenosis]

OBJECTIVES

To study the involvement of vasospasm as the trigger of acute myocardial infarction without significant stenosis, the circadian variation of the time of onset of acute myocardial infarction was compared with that of vasospastic angina without significant stenosis.

METHODS

The subjects consisted of 3 groups, 64 patients with acute myocardial infarction without significant stenosis, 101 patients with acute myocardial infarction with one vessel disease and 98 patients with vasospastic angina without significant stenosis. The times of onset of acute myocardial infarction and spontaneous attack of vasospastic angina were recorded and classified according to the 4 periods (0:00-6:00, 6:00-12:00, 12:00-18:00, 18:00-24:00) and the pattern of distribution was compared between the 3 groups.

RESULTS

The time distribution of acute myocardial infarction without significant stenosis showed a double peaked pattern at 6:00-12:00 and 18:00-24:00 and was similar to the pattern of acute myocardial infarction with one vessel disease(p = 0.93). Only a single peak in 0:00-6:00 was found in the pattern of distribution of vasospastic angina without significant stenosis and differed significantly from acute myocardial infarction(p < 0.01).

CONCLUSIONS

The circadian variation of the time of onset of acute myocardial infarction was similar in patients with or without significant stenosis, and differed significantly from that in patients with vasospastic angina.

Developmental changes in expression of the three ryanodine receptor mRNAs in the mouse brain

Ryanodine receptors (RyR) are Ca(2+)-induced Ca(2+) release channels located on the endoplasmic reticulum, and consist of three isoforms, termed RyR1-3. We examined their expression in developing mouse brains by in situ hybridization. During the embryonic stage, RyR1 mRNA levels were highest in the rostral cortical plate, whereas RyR3 mRNA was most prominent in the caudal cortical plate and hippocampus. Initially, low levels of RyR2 mRNA were distributed in the diencephalon and brainstem. However, from postnatal day 7 onward, RyR2 mRNA became the major isoform in many brain regions, while RyR1 mRNA became prominent in the dentate gyrus and Purkinje cell layer. Postnatal down-regulation in the caudal cerebral cortex restricted RyR3 mRNA expression to the hippocampus, particularly the CA1 region. Therefore, RyR expression undergoes dynamic changes during the early postnatal period, when neurons are undergoing structural and functional differentiation.

Hemorrhages of dorsal root ganglia and spinal cord in congenitally hydrocephalic HTX rat

The effects on the brain caused by hydrocephalus have been examined in detail. However, only little attention has been paid to the possibility that hydrocephalus may affect the spinal cord and the spinal ganglia via the spinal canal. Therefore, the present study focused on the pathological changes seen in the spinal cord and the dorsal root ganglia. A total of 651 congenitally hydrocephalic HTX rats were used in this study. The age ranged from postnatal day 0 to postnatal day 520. All of the HTX rats were from littermates raised in our laboratory. Macroscopic and microscopic investigations demonstrated hemorrhages of the dorsal root ganglia in 134 rats among the 235 affected HTX rats. The hemorrhages of the dorsal root ganglia were observed most frequently in the lumbar ganglia and, less frequently, in the cervical ganglia. Of the 134 rats with hemorrhages in the dorsal root ganglia, 34 rats had hemorrhages both in the spinal cord and in the dorsal root ganglia. The spinal cord hemorrhages were distributed mainly around the central canal and in the ventral parts of the posterior funiculus at the lower thoracic and upper lumbar cords. These hemorrhages were seen only in those rats having progressive hydrocephalus. These findings suggest that increased cerebrospinal fluid pressure can cause congestion of the radicular veins, leading to hemorrhages of the spinal cord and the dorsal root ganglia.

Scanning laser ophthalmoscope correlations with biomicroscopic findings and foveal function after macular hole closure

OBJECTIVE

To investigate the relation between foveal findings and visual function in eyes with a resolved idiopathic macular hole after vitreous surgery.

METHODS

We divided 28 eyes with postoperative idiopathic macular hole resolution into 3 groups based on postoperative biomicroscopic foveal findings of complete closure, partial closure, or atrophic closure. To evaluate foveal retinal function, scanning laser ophthalmoscope (SLO) microperimetry was performed preoperatively and 6 months postoperatively.

