Previous outpatient antibiotic use in patients admitted to hospital for COPD exacerbations: room for improvement.

PURPOSE: Several studies have analyzed factors associated to hospitalization in chronic obstructive pulmonary disease (COPD) patients. However, data are lacking on the quality of treatment received by patients prior to hospital admission. The present study analyzed how often patients requiring hospitalization for a COPD exacerbation had received previous treatment for the exacerbation, particularly antibiotics. METHODS: This was a multicenter, cross-sectional, observational study conducted in 30 Spanish hospitals among COPD patients aged >40 years who were hospitalized for an acute exacerbation. Patients were grouped according to whether or not they had received treatment prior to admission and, subsequently, according to whether or not they had received antibiotics. Patient eligibility for antibiotic therapy was assessed using both national and European guidelines. RESULTS: The study population consisted of 298 patients, of which 277 (93 %) were men, with a mean [standard deviation (SD)] age of 69.1 (9.5) years. One hundred and thirty-three patients (45 %) had received treatment prior to admission; among these, 76/133 (57 %) had received antibiotic therapy. However, 81-91 % of these patients fulfilled criteria for this therapy. Antibiotic use was significantly associated with yellow or green-yellow sputum prior to the exacerbation, a higher number of exacerbations in the previous year, more visits to emergency departments, and bronchiectasis. On the other hand, 10-20 % of patients who did receive antibiotics were not eligible for this therapy according to guidelines. CONCLUSIONS: This study demonstrates a low rate of previous outpatient treatment and antibiotic use among patients with a COPD exacerbation requiring hospital admission.

Ultrastructural characterization of relationship between serotonergic and GABAergic structures in the ventral part of the oral pontine reticular nucleus.

The ventral part of the oral pontine reticular nucleus (vRPO) is involved in the generation and maintenance of rapid eye movement (REM) sleep. Both GABAergic and serotonergic neurotransmission have been implicated in the control of the sleep-wakefulness cycle. Nevertheless, the synaptic organization of serotonergic terminals in the vRPO has not yet been characterized. We performed an electron microscope study of serotonin-immunoreactive (5-HT-IR) terminals using immunoperoxidase or immunogold-silver methods. In a second set of experiments, combining GABA immunoperoxidase and 5-HT immunogold-silver techniques, we examined inputs from GABA-immunoreactive (GABA-IR) terminals to serotonergic neurons. 5-HT-IR terminals were located primarily on dendrites and occasionally on somata of unlabeled and 5-HT-IR neurons. The majority of the synapses formed by 5-HT-IR terminals were of the symmetrical type, making contacts primarily with unlabeled dendritic profiles. Moreover, 5-HT-IR terminals contacted unlabeled axon terminals that formed asymmetric synapses on dendrites. Double immunolabeling experiments showed 5-HT-IR and GABA-IR afferents, in apposition to each other, making synapses with the same dendrites. Finally, GABA-IR terminals innervated 5-HT-IR and GABA-IR dendrites. Our findings indicate that serotonin would modulate the neuronal activity through inhibitory or excitatory influences, although the action of serotonin on the vRPO would predominantly be inhibitory. Moreover, the present results suggest that the serotonin modulation of vRPO neurons might involve indirect connections. In addition, GABA might contribute to the induction and maintenance of REM sleep by inhibiting serotonergic and GABAergic neurons in the vRPO.

Efficacy of moxifloxacin in the treatment of bronchial colonisation in COPD.

This study was designed to investigate the efficacy of moxifloxacin for the eradication of bacterial colonisation of the airways in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD). Out of 119 stable patients with COPD screened, 40 (mean age 69 yrs, mean forced expiratory volume in 1 s 50% predicted) were colonised with potentially pathogenic microorganisms (PPMs) and were included in a randomised, double-blind, placebo-controlled trial with moxifloxacin 400 mg daily for 5 days. Eradication rates were 75% with moxifloxacin and 30% with placebo at 2 weeks (p = 0.01). Bacterial persistence at 8 weeks was still higher (not significantly) in the placebo arm (five (25%) out of 20 versus one (5%) out of 20; p = 0.18). The frequencies of acquisition of a new PPM were high and similar in both treatment groups; consequently, the prevalence of colonisation at 8 weeks was also similar between treatment arms. No difference was found in the number of patients with exacerbations during the 5-month follow-up. Only the acquisition of a new PPM during follow-up showed a statistically significant relationship with occurrence of an exacerbation. Moxifloxacin was effective in eradicating PPMs in patients with positive sputum cultures. However, most patients were recolonised after 8 weeks of follow-up. Acquisition of a new strain of bacteria was associated with an increased risk of developing an exacerbation.

