Conditioned and unconditioned forelimb reflex systems in the cat: involvement of the intermediate cerebellum

 Temporary inactivation of the cerebellar interposed nuclei was used to assess the role of the intermediate cerebellum in the performance of forelimb cutaneo-muscular reflexes in the cat. The following types of reflexive responses were evaluated: the classically conditioned and unconditioned forelimb withdrawal responses and the forelimb tactile placing, hopping and magnet responses. The experiments tested the hypothesis that the intermediate cerebellum is involved in the performance of all the above forelimb reflexes. The forelimb withdrawal reflex was classically conditioned in a newly developed paradigm in which animals were first operantly conditioned to stand on four elevated platforms. Trained animals were microinjected with a γ-aminobutyric acid (GABA) agonist, muscimol, in the interposed nuclei, and the effects of inactivation of the intermediate cerebellar output on the forelimb reflexes were examined. The main findings of these experiments are that unilateral muscimol inactivation of the interposed nuclei in the cat abolished the expression of the classically conditioned limb flexion reflex, suppressed the performance of the unconditioned withdrawal reflex and, in parallel, downregulated the tactile placing, hopping and magnet postural responses in the ipsilateral forelimb. These observations are inconsistent with concepts indicating exclusive involvement of the intermediate cerebellum in the classically conditioned reflexes elicited by aversive stimuli. On the contrary, they support the hypothesis of a more global involvement of this structure in learned and unlearned defensive flexion reflexes and in automatic postural response systems. Received: 29 July 1996 / Accepted: 26 September 1996     

Galanin gene expression declines with adulthood in the cholinergic fields of the horizontal diagonal band of male rats

The neuropeptide galanin (GAL) influences leaming and memory processes, perhaps by inhibiting cholinergic function. We recently reported that, in the rat, the nucleus of the horizontal limb of the diagonal band (HDB) exhibits the highest level of GAL mRNA coexpression by basal forebrain (BF) cholinergic neurons and, in the HDB, virtually all GAL mRNA-expressing neurons correspond to the cholinergic cell type. Since GAL gene expression is induced across puberty in many brain regions, we used in situ hybridization histochemistry and quantitative autoradiography to assess GAL gene expression across the rostro-caudal extent of the HDB in prepubertal and adult male rats and to determine whether GAL gene expression is also regulated during maturation in this BF region. Our results show that the number of GAL mRNA-expressing cells per section is significantly reduced in the HDB with adulthood. Post-hoc analysis indicated that these age-associated differences in the number of GAL mRNA-expressing cells per section could be ascribed to the rostral and central subregions of the HDB. Age-related differences in the labeling intensity of GAL mRNA-expressing neurons were also detected in the rostral and central subregions of the HDB. No age-associated differences in GAL gene expression were found in the caudal HDB subregion. These results suggest that: (1) in contrast to other brain regions, GAL gene expression in the cholinergic BF may be negatively regulated by factors concomitant with puberty; and (2) the inhibition of cholinergic function by cosecreted GAL may be enhanced prior to puberty within cholinergic neurons of the rostral and central aspects of the HDB.     

The effect of vitamin C nutriture on complement component C1q concentrations in guinea pig plasma

This study shows that guinea pigs fed 100 times the amount of vitamin C needed for growth and for prevention of scurvy have elevated levels of complement component C1q. C1q is a plasma protein rich in hydroxyproline, an amino acid whose biosynthesis requires ascorbate. C1q is essential for host defense against pathogens, both as a component of the classical complement pathway and as an opsonin in the phagocytosis process. We measured C1q in vitamin C-depleted guinea pigs that had been repleted for 4 wks with the following daily doses of ascorbate (mg/100 g body wt): 0.50 (suboptimal), 2.0 (adequate), 10 (ample) and 50 (tissue saturating). We measured C1q in three ways: indirectly by quantifying protein-bound hydroxyproline and directly by hemolytic assay and by immunodiffusion against anti-C1q. Regardless of the method, plasma C1q was 30-50% higher in animals fed tissue-saturating ascorbate than in those fed adequate or suboptimal amounts of the vitamin (p less than 0.05, one-way analysis of variance, least significant difference test). These data confirm and significantly extend earlier work that provided indirect evidence for a relationship between C1q and ascorbate nutriture in the guinea pig. They are consistent with a possible relationship between ascorbate nutriture and host defense.     

