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M L Weiss

Publications and source records attributed to M L Weiss.

At least 19 recordsLinked to original sources
PubMed2004

Transplantation of pig stem cells into rat brain: proliferation during the first 8 weeks.

Previous work indicated that pig umbilical cord matrix (pUCM) cells are a type of primitive stem cell and that these cells could be recovered after central or peripheral injection into rats that did not receive immune suppression therapy. To determine the safety and proliferation potential of pUCM cells after brain transplantation, approximately 150 pUCM cells were transplanted into the brains of rats that previously received a striatal injection of the neurotoxin 6-hydroxydopamine (6-OHDA). The pUCM cells were previously engineered to express enhanced green fluorescent protein (eGFP); in this way, the graft cells were identified. The rats did not receive immune suppression therapy. There were no postsurgical complications and the animals thrived following transplantation. At 2, 4, 6, and 8 weeks after transplantation, two rats were sacrificed and the morphology, size and number of graft cells, and the percentage of tyrosine hydroxylase (TH)-positive graft cells were determined. The size distribution of the grafted pUCM cells was unimodal and normal, and the average size increased significantly over the 2- to 8-week survival period. The number of pUCM cells increased from approximately 5400 cells at the 2-week survival period post-transplantation to approximately 20,000 cells at the 8-week survival period. There was an increase in the percentage of TH-positive pUCM cells from approximately 1% at the 2-week survival period to approximately 6% at the 8-week survival period. There was no evidence of a significant host immune response at any time; for example, no accumulation of CD-4, CD-8, CD-11b, CD-161 cells in the transplantation site. These results suggest that pUCM cells engraft and proliferate without requiring immune suppression. These findings also suggest that a subset of pUCM cells can differentiate into TH-positive cells within 8 weeks after transplantation into the 6-OHDA lesioned rat brain.

Animals↗
PubMed2003

Transplantation of porcine umbilical cord matrix cells into the rat brain.

Immune rejection of transplanted material is a potential complication of organ donation. In response to tissue transplantation, immune rejection has two components: a host defense directed against the grafted tissue and an immune response from the grafted tissue against the host (graft vs host disease). To treat immune rejection, transplant recipients are typically put on immunosuppression therapy. Complications may arise from immune suppression or from secondary effects of immunosuppression drugs. Our preliminary work indicated that stem cells may be xenotransplanted without immunosuppression therapy. Here, we investigated the survival of pig stem cells derived from umbilical cord mucous connective tissue (UCM) after transplantation into rats. Our data demonstrate that UCM cells survive at least 6 weeks without immune suppression of the host animals after transplantation into either the brain or the periphery. In the first experiment, UCM cells were transplanted into the rat brain and recovered in that tissue 2-6 weeks posttransplantation. At 4 weeks posttransplantation, the UCM cells engrafted into the brain along the injection tract. The cells were small and roughly spherical. The transplanted cells were positively immunostained using a pig-specific antibody for neuronal filament 70 (NF70). In contrast, 6 weeks posttransplantation, about 10% of the UCM cells that were recovered had migrated away from the injection site into the region just ventral to the corpus callosum; these cells also stained positively for NF70. In our second experiment, UCM cells that were engineered to constitutively express enhanced green fluorescent protein (eGFP) were transplanted. These cells were recovered 2-4 weeks after brain transplantation. Engrafted cells expressing eGFP and positively staining for NF70 were recovered. This finding indicates a potential for gene therapy. In the third experiment, to determine whether depositing the graft into the brain protected UCM cells from immune detection/clearance, UCM cells were injected into the tail vein and/or the semitendinosis muscle in a group of animals. UCM cells were recovered from the muscle or within the kidney 3 weeks posttransplantation. In control experiments, rat brains were injected with PKH 26-labeled UCM cells that had been lysed by repeated sonic disruption. One and 2 weeks following injection, no PKH 26-labeled neurons or glia were observed. Taken together, these data indicate that UCM cells can survive xenotransplantation and that a subset of the UCM cells respond to local signals to differentiate along a neural lineage.

Animals↗
PubMed2003

The paraventricular nucleus: an important component of the central neurocircuitry regulating sympathetic nerve outflow.