GABAergic structures in the ventral part of the oral pontine reticular nucleus: An ultrastructural immunogold analysis.

GABA mediates inhibitory effects in neurons of the ventral part of the oral pontine reticular nucleus (vRPO). Evidence increasingly suggests that GABA plays an important role in the modulation of rapid eye movement (REM) sleep generation in the cat vRPO. Here, we investigate the anatomical substrate of this modulation using GABA immunocytochemistry. Immunoperoxidase labeling revealed a few small GABA-immunoreactive cell bodies scattered throughout the vRPO. The numerical densities of all vRPO synapses and the GABA-immunoreactive synapses were estimated, at the electron microscopical level, by using a combination of the physical disector and the post-embedding immunogold techniques. We estimated that 30% of all vRPO synaptic terminals were immunoreactive to GABA. Our findings support the hypothesis that vRPO neuron activity is significantly controlled by inhibitory GABAergic terminals that directly target somata and the different parts of the dendritic tree, including distal regions. GABAergic input could inhibit vRPO REM sleep-inducing neurons during other states of the sleep-wakefulness cycle such as wakefulness or non-REM sleep.

Alpha-1-antitrypsin deficiency: optimal therapeutic regimen based on population pharmacokinetics.

BACKGROUND: Exogenous doses of 60 mg/kg alpha(1)-antitrypsin (AAT) every 7 days are recommended in patients with severe AAT deficiency. However, long term administration of weekly doses is not well accepted by patients. Using pharmacokinetic simulations, we evaluated whether steady state minimum concentrations of total AAT can be maintained above the threshold of 0.5 g/l with longer intervals between doses. METHODS: Several sets of exogenous AAT versus time simulations were studied using a non-linear mixed effect approach with dosage regimens every 7, 14, 21, and 28 days. For each regimen the mean exogenous AAT trough concentrations and 5/95th percentiles were determined. The results obtained were applied to estimate the individual optimal dose at 7, 14, and 21 days in six patients using Bayesian analysis. RESULTS: The simulations showed that a dose of 50 mg/kg AAT every 7 days was sufficient to obtain nadir concentrations. Doses of 120 and 100 mg/kg every 14 days were also adequate, but 180 mg/kg given every 21 days required total AAT monitoring to avoid underdosage. Longer intervals were inappropriate. Dosage individualisation confirmed that AAT infusions given every 14 days maintained the nadir level of 0.5 g/l without a significant dose increase compared with current practice. When the time span between doses was fixed at 21 days, a mean relative AAT dose enhancement of 91% and 13%, respectively, was required to achieve sustained total AAT concentrations above the target level for 100% and 85% of the interval between doses. CONCLUSIONS: It is feasible to extend the interval between doses of AAT to 14 or 21 days to achieve adequate trough total AAT concentrations. This study might be used as a starting point for clinical evaluation of the regimens described.

[Attitudes toward the diagnosis of chronic obstructive pulmonary disease in primary care]. / Problemas con el diagnóstico de la EPOC en atención primaria.

OBJECTIVE: Although the prevalence of chronic obstructive pulmonary disease (COPD) has increased among women, it is still considered a disease that mainly affects men. This study aimed to identify the diagnostic attitudes of primary care physicians toward patients with COPD according to gender and spirometric results. METHODS: A representative sample of 839 primary care physicians participated in the study. Each physician dealt with 1 of 8 hypothetical cases based on a patient diagnosed with COPD. In half the cases, the physician was told the patient was a man. The other half of the physicians were told the same patient was a woman. After presentation of the medical history and results of physical examination, the physicians were asked to state a probable diagnosis and indicate the diagnostic tests that were necessary. They were then told the results of spirometry, which indicated obstruction ranging from moderate to severe. Negative results of bronchodilator tests and oral corticosteroid tests were then communicated. RESULTS: COPD was more likely to be the preliminary diagnosis for male patients than for females (odds ratio [OR], 1.55; 95% confidence interval [CI], 1.15-2.1). This gender bias disappeared once the physicians were shown the abnormal results of spirometry. Patients with severe obstruction were more likely to be diagnosed with COPD than those with moderate obstruction (OR, 1.5; 95% CI, 1.08-2.09). CONCLUSIONS: There is gender bias in the diagnosis of COPD. Patients with moderate obstruction are often believed not to have COPD. These biases may compromise the early diagnosis of the disease in a group of patients with ever increasing risk.