RESULTS

Postoperatively in 18 eyes (64%), the foveal images became normal or almost normal and were classified as having complete closure, 6 eyes (21%) were classified as having partial closure, and 4 eyes (14%) as having atrophic closure. The corresponding visual acuity levels 6 months postoperatively were, respectively, 0.10, 0.35, and 0.64 (P<.01) based on LogMAR analysis. Preoperative SLO microperimetry detected an absolute scotoma at the bottom of all macular holes; postoperatively, the absolute scotoma disappeared in the 18 eyes with complete hole closure, but a relative scotoma was detected in 6 eyes. Of 6 eyes with partial closure, 1 had an absolute scotoma and 5 had a relative scotoma. An absolute scotoma was detected in 4 eyes with atrophic closure.

CONCLUSIONS

After macular hole closure, SLO findings correlate both with biomicroscopic findings and foveal function. Better anatomical foveal recovery in eyes after macular hole closure results in better improvement of vision than in eyes in which the foveal anatomical findings are not as good.

[Significance of the time course of ST segment elevation just after reperfusion therapy for acute myocardial infarction]

The significance of the time course of ST segment elevation just after reperfusion therapy for acute myocardial infarction was investigated in 25 consecutive patients with acute myocardial infarction and ST elevation. The most elevated ST lead from the standard electrocardiogram on admission was continuously monitored as the ST trend for 72 hr including during the reperfusion procedure. The culprit artery was totally occluded and reperfused without flow delay. Left ventriculograms were obtained after reperfusion and 3-4 weeks later. The most elevated ST level before reperfusion was measured as the maximal level and the ST level 30 min after reperfusion as the reperfused level. The patients were divided into 2 groups, group ST > or = 50% (n = 12) with a decrease of less than 50% of the maximal ST level and group ST < 50% (n = 13) with a decrease of 50% or over 50%. Regional left ventricular wall motion of infarct site, end-diastolic left ventricular volume and ejection fraction were compared between the acute and chronic phase left ventriculograms in each group. In group ST > or = 50%, no significant change was detected in both regional and global ejection fraction, whereas end-diastolic left ventricular volume enlarged significantly in the chronic phase (acute 80 +/- 25 ml/m2 to chronic 95 +/- 17 ml/m2, p < 0.01). In group ST < 50%, regional and global ejection fraction both improved significantly (SD/chord: acute -2.2 +/- 1.5 to chronic -1.4 +/- 0.4, p < 0.001; ejection fraction: acute 50 +/- 14% to chronic 57 +/- 13%, p < 0.01) but end-diastolic left ventricular volume remained the same in the chronic phase. The peak creatine kinase level and the frequency of ST re-elevation at reperfusion were significantly higher in group ST > or = 50% than in group ST < 50% (creatine kinase: group ST > or = 50% 5,496 +/- 2,219 IU/l, group ST < 50% 1,913 +/- 1,180 IU/l, p < 0.0001; ST re-elevation: group ST > or = 50% 83%, group ST < 50% 38%, p < 0.05), although the time from onset of myocardial infarction to reperfusion, the maximal ST level, the degree of collateral development, and the frequency of pre-infarction angina were not different between the 2 groups. Rapid resolution of ST elevation after reperfusion is a useful marker of the improvement of left ventricular function in acute myocardial infarction.

[Should the patient with an interatrial defect recognized in adulthood always be operated on?]

BACKGROUND

Atrial septal defect (ASD) can be recognized in adult age, mostly in asymptomatic or scarcely symptomatic patients. These patients differ from patients in "historical" clinical series, in whom diagnosis was done on the basis of clinical evidence, and their natural history is probably different.

AIM OF THE STUDY

Our aim was to verify retrospectively results of surgery versus medical follow-up in an adult population with ASD with age at first diagnosis > or = 30 years.