AIM: The sympathetic nervous system plays an important role in the regulation of physiological homeostasis under basal conditions and in response to acute and chronic stressors. It is known that multiple levels of the neuroaxis, including the paraventricular nucleus (PVN) of the hypothalamus, are involved in regulation of efferent sympathetic nerve discharge (SND). This review focuses on the role of the PVN in regulation of functional characteristics of efferent SND. RESULTS: The available experimental evidence indicates that the level of efferent sympathetic nerve activity is altered after microinjection of numerous substances into the PVN, including excitatory amino acids, gamma-aminobutyric acid (GABAA) receptor agonists and antagonists, and PVN nitric oxide synthase inhibitors. In addition, antagonism of PVN GABAA receptors changes the pattern of synchronized discharge bursts in efferent sympathetic nerves and enhances the frequency-domain coupling between low-frequency bursts in sympathetic nerve pairs. Finally, PVN microinjections of excitatory amino acids (L-glutamate, D,L-homocysteic acid) have been shown to produce non-uniform changes in the level of efferent sympathetic nerve activity. CONCLUSION: These findings support the concept that the PVN is an important component of the central neurocircuitry regulating functional characteristics (basal level of activity, bursting pattern, and relationships between discharges in nerves innervating different targets) of efferent sympathetic nerve outflow.

Action Potentials↗
PubMed2003

Modifications to central neural circuitry during heart failure.

AIM: During heart failure (HF), excess sodium retention is triggered by increased plasma renin-angiotensin-aldosterone activity and increased basal sympathetic nerve discharge (SND). Enhanced basal SND in the renal nerves plays a role in sodium retention. Therefore, as a hypothetical model for the central sympathetic control pathways that are dysregulated as a consequence of HF, the central neural pathways regulating the sympathetic motor output to the kidney are reviewed in the context of their role during HF. CONCLUSION: From these findings, a model of the neuroanatomical circuitry that may be affected during HF is constructed.

Animals↗
PubMed2003

Incorporation of bovine bone marrow stromal cells into porcine foetal tissues after xenotransplantation.

Bovine bone marrow stromal cells (BMSCs) were injected into the liver of foetal pigs at about 40 days of gestation to test whether these cells could populate developing tissue, and if so, which ones. Approximately 40 days after injection, the foetuses were harvested and tissue sections from many areas of the body were analysed for the presence of bovine cells using two different methods. First, using PCR, bovine repetitive DNA was found to be present in DNA extracted from foetal pig tissues. Secondly, using oligonucleotide primed in situ synthesis (PRINS), the in situ presence of bovine cells was found within porcine tissue sections. PRINS-labelled cells were found within cartilage, perichondrium, connective tissue and smooth muscle. These data suggest that bovine BMSCs integrate throughout the foetal pig.

Animals↗
PubMed2003

Normal anatomical and histochemical characteristics of the lacrimal glands in the American bison and cattle.

Dorsal lacrimal glands, superior glands of the third eyelid and Harderian glands (deep gland of the third eyelid) from 19 bison and 18 cattle free of apparent ocular disease were examined to compare the normal anatomical properties of these glands. All glands were characterized and measured (length and width). The gross anatomy of the dorsal lacrimal glands was similar, with the exception of a bipartite gland in cattle. The bison's superior gland of the third eyelid and Harderian gland was longer as compared with cattle. A subset of the bison and cattle samples (five bison and five cattle) was sectioned for histological and histochemical analysis. The histology of the dorsal lacrimal and superior gland of the third eyelid revealed tubuloalveolar cells with basophilic vacuolated cytoplasm in bison and eosinophilic granular cytoplasm in cattle. The Harderian glands consisted of a tubuloalveolar anterior part combined with large lumens acini lined with cuboidal epithelium in the posterior part; the posterior part of the bison Harderian gland was more predominant than in cattle samples. Mucosubstance histochemistry revealed acidic and neutral glycoproteins with similar staining patterns in all glands of both species.

Animals↗
PubMed2002

Bovine herpesvirus 5 (BHV-5) Us9 is essential for BHV-5 neuropathogenesis.

