Mass stranding of Odontoceti caused by parasitogenic eighth cranial neuropathy

Hearing organs of the Odontoceti from two mass strandings in 1983 and 1986 were examined histopathologically. In the 1983 stranding, two of three pilot whales (Globicephala macrorhynchus) were necropsied and numerous Nasitrema sp. were found close to the eighth cranial nerve (nervus vistibulo cochlearis) in both animals. Patchy degeneration of the eighth cranial nerve in and out of the modiolus of the cochlea was observed. In the 1986 stranding, five of 125 false killer whales (Pseudorca crassiclens) were examined and numerous trematodes (Nasitrema gondo) were found in the tympanic cavities. Severe degeneration of the eighth cranial nerve was discovered and there were many trematode eggs in the nervous and surrounding tissues. Parasitogenic eighth neuropathy is proposed again as the cause of mass stranding of the Odontoceti.     

Nasitrema sp.-associated encephalitis in a striped dolphin (Stenella coeruleoalba) stranded in the Gulf of Mexico.

An immature female striped dolphin (Stenella coeruleoalba) found dead on a northwestern Florida beach in 1988 exhibited severe inflammation bilaterally in the dorsal and mid-thalamus in association with adult trematodes (Nasitrema sp.) and trematode eggs. Numerous specimens of Nasitrema sp. also were present in the pterygoid sinuses. Pneumonia in association with a heavy growth of Vibrio damsela was observed also. This report confirms the occurrence of Nasitrema sp.-associated encephalitis in striped dolphins and in small cetaceans from the Gulf of Mexico.     

Brain lesions in a Pacific white-sided dolphin (Lagenorhynchus obliquidens)

A young, male, free-ranging Pacific white-sided dolphin (Lagenorhynchus obliquidens) was found disoriented and died after being held in captivity for several months. Malacic lesions in several areas of the brain were associated with helminth eggs. The appearance and location of these eggs suggested they were of the genus Nasitrema.     

Nasitrema attenuata (Trematoda) infection of Tursiops truncatus and its potentialities as an aetiological agent of chronic pulmonary lesions.

Two cases of Nasitrema sp (Trematoda) infection of the bottlenosed dolphin, Tursiops truncatus, are reported and N. attenuata is briefly redescribed. The adults of the trematode occurring in the nasal sinuses and posterior nasal passage of the dolphins are considered as practically harmless for the host but thier eggs, aspirated deep into the bronchial tree, may initiate a foreign-body of inflammatory reaction in the lungs and continuous aspiration of such eggs may provoke a chronic pneumonia condition.     

Evolutionary relationships between digeneans of the family Brachycladiidae Odhner, 1905 and their marine mammal hosts: A cophylogenetic study

Cophylogenetic studies examine the congruence between host and parasite phylogenies. There are few studies that quantify the relative contribution of coevolutionary events, i.e. duplication, loss, failure-to-diverge, host-switching and spreading in trophically-transmitted parasites at the marine realm. We addressed this issue in the Brachycladiidae, a cosmopolitan digenean family specific to marine mammals. We used, for the first time, distance-based and event-based methods to explicitly test the coevolutionary events that have shaped the current brachycladiid-marine mammal associations. Parasite phylogeny was constructed using mtDNA ND3 sequences of nine brachycladiid species, and host phylogeny using cytochrome b sequences of 104 mammalian species. A total of 50 host-parasite links were identified. Distance-based methods supported the hypothesis of a global non-random association of host and parasite phylogenies. Significant individual links (i.e., 24 out of 50) were those related to Campula oblonga, Nasitrema delphini, N. globicephalae and Brachycladium atlanticum and their associated taxa from the Delphinoidea. Regarding event-based methods, we explored 54 schemes using different combinations of costs for each potential coevolutionary event. Three coevolutionary scenarios were identified across all schemes and in all cases the number of loss events (87–156) was the most numerous, followed by failure-to-diverge (40), duplication (3–6), host-switching (0–3) and cospeciation (0–2). We developed a framework to interpret the evolution of this host-parasite system and confirmed that failure-to-diverge and colonization with or without subsequent diversification could have been decisive in the establishment of the associations between brachycladiids and marine mammals.     