PATIENTS AND METHODS

Seventy-two patients with ASD, 52 females (72%), observed at our Institution since 1978, were considered. Mean age at diagnosis was 48 +/- 12 years (range 30-79); 36 patients (50%, group A) are still on medical therapy, 36 patients (group B) were operated. As groups A and B did not differ significantly in any demographic, clinical or echocardiographic parameter, they were compared for the incidence of complications.

RESULTS

During follow-up (100 +/- 70 months, range 12-240), the incidence of major clinical events showed no significant differences in the two groups, as cardiac death or cardiovascular complications (cerebral ischemic events, severe mitral insufficiency, reoperation) occurred in 4 patients in group A (11%) and in 4 patients in group B (11%). Worsening of NYHA class was observed in 3 patients from group A (8%) and 2 patients from group B (5.5%; p = ns). New onset of supraventricular arrhythmias occurred more frequently in group B (14 patients, 39%) than in group A (5 patients, 14%) (p = 0.01; OR = 3.9; CI 95%: 1.2-12.6).

CONCLUSIONS

In an adult population affected with asymptomatic or mildly symptomatic ASD and age at first diagnosis > or = 30 years, surgical closure of the defect did not modify morbidity and mortality at a mid-term follow-up. We suggest that, mostly in older asymptomatic patients, surgery should not be a routine choice and clinical decision-making should be individualized in each case.

Morphology of single pontine reticulospinal axons in the lumbar enlargement of the cat: a study using the anterograde tracer PHA-L

The fine morphology of single pontine reticulospinal axons in the lumbar enlargement was investigated by using an anterograde Phaseolus vulgaris-leucoagglutinin (PHA-L) tracing technique. Localized injections of PHA-L were made into the nuclei reticularis pontis oralis and caudalis in four cats. Following survival periods of 8-9 weeks, PHA-L-labeled axons were found throughout the lumbar enlargement from segments L4 to S2, in which the diameter of labeled axons was 0.6-2.5 microns. From serial transverse sections (50 microns), trajectories of 21 single pontine reticulospinal axons were traced in continuity over distances of 18.9-36.3 mm, corresponding to three to six segments, respectively. All the identified axons gave off multiple (two to nine) axon collaterals along their courses, with mean intercollateral distances of approximately 5-6 mm. Detailed reconstruction of the collateral arborization in the lumbar enlargement showed a high degree of similarity to that of single axons in the cervical enlargement previously reported (Matsuyama et al. [1997] J. Comp. Neurol. 377:234-250). First, axon collaterals arising from a majority (n = 18) of identified axons innervated the gray matter unilaterally, ipsilateral to the parent axons, whereas those from the remaining three axons innervated the gray matter bilaterally. Second, collateral projections terminated mainly in laminae VIII and VII, with the arborization field confined to a narrow rostrocaudal extent (< 1 mm). Third, the termination fields of axon collaterals arising from a given reticulospinal axon were similar at each segmental level and differed from one stem axon to another. These results suggest that the long descending pontine reticulospinal pathway is composed of different types of axons that may innervate the cervical and lumbar enlargements in continuity in a similar manner.

Diurnal variation of corneal autofluorescence in normal and diabetic eyes

PURPOSE

To examine the diurnal variations in corneal autofluorescence in normal and diabetic patients.

METHODS

We measured corneal autofluorescence using a fluorophotometer fitted with an anterior segment adapter. Corneal autofluorescence was measured 10 times at 3 min intervals to evaluate the reproducibility of this instrument in 4 eyes of 4 normal subjects. The diurnal variation in corneal autofluorescence was determined by measuring the fluctuations in 10 eyes in 10 normal subjects and one unoperated eye each of 10 patients with proliferative diabetic retinopathy (PDR). We performed five consecutive measurements at 1000, 1130, 1400, 1630 and 1900 hours. The mean value of five measurements, the variation range and the coefficient of variation were analysed.

RESULTS

The mean coefficient of variation in the measurement using this instrument was 8.6 +/- 1.0%. In the patients with PDR, the mean corneal autofluorescence value was significantly higher (p < 0.001), the variation range was significantly wider (p < 0.001) and the coefficient of variation was significantly greater (p < 0.01) than in the normal subjects.