Bovine herpesvirus 5 (BHV-5) is a neurovirulent alphaherpesvirus that causes fatal encephalitis in calves. In a rabbit model, the virus invades the central nervous system (CNS) anterogradely from the olfactory mucosa following intranasal infection. In addition to glycoproteins E and I (gE and gI, respectively), Us9 and its homologue in alphaherpesviruses are necessary for the viral anterograde spread from the presynaptic to postsynaptic neurons. The BHV-5 Us9 gene sequence was determined, and the predicted amino acid sequence of BHV-5 Us9 was compared with the corresponding Us9 sequences of BHV-1.1. Alignment results showed that they share 77% identity and 83% similarity. BHV-5 Us9 peptide-specific antibody recognized a doublet of 17- and 19-kDa protein bands in BHV-5-infected cell lysates and in purified virions. To determine the role of the BHV-5 Us9 gene in BHV-5 neuropathogenesis, a BHV-5 Us9 deletion recombinant was generated and its neurovirulence and neuroinvasive properties were compared with those of a Us9 rescue mutant of BHV-5 in a rabbit model. Following intranasal infection, the Us9 rescue mutant of BHV-5 displayed a wild-type level of neurovirulence and neural spread in the olfactory pathway, but the Us9 deletion mutant of BHV-5 was virtually avirulent and failed to invade the CNS. In the olfactory mucosa containing the olfactory receptor neurons, the Us9 deletion mutant virus replicated with an efficiency similar to that of the Us9 rescue mutant of BHV-5. However, the Us9 deletion mutant virus was not transported to the bulb. Confocal microscopy of the olfactory epithelium detected similar amounts of virus-specific antigens in the cell bodies of olfactory receptor neuron for both the viruses, but only the Us9 rescue mutant viral proteins were detected in the processes of the olfactory receptor neurons. When injected directly into the bulb, both viruses were equally neurovirulent, and they were transported retrogradely to areas connected to the bulb. Taken together, these results indicate that Us9 is essential for the anterograde spread of the virus from the olfactory mucosa to the bulb.

Amino Acid Sequence↗
PubMed2001

Neural circuitry of the kidney: NO-containing neurons.

The neurons synthesizing nitric oxide (NO) that are part of the renal sympathetic pathways were located by double-staining for the neuronal isoform of nitric oxide synthase (nNOS) using immunocytochemistry to identify NO-synthesizing neurons and transneuronal tracing following infection of the left kidney with pseudorabies virus (PRV). Following kidney injection with PRV, the animals survived 4-day post-inoculation prior to sacrifice and tissue processing. PRV-infected neurons that double-stained for nNOS were found in the paraventricular hypothalamic nucleus (PVN), the raphe obscurus nucleus (ROb), the ventromedial medulla (VMM), the rostral ventrolateral medulla (rVLM) and the A5 cell group. In the thoracolumbar spinal cord, nNOS neurons co-localized with PRV-infected cells in the dorsal horn in laminae I, III-V ipsilateral to the injected kidney and in lamina X, the intermediolateral cell column, the lateral funiculus, the intercalated nucleus and the central autonomic area. We conclude that NO synthesizing cells may significantly affect renal autonomic pathways in the rat by interacting with the renal sensory and sympathomotor circuitry at multiple sites.

Afferent Pathways↗
PubMed2001

The estrous cycle affects pseudorabies virus (PRV) infection of the CNS.

