The postnatal development of geniculocortical axon arbors in owl monkeys

To characterize the postnatal development of geniculocortical axon arbor morphology in owl monkeys at a series of ages from birth to adulthood, individual arbors were bulk-filled with HRP in brain slice preparations and were reconstructed from serial sections. At all ages, cortical layers and sublayers were obvious. Presumed M or magnocellular arbors were largely confined to layer IV alpha, but they also extended into layer IIIc (IVB of Brodmann, 1909); presumed P or parvocellular arbors were almost exclusively confined to layer IV beta. Other axons that may reflect feedback projections from MT terminated in layer IIIc. Overall, M axon arbors increased in size and complexity from birth to adulthood with mean surface-view arbor areas ranging from 0.08 +/- 0.01 mm2 in newborns to 0.24 +/- 0.02 mm2 in adults. The developing P arbor areas were, on average, as large or larger than adult (newborn = 0.07 +/- 0.01 mm2, adult = 0.047 +/- 0.01 mm2; n.s.) but the arbors were somewhat less complex. Since the brain and area 17 increase in size postnatally, the proportion of area 17 subserved by each P arbor would decrease in postnatal development. Terminal boutons with immature features were evident in both M and P populations at all developmental ages. The results indicate that, while both LGN axon types in monkeys undergo morphological changes postnatally, M arbors appear to mature by increasing arbor size and terminal branching complexity, whereas P arbors increase in complexity but not in size. These distinct programs of axon arbor development suggest that the periods of susceptibility of geniculocortical axon arbors to postnatal influences of the environment, and the types of plastic responses they potentially exhibit, are class-specific.     

Early detection of breast cancer in Navarra. Diagnostic approach in women sent to a referral hospital

BACKGROUND: Breast cancer screening programs represent an important increase in the number of patients to be evaluated and a higher proportion of subclinical lesions detected in reference hospitals. The authors' experience related to an early detection program initiated in Navarra, Spain (PDPCM) is herein presented. METHODS: The diagnoses made in 319 women referred from the PDPCM to the authors' hospital for mammographic suspicion of malignancy were reviewed. Directed surgical biopsy was carried out in 89 women (27.9%) without previous cytologic study. Fine needle aspiration punction and cytology (FNAP-cytology) were performed as the first diagnostic test in 216 lesions (67.7%) 53 of which were palpable and 163 nonpalpable. Aggressive techniques were not indicated in 14 cases (4.4%). RESULTS: A total of 136 carcinomas (42.6%) were diagnosed and benign lesions were find at biopsy in 112 (35.1%) women. The fifty-seven lesions (17.9%) which did not show malignancy on FNAP-cytology were not biopsied given the insufficient degree of suspicion. Only one false negative has appeared in this group from 27 to 48 months after the first consultation. The global diagnostic reliability was of 99.68%. CONCLUSIONS: Directed surgical biopsy is the most reliable technique for the diagnosis of nonpalpable breast lesions in early stages and is always necessary when there is medium or high radiologic suspicion of malignancy. Fine needle aspiration puncture is a very useful technique to confirm malignancy and to avoid unnecessary biopsies in low suspicion lesions.     

Three-point boundary value problems for difference equations

In this paper, the existence and nonexistence of positive solutions for three-point nonlinear boundary value problems of difference equations are considered.     

Quasi-TEM model of magnetostatic-surface wave excitation in microstrip lines

The per unit length capacitance and inductance of a YIG-loaded microstrip line are computed in the frame of a quasi-transverse electromagnetic approach. The transmission line parameters, i.e., the complex propagation constant and the complex characteristic impedance are computed from them and the insertion loss of a finite-length YIG-loaded microstrip line is obtained using the simple transmission line model. In particular, it is shown that this model is suitable even for the magnetostatic regime.     

Subanesthetic effects of the noncompetitive NMDA antagonist, ketamine, in humans. Psychotomimetic, perceptual, cognitive, and neuroendocrine responses

BACKGROUND: To characterize further behavioral, cognitive, neuroendocrine, and physiological effects of subanesthetic doses of ketamine hydrochloride in healthy human subjects. Ketamine, a phencyclidine hydrochloride derivative, is a dissociative anesthetic and a noncompetitive antagonist of the N-methyl-D-aspartate subtype of excitatory amino acid receptor. METHODS: Nineteen healthy subjects recruited by advertisements from the community participated in this randomized, double-blind, placebo-controlled study. Subjects completed three test days involving the 40-minute intravenous administration of placebo, ketamine hydrochloride (0.1 mg/kg), or ketamine hydrochloride (0.5 mg/kg). Behaviors associated with the positive and negative symptoms of schizophrenia were assessed by using the Brief Psychiatric Rating Scale. Changes in perception and behaviors associated with dissociative states were assessed by the Perceptual Aberration Subscale of the Wisconsin Psychosis Proneness Scale and the Clinician-Administered Dissociative States Scale. Cognitive function was assessed by using the (1) Mini-Mental State Examination; (2) tests sensitive to frontal cortical dysfunction, including a continuous performance vigilance task, a verbal fluency task, and the Wisconsin Card Sorting Test; and (3) tests of immediate and delayed recall. Plasma levels of cortisol, prolactin, homovanillic acid, and 3-methoxy-4-hydroxyphenethyleneglycol were measured. RESULTS: Ketamine (1) produced behaviors similar to the positive and negative symptoms of schizophrenia; (2) elicited alterations in perception; (3) impaired performance on tests of vigilance, verbal fluency, and the Wisconsin Card Sorting Test; (4) evoked symptoms similar to dissociative states; and (5) preferentially disrupted delayed word recall, sparing immediate recall and postdistraction recall. Ketamine had no significant effect on the Mini-Mental State Examination at the doses studied. Ketamine also had no effect on plasma 3-methoxy-4-hydroxyphenethyleneglycol levels, although it blunted a test day decline in plasma homovanillic acid levels at the higher dose. It also dose dependently increased plasma cortisol and prolactin levels. Ketamine produced small dose-dependent increases in blood pressure. CONCLUSIONS: These data indicate that N-methyl-D-aspartate antagonists produce a broad range of symptoms, behaviors, and cognitive deficits that resemble aspects of endogenous psychoses, particularly schizophrenia and dissociative states.