CONCLUSIONS

The results of this study suggest that corneal autofluorescence changes over the course of a day in patients with diabetes. This may be caused by the breakdown of the blood-aqueous barrier that we reported previously.

[Cardiac events in vasospastic angina: site and morphology of coronary artery spasm is related to the long-term prognosis of vasospastic angina]

To determine whether the site and morphology of coronary artery spasm provoked with acetylcholine can predict the long-term prognosis of vasospastic angina, coronary artery spasm (more than 90% narrowing) provoked with acetylcholine was studied in 66 consecutive patients (56 males, 10 females, mean age 56 +/- 9 years) with vasospastic angina. All patients were followed for 6.7 +/- 0.9 years and the incidence of cardiac events such as sudden death, myocardial infarction or worsened unstable angina was compared with the site and morphology of provoked spasm. The site of spasm was regarded as proximal when spasm occurred in the proximal site of 3 major coronary arteries which was designated as segment 1, 6 or 11, according to the classification of the American Heart Association, and distal in other segments. The morphology of spasm was classified into 3 types, focal (12 cases, localized more than 90% narrowing with adjoining parts constricting less than 25%), diffuse (17 cases, diffuse more than 90% narrowing), and intermediate (37 cases, localized more than 90% narrowing with adjoining parts constricting 25-90%). The site of spasm was classified into 2 types, the proximal group (24 cases) and the distal group (42 cases). Cardiac events occurred in 7 patients during the follow-up period: sudden death in 2, myocardial infarction in 2, and worsened unstable angina in 3. As to the site of spasm, the incidence of cardiac events was 21% (5/24 patients) in the proximal group, significantly higher than 5% (2/42) in the distal group (p < 0.05). As to the site of spasm, the incidence of cardiac events was 41% (5/12) in the focal group, significantly higher than 3% (1/37) in the intermediate group and 6% (1/17) in the diffuse group (p < 0.001). The presence of proximal and focal coronary artery spasm was associated with a significantly higher incidence of cardiac events. The site and morphology of coronary artery spasm provoked with acetylcholine is related to the long-term prognosis of vasospastic angina.

[Bactericidal and anti-toxin activities of catechin on enterohemorrhagic Escherichia coli]

We examined the bactericidal activity of catechin, an astringent ingredient of tea, on enterohemorrhagic Escherichia coli (EHEC) O157:H7 and the anti-toxin activity of catechin on vero toxin (VT), the main pathogenic factor of EHEC O157:H7. To examine bactericidal activity, we added 1 X 10(4) CFU/ml bacteria to 1.25 to 20 W/V% of green tea extract or the PBS solution containing 25 to 400 micrograms/ml of (-) epigallocatechin gallate (EGCg), which is the main catechin ingredient of green tea leaf, and counted the number of live bacteria at various intervals. After 3 to 5 hours, no live bacteria were seen in 1.25 to 2.5 (regular drinking concentration) % green tea extract. In the high concentrations of 100 to 400 micrograms/ml EGCg the number of live bacteria decreased with time and after 24 hours no survivors were seen. In the low concentrations of 25 to 50 micrograms/ml EGCg, however, no change was observed in the number of live bacteria during 5 hours. After 24 hours the bacteria in 50 micrograms/ml were killed and the number of bacteria in 25 micrograms/ml decreased to one tenth of that at the start. To examine the anti-toxin activity, we mixed equal volumes of 2 ng/0.1 ml VT2 and 0.5 to 2 mg/0.1 ml catechin in vitro and incubated them at 37 degrees C for various times. Then we inoculated 0.2 ml of the mixture intraperitonealy to BALB/c mice. One mg of catechin inhibited by 100% the lethal toxicity of 2 ng of VT2 (LD 100) to mice. The inhibition of lethal toxicity of VT2 by catechin depended on the incubation time. The rate of inhibition was 0, 40 and 100% for 9, 12 and 18-24 hours incubation, respectively. These results suggest that catechin has not only bactericidal activity on EHEC O157:H7 but also anti-toxin activity on vero toxin.