Changes in the glycosylation pattern of prion protein in murine scrapie. Implications for the mechanism of neurodegeneration in prion diseases

In prion diseases, the normal prion protein (PrP(c)) undergoes a conformational change that results in the abnormal form, named scrapie prion protein (PrP(sc)). The visual system of rodents provides a relatively simple neuronal model in which the cell bodies of neurons are confined to the retina and the axons constitute the optic nerve. We investigated by Western blot the profile of PrP(c) in the optic nerve and retina of normal hamsters and mice. We found that in the optic nerve the amount of PrP(c) is significantly higher than in the retina. A less abundant non-glycosylated band was observed in retinas compared with the optic nerve and brain. Similar results were found in the gray and white matter from normal mice and hamsters. After stereotaxic injection of ME7 or 139A in the superior colliculus, a visual target area, the proportion and glycopattern of PrP changed in the retina and optic nerve throughout the course of the disease. Similar results were found in the gray and white matter at terminal stage of scrapie after injection of ME7 and 139A in the dorsal hippocampus. This is the first time that changes in the distribution and glycopattern of PrP have been described in an in vivo model of prion diseases.     

Continuation of fast axonal transport in regenerating axons in vitro.

A previous study by McLean and co-workers reported that regenerating axons of the rabbit vagus nerve were unable to sustain axonal transport in vitro for several months after nerve injury. In contrast, we found that sensory axons of the rat sciatic nerve were able to transport 3H-labeled protein into their regenerating portions distal to the site of injury within a week after injury when placed in vitro. Transport in vitro was not significantly less than transport in axons maintained in vivo for the same period. Transport occurred in the medium that was used by the McLean group, but was significantly reduced in calcium-free medium. When axon regeneration was delared, only small amounts of activity were present in the nerve distal to the site of injury, showing that labeled protein normally present in that part of the nerve was associated with axons and was not a result of local precursor uptake by nonneural elements in the sciatic nerve. We were not able to explain the failure of McLean and co-workers to demonstrate transport in vitro in regenerating vagus nerve, but we conclude that there is no general peculiarity of growing axons that makes them unable to sustain transport in vitro.     

The recovery of motor innervation during treatment with ethanol

We have studied the effects of the fluidizing action of ethanol on motor reinnervation in order to clarify if membrane fluidity changes affect synaptic plasticity and nerve regeneration. Sprague Dawley rats were denervated by crushing the sciatic nerve and subsequently, on the 16th day, the degree of reinnervation of the EDL muscle was observed by electrophysiological technique: in particular an observation was made of the resting potential and the m.e.p.p.s frequency by intracellular recordings in muscle fibers. During the nerve regeneration period, the rats were treated with 3 g of ethanol per kilogram of body weight per day. We have found that ethanol quickens the resting potential recovery but does not affect the m.e.p.p.s frequency.     

Relevance of the lesser occipital nerve in facial rejuvenation surgery

Nerve injuries are possible during facial rejuvenation surgery. The great auricular nerve has been studied; however, little is known about the lesser occipital nerve and its relevance in facial rejuvenation surgery. To understand the importance of the lesser occipital nerve in a face lift procedure, the specific anatomy of the nerve was studied in the laboratory in 19 hemifaces, with additional nerve observations in the operating room. The course of the lesser occipital nerve, its branches, and the relationship with the surrounding structures were evaluated and recorded. The great auricular nerve was also dissected to compare the two nerve territories. In the majority of the dissections, the lesser occipital nerve supplied the superior ear and the mastoid area, whereas the great auricular nerve innervated the inferior ear and a portion of the preauricular area. The nerves, however, were variable in size and distribution. Five lesser occipital nerves provided the dominant supply to the ear, compensating for a small great auricular nerve contribution. Therefore, injury to the lesser occipital nerve can result in a major sensory deficit of the ear. We also found the lesser occipital nerve to have a subcutaneous course at a proximal and variable level. These nerve branches can be superficial, and therefore postauricular flap dissection can injure the nerve if the flap is dissected at the fascial level. We therefore suggest that the dissection be at a more superficial level to avoid nerve injury. And finally, if SMAS/platysma suspension sutures are placed, we suggest these be done in a vertical-oblique direction along the course of the lesser occipital nerve, because this should minimize the possibility of trapping terminal branches.     

