Aberrant retinal projections to midbrain targets mediate spared visual orienting function in hamsters with neonatal lesions of superior colliculus

Summary Rodents, cats, and most nonmammalian vertebrates with bilateral tectal deafferentation or ablation in adulthood are extremely deficient at orienting to visual stimuli; yet animals with neonatal lesions of superficial layers of the superior colliculus (SC) show partial sparing of this response, particularly for targets in the central visual field. In this study, we sought to determine whether these spared orienting abilities are mediated by aberrant retinal projections to the remaining intermediate layers of the SC, or whether visual cortex (VC) mechanisms or alternative behavioral strategies are responsible. Neonatal golden hamsters received either bilateral heat lesions of the SC (rlSC), or a heat lesion of the right SC and enucleation of the right eye (rSCrE). This latter procedure causes axons from the left eye to recross the tectal midline and terminate in the wrong (left) SC (Schneider 1973). As adults, both groups of hamsters were extremely deficient in visually guided approach to stationary targets, although rlSC-lesioned hamsters showed some sparing for central field targets and rSCrE-lesioned hamsters often made wrong-direction turns for targets in the left peripheral field. We then subjected both groups of neonatally lesioned hamsters to bilateral aspiration lesions of the VC. Retesting showed no change in visual orienting behavior as a result of the cortical lesions. Labeling of the optic tract with horseradish peroxidase (HRP) revealed abundant aberrant retinal projections to remaining intermediate layers of the SC and thalamic nucleus lateralis posterior (LP), as well as supernormal innervation of pretectal nuclei, the dorsal terminal nucleus of the accessory optic tract, and the ventral nucleus of the lateral geniculate body (LGv). We conclude that the spared visual orienting capabilities of hamsters with rlSC and rSCrE lesions are mediated by the aberrant midbrain projections, and that cortical mechanisms are not involved in spared visual orienting functions following these neonatal lesions.     

The nucleotide sequence and genome organization of the RNA2 and RNA3 segments in broad bean mottle virus.

Complete nucleotide sequences of broad bean mottle virus (BBMV) genomic RNAs 2 and 3 were determined. They consist of 2811 and 2293 nucleotides, respectively. Both RNAs are caped and, unlike in other tricornaviruses, both initiate with an A residue. BBMV RNA2 is monocistronic and encodes an 815 amino acid 2a protein, whereas RNA3 is dicistronic, encoding for a 295 amino acid 3a protein and for the 190 amino acid coat protein. A central, 423 amino acid 2a protein core region is highly homologous among the three bromoviruses, whereas both N- and C-termini are more heterologous. Most of the homologies among 3a proteins are concentrated within the N-termini two-thirds of the molecule that is predominantly hydrophobic, whereas the C-terminal one-third contains a large number of charged amino acids. The homologies among coat proteins are clustered within several mostly hydrophobic, or neutral, domains. The 5' noncoding region of the RNA2 has 110 nucleotides, whereas that of RNA3 contains 330 nucleotides. As in cowpea chlorotic mottle virus, but unlike in Brome mosaic virus, the 5' noncoding region includes subgenomic promoter-like sequences. The BBMV RNA3 intercistronic region also has subgenomic promoter sequences and contains a long poly(A) stretch. At the 3' end, BBMV RNAs 2 and 3 have 257 and 236 noncoding nucleotides, respectively.     

Gender-specific and gonadectomy-specific effects upon swim analgesia: role of steroid replacement therapy

Both gender-specific and gonadectomy-specific effects have been observed for the analgesic responses following continuous and intermittent cold-water swims (CCWS and ICWS respectively): female rats display significantly less analgesia than males, and gonadectomized rats display significantly less analgesia than sham-operated controls. The present study evaluated the effects of steroid replacement therapy with testosterone propionate (TP: 2 mg/kg, SC) upon CCWS and ICWS analgesia on the tail-flick and jump tests and hypothermia in sham-operated or gonadectomized male and female rats. Thirty days following surgery, rats received either no treatment, a sesame oil vehicle or TP for 14 days prior to, and then during testing. Relative to the no treatment condition, repeated vehicle injections in sham-operated rats eliminated the gender-specific, but did not affect the gonadectomy-specific effects upon CCWS and ICWS analgesia. TP reversed the deficits in CCWS and ICWS analgesia observed in both castrated and ovariectomized rats on both pain tests. TP only potentiated CCWS analgesia in sham-operated males on the tail-flick test. TP potentiated CCWS and ICWS hypothermia in gonadectomized rats and in male sham-operated rats. These data indicate that gonadal steroids play a major modulatory role in the etiology of swim analgesia, and that the observed gender effects are sensitive to possible adaptational variables.     

Development of enhanced blood flow responses to prostaglandin E1 in carrageenan-induced granulation tissue

The distribution of cardiac output (c.o.) was measured by the radioactive microsphere method in rats at different time intervals after the implantation of carrageenanimpregnated sponges. The amount of blood distributed to the developing granulomata increased from day 5 after sponge implantation to day 7, but showed no further increase at day 10. A similar pattern in blood flow was observed in the skin covering the granulomata. Injection of PGE₁ (100 ng) into the sponges led to an increase in blood flow, the magnitude of which became gradually larger between days 5 and 10. A similar, though less marked increase in sensitivity to PGE₁ was observed in the skin covering the granulomata, PGE₁ causing a significant increase in blood flow to the skin on day 10. These changes in sensitivity to exogenous PGE₁ may be due to decreasing levels of endogenous PGE and/or maturation of the newly formed blood vessels in the granulation tissue.     