Previous work had suggested that mucosal immunity may be affected by the stage of the estrous cycle. Here, susceptibility to a neurotropic virus infection at different stages of the estrous cycle was assessed in a rodent model after direct injection of the virus into visceral organs. In the first two experiments, female Sprague-Dawley rats were infected with pseudorabies virus (PRV, Bartha's K-strain) by injection into either the cervix or the kidney after monitoring their estrous cycle. After either 4- or 5-day survival period post-infection, the rats were euthanized by transcardially perfusion and peripheral and central nervous system tissues were removed for immunocytochemical staining. The number of infected neurons was counted in various regions. Statistical analysis revealed that: (1) the number of infected cells in the sympathetic or parasympathetic ganglion, or the dorsal root ganglia was not affected regardless of the stage of the estrous cycle after cervix injection with PRV; (2) in contrast, the number of infected neurons in the spinal cord was affected significantly by the stage of the estrous cycle during viral infection of the cervix; (3) after kidney infection, the number of infected neurons found within the spinal cord or dorsal root ganglia varied significantly across the estrous cycle. In both cases, animals infected in proestrus or estrus had fewer infected neurons than animals infected in diestrus I or diestrus II (proestrous and estrous animals had less than 20% of infected cells found in diestrus I or diestrus II rats). In the third experiment, older, persistent estrous or persistent diestrous rats were infected by kidney injection and given a 4-day survival period, prior to virus isolation from lower thoracic spinal cord. Animals in persistent estrous had significantly less virus per gram of tissue than the persistent diestrous rats. These data suggest that the CNS of animals in proestrus or estrus is less susceptible to PRV infection compared to animals in either diestrus I or diestrus II. Because estrogen replacement therapy is known to restore some immune functions during reproductive ageing, it is speculated that plasma estrogen levels modulate the central nervous system's susceptibility to viral infections.

Animals↗
PubMed2001

Silver-haired bat rabies virus variant does not induce apoptosis in the brain of experimentally infected mice.

To examine whether induction of apoptosis plays a role in the pathogenesis of street rabies, we compared the distribution of viral antigens, histopathology, and the induction of apoptosis in the brain of mice infected with a street rabies virus (silver-haired bat rabies virus, SHBRV) and with a mouse-adapted laboratory rabies virus strain (challenge virus standard, CVS-24). Inflammation was identified in the meninges, but not in the parenchyma of the brain of mice infected with either CVS-24 or SHBRV. Necrosis was present in numerous cortical, hippocampal, and Purkinje neurons in CVS-24-infected mice, but only minimal necrosis was identified in mice infected with SHBRV. Likewise, extensive terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end-labeling (TUNEL) staining was observed in the brain of mice infected with CVS-24 but little or none in the brain of mice infected with SHBRV. Rabies virus antigens were distributed similarly in the CNS infected with either virus. However, the expression of the glycoprotein (G) is more widespread and the staining of G is generally stronger in CVS- than SHBRV-infected mice, whereas the expression of rabies virus nucleoprotein (N) is similar in mice infected with either CVS or SHBRV. The positive TUNEL staining thus correlates with the high level of G expression in CVS-infected mouse brain. Northern blot hybridization revealed that the ratio between the N and G transcripts is similar in brains infected with either virus, indicating that the reduced expression of G protein is not caused by reduced transcription in SHBRV-infected animals. Taken together, these observations suggest that apoptosis is not an essential pathogenic mechanism for the outcome of a street rabies virus infection and that other pathologic processes may contribute to the profound neuronal dysfunction characteristic of street rabies.

Animals↗
PubMed2001

Renal sympathetic nerve regulation to heating is altered in rats with heart failure.

Heart failure (HF) alters the regulation of basal sympathetic nerve discharge (SND); however, the effect of HF on SND responses to acute stress is not well established. In the present study, renal SND responses to hyperthermia were determined in chloralose-anesthetized HF rats and in sham controls. Whole body heating (colonic temperature increased from 38 to 41 degrees C) was used as an acute stressor because increased internal body temperature provides a potent stimulus to the sympathetic nervous system. Left ventricular end-diastolic pressure and the right ventricular wt-to-body wt ratio were increased (P < 0.05) in HF compared with sham rats. The following observations were made: 1) renal sympathoexcitatory responses to heating were significantly reduced in HF compared with sham rats, 2) renal blood flow remained unchanged from control levels during heating in HF rats but was significantly reduced in sham rats, and 3) renal SND responses to heating were significantly higher in HF rats with bilateral lesions of the hypothalamic paraventricular nucleus (PVN) compared with sham PVN-lesioned HF rats. These results demonstrate a marked attenuation in the responsiveness of renal SND to heating in HF rats and suggest that HF alters the organization of neural pathways mediating SND responses to heating.

Animals↗
PubMed2001

Paraventricular nucleus bicuculline alters frequency components of sympathetic nerve discharge bursts.