Results of a case-detection programme for alpha1-antitrypsin deficiency in COPD patients.

Alpha1-antitrypsin (alpha1-AT) deficiency is an underdiagnosed condition in patients with chronic obstructive pulmonary disease (COPD). The present authors have conducted a nationwide case detection programme of alpha1-AT deficiency in unselected patients with COPD using dried blood spots. The first phase analysed samples from 971 patients by determining alpha1-AT concentrations and identifying the deficient Z allele by genotyping using rapid real-time PCR. The second phase analysed 1,166 samples with alpha1-AT concentrations and identified both the S and the Z allele, but only in samples with low alpha1-AT concentrations. A total of eight (0.37%) individuals with the severe deficiency PiZZ were detected. In addition, three patients were identified with the PiSZ genotype in the second phase (0.3%). The global cost of the programme was 41,512, which represents 19.42 per sample and 5,189 per PiZZ detected. A sensitivity analysis demonstrated that performing Z genotype to all samples would have resulted in increased costs of 28 per sample and 7,479.5 per PiZZ case identified. In conclusion, a case detection programme of alpha1-antitrypsin deficiency in patients with chronic obstructive pulmonary disease using dried blood spots is feasible and at a reasonable cost per case detected. Diagnostic yield and costs depend largely on inclusion criteria and the protocol for processing of samples.

[A comparison of moxifloxacin and amoxicillin in the treatment of community-acquired pneumonia in Latin America: results of a multicenter clinical trial]. / Moxifloxacino frente a amoxicilina en el tratamiento de la neumonía adquirida en la comunidad en América Latina. Resultados de un ensayo clínico multicéntrico.

Since community-acquired pneumonia (CAP) is a common disease with a high morbidity rate, it is important to obtain information concerning its etiology and susceptibility to antibiotics across different geographic areas. This study presents data obtained in 5 Latin American counties in the course of an international clinical trial that evaluated the efficacy and safety of treatment with either moxifloxacin or amoxicillin administered for 10 days to patients suspected of having CAP caused by a pneumococcal infection. Details are given of the pathogens identified, the patterns of sensitivity to antibiotics observed, and the clinical and microbiological results obtained.A total of 84 patients were studied, of whom 70 (83.3%) were evaluated at the end of the trial to determine the efficacy and safety of the treatment received. Gram-positive bacteria were found in samples from 29 patients (80.5%). The pathogen was Streptococcus pneumoniae in 28 of those cases (77.7%). Gram-negative bacteria were found in 7 patients (19.4%), the most common being Haemophilus influenzae in 3 patients (8.3%). The presence of atypical microorganisms was detected in 18 of the 70 patients (25%), mainly Mycobacterium pneumoniae (n=11), and in 6 cases (8.5%) the infection was mixed. Ten strains of S. pneumoniae (35.7%) were shown to be susceptible to penicillin, 2 (7.1%) were highly resistant, and 16 (57.1%) showed moderate resistance. The clinical success rate at the final visit after treatment was 94.1% for moxifloxacin and 91.7% for amoxicillin. The results of this trial demonstrate a high prevalence of S. pneumoniae with reduced susceptibility to penicillin in patients with CAP in Latin America. It also revealed a high incidence of atypical pathogens and mixed infection in 8.6% of patients. This information should be taken into account when establishing protocols for empirical treatment of CAP in Latin America.

[Screening program for alpha-1 antitrypsin deficiency in patients with chronic obstructive pulmonary disease, using dried blood spots on filter paper]. / Programa de cribado para el déficit de alpha 1-antitripsina en pacientes con EPOC mediante el uso de gota de sangre en papel secante.

Alpha-1 antitrypsin (AAT) deficiency is an under-diagnosed disease and screening programs have therefore been recommended for patients with chronic obstructive pulmonary disease (COPD). We present the results of the pilot phase of a screening program for AAT deficiency in order to evaluate the technique used, the procedures for transporting samples and the results obtained. Over a period of one month, five centers collected samples from all COPD patients for whom plasma concentrations of AAT or Pi phenotype had not yet been determined. Capillary blood spots were dried on filter paper and then sent by surface mail to a central laboratory for study. An immunonephelometric assay was used to determine AAT and DNA phenotyping was done by use of a Light Cycler. Samples were analyzed from 86 COPD patients (76 men, 10 women) with a mean age of 68.2 years. AAT deficiency was ruled out for 74 patients (86%) who had concentrations above the cutoff established, although one of them was MZ heterozygote by genotype. Among the 12 remaining patients (13.9%), only two also had a Z allele. The rest were individuals with concentrations below the established threshold and no evidence of a Z allele (10 patients, 11.6%). The Z allele frequency observed (3/172; 1.74%) was very similar to that found in the general population. The results of this pilot study allowed us to confirm that the method used to collect samples worked well. The sampling method is applicable, easy and well-accepted by participating physicians. It allowed AAT concentrations and Z allele deficiency to be determined. The method correlates well with standard techniques used for samples in whole blood.