Induction of a cytotoxic T cell response by co-injection of a T helper peptide and a cytotoxic T lymphocyte peptide in incomplete Freund's adjuvant (IFA): Further enhancement by pre-injection of IFA alone

We have previously demonstrated that it is possible to induce a consistent and strong cytolytic T lymphocyte (CTL) response to synthetic peptides, corresponding to poorly immunogenic malaria CTL epitopes, by co-injecting them with peptides representing defined T helper (Th) epitopes in incomplete Freund's adjuvant (IFA). In this study we have tested different immunization protocols to improve further the elicitation of the CTL response. We show that the CTL response to a mixture of Th + CTL peptides administered in IFA was further enhanced by a previous injection of the Th epitope peptide in IFA. Moreover, we found that the response could be significantly augmented by a pre-injection of IFA alone. This enhancement was observed only if the Th epitope was also present in the second injection. The number of lymph node cells recovered was 2–3-fold higher in mice pre-injected with IFA, but the increase in specific CTL activity, expressed as lytic units per animal, by pre-injection of IFA was at least 10–20-fold. Thus, pre-injection of IFA clearly increases the magnitude of a subsequent CTL response.     

Bioavailablility of elderberry anthocyanins

Considerable epidemiological evidence suggests a link between the consumption of diets rich in fruits and vegetables and a decreased risk of cardiovascular disease and cancers. Anthocyanins have received attention as important dietary constituents that may provide health benefits and contribute antioxidant capacity beyond that provided by essential micronutrients such as ascorbate, tocopherols, and selenium. The emergence of renewed interest by industrial countries in traditional herbal medicines and the development of 'functional foods' are stimulating the need for more information regarding the bioavailability and efficacy of plant polyphenols. Flavonoids represent a numerous group of secondary plant metabolites based on the structure of a pyran ring flanked by two or more phenyl rings and varying subtly in the degree of unsaturation and the pattern of hydroxylation or methylation. Flavonoids also vary in the type of sugar attached or the degree of polymerization. Anthocyanins, potent flavonoid antioxidants widely distributed in fruits, vegetables and red wines, normally occur in nature as glycosides, a form not usually considered as bioavailable. We have examined the bioavailability and pharmacokinetics of anthocyanins in humans. Anthocyanins were detected as glycosides in both plasma and urine samples. The elimination of plasma anthocyanins appeared to follow first-order kinetics and most anthocyanin compounds were excreted in urine within 4 h after feeding. The current findings appear to refute assumptions that anthocyanins are not absorbed in their unchanged glycosylated forms in humans.     

Postnatal naltrindole treatments induce behavioural modifications in preweanling rats

To investigate the physiological role of the delta-opioid receptor during the preweanling period, we have studied the effects of chronic (daily injections from birth to postnatal day 19) and acute treatments with the selective delta-antagonist naltrindole (1 mg/kg), on behavioural and nociceptive responses in 20-day old male rats. Behavioural testing was performed using an open field paradigm. Acute naltrindole induced significant decreases in external and total ambulation (horizontal activity) and rearing behaviour (vertical activity), as well as a significant increase in grooming frequency. In animals chronically treated with naltrindole there was an increase in total ambulation one day after the discontinuation of the treatment. In a test of nociception (tail immersion) no significant effect of chronic naltrindole treatment on baseline latencies or of acute naltrindole on latency quotients (post-treatment latency/pre-treatment latency) were found. However, chronic naltrindole administration significantly decreased the latency quotients. The results show that the delta-opioid receptor participates in the tonic regulation of motor activity during the preweanling period and might be involved in certain aspects of stress responsiveness.     

Leukocyte-reduced transfusions in cardiac surgery results of an implementation trial

An implementation trial of leukocyte-reduced transfusions in cardiac surgery (primary coronary artery bypass graft and valve replacement) was performed from July to December 1998; comparisons were made with data from the same period in 1997. Patients from both periods were similar in important preoperative and intraoperative variables (age, sex, weight, number of units of RBCs transfused, ejection fraction). The mean total number of complications was statistically significantly decreasedfrom 0.26 complications per patient in the non-leukocyte-reduced to 0.19 in the leukocyte-reduced recipients. Overall, the mean +/- ISD costs of care per patient decreasedfrom 1997 ($27,615 +/- $33,973) to 1998 ($27,038 +/- $24,107). Mean costs decreased $1,700 per patient for recipients of leukocyte-reduced blood in 1998 compared with recipients of non-leukocyte-reduced blood in 1997 Mean costs increased $4,000 per patient in patients who did not receive transfusions in 1998 compared with 1997. Hospitalization costs decreased when leukocyte-reduced transfusions were implemented for patients undergoing cardiac surgery in our institution. Implementation of leukocyte reduction may be cost neutral or cost saving in at least some settings.