Upper Gastrointestinal Hemorrhage from Ischemia of an Interposed Jejunal Segment in the Esophagus

We report a patient who presented with hematemesis due to ischemic injury to the jejunal segment which had been interposed following distal esophagectomy for a benign esophageal stricture. The complications of this surgery are reviewed.     

Prolonged stenting does not prevent obstruction after TIP repair when the glans was deeply incised.

PURPOSE: To evaluate whether prolonged postoperative stenting may reduce the risk of obstruction of the neourethra after TIP repair with deep glanular incision. METHODS: In a 1-year period 27 patients were operated for penile hypospadias using the TIP technique described by Snodgrass. In contrast to a previous study with 8 - 10 days of postoperative catheter drainage, the indwelling transurethral catheter was kept in place for 12 - 14 days. Deep incision of the urethral plate up to the tip of the glans is the most remarkable surgical detail, resulting in a meatus on top of the glans but in a defect on the dorsal rim of the neomeatus as well. After 3 - 6 months 22 patients were re-investigated during an outpatient visit using a scheme to describe the position of the neomeatus. Uroflowmetry was also performed. Information in three toddlers was gained by phone and 2 patients were lost to follow-up. RESULTS: Two patients returned with significant obstruction including an urethrocutaneous fistula in one. In contrast to the good assessment by parents and compared to the early appearance after catheter removal a change in meatal position was observed in the majority of patients. Only 6 patients presented with an unchanged meatal position whereas in 16 patients the meatus lost its oval or slit-like shape as well as its position on the tip of the glans. However, despite one obstructive meatus in the coronal position 15 patients showed a sufficient size and position of the meatus underneath the tip of the glans. Uroflowmetry revealed reduced peak-flow values (mean: 8.1 ml/s) in some of the 9 patients evaluated. CONCLUSIONS: Our data indicate that prolonged stenting does not give better results in those TIP repairs, in whom the urethral plate was incised across the rim of the neomeatus. The early excellent aspect of the glans after stent removal is often impaired by partial closure of the glans incision with a short-term change in size and position of the meatus. To prevent this, the rim of the meatus during reconstruction should be kept completely epithelialised.     

Dissociation of the Medial Prefrontal, Posterior Parietal, and Posterior Temporal Cortex for Spatial Navigation and Recognition Memory in the Rat

Rats with lesions of the medial prefrontal, posterior parietal,or posterior temporal cortex were tested in five spatial navigationtasks, which varied in egocentric or allocentric demands, avisual discrimination task, and two delayed nonmatching-to-sampletasks. Rats with prefrontal lesions were impaired at every spatialnavigation task, whereas rats with posterior parietal lesionshad selective spatial navigation impairments. Rats with prefrontallesions were also impaired at a visual delayed nonmatching-to-sampletask, as they were unable to learn the task, even with no delay.The results are consistent with the idea that the basic planof mammalian cortex includes prefrontal, posterior parietal,and posterior temporal regions, each of which have generallysimilar functions across mammalian taxa. There are, however,species-typical differences that reflect specific ecologicalpressures on the development of the different regions.     

A critical survey of hypotheses regarding Post-traumatic Stress Disorders in light of recent research findings

This paper reviews briefly recent findings from psychobiological research upon Post-traumatic Stress Disorders. A critical assay is provided of the various hypotheses advanced as the result of this research data. The author suggests neuropsychological theory provides the best explanation for understanding and classifying both the clinical phenomenology and the biological abnormalities discovered in the chronic forms of PTSD.Initial draft presented at a workshop Delayed Effects of Post Traumatic Stress Disorders, sponsored by the Emergency Services Branch of the National Institutes of Mental Health April 14–15, 1986.