[Importance of serum interleukin-6 as a mediator of systemic inflammation in patients with alpha-1 antitrypsin deficiency]. / Importancia de la medición de la interleucina 6 en suero como mediador de inflamación sistémica en pacientes con deficiencia de alfa-1-antitripsina.

The objective of this study was to determine whether high concentrations of circulating interleukin-6 (IL-6) and/or the soluble receptor of IL-6 (SRIL-6) may mediate systemic inflammatory activity in patients with alpha-1 antitrypsin deficiency (AATD). To that end we assessed serum concentrations of IL-6 and SRIL-6 for 7 patients with AATD in stable phase. The patients' mean age was 51 years (SD 5.2); mean FEV1% was 35.5% (SD 15%). IL-6 and SRIL-6 concentrations were compared with those of 23 non-AATD patients with COPD but with similar changes in lung function (mean age 63 years, SD 10.1; FEV1% 38.3%, SD 11%). The AADT patients had mean IL-6 concentrations of 4.7 pg/mL (interquartile range [IR( 4.0) and RSIL-6 levels of 129.1 ng/mL (IR 31.5). The COPD patients had IL-6 concentrations of 4.1 pg/mL (IR 4.2) and SRIL-6 levels of 140.8 ng/mL (IR 71). No significant differences between the AADT group and the COPD group were observed for either cytokine (non-parametric Mann Whitney U test, p > 0.05). Only one AADT patient had an IL-6 concentration that was higher than normal. In conclusion, the serum IL-6 and SRIL-6 concentrations of patients with AADT are not different from those of patients with COPD, similarly altered respiratory function and normal alpha-1 antitrypsin levels. These results do not point to a role for alpha-1 antitrypsin in systemic inflammatory stimulation in patients with AADT.

Influence of deficient alpha1-anti-trypsin phenotypes on clinical characteristics and severity of asthma in adults.

Severe alpha1-anti-trypsin (AAT) deficiency implies a high risk of pulmonary emphysema development. The possible relationship between partial deficiencies of this enzyme and bronchial asthma remains controversial. The objective of this study was to ascertain the distribution of AAT phenotypes in a non-selected asthmatic patient population. Across-sectional study on a sample of 111 patients with asthma was carried out. Demographic and clinical variables were collected with serum IgE concentrations, plasma eosinophil number and serum AAT concentrations determined, together with the Pi phenotype. Asthma was mild in 36 (32.4%) patients, moderate in 45 (40.5%) and severe in 30 (27%). No differences were observed in eosinophil count or serum IgE or AAT concentrations among patients with different degrees of severity. Twenty-two (19.8%) asthmatics with deficient phenotypes for AAT were identified, distributed equally in all severity stages of the disease. No significant differences were found in clinical and functional characteristics, or in asthma morbidity between PiMM and PiMS patients or the heterozygote group (PiMS and PiMZ). Eosinophil count and IgE concentrations did not differ significantly between asthmatics with normal phenotype and heterozygotes. In conclusion, the distribution of AAT phenotypes in asthmatic patients did not differ from that found in the general population. Heterozygote phenotypes for the deficiency do not appear to confer greater severity or different clinical expression of asthma in adults.

Ultrastructural synaptic organization of axon terminals in the ventral part of the cat oral pontine reticular nucleus.