Specific retinal diacylglycerol and protein kinase C beta isoform modulation mimics abnormal retinal hemodynamics in diabetic rats

PURPOSE

Elevation of diacylglycerol (DAG) and protein kinase C (PKC) levels in diabetic vascular tissue is associated with abnormalities of retinal and renal hemodynamics. The object of this study was to determine whether direct elevation of retinal DAG levels, in the absence of diabetes or hyperglycemia, can mimic the hemodynamic abnormalities normally observed in diabetic rats. Retinal DAG levels were elevated using an inhibitor of DAG kinase that converts DAG to phosphatidic acid. The effectiveness of a specific PKC-beta isoform inhibitor introduced directly into the retinas of diabetic rats in reversing diabetes-related abnormal retinal hemodynamics was also investigated.

METHODS

For retinal blood flow studies, diacylglycerol kinase (DGK) inhibitor R59949, at various concentrations, was injected into the vitreous of nondiabetic Sprague-Dawley rats (n = 33), and a PKC-beta isoform-selective inhibitor LY333531 was injected into the vitreous of rats with streptozotocin (STZ)-induced diabetes of 2 weeks' duration (n = 21). Retinal hemodynamic changes were quantitated using video-based fluorescein angiography. Total DAG levels were assayed from five nondiabetic rat retinas after DGK inhibition and retinal PKC activities were assayed from six diabetic rat retinas after PKC-beta inhibition.

RESULTS

DGK inhibitor R59949 injected into the vitreous dose dependently increased the mean circulation time (MCT) and decreased retinal blood flow (EC50 = 10(-8) M). After 30 minutes, 10(-5) M R59949 induced a 1.7-fold increase in total retinal DAG levels, compared with the levels in vehicle-injected eyes, an increase in MCT from 0.87 +/- 0.05 seconds to 1.44 +/- 0.12 seconds (P < 0.01) and a decrease in retinal blood flow from 105.3 +/- 6.5 pixel2/second to 64.1 +/- 5 pixel2/second (P < 0.01). The effect of R59949 was sustained for 60 minutes after injection. These retinal hemodynamic parameters after DGK inhibition were comparable to those measured at baseline in rats with STZ-induced diabetes of 2 weeks' duration (MCT = 1.38 +/- 0.20 seconds; retinal blood flow = 68 +/- 11.2 pixel2/second). Intravitreal injection of the PKC-beta inhibitor (LY333531) at 10(-5) M in diabetic rats decreased by a factor of 1.6 the diabetes-related increased PKC activation, decreased the prolonged MCT (0.98 +/- 0.13 seconds; P < 0.01) and increased retinal blood flow (93.4 +/- 14.2 pixel2/second; P < 0.01). The measured retinal circulatory parameters after PKC inhibition in the retina were comparable to those measured at baseline in the nondiabetic rats.

CONCLUSIONS

These results provide direct evidence that DAG elevation and subsequent PKC-beta isoform activation are the primary biochemical sequelae responsible for the development of the abnormal retinal hemodynamics observed in diabetic rats.

Vascular endothelial growth factor and severity of nonproliferative diabetic retinopathy mediate retinal hemodynamics in vivo: a potential role for vascular endothelial growth factor in the progression of nonproliferative diabetic retinopathy

PURPOSE

To determine the effect of vascular endothelial growth factor and retinopathy level on retinal hemodynamics in nondiabetic and diabetic rats and to evaluate retinal hemodynamics in nondiabetic and diabetic patients.

METHODS

Forty-eight diabetic and 22 nondiabetic patients had their diabetic retinopathy levels determined from fundus photographs according to Early Treatment Diabetic Retinopathy Study (ETDRS). Fluorescein angiograms were recorded from the left eye by video fluorescein angiography. Retinal blood flow was calculated from the digitized angiograms. Human recombinant vascular endothelial growth factor or vehicle alone was injected intravitreally into 13 nondiabetic and 11 diabetic rats.