Autospectral and coherence analyses were used to determine the effect of paraventricular nucleus (PVN) GABA(A) receptor antagonism [microinfusion or microinjections of bicuculline methiodide (BMI) 100 pmoles] on sympathetic nerve discharge (SND) frequency components (bursting pattern and relationships between discharges in regionally selective nerves) in alpha-chloralose-anesthetized rats. SND was recorded from the renal, splenic, and lumbar nerves. The following observations were made. First, PVN BMI microinjections, but not PVN saline or cortical BMI microinjections, transformed the cardiac-related SND bursting pattern in baroreceptor-innervated rats to one characterized by the presence of low-frequency bursts not synchronized to the cardiac cycle or phrenic nerve discharge bursts. Second, SND pattern changes were similar in the renal, splenic, and lumbar nerves, and peak coherence values relating low-frequency bursts in sympathetic nerve pairs (renal-splenic, renal-lumbar, and splenic-lumbar) were significantly increased from preinjection control after PVN BMI microinjection. Third, PVN BMI microinjections significantly increased the coupling between low-frequency SND bursts in baroreceptor-denervated rats. Finally, PVN BMI-induced changes in the SND bursting pattern were not observed after PVN pretreatment with muscimol (GABA agonist, 1 nmole). We conclude that PVN GABA(A) receptor antagonism profoundly alters the frequency components in sympathetic nerves.

Animals↗
PubMed2000

Activation of renal afferent pathways following furosemide treatment. I. Effects Of survival time and renal denervation.

Three experiments were performed to determine whether renal afferent pathways were activated by the diuretic drug, furosemide. It was hypothesized that activated neurons of the renal afferent pathway would express the protein product Fos of the c-fos immediate early gene and be identified by immunocytochemical staining for Fos in the cell nucleus. In the first two experiments, rats were injected with either furosemide (5 mg) or vehicle solution (sterile isotonic saline) and sacrificed either 1.75 h (short-survival experiment) or 3.5 h (long-survival experiment) after injection. In both experiments, the furosemide-treated rats had significantly more Fos-positive cell nuclei than vehicle-treated rats in the subfornical organ (SFO), organum vasculosum lamina terminalis (OVLT), supraoptic nuclei (SON), and magnocellular region of the paraventricular nuclei (PVN) - areas previously shown to be activated by hypovolemia or peripheral angiotensin. In the short-survival experiment, the furosemide-treated rats had more Fos-positive cell nuclei in the nucleus of the solitary tract (NTS) and in the dorsal horn of the spinal cord at spinal levels T(11), T(12), and T(13). In contrast, furosemide treatment did not produce more Fos-positive cell nuclei in the NTS and dorsal horn of the spinal cord in the long-survival experiment. These results suggest that the activation of the SFO, OVLT, SON and PVN may be via a different mechanism than that of NTS or spinal cord dorsal horn. Based upon our previous work, we hypothesized that the NTS and spinal cord dorsal horn labeling was due to activation of sympathetic afferents originating in the kidney and labeling in forebrain structures was due to stimulation by angiotensin generated by renal renin release. To test this hypothesis, a third experiment was devised that was identical to the short-survival experiment, except that all rats had bilateral renal denervation surgery 1 week previously. In this experiment, furosemide administration increased the number of Fos-positive cells in the SFO, OVLT, SON and PVN, but not in the caudal thoracic spinal cord or NTS. These results together with the results of first two experiments lend support to our hypothesis that furosemide-induced neuronal activation in the thoracic spinal cord and NTS is due to activation of second- and/or third-order neurons of a renal sympathetic afferent pathway. Furosemide-induced activation in the SFO, OVLT, SON and PVN does not depend on renal innervation. It is hypothesized that activation in these forebrain regions depends on the action of angiotensin II that is generated after furosemide treatment. Our results indicate that both a hormonal pathway and a renal sympathetic afferent pathway conduct information from the kidney to the central nervous system (CNS) after furosemide treatment.

Afferent Pathways↗
PubMed2000

Activation of renal afferent pathways following furosemide treatment. II. Effect Of angiotensin blockade.