In an attempt to contribute to the current knowledge of the brainstem reticular formation synaptic organization, the ultrastructure and distribution of synaptic terminal profiles on neurons in the ventral part of the oral pontine reticular nucleus (vRPO), the rapid eye movement (REM) sleep-induction site, were studied quantitatively. Terminals with asymmetric contacts and rounded vesicles were classified according to vesicle density as type I or II (high or low density, respectively). The area, apposed perimeter length, and mitochondrial area of type I terminals, on average, were significantly smaller than those of type II terminals. Type III and IV terminals had symmetric contacts and oval and/or flattened vesicles; type III terminals formed synapses between them and on initial axons. Type V and VI terminals showed characteristics intermediate to those of asymmetric and symmetric synapses. Interestingly, some terminal features were related to both terminal area and postsynaptic dendritic diameter. The percentages of different synapses sampled on somata were as follows: asymmetric synapses (usually formed by type II terminals; mean +/- S.D.), 26.4% +/- 3%; symmetric synapses, 46.7% +/- 5.2%; and intermediate synapses, 26.9% +/- 6.1%. The percentages of different synapses sampled on dendrites were asymmetric synapses, 62.1% +/- 9%; symmetric synapses, 25.6% +/- 8.1%; and intermediate synapses, 12.3% +/- 1.7%. Comparison between large- and small-diameter dendrites revealed that the percentages of symmetric synapses and type II terminals decreased, whereas the percentages of type I terminals increased as postsynaptic dendritic diameters became smaller. Synaptic density was approximately four times lower on somata than on dendrites. The vRPO synaptic organization reflects some patterns that are similar to those found in other regions of the central nervous system as well as specific synaptic patterns that are probably related to its functions: the generation and maintenance of REM sleep and the control of eye movement or limb muscle tone.

Electrophysiological properties and cholinergic responses of rat ventral oral pontine reticular neurons in vitro.

In order to characterize the electrophysiological properties of morphologically identified neurons of the ventral part of the oral pontine reticular (vRPO) nucleus and the effects of cholinergic agonists on them, intracellular recordings were obtained from 45 cells in a rat brain-slice preparation. Intracellular staining was performed with 2% biocytin in potassium acetate (1 M)-filled micropipettes. Results demonstrated the presence of two types of vRPO neurons. Type I cells (n = 12, 24%) were characterized by a break with a decrease of the depolarizing slope following hyperpolarizing pulses which delayed the return to the resting Vm and subsequent spike-firing. The delay was antagonized by 4-AP (200-500 microM) which specifically blocks the transient outward K+-mediated current I(A). Type II neurons (n = 38, 76%) displayed a typical depolarizing sag during hyperpolarizing current pulses which was blocked by Cs+. This behavior is characteristic of the hyperpolarization-activated current I(Q). These two neuronal types displayed different morphological features. Most type I and II cells (100 and 73.7%, respectively) were depolarized by acetylcholine (1-15 microM), carbachol (0.5-1 microM) and muscarine (1-10 microM) through the activation of post-synaptic muscarinic receptors. The remaining type II cells (26.3%) were hyperpolarized (1-10 min, 3-15 mV) through the activation of post-synaptic muscarinic receptors. Results are consistent with the hypothesis that the vRPO could be a neuronal target of Cch in eliciting paradoxical sleep because most of its neurons are activated by muscarinic agonists.

The effect of age on the monoamines of the hypothalamus.

Measurement of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) homovanillic acid (HVA), 3-methoxytyramine (3-MT), noradrenaline (NA), 3-methoxy-4-hydroxyphenyl glycol (MHPG) and serotonin (5-HT) and its main metabolite, 5-hydroxyindol-3-acetic acid (5-HIAA) was assessed in hypothalamus and median eminence of aged rats. Age-related changes were not observed in the concentration of NA and its metabolites in median eminence. In contrast, there was a significant NA decrease in aged hypothalamus compared with 12 months (no differences were found compared with 3 months). No significant differences were found in DA concentration and its metabolites in hypothalamus but DA decreased significantly in aged median eminence compared with 12 months. The ratio 5-HIAA/5-HT, indicative of 5-HT turnover, appeared to increase in the hypothalamus and median eminence of the aged rat. Morphological dissimilarities between hypothalamus of young and aged rats were demonstrated using serotonin-immunocytochemistry. A degeneration of the serotoninergic system, denoted by the appearance of enlarged or swollen varicosities, was observed in the hypothalamus of the aged rat. These aberrant serotoninergic fibers may reflect the local degeneration of serotoninergic hypothalamic afferents during ageing. Such differential age-dependent alterations of the serotoninergic system might be responsible for at least some of the functional deficits in aged animals.

Expression of choline acetyltransferase immunoreactivity in the rat red nucleus after postnatal enucleation.

The presence of cholinergic neurones in the rat red nucleus (RN) is a controversial subject. We investigated this issue by immunocytochemistry in both adult, normal and neonatally enucleated rats. Choline acetyltransferase (ChAT)-immunoreactive neurones were found in the RN only of enucleated rats. An increase in cytochrome oxidase staining was also observed in the RN of enucleated rats. Our data support the concept that neurones in the rat RN are cholinergic and suggest that their activity could be modulated by the visual input.