RESULTS

Retinal blood flow decreased 33% in patients with ETDRS retinopathy level 10 compared with control patients (P = .001) and increased sequentially in more advanced stages of retinopathy, with a strong correlation between retinal blood flow and retinopathy level (r2 = 0.434, P = .001). In the diabetic rats, retinal blood flow was decreased 35.6% (P = .01). Vascular endothelial growth factor maximally increased retinal blood flow by 36.1% in nondiabetic rats after 25 minutes (P = .001) and by 73.7% in diabetic rats after only 5 minutes (P = .01) and caused a greater response in diabetic than in nondiabetic rats.

CONCLUSIONS

Retinal blood flow increases with advancing nonproliferative diabetic retinopathy in humans, and diabetes accentuates the vascular endothelial growth factor-induced increase in retinal blood flow and venous dilation in rats. Vascular endothelial growth factor may contribute to the changes in retinal hemodynamics and morphology observed in early diabetic retinopathy.

Vascular endothelial growth factor-induced retinal permeability is mediated by protein kinase C in vivo and suppressed by an orally effective beta-isoform-selective inhibitor

Increased vascular permeability and excessive neovascularization are the hallmarks of endothelial dysfunction, which can lead to diabetic macular edema and proliferative diabetic retinopathy in the eye. Vascular endothelial growth factor (VEGF) is an important mediator of ocular neovascularization and a known vasopermeability factor in nonocular tissues. In these studies, we demonstrate that intravitreal injection of VEGF rapidly activates protein kinase C (PKC) in the retina at concentrations observed clinically, inducing membrane translocation of PKC isoforms alpha, betaII, and delta and >threefold increases in retinal vasopermeability in vivo. The effect of VEGF on retinal vascular permeability appears to be mediated predominantly by the beta-isoform of PKC with >95% inhibition of VEGF-induced permeability by intravitreal or oral administration of a PKC beta-isoform-selective inhibitor that did not inhibit histamine-mediated effects. These studies represent the first direct demonstration that VEGF can increase intraocular vascular permeability through activation of PKC in vivo and suggest that oral pharmacological therapies involving PKC beta-isoform-selective inhibitors may prove efficacious for the treatment of VEGF-associated ocular disorders such as diabetic retinopathy.

Fetal transplants alter the development of function after spinal cord transection in newborn rats

Pieces of fetal spinal tissue were transplanted into the site of complete midthoracic spinal transections in neonatal rat pups (transplant rats). The development of locomotion in these animals was compared with that of unoperated control rats and rats that received spinal transections alone (spinal rats). Reflex, treadmill and overground locomotion, staircase descent, and horizontal ladder crossing for a water reward were tested in control, spinal, and transplant rats from 3 weeks to adulthood. All tests were readily performed by control animals. Most spinal rats were unable to make many linked weight-supported steps on these tasks. Transplant rats were variable in their locomotor capabilities, but a subset of rats were able to demonstrate coordinated and adaptable locomotion on these tasks. Some transplant rats performed better on more challenging tasks, suggesting that motor strategies for these tasks used different information, perhaps from descending systems. Transplanted tissue survived, and in most cases there was immunocytochemical staining of serotonergic fibers passing into and caudal to the transplant, supporting the conclusion that descending systems grew through the transplanted tissue. Integration with the host tissue was often poor, suggesting that nonspecific or trophic effects of the transplant might also contribute to the development of locomotor function. Therefore several mechanisms may contribute to the repair of injured spinal cord provided by transplants that permit the development of useful locomotion.

[A case report of Listeria monocytogenes infection in a patient with AIDS. Efficacy of treatment with cotrimoxazole associated with rHuG-CSF (filgrastim)]

Listeriosis is an emerging opportunistic infection in the immunocompromised host. A case of sepsis due to Listeria monocytogenes in a patient with advanced HIV infection and severe neutropenia, treated for an underlying non-Hodgkin's lymphoma, is described. Therapy with cotrimoxazole associated with rHuG-CSF (filgrastim) led to a rapidly favourable clinical and microbiological outcome, and to the correction of concurrent neutropenia. The case report is discussed according to a literature review of all cases of listeriosis reported until now in the setting of HIV infection and AIDS. In particular, the role of both cotrimoxazole and rHuG-CSF adjunct in the treatment of listeriosis in the immunocompromised patient is focused.