The goal here and in the accompanying paper was to evaluate the two pathways used by the kidney to provide information to the central nervous system (CNS); e.g., the indirect, hormonal route via activation of the renin-angiotensin system and the direct pathway via activation of sympathetic afferents in the caudal thoracic spinal cord. Here, three experiments were designed to evaluate the actions of angiotensin elicited by subcutaneous injection of furosemide on neural activation of the CNS. The number of neurons immunocytochemically staining for the protein product (Fos) of the c-fos gene was used as an index of neuronal activation. In the first experiment, furosemide injection was preceded by treatment with a dose of Captopril, CAP, (an angiotensin-converting enzyme (ACE) inhibitor) that blocks the peripheral but not the central formation of angiotensin II. In the second experiment, furosemide injection was preceded by treatment with a higher dose of CAP; this dosage blocks the peripheral and central formation of angiotensin II. In the third experiment, furosemide injection was preceded by treatment with Losartan, a competitive receptor antagonist of type I angiotensin II receptors at a dose that would block central and peripheral angiotensin receptors. Control animals in each experiment received injections of vehicle (sterile isotonic saline) instead of furosemide. In each experiment, rats were sacrificed 1.75 h following furosemide or saline injection by transcardial perfusion and tissues were immunocytochemically processed for demonstration of Fos antigen. Rats receiving furosemide plus the low CAP dose showed more Fos-positive cells than control rats in the subfornical organ (SFO), organum vasculosum lamina terminalis (OVLT), supraoptic nucleus (SON), magnocellular region of the paraventricular nucleus, nucleus of the solitary tract (NTS), and caudal thoracic/rostral lumbar spinal cord dorsal horn. Rats receiving furosemide plus Losartan or furosemide plus the higher CAP dose did not show increased Fos immunoreactivity in any of the abovementioned structures relative to their respective control animals. We conclude that the receptor-mediated action of angiotensin II is in some way involved in the activation of the pathway that occurs in the SFO, OVLT, SON, and magnocellular region of the paraventricular nucleus (PVN) in response to furosemide treatment. It is possible that the furosemide-induced activation in the SON and PVN is not due to direct actions of angiotensin II on angiotensin receptors in those structures, but instead occurs synaptically as a result of inputs from the SFO and OVLT, which have themselves been activated directly by angiotensin II. In the accompanying paper, furosemide-induced activation in the NTS and caudal thoracic spinal cord is abolished by prior bilateral renal denervation, meaning that these neurons are likely part of a renal afferent pathway. Here, these structures did not elaborate Fos in animals injected with furosemide plus the high CAP dose or furosemide plus Losartan. Thus, the present results also suggest that the central blockade of the formation of angiotensin II or blockade of the actions of angiotensin II prevents in some way the activation of the renal afferent pathway mediated by the renal nerves (the direct pathway) in response to the actions of furosemide. Therefore, these results suggest that central angiotensin II is somehow involved in "priming" or increasing the sensitivity of the direct renal afferent pathway. Taken together with the accompanying paper, our results indicate that interruption of the direct pathway via renal denervation did not interfere with the elaboration of Fos in the lamina terminalis; in contrast, modification of the humoral renal afferent pathway can affect the sensitivity of the direct pathway. These results may have important implications for pathophysiological changes associated with fluid balance disorders including renal hypertension.

Afferent Pathways↗
PubMed2000

Bioelectrical impedance analysis is a useful bedside technique to assess malnutrition in cirrhotic patients with and without ascites.