Age-related changes on monoamine turnover in hippocampus of rats.

After pargyline treatment the turnover rates of dopamine (DA), noradrenaline (NA), 3,4-dihydroxyphenylacetic acid (DOPAC), serotonin (5-hydroxytryptamine (5-HT) and 5-hydroxy-3-indolacetic acid (5-HIAA) has been measured in control and aged hippocampus of the rats. In addition, the tyrosine hydroxylase (TH) activity and monoamine oxidase-A and monoamine oxidase-B activities have also been studied. The TH activity did not change in aged hippocampus as compared to controls. The monoamine oxidase-B: monoamine oxidase-A ratio increased in 26-month-old rats compared with controls. The turnover of DA, DOPAC and NA did not show significant changes while 5-HT synthesis, 5-HT accumulation rate and 5-HIAA turnover increased in aged rats. Serotonin fibers showed morphological dissimilarities between the hippocampus of young and aged rats using immunocytochemistry techniques. In aged rats aberrant serotoninergic fibers mainly appear in the molecular layer of the dentate gyrus and molecular of the hippocampal CA1. It is suggested that the aberrant morphology of 5-HT fibers may reflect the local degeneration of serotoninergic hippocampal afferents during aging. Increase of 5-HT turnover in aged might be a signal of degeneration.

Changes in neurotransmitters in superior colliculus after neonatal enucleation: biochemical and immunocytochemical studies.

The turnover rate of dopamine and serotonin and the level of glutamate in superior colliculus are increased in adult, neonatally enucleated rats compared with normal control adult animals. Moreover, immunocytochemical data showed that the stratum zonale and the stratum griseum superficiale of the superior colliculus, specifically of bienucleated rats, display a dense network of serotonin-immunoreactive fibres, suggesting an increase in serotoninergic innervation. At the electron microscope level, serotonin-immunoreactive fibres and large postsynaptic serotonin-immunoreactive profiles exhibiting microtubules could be observed in the stratum zonale and the stratum griseum superficiale of the bienucleated rat. These results suggest that neonatal enucleation produces reorganization of serotoninergic and glutamatergic inputs. It is possible that serotonin may exert a profound influence upon collicular function.

Cytoplasmic organelles in neurons of the dorsal lateral geniculate nucleus of aged rats.

The ultrastructural characteristics of the neurons containing complex convolutions have been studied in the dorsal lateral geniculate nucleus of the 31-month-old rat. Neurons were seen to contain oval or round dense bodies which were surrounded by a nuclear membrane and granular endoplasmic reticulum. Their perikarya showed rarely clusters of pleomorphic and small clear vesicles intermingled with a few larger vesicles of dense material. Dendrites occasionally exhibited intermediate forms between laminated bodies and complex convolutions. The significance of these features has been discussed.

Complex convolutions in neurons of the dorsal lateral geniculate nucleus of the normal albino rat.

The postnatal development of complex convolutions (CCs) of the dorsal lateral geniculate nucleus (LGNd) in normal rats has been studied quantitatively with light microscopy. We report that immature neurons do not contain these scarcely understood organelles, since they can be seen for the first time in very few, mature neurons of the 30 day rat; their number constantly increases during the following 4 months. These cytoplasmic inclusions can be equally seen in the aged rat. CCs are present in neurons of all sizes, except the smallest, which correspond to the interneuron population. Although, morphologically, CCs of the LGNd of the rat are similar, but not identical, to the cytoplasmic multilaminated bodies of the cat, intermediate forms are described.

A morphologic analysis of neurons and neuropil in the dorsal lateral geniculate nucleus of aged rats.

Light and electron microscopy were used to investigate the morphology of neuropil and neuronal cell bodies of the dorsal lateral geniculate nucleus (LGNd) of aged rats. Light microscopic examination reveals that, despite the optic tract showing signs of degeneration, the LGNd is scarcely affected. Thus, a slight but significant reduction in the diameters of both soma and nuclei is observed in aged neurons of the LGNd. Ultrastructural analysis demonstrates a few degenerating profiles of the neuropil. Neurons resembling relay cells exhibit typical features of aged neurons. Cells showing a very infolded nucleus, most of the ER cisternae connected with the nuclear envelope, abundant free polyribosomes and subsurface cisterns associated with mitochondria are similar to interneurons of adult rats. Therefore, aging and partial loss of visual input appear to induce small changes in the morphology of most of LGNd neurons.