Ultrastructural examination of B-50(GAP-43) immunoreactivity in rat jejunal villi

Summary The lamina propria of rat jejunum is densely innervated with nerve fibres extending to the tips of the villi. A large number of these nerve fibres were previously shown to be B-50-immunoreactive at the light microscope level, whereas neurofilament immunoreactivity was found to be sparse in the mucosa. In this study we used immunoelectron microscopy to determine what proportion of nerve fibres in the lamina propria express B-50. Jejuna from male Lewis rats were immunolabelled for B-50 and neurofilament proteins. For electron microscopy, postembedding immunogold-silver techniques and LR White embedded tissues were used. Light microscopical immunostaining was performed by the streptavidin-biotin-peroxidase technique on deparaffinized tissue sections. We found that all ultrastructurally identifiable nerve profiles in jejunum were B-50 immunoreactive. Immunoelectron microscopy for neurofilament proteins failed to label fibres in the villi, whereas myelinated nerves in tongue sections processed in parallel (positive controls) were strongly neurofilament-protein-immunoreactive. The dominant B-50-positive and neurofilament-protein-negative phenotype supports the hypothesis of ongoing modelling or plasticity of intestinal mucosal nerves.     

戊巴比妥对大鼠骨胳肌辣根过氧化物酶(HRP)的轴突摄取和逆行传送作用

腓肠肌内注射HRP后,用生物化学法测定坐骨神经、L_(4-6)节段背根和腹根神经的HRP含量。在戊巴比妥连续全身麻醉大鼠的HRP含量明显低于不麻醉的大鼠,而肌肉不活动(TTX中毒和切腱)大鼠神经组织中的HRP含量无甚变化。刺激神经不能改变麻醉大鼠的HRP含量。上述结果提示:除麻醉剂造成的肌肉不活动因素外,戊巴比妥对大鼠骨胳肌HRP的轴突摄取和逆行传送具有另外的抑制作用。已有研究报道:破伤风和单纯性疱疹病毒脑炎都是由于它们的毒素或病毒,通过外周神经摄取然后逆行传送到各级中枢而致病的。     

Heterogeneous distribution of neurocalcin-immunoreactive nerve terminals in the mouse adrenal medulla

Neurocalcin is a novel calcium-binding protein found in bovine brain tissue. We investigated immunoreactivity for neurocalcin in the mouse adrenal medulla using light and electron microscopy. The immunoreactivity was present in nerve fibers, nerve terminals, and ganglion cells in the adrenal medulla, but chromaffin cells, sustentacular cells, and Schwann cells were negative in reaction. Nerve bundles containing neurocalcin-immunoreactive fibers passed through the adrenal cortex and extended into the medulla. Immunopositive nerve fibers branched off and projected varicose terminals around the chromaffin cells. These varicose terminals contained small and large-cored vesicles and made synapses with the chromaffin cells. We performed paraformaldehyde-induced fluorescence-histochemical studies for catecholamine combined with immunohistochemical studies for neurocalcin. Neurocalcin-immunoreactive nerve terminals were more abundant at noradrenaline (fluorescent) cell-rich regions than at adrenaline (non-fluorescent) cell-rich regions. These results show that neurocalcin-immunoreactive nerves mainly innervate noradrenaline-containing chromaffin cells in the mouse adrenal medulla and that neurocalcin may regulate synaptic function in the nerve terminals. Received: 21 October 1996 / Accepted: 12 February 1997     

Evidence for a systemic regulation of neurotrophin synthesis in response to peripheral nerve injury

Up-regulation of neurotrophin synthesis is an important mechanism of peripheral nerve regeneration after injury. Neurotrophin expression is regulated by a complex series of events including cell interactions and multiple molecular stimuli. We have studied neurotrophin synthesis at 2?weeks time-point in a transvertebral model of unilateral or bilateral transection of sciatic nerve in rats. We have found that unilateral sciatic nerve transection results in the elevation of nerve growth factor (NGF) and NT-3, but not glial cell-line derived neurotrophic factor or brain-derived neural factor, in the uninjured nerve on the contralateral side, commonly considered as a control. Bilateral transection further increased NGF but not other neurotrophins in the nerve segment distal to the transection site, as compared to the unilateral injury. To further investigate the distinct role of NGF in regeneration and its potential for peripheral nerve repair, we transduced isogeneic Schwann cells with NGF-encoding lentivirus and transplanted the over-expressing cells into the distal segment of a transected nerve. Axonal regeneration was studied at 2?weeks time-point using pan-neuronal marker NF-200 and found to directly correlate with NGF levels in the regenerating nerve.     

Nerve Cross-Bridging to Enhance Nerve Regeneration in a Rat Model of Delayed Nerve Repair

There are currently no available options to promote nerve regeneration through chronically denervated distal nerve stumps. Here we used a rat model of delayed nerve repair asking of prior insertion of side-to-side cross-bridges between a donor tibial (TIB) nerve and a recipient denervated common peroneal (CP) nerve stump ameliorates poor nerve regeneration. First, numbers of retrogradely-labelled TIB neurons that grew axons into the nerve stump within three months, increased with the size of the perineurial windows opened in the TIB and CP nerves. Equal numbers of donor TIB axons regenerated into CP stumps either side of the cross-bridges, not being affected by target neurotrophic effects, or by removing the perineurium to insert 5-9 cross-bridges. Second, CP nerve stumps were coapted three months after inserting 0-9 cross-bridges and the number of 1) CP neurons that regenerated their axons within three months or 2) CP motor nerves that reinnervated the extensor digitorum longus (EDL) muscle within five months was determined by counting and motor unit number estimation (MUNE), respectively. We found that three but not more cross-bridges promoted the regeneration of axons and reinnervation of EDL muscle by all the CP motoneurons as compared to only 33% regenerating their axons when no cross-bridges were inserted. The same 3-fold increase in sensory nerve regeneration was found. In conclusion, side-to-side cross-bridges ameliorate poor regeneration after delayed nerve repair possibly by sustaining the growth-permissive state of denervated nerve stumps. Such autografts may be used in human repair surgery to improve outcomes after unavoidable delays.     

Innervation of interstitial cells of Cajal by vasoactive intestinal polypeptide containing nerves in canine colon.

The hypothesis was tested, through structural and functional studies, that interstitial cells of Cajal receive and can respond to direct innervation from nerves containing the vasoactive intestinal polypeptide neuromediator. The submucosal network of interstitial cells of Cajal has been postulated to provide pacemaking activity for the circular muscle and to be involved in neurotransmission from nonadrenergic, noncholinergic nerves for which vasoactive intestinal polypeptide is a putative mediator. The distribution of vasoactive intestinal polypeptide and substance P immunoreactive material in nerve profiles of the enteric nervous system of the canine colon was examined. In addition, electrophysiological studies were done on the interstitial cells bordering the submucosal side of the circular muscle layer after they were electrically isolated using heptanol. The vasoactive intestinal polypeptide immunoreactivity, located exclusively in nerve large granular vesicles, was found throughout the enteric nervous system (myenteric plexus, submucous plexus, and circular muscle--submucosa interface). The highest proportion (38% compared with 22-24%) of profiles of large granular vesicles with vasoactive intestinal polypeptide immunoreactivity was found in nerve profiles of the circular muscle--submucosa interface. In contrast, substance P immunoreactivity was found in nerve profiles of myenteric plexus (33% of large granular vesicles were positive) but not associated with submucosal interstitial cell nerve network. The vasoactive intestinal polypeptide hyperpolarized interstitial cells by 9 mV when electrically isolated by 1 mM heptanol and markedly reduced (about 50%) their input membrane resistance. We conclude that the distribution of vasoactive intestinal polypeptide immunoreactivity and its action are consistent with a postulated role of the interstitial cells as a major site of neurally mediated inhibition of colonic pacemaker activity.     

VIP-, Bombesin- and Neurotensin-Like Immunoreactivity in Neurons of the Gut of the Holostean Fish,Lepisosteus platyrhincus

VIP-like immunoreactivity was found in nerve fibres in all layers of the gut wall in both stomach and intestine, and was abundant in the myenteric and submucous plexuses. A few fibres were associated with blood vessels. Nerve cells showing VIP-like immunoreactivity were found in the myenteric plexus. Neurotensin-like immunoreactivity was found in nerve cells and numerous nerve fibres in the myenteric plexus of both stomach and intestine and in nerve fibres of the circular muscle layer, while bombesin-like immunoreactivity was confined to a low number of nerve fibres in the myenteric plexus of the stomach. The results indicate that a VIP-like, a neurotensin-like and a bombesin-like peptide are present in neurons of the gut of Lepisosteus.     

Quantitative evaluation of sensory nerve endings in hypertrophy of labia minora pudendi in women.

The authors studied the types of sensory nerve endings in hypertrophic labia minora pudendi in women aged between 18 and 69. The nervous tissue was impregnated with silver nitrate by Lavrentyev's modification of the Bielschowski-Gross method. The sensory nerve endings were divided into the following groups: free endings and arborizations, spray-like endings, seven types of clew-like nerve endings, and Pacinian corpuscles. It is the clew-like endings that absolutely predominate, they were 2,027 in number. The arborizations and spray-like endings found were 105 in number and only 4 of Pacinian corpuscles were found. As compared with normal labia there are no principal differences among the types of sensory nerve endings. The main difference consists in the rate of occurrence (89.6 as against 57.8) and in the thickness of the capsule, while the nerve clew proper does not grow in diameter. Therefore, we are of theopinion that a more frequent occurrence and larger size of the capsule is associated with local changes in the organ (especially with hypertrophy of the connective tissue). We observed no differences due to age either in the occurrence of the individual types or in the thickness of the capsule. Great individual variability in both directions was seen. The findings corroborated again the rare occurrence of meissner's endings in the labia minora in woman. Therefore it may be assumed that it is rather a random finding and that it is a type of clew-like nerve ending. Finally, we presume that the individually varying rate of occurrence of the nerve endings in the external genitals could also affect general sensitivity in this region, including sexual sensitivity.     

Spider silk fibres in artificial nerve constructs promote peripheral nerve regeneration

Abstract.  Objective : In our study, we describe the use of spider silk fibres as a new material in nerve tissue engineering, in a 20-mm sciatic nerve defect in rats. Materials and methods : We compared isogenic nerve grafts to vein grafts with spider silk fibres, either alone or supplemented with Schwann cells, or Schwann cells and matrigel. Controls, consisting of veins and matrigel, were transplanted. After 6 months, regeneration was evaluated for clinical outcome, as well as for histological and morphometrical performance. Results : Nerve regeneration was achieved with isogenic nerve grafts as well as with all constructs, but not in the control group. Effective regeneration by isogenic nerve grafts and grafts containing spider silk was corroborated by diminished degeneration of the gastrocnemius muscle and by good histological evaluation results. Nerves stained for S-100 and neurofilament indicated existence of Schwann cells and axonal re-growth. Axons were aligned regularly and had a healthy appearance on ultrastructural examination. Interestingly, in contrast to recently published studies, we found that bridging an extensive gap by cell-free constructs based on vein and spider silk was highly effective in nerve regeneration. Conclusion : We conclude that spider silk is a viable guiding material for Schwann cell migration and proliferation as well as for axonal re-growth in a long-distance model for peripheral nerve regeneration.     

Occurrence of a dense plexus of sensory nerve fibers immunoreactive to calcitonin-gene-related peptide in the cauda epididymidis of rats

The occurrence, distribution and ontogeny of nerves displaying calcitonin-gene-related peptide (CGRP)-like immunoreactivity were studied in the male reproductive tract of rats. A marked regional difference in number of CGRP-immunoreactive nerve fibers was observed in the epididymis. The immunoreactive nerve fibers were particularly numerous in the cauda epididymidis, where the nerves were found in the capsular and interstitial connective tissue and further in the smooth muscle layer and the subepithelial connective tissue surrounding the duct. In the remaining portions of the reproductive tract proximal and distal to the epididymis, CGRP-immunoreactive nerve fibers were scarcely found in the connective tissues surrounding the duct, although a small number of the CGRP-immunoreactive nerve fibers was constantly found adjacent to small blood vessels throughout the male reproductive tract. CGRP-immunoreactive nerve fibers in the epididymis were first detected at embryonic day 18 when thin bundles or single fibers were evenly distributed in the interstitial connective tissue of the entire epididymal duct. A marked regional difference in number of CGRP-immunoreactive nerve fibers seen in the adult epididymis was established by postnatal day 14. In the epididymis of young rats treated neonatally with capsaicin, CGRP-immunoreactive nerve fibers were almost completely absent. This finding together with the distribution pattern of CGRP-immunoreactive nerve fibers different from that of the autonomic nerves so far reported strongly suggests that the immunoreactive nerves were sensory in nature.