Protein-calorie malnutrition is associated with poor prognosis in chronic liver disease, but reliable assessment is hampered by changes in body water. We prospectively evaluated the effect of fluid retention on bioelectrical impedance analysis (BIA) as a simple method for the estimation of body cell mass (BCM(BIA)) in 41 patients with cirrhosis (n = 20 with ascites; n = 21 without ascites) using total body potassium counting (BCM(TBP)) as a reference method. Arm muscle area and creatinine-derived lean body mass were compared with total body potassium data. In patients total body potassium was 24.4% lower than in controls and this loss was more severe in patients with ascites (-34.1%; P<.01). BCM(BIA) and BCM(TBP) were closely correlated in controls (r(2) =.87, P<.0001), patients without ascites (r(2) =.94, P <.0001) and patients with ascites (r(2) =.56, P<.0001). Removal of 6.2 +/- 3 L of ascites had only minor effects on BCM(BIA) (deviation of -0.18 kg/L ascites). Limits of agreement between both methods were wider in patients with ascites than in patients without (6.2 vs. 4.2 kg). In patients without ascites arm muscle area (r(2) =.64; P<.001) and lean body mass (r(2) =.55; P<.001) correlated significantly with total body potassium, but not in patients with ascites. For assessment of protein malnutrition in patients with cirrhosis, body cell mass determination by use of BIA offers a considerable advantage over other widely available but less accurate methods like anthropometry or the creatinine approach. Despite some limitations in patients with ascites, BIA is a reliable bedside tool for the determination of body cell mass in cirrhotic patients with and without ascites.

Adult↗
PubMed2000

Bovine herpesvirus 5 glycoprotein E is important for neuroinvasiveness and neurovirulence in the olfactory pathway of the rabbit.

Glycoprotein E (gE) is important for full virulence potential of the alphaherpesviruses in both natural and laboratory hosts. The gE sequence of the neurovirulent bovine herpesvirus 5 (BHV-5) was determined and compared with that of the nonneurovirulent BHV-1. Alignment of the predicted amino acid sequences of BHV-1 and BHV-5 gE open reading frames showed that they had 72% identity and 77% similarity. To determine the role of gE in the differential neuropathogenesis of BHV-1 and BHV-5, we have constructed BHV-1 and BHV-5 recombinants: gE-deleted BHV-5 (BHV-5gEDelta), BHV-5 expressing BHV-1 gE (BHV-5gE1), and BHV-1 expressing BHV-5 gE (BHV-1gE5). Neurovirulence properties of these recombinant viruses were analyzed using a rabbit seizure model (S. I. Chowdhury et al., J. Comp. Pathol. 117:295-310, 1997) that distinguished wild-type BHV-1 and -5 based on their differential neuropathogenesis. Intranasal inoculation of BHV-5 gEDelta and BHV-5gE1 produced significantly reduced neurological signs that affected only 10% of the infected rabbits. The recombinant BHV-1gE5 did not invade the central nervous system (CNS). Virus isolation and immunohistochemistry data suggest that these recombinants replicate and spread significantly less efficiently in the brain than BHV-5 gE revertant or wild-type BHV-5, which produced severe neurological signs in 70 to 80% rabbits. Taken together, the results of neurological signs, brain lesions, virus isolation, and immunohistochemistry indicate that BHV-5 gE is important for efficient neural spread and neurovirulence within the CNS and could not be replaced by BHV-1 gE. However, BHV-5 gE is not required for initial viral entry into olfactory pathway.

Alphaherpesvirinae↗
PubMed2000

Effects of midbrain and spinal cord transections on sympathetic nerve responses to heating.

In the present study, we investigated the contributions of forebrain, brain stem, and spinal neural circuits to heating-induced sympathetic nerve discharge (SND) responses in chloralose-anesthetized rats. Frequency characteristics of renal and splenic SND bursts and the level of activity in these nerves were determined in midbrain-transected (superior colliculus), spinal cord-transected [first cervical vertebra (C1)], and sham-transected (midbrain and spinal cord) rats during progressive increases in colonic temperature (T(c)) from 38 to 41.6-41.7 degrees C. The following observations were made. 1) Significant increases in renal and splenic SND were observed during hyperthermia in midbrain-transected, sham midbrain-transected, C1-transected, and sham C1-transected rats. 2) Heating changed the discharge pattern of renal and splenic SND bursts and was associated with prominent coupling between renal-splenic discharge bursts in midbrain-transected, sham midbrain-transected, and sham C1-transected rats. 3) The pattern of renal and splenic SND bursts remained unchanged from posttransection recovery levels during heating in C1-transected rats. We conclude that an intact forebrain is not required for the full expression of SND responses to increased T(c) and that spinal neural systems, in the absence of supraspinal circuits, are unable to markedly alter the frequency characteristics of SND in response to acute heat stress.